EQUIPMENT THAT COMPANY USES THE ELECTRICAL SYSTEM

Position lights - any of the lights mounted on a night-flying airplane to serve as a warning to other airplanes (as a red light on the port side, a green light on the starboard side, and a white light aft)

A position light signal is one where the position of the lights, rather than their colour, determines the meaning. The aspect consists solely of a pattern of illuminated lights, which are all of the same colour (typically a lemon yellow colour on mast signals with a frosted white on the dwarfs in U.S. service, colour having been added on the N&W, now Norfolk Southern's, position lights). In many countries, small position light signals are used as shunting signals, while the main signals are of colour light form. Also, many tramway systems (such as the Metro of Wolverhampton) use position light signals.

On the Pennsylvania Railroad (PRR) as on other railroads, initial efforts were made to replace the semaphore with illumination of the position of the blade rather than by colour lamps alone. Lamps with inverted half toric optic lenses, covered with a light yellow tinted conical cover glass with a frosted tip to avoid phantom indications were displayed in rows of three, corresponding to the positions of a semaphore blade. Multiple signal heads were used at interlockings for "Speed Signaling" purposes. The PRR chose to use their Superintendent of Signaling, A.H.Rudd's, in-house yet scientifically developed position light signals (as well as his "Speed Signaling" system of aspects and indications) to both replace the semaphores and their moving parts, also because the intense lemon yellow light provided superior visibility in adverse weather conditions such as rain or fog. The earliest installation of position lights used rows of four lamps in an offset fashion, much as with the upper right hand three position semaphore. The first installation of the four 5 volt, 10 watt lamp position light signals occurred on the Main Line between Philadelphia and Paoli, in conjunction with the 1915 electrification. These first signals differed from the later ones in that the lamps were mounted separately in front of a tombstone-shaped black painted metal backing. There were found issues with wind damage due to the rather larger "sail area" of the "tombstone backing." Soon thereafter, the lamps were reduced in number to three per row, without adversely affecting long range indication comprehension and the background as it is called correspondingly reduced in size and mounted as a disc. The lamp units and background on a mounting system known as a "spider," were integrated into a single unit.

Two-head colour position signal on CSXT mainline near Magnolia, West Virginia. The left head displays "Stop"; the right head, "Clear".Colour-position signals[edit]A system combining aspects of the colour and position systems was developed on the Baltimore and Ohio Railroad (B&O) in 1920 and was patented by L.F. Loree and F.P. Patenall. In effect, it is a "digital" semaphore. It was also applied to the Chicago and Alton Railroad when the latter was under B&O control. The colour position lights (CPLs) were first installed as a pilot on the Staten Island Railway in New York City, a former B&O subsidiary, later turned rapid transit line operated by the Metropolitan Transportation Authority. The B&O system used a central round head with pairs of lights providing 14 discrete indications with red only being used for stop. This was possibly superior to but definitely different from the speed signalling system of semaphore blade positions developed by A.H. Rudd and accepted as standard by the American Railway Association Signal Section in 1915 where multiple red aspects are most common. It used pairs of standard 8 3/8" doublet lens, colour-light units (green |, yellow /, red --). with a lunar white \ also being present in some installations.

Anti-collision lights - a flashing light fitted on the vertical fin and belly of an aircraft. It increases an aircraft's visibility to other aircraft in flight especially at night and in poor visibility conditions. The high-intensity light is visible 360 around the aircraft.All aircraft must have an approved anti-collision light and position light system for nighttime operations. The position lights consist of anAviation Red on the left side, an Aviation Green on the right and an Aviation White Taillight (REF. FAR 23.1389).The anti-collision lighting system is required under FAR PART 91.205(c). There are different requirements affecting different aircraft. Theseaircraft are categorized by the date of application for type certificate. Home built aircraft are determined by the date of issuance of theExperimental Operating Limitations. The different categories are as follows:Aircraft for which type certificate was applied for After April 1, 1957 to August 10, 1971:These anti-collision systems must produce a minimum of 100 effective candela in Aviation Red or White (REF. FAR 23.1397), 360 around theaircrafts vertical axis, 30 above and below the horizontal plane (REF. FAR 23.1401).Aircraft for which type certificate was applied for After August 11, 1971 to July 18, 1977:These anti-collision systems must produce a minimum of 400 effective candela in Aviation Red or White (REF. FAR 23.1397), 360 around theaircrafts vertical axis, 30 above and below the horizontal plane (REF. FAR 23.1401).Aircraft for which type certificate was applied for After July 18, 1977:These anti-collision systems must produce a minimum of 400 effective candela in Aviation Red or White (REF. FAR 23.1397), 360 around theaircrafts vertical axis, 75 above and below the horizontal plane (REF. FAR 23.1401).Note: The position lights must be wired independently of anti-collision lights.An approved anti-collision, strobe light system , must project light 360 , around the aircrafts vertical axis. One or more strobe lights can be used. An approved anti-collision strobe light system must project light + or - 30 above and below the horizontal plane of the aircraft.

One or more strobe lights can be used. The + or - 75 projected light is required sinceJuly 18, 1977. Wingtip: The major difference in systems is the location of the strobe power supplies which can be mounted locally, one in each wingtip, ora single power supply can be mounted in the fuselage. Installation time can be greatly reduced if done in conjunction with an annual or onehundred-hour inspection. Properly installed power supplies and cabling are necessary for the safe operation of Whelen or any light systems.Fuselage: Fuselage mounted units can be either self-contained with the power supply and lighthead as one unit, or remote lightheads run off a separate power supply. To meet the field of coverage, one must be on the top of the fuselage and one on the bottom.Vertical Fin: Finally, if applicable, a single anti-collision light can be mounted on the vertical stabilizer. It can be either a self-contained orremote lighthead depending on the aircraft.

VERTICAL FINOne anti-collision strobe light mountedon the vertical fin will meet theminimum requirements on most aircraft.A half red and half white lens isrecommended.WINGTIPTwo wingtip strobe lights that protrudebeyond the wingtip.ENCLOSED WINGTIPEnclosed wingtip anti-collision strobelights, require a third strobe light onthe tail or vertical fin, to fill in therequired light envelope. This is anapproved anti-collision system.FUSELAGEIn a fuselage mounted anti-collisionstrobe light system, a minimum oftwo strobe lights are necessary to getthe required vertical coverage. This isan approved anti-collision system

Taxi-lights - lights similar to landing lights on an aircraft aimed in such a way that they illuminate the runway or taxiway when the aircraft is taxiing. In some aircraft, landing lights have two positions: taxiing and landing. Taxi-lights are normally located under the wing or on the wing's leading edges. In some aircraft, they are located on the nose cowling or the strut.

Taxiway Edge Markings Used to define the edge of the taxiway when the edge does not correspond with the edge of the pavement.Continuous markings consist of a continuous double yellow line, with each line being at least 15 centimetres (6 in) in width, spaced 15 centimetres (6 in) apart. They divide the taxiway edge from the shoulder or some other abutting paved surface not intended for use by aircraft.Dashed markings define the edge of a taxiway on a paved surface where the adjoining pavement to the taxiway edge is intended for use by aircraft, e.g. an apron. These markings consist of a broken double yellow line, with each line being at least 15 centimetres (6 in) in width, spaced 15 centimetres (6 in) apart (edge to edge). These lines are 15 feet (4.6 m) in length with 25 foot (7.6 m) gaps.Taxi Shoulder Markings Taxiways, holding bays, and aprons are sometimes provided with paved shoulders to prevent blast and water erosion. Shoulders are not intended for use by aircraft, and may be unable to carry the aircraft load. Taxiway shoulder markings are yellow lines perpendicular to the taxiway edge, from taxiway edge to pavement edge, about 3 metres.Surface Painted Taxiway Direction Signs Yellow background with a black inscription, provided when it is not possible to provide taxiway direction signs at intersections, or when necessary to supplement such signs. These markings are located on either side of the taxiway.

Radio equipment - any equipment or interconnected system or subsystem of equipment (both transmission and reception) that is used to communicate over a distance by modulating and radiating electromagnetic waves in space without artificial guide. This does not include such items as microwave, satellite, or cellular telephone equipment.

It used to be that a wing wave or rapid tail deflection was all that was needed by the pilot of an aircraft to acknowledge a visual queue from a person on the ground. The evolution of electronic communications equipment is almost as dramatic as the evolution of the aircraft. In fact the radio age came about at almost the same time as the Wright Brothers took to the air. (Sorry but I could not resist the pun.)Traditional aircraft communications are based on analog voice on either a Very High Frequency (VHF) or High Frequency (HF) radio waves. In the mid 1980s the use of data-based communications became a reality. Airspace management is transcending into the computer age and as new requirements evolve and the choice of communications technologies expand, regulating the worlds air traffic flow can safely become more automated. Aircraft are currently being equipped with communications technologies that transport data via satellite plus while they are on the ground; mobile communication and in some cases broadband networks can receive or broadcast strategic information regarding aircraft situation and even maintenance trends. Aircraft communications are being expanded; in fact, in recent years a new abbreviation has surfaced. CNS ATM stands for Communication, Navigation, and Surveillance and Air Traffic Management which was created to support modernization of the dated and overload prone Air Traffic Control system. Aircraft that are intended to transport passengers are equipped with radios that enable analog voice communications. This is currently and will be for the foreseeable future the primary means for pilots to communicate withdifferent entities of the Air Traffic Control (ATC) system.ITU radio spectrum allocationsThe allocation of radio spectrum is defined by the International Telecommunications Union (ITU) and relates the use of a frequency to a specific service. In the case of civil aviation there are separate ITU allocations for communications, navigation, and surveillance. Such differentiation between functions corresponds to the safety requirements for Air Traffic Control. The ITU has assigned frequencies for use by aircraft analog voice dialogue in parts of the High Frequency (3-30 MHz) band and in the 118-137 MHz section of the wider Very High Frequency range. Aircraft can use radios operating in the HF radio band for long-range communications as the signals are reflected by the ionosphere. Unfortunately when using HF the link audio quality is very poor due to this long propagation of the wave. Aircraft can use radios operating in the VHF band to communicate with other radios in line-of-sight coverage. These signals do not reflect off the ionosphere or penetrate obstacles such as mountains or buildings. The advantage of VHF over HF is that the link quality is much better and there is greater reuse of the frequency channel. The use of the word analog in relation to voice radio communications means that the changes in the sound of the voice are converted by the transmitter into corresponding variations in the radio signal and converted back by the receiver.Turn Indicator - an instrument for indicating either the amount or the rate of turn of an airplane about its vertical axis - compare relative inclinometer.There are two types of turn indicators in aircraft. These are: the Turn and Bank Indicator (T/B) and the Turn Coordinator (T/C). Both are gyro driven and indicate the rate of turn but the turn coordinator can also indicate rate of roll. The T/B has a needle indicator where the T/C has an aircraft picture on the face of the instrument.Neither of these instrument give an direct indication of bank angle. For that you will need the speed of the aircraft and rate of turn to calculate the bank angle, or have an attitude indicator.Also note that these indicators are part of the basic six instruments in an aircraft the pilot needs for legal instrument flying. Nowadays you see more and more EFIS panels where the original T/C and T/B are used as standby and backup in case of failure.Turn indicators use a rate gyro (see image) to detect how fast the aircraft is changing direction. The T/B has a vertical needle and a slip ball; note that the Turn Coodinator has an aircraft picture. Both indicate a two minute turn, thus a 360 turn is completed in two minutes or put differently: three degrees/second (3/s, not that famous group) which is a rate one turn.Coordination Ball The coordination ball indicates the direction of the g-forces and its the pilots job to keep the ball centered by 'stepping on the ball' with the rudder. Thus: ball to the right -> apply right rudder or trim (and less left rudder) and vice versa.Rate gyro operation This gyro has only one plane of freedom where it can move (not the plane of rotation). The tilting of the vertical axis though the aircraft causes precession and this is used to indicate the rate of turn about that axis. The amount of tilt (linear with the rate of turn) is balanced against a restraining spring.Turn Coordinator T/B or T/C In a T/B the gyro is mounted in such a way that the rotation (or turn) axis is from wingtip to wingtip. In the T/C the turn axis gimbal is mounted on a 30 angle upward from the longitudinal axis of the aircraft, and this gives it the ability to sense rate of roll.Springs The springs used in the rate gyro give proper indication of rate of turn by being able to adjust the spring tension against the precession force of the gyro, without the springs the gyro would just bounce around. This is then indicated on the face place.Damping Due to air turbulence and aircraft movement by the pilot there will always be a force on the gyro causing precession and thus needle movement. To stabilize the indication the gyro has internal damping devices limiting these movements and presenting a stable indication.Mechanical stops The gimbal ring reaches a mechanical stop when the aircraft turns about 20/second. And with only one gimbal ring the gyro will not topple as with the attitude and heading gyro's.

Fuel gauge - an instrument used to indicate the level of fuel contained in a tank. Commonly used in most motor vehicles, these may also be used for any tank including underground storage tanks. As used in vehicles, the gauge consists of two parts: The sensing unit. The indicator.The sensing unit usually uses a float connected to a potentiometer, typically printed ink design in a modern automobile. As the tank empties, the float drops and slides a moving contact along the resistor, increasing its resistance.[2] In addition, when the resistance is at a certain point, it will also turn on a "low fuel" light on some vehicles.Meanwhile, the indicator unit (usually mounted on the dashboard) is measuring and displaying the amount of electrical current flowing through the sending unit. When the tank level is high and maximum current is flowing, the needle points to "F" indicating a full tank. When the tank is empty and the least current is flowing, the needle points to "E" indicating an empty tank.The system can be fail-safe. If an electrical fault opens, the electrical circuit causes the indicator to show the tank as being empty (theoretically provoking the driver to refill the tank) rather than full (which would allow the driver to run out of fuel with no prior notification). Corrosion or wear of the potentiometer will provide erroneous readings of fuel level. However, this system has a potential risk associated with it. An electric current is sent through the variable resistor to which a float is connected, so that the value of resistance depends on the fuel level. In most automotive fuel gauges such resistors are on the inward side of the gauge, i.e., inside the fuel tank. Sending current through such a resistor has a fire hazard and an explosion risk associated with it. These resistance sensors are also showing an increased failure rate with the incremental additions of alcohol in automotive gasoline fuel. Alcohol increases the corrosion rate at the potentiometer, as it is capable of carrying current like water. Potentiometer applications for alcohol fuel use a pulse-and-hold methodology, with a periodic signal being sent to determine fuel level decreasing the corrosion potential. Therefore, demand for another safer, non-contact method for fuel level is desired.Magnetoresistance type fuel level sensors, now becoming common in small aircraft applications, offer a potential alternative for automotive use. These fuel level sensors work similar to the potentiometer example, however a sealed detector at the float pivot determines the angular position of a magnet pair at the pivot end of the float arm. These are highly accurate, and the electronics are completely outside the fuel. The non-contact nature of these sensors address the fire and explosion hazard, and also the issues related to any fuel combinations or additives to gasoline or to any alcohol fuel mixtures. Magneto resistive sensors are suitable for all fuel or fluid combinations, including LPG and LNG. The fuel level output for these senders can be ratiometric voltage or preferable CAN bus digital. These sensors also fail-safe in that they either provide a level output or nothing.

Systems that measure large fuel tanks (including underground storage tanks) may use the same electro-mechanical principle or may make use of a pressure sensor, sometimes connected to a mercury manometer.Many large transport aircraft use a different fuel gauge design principle. An aircraft may use a number (around 30 on an A320) of low voltage tubular capacitor probes where the fuel becomes the dielectric. At different fuel levels, different values of capacitance are measured and therefore the level of fuel can be determined. In early designs, the profiles and values of individual probes were chosen to compensate for fuel tank shape and aircraft pitch and roll attitudes. In more modern aircraft, the probes tend to be linear (capacitance proportional to fuel height) and the fuel computer works out how much fuel there is (slightly different on different manufacturers). This has the advantage that a faulty probe may be identified and eliminated from the fuel calculations. In total this system can be more than 99% accurate. Since most commercial aircraft only take on board fuel necessary for the intended flight (with appropriate safety margins), the system allows the fuel load to be preselected, causing the fuel delivery to be shut off when the intended load has been taken on board.

Electric Fuel Pump - creates positive pressure in the fuel lines, pushing the gasoline to the engine. The higher gasoline pressure raises the boiling point. Placing the pump in the tank puts the component least likely to handle gasoline vapor well (the pump itself) farthest from the engine, submersed in cool liquid. Another benefit to placing the pump inside the tank is that it is less likely to start a fire. In many modern cars the fuel pump is usually electric and located inside the fuel tank. The pump creates positive pressure in the fuel lines, pushing the gasoline to the engine. The higher gasoline pressure raises the boiling point. Placing the pump in the tank puts the component least likely to handle gasoline vapor well (the pump itself) farthest from the engine, submersed in cool liquid. Another benefit to placing the pump inside the tank is that it is less likely to start a fire. Though electrical components (such as a fuel pump) can spark and ignite fuel vapors, liquid fuel will not explode (see flammability limit) and therefore submerging the pump in the tank is one of the safest places to put it. In most cars, the fuel pump delivers a constant flow of gasoline to the engine; fuel not used is returned to the tank. This further reduces the chance of the fuel boiling, since it is never kept close to the hot engine for too long.The ignition switch does not carry the power to the fuel pump; instead, it activates a relay which will handle the higher current load. It is common for the fuel pump relay to become oxidized and cease functioning; this is much more common than the actual fuel pump failing. Modern engines utilize solid-state control which allows the fuel pressure to be controlled via pulse-width modulation of the pump voltage. This increases the life of the pump, allows a smaller and lighter device to be used, and reduces electrical load.Cars with electronic fuel injection have an electronic control unit (ECU) and this may be programmed with safety logic that will shut the electric fuel pump off, even if the engine is running. In the event of a collision this will prevent fuel leaking from any ruptured fuel line. Additionally, cars may have an inertia switch (usually located underneath the front passenger seat) that is "tripped" in the event of an impact, or a roll-over valve that will shut off the fuel pump in case the car rolls over.Some ECUs may also be programmed to shut off the fuel pump if they detect low or zero oil pressure, for instance if the engine has suffered a terminal failure (with the subsequent risk of fire in the engine compartment).The fuel sending unit assembly may be a combination of the electric fuel pump, the filter, the strainer, and the electronic device used to measure the amount of fuel in the tank via a float attached to a sensor which sends data to the dash-mounted fuel gauge. The fuel pump by itself is a relatively inexpensive part. But a mechanic at a garage might have a preference to install the entire unit assembly.

Stall warning system - An aircraft Stall Warning System is that system which provides the pilot with advance warning of an impending stall.An aircraft Stall Warning System is that system which provides the pilot with advance warning of an impending stall.Regulatory Requirement As is the case with most safety related equipment, the requirement for a Stall Warning System will be found within the aviation regulations for the State of Manufacture and the State of the Operator for any given aircraft. The required operational parameters of the Stall Warning System on a particular aircraft will, in part, be dependent upon the aircraft weight, capacity and purpose and the regulations under which the aircraft Type Certificate was issued.The regulations concerning a Stall Warning System for aircraft other than Transport Category Aircraft include the following requirements:There must be a clear and distinctive stall warning, in both straight and turning flight, with the flaps and landing gear in any normal positionThe stall warning may be furnished through the inherent aerodynamic qualities of the aircraft or by a device that will give clear, unambiguous indications under the expected conditions of flight. A visual stall warning device requiring the attention of the crew within the cockpit is not acceptable by itselfDuring a wings level, decelerating condition in any normal configuration, the stall warning must begin at a speed which is a minimum of 5 knots greater than stalling speed (Vs) and continue until the stall occursDuring a turn or in the case of a turning accelerated stall, the stall warning must begin sufficiently in advance of the stall to allow the stall to be averted if the pilot takes appropriate actionThe regulatory requirements for a Transport Category Aircraft are somewhat more robust and the regulations themselves are more prescriptive. As examples:When the speed is reduced at rates not exceeding one knot per second, the stall warning, in each normal configuration, must begin at a speed (Vsw) which exceeds the stall speed by not less than five knots or by five percent of the calibrated airspeed, whichever is greater. Once initiated, the stall warning must continue until the angle of attack is reduced to approximately that at which the stall warning beganDuring decelerating turns, with a load factor of at least 1.5g and airspeed reductions of at least two knots per second with flaps and gear in any normal position, the stall warning margin must be sufficient to allow the pilot to prevent stalling when the recovery is initiated not less than one second after the onset of the stall warningStall warning must be provided in each abnormal configuration of the high lift devices that is likely to be used in the event of a system failure inclusive of all configurations addressed by AFM proceduresWarning Systems As per the regulations, the stall warning system requirements can be satisfied by the inherent stall characteristics of the aircraft itself or by other appropriate means. Some of the most common stall warning systems are as follows:Pre-Stall Buffet. In this case, the warning of the impending stall is provided solely by aerodynamic buffet. As the aircraft approaches the stall, the airflow across the upper cambered surface of the wing ceases to flow smoothly, it looses contact with the wing surface and it becomes turbulent. If the turbulent air then flows across the horizontal stabiliser, buffet results. In many aircraft, even some as large as the AC-130 Spectre, this buffet provides the sole warning of the impending stall.Audible Warning. Stall warning is provided by an electronic or mechanical device that sounds an audible warning as the stall speed is approached. The simplest such device is an airframe mounted stall warning horn which sounds when the airflow through it occurs at a specific angle. Slightly more sophisticated audible warning devices consist of either a pressure sensor or a moveable metal tab that actuates a switch as the stall is approached. The switch, in turn, activates an audible warning horn. In some installations, the audible warning is provided by a synthetic voice which helps to reduce warning ambiguity.Stick Shaker. A stick shaker is a mechanical device that shakes the control column to warn of the onset of stall. A stick pusher may be installed in association with a stick shaker system in aircraft which are susceptible to the deep stall phenomenon. A deep stall affects certain aircraft designs, most notably those with a T-tail configuration, and results in a substantial reduction or loss of elevator authority making normal stall recovery actions ineffective; in many cases, a deep stall might be unrecoverable. The stick pusher is designed to prevent the pilot from allowing the aircraft to enter a stallAngle of Attack. Stall warning systems often involve inputs from a broad range of sensors and systems and include a dedicated angle of attack sensor. At a predetermined angle of attack, calculated for each possible configuration, the angle of attack sensor triggers the activation of the stick shaker or the audible warning device as appropriate to the aircraft fitment. An angle of attack indicator may or may not be incorporated into the pilot's instrument panel. When installed, the indicator will give a visual indication of the aircraft proximity to the critical angle of attack.

Icing Stall warning systems are designed to activate based on the stall characteristics of clean, contamination free surfaces. Airframe contamination can occur both on the ground and during flight. Contamination present whilst still on the ground must be removed by a ground deicing process prior to flight. Should icing conditions be encountered during flight, Ice Protection Systems should be activated. An ice-affected wing will almost certainly stall at a lower angle of attack. Stall warning margins are almost always significantly reduced and the pilot will frequently receive no notice of the impending stall.Mach Number EffectAs altitude increases and air density decreases, the gap between IAS and TAS increases, until the TAS becomes a significant proportion of the speed of sound. Eventually the airspeed over the upper surface exceeds the local speed of sound, and shock waves form toward the trailing edge. These shocks will eventually cause a high speed buffet but only at Mach numbers well above Mmo. Shock waves can also form near the leading edge at a high angle of incidence and high altitude and these will progressively limit the achievable incidence, so the stalling speed, IAS, will increase. Therefore, if buffet occurs at high altitude it could be due to either under or over-speed, the clue is the angle of incidence - lower than normal cruise incidence = high speed buffet, higher than normal cruise incidence = low speed buffet (but at an IAS rather larger than normal low speed stall occurs). It follows that pilots must be aware of their normal operating conditions in order to correctly diagnose any anomaly. Note that while some modern aircraft have stall-warning systems that adjust for Mach number, others do not and a stall as just described can occur without an accompanying stall warning

Starting Motor- is an electric motor, pneumatic motor, hydraulic motor, an internal-combustion engine in case of very large engines or other device used for rotating an internal-combustion engine so as to initiate the engine's operation under its own power.Before the advent of the starter motor, engines were started by various methods including wind-up springs, gunpowder cylinders, and human-powered techniques such as a removable crank handle which engaged the front of the crankshaft, pulling on an airplane propeller, or pulling a cord that was wound around an open-face pulley.Originally, a hand-crank was used to start engines, but it was inconvenient, difficult, and dangerous. The behavior of an engine during starting is not always predictable. The engine can kick back, causing sudden reverse rotation. Many manual starters included a one-directional slip or release provision so that once engine rotation began, the starter would disengage from the engine. In the event of a kickback, the reverse rotation of the engine could suddenly engage the starter, causing the crank to unexpectedly and violently jerk, possibly injuring the operator. For cord-wound starters, a kickback could pull the operator towards the engine or machine, or swing the starter cord and handle at high speed around the starter pulley. Even though cranks had an overrun mechanism, when the engine started, the crank could begin to spin along with the crankshaft and potentially strike the person cranking the engine. Additionally, care had to be taken to retard the spark in order to prevent backfiring; with an advanced spark setting, the engine could kick back (run in reverse), pulling the crank with it, because the overrun safety mechanism works in one direction only.Although users were advised to cup their fingers and thumb under the crank and pull up, it felt natural for operators to grasp the handle with the fingers on one side, the thumb on the other. Even a simple backfire could result in a broken thumb; it was possible to end up with a broken wrist, or worse. Moreover, increasingly larger engines with higher compression ratios made hand cranking a more physically demanding endeavour.The first electric starter was installed on an Arnold, an adaptation of the Benz Velo, built 1896 in East Peckham, England by electrical engineer H. J. Dowsing.[1]In 1911, Charles F. Kettering, with Henry M. Leland, of Dayton Engineering Laboratories Company (DELCO) invented and filed U.S. Patent 1,150,523 for the first electric starter in America. (Kettering had replaced the hand crank on NCR's cash registers with an electric motor five years earlier.)One aspect of the invention lay in the realization that a relatively small motor, driven with higher voltage and current than would be feasible for continuous operation, could deliver enough power to crank the engine for starting. At the voltage and current levels required, such a motor would burn out in a few minutes of continuous operation, but not during the few seconds needed to start the engine. The starters were first installed by Cadillac on production models in 1912, with the same system being adopted by Lanchester later that year.[2] These starters also worked as generators once the engine was running, a concept that is now being revived in hybrid vehicles.

Although the electric starter motor was to come to dominate the car market, in 1912 there were several competing types of starter,[2] with the Adams, S.C.A.T. and Wolseley cars having direct air starters, and Sunbeam introducing an air starter motor with similar approach to that used for the Delco and Scott-Crossley electrical starter motors (i.e. engaging with a toothed ring on the flywheel). The Star and Adler cars had spring motors (sometimes referred to as clockwork motors), which used the energy stored in a spring driving through a reduction gear. If the car failed to start the starter handle could be used to wind up the spring for a further attempt.The Ford Model T relied on hand cranks until 1919; by 1920 most manufacturers included self-starters, thus ensuring that anyone, regardless of strength or physical handicap, could easily start a car with an internal combustion engine. It was still common for cars to be supplied with starter handles into the 1960s, and this continued much later for some makes (e.g. Citron 2CV until end of production in 1990).Before Chrysler's 1949 innovation of the key-operated combination ignition-starter switch,[3] the starter was often operated by the driver pressing a button mounted on the floor or dashboard. Some vehicles had a pedal in the floor that manually engaged the starter drive pinion with the flywheel ring gear, then completed the electrical circuit to the starter motor once the pedal reached the end of its travel. Ferguson tractors from the 1940s, including the Ferguson TE20, had an extra position on the gear lever that engaged the starter switch, ensuring safety by preventing the tractors from being started in gear.[4]The electric starter motor or starting motor is the most common type used on gasoline engines and small Diesel engines. The modern starter motor is either a permanent-magnet or a series-parallel wound direct current electric motor with a starter solenoid (similar to a relay) mounted on it. When current from the starting battery is applied to the solenoid, usually through a key-operated switch, the solenoid engages a lever that pushes out the drive pinion on the starter driveshaft and meshes the pinion with the starter ring gear on the flywheel of the engine.

The solenoid also closes high-current contacts for the starter motor, which begins to turn. Once the engine starts, the key-operated switch is opened, a spring in the solenoid assembly pulls the pinion gear away from the ring gear, and the starter motor stops. The starter's pinion is clutched to its drive shaft through an overrunning sprag clutch which permits the pinion to transmit drive in only one direction. In this manner, drive is transmitted through the pinion to the flywheel ring gear, but if the pinion remains engaged (as for example because the operator fails to release the key as soon as the engine starts, or if there is a short and the solenoid remains engaged), the pinion will spin independently of its drive shaft. This prevents the engine driving the starter, for such backdrive would cause the starter to spin so fast as to fly apart.

However, this sprag clutch arrangement would preclude the use of the starter as a generator if employed in hybrid scheme mentioned above, unless modifications were made. Also, a standard starter motor is only designed for intermittent use which would preclude its use as a generator; the electrical components are designed only to operate for typically under 30 seconds before overheating (by too-slow dissipation of heat from ohmic losses), to save weight and cost. This is the same reason why most automobile owner's manuals instruct the operator to pause for at least ten seconds after each ten or fifteen seconds of cranking the engine, when trying to start an engine that does not start immediately.This overrunning-clutch pinion arrangement was phased into use beginning in the early 1960s; before that time, a Bendix drive was used. The Bendix system places the starter drive pinion on a helically cut drive shaft. When the starter motor begins turning, the inertia of the drive pinion assembly causes it to ride forward on the helix and thus engage with the ring gear. When the engine starts, backdrive from the ring gear causes the drive pinion to exceed the rotative speed of the starter, at which point the drive pinion is forced back down the helical shaft and thus out of mesh with the ring gear.[5]Hear a Folo-Thru starterMENU0:00A starter motor with Bendix Folo-Thru drive cranks a Chrysler Slant-6 engine. The Folo-Thru drive pinion stays engaged through a cylinder firing but not causing the engine to startProblems playing this file? See media help.An intermediate development between the Bendix drive developed in the 1930s and the overrunning-clutch designs introduced in the 1960s was the Bendix Folo-Thru drive. The standard Bendix drive would disengage from the ring gear as soon as the engine fired, even if it did not continue to run. The Folo-Thru drive contains a latching mechanism and a set of flyweights in the body of the drive unit. When the starter motor begins turning and the drive unit is forced forward on the helical shaft by inertia, it is latched into the engaged position. Only once the drive unit is spun at a speed higher than that attained by the starter motor itself (i.e., it is backdriven by the running engine) will the flyweights pull radially outward, releasing the latch and permitting the overdriven drive unit to be spun out of engagement. In this manner, unwanted starter disengagement is avoided before a successful engine start.

Hear a gear-reduction starterMENU0:00A Chrysler gear-reduction starter cranks a V8 engineProblems playing this file? See media help.Chrysler Corporation contributed materially to the modern development of the starter motor. In 1962, Chrysler introduced a starter incorporating a geartrain between the motor and the drive shaft. Rolls Royce had introduced a conceptually similar starter in 1946,[citation needed] but Chrysler's was the first volume-production unit. The motor shaft has integrally cut gear teeth forming a pinion which meshes with a larger adjacent driven gear to provide a gear reduction ratio of 3.75:1. This permits the use of a higher-speed, lower-current, lighter and more compact motor assembly while increasing cranking torque.[6] Variants of this starter design were used on most rear- and four-wheel-drive vehicles produced by Chrysler Corporation from 1962 through 1987. It makes a unique, distinct sound when cranking the engine, which led to it being nicknamed the "Highland Park Hummingbird"a reference to Chrysler's headquarters in Highland Park, Michigan.[7]The Chrysler gear-reduction starter formed the conceptual basis for the gear-reduction starters that now predominate in vehicles on the road. Many Japanese automakers phased in gear reduction starters in the 1970s and 1980s.[citation needed] Light aircraft engines also made extensive use of this kind of starter, because its light weight offered an advantage.Those starters not employing offset gear trains like the Chrysler unit generally employ planetary epicyclic gear trains instead. Direct-drive starters are almost entirely obsolete owing to their larger size, heavier weight and higher current requirements.[citation needed]Movable pole shoeFord also issued a nonstandard starter, a direct-drive "movable pole shoe" design that provided cost reduction rather than electrical or mechanical benefits. This type of starter eliminated the solenoid, replacing it with a movable pole shoe and a separate starter relay. This starter operates as follows: The driver turns the key, activating the starter switch. A small electric current flows through the solenoid actuated starter relay, closing the contacts and sending large battery current to the starter motor. One of the pole shoes, hinged at the front, linked to the starter drive, and spring-loaded away from its normal operating position, is swung into position by the magnetic field created by electricity flowing through its field coil. This moves the starter drive forward to engage the flywheel ring gear, and simultaneously closes a pair of contacts supplying current to the rest of the starter motor winding. Once the engine starts and the driver releases the starter switch, a spring retracts the pole shoe, which pulls the starter drive out of engagement with the ring gear.

This starter was used on Ford vehicles from 1973 through 1990, when a gear-reduction unit conceptually similar to the Chrysler unit replaced it.Inertia starterA variant on the electric starter motor is the inertia starter (not to be confused with the Bendix-type starter described above). Here the starter motor does not turn the engine directly. Instead, when energized, the motor turns a heavy flywheel built into its casing (not the main flywheel of the engine). Once the flywheel/motor unit has reached a constant speed the current to the motor is turned off and the drive between the motor and flywheel is disengaged by a freewheel mechanism. The spinning flywheel is then connected to the main engine and its inertia turns it over to start it. These stages are commonly automated by solenoid switches, with the machine operator using a two-position control switch, which is held in one position to spin the motor and then moved to the other to cut the current to the motor and engage the flywheel to the engine.The advantage of the inertia starter is that, because the motor is not driving the engine directly, it can be of much lower power than the standard starter for an engine of the same size. This allows for a motor of much lower weight and smaller size, as well as lighter cables and smaller batteries to power the motor. This made the inertia starter a common choice for aircraft with large radial piston engines. The disadvantage is the increased time required to start the engine - spinning up the flywheel to the required speed can take between 10 and 20 seconds. If the engine does not start by the time the flywheel has lost its inertia then the process must be repeated for the next attempt.Other usesStarter motors have extremely high torque and can in nearly all cases move the vehicle unaided when required. If a vehicle is stranded in a dangerous place, e.g. a railway level crossing and the engine will not fire, the car can be put into gear and driven to a place of safety by cranking the engine on the starter. Most modern vehicles have a clutch interlock which prevents this. There are also issues concerning some automatic transmission systems. Use of the starter in this way is not recommended except in emergencies.PneumaticSome gas turbine engines and Diesel engines, particularly on trucks, use a pneumatic self-starter. In ground vehicles the system consists of a geared turbine, an air compressor and a pressure tank. Compressed air released from the tank is used to spin the turbine, and through a set of reduction gears, engages the ring gear on the flywheel, much like an electric starter. The engine, once running, drives the compressor to recharge the tank.

Aircraft with large gas turbine engines are typically started using a large volume of low-pressure compressed air, supplied from a very small engine referred to as an auxiliary power unit, located elsewhere in the aircraft. Alternately, aircraft gas turbine engines can be rapidly started using a mobile ground-based pneumatic starting engine, referred to as a start cart or air start cart.

On larger diesel generators found in large shore installations and especially on ships, a pneumatic starting gear is used. The air motor is normally powered by compressed air at pressures of 1030 bar. The air motor is made up of a center drum about the size of a soup can with four or more slots cut into it to allow for the vanes to be placed radially on the drum to form chambers around the drum. The drum is offset inside a round casing so that the inlet air for starting is admitted at the area where the drum and vanes form a small chamber compared to the others. The compressed air can only expand by rotating the drum, which allows the small chamber to become larger and puts another one of the cambers in the air inlet. The air motor spins much too fast to be used directly on the flywheel of the engine; instead a large gearing reduction, such as a planetary gear, is used to lower the output speed. A Bendix gear is used to engage the flywheel.

Large Diesel generators and almost all Diesel engines used as the prime mover of ships use compressed air acting directly on the cylinder head. This is not ideal for smaller Diesels, as it provides too much cooling on starting. Also, the cylinder head needs to have enough space to support an extra valve for the air start system. The air start system is conceptually very similar to a distributor in a car. There is an air distributor that is geared to the camshaft of the Diesel engine; on the top of the air distributor is a single lobe similar to what is found on a camshaft. Arranged radially around this lobe are roller tip followers for every cylinder. When the lobe of the air distributor hits one of the followers it will send an air signal that acts upon the back of the air start valve located in the cylinder head, causing it to open. Compressed air is provided from a large reservoir that feeds into a header located along the engine. As soon as the air start valve is opened, the compressed air is admitted and the engine will begin turning. It can be used on 2-cycle and 4-cycle engines and on reversing engines. On large 2-stroke engines less than one revolution of the crankshaft is needed for starting.

Since large trucks typically use air brakes, the system does double duty, supplying compressed air to the brake system. Pneumatic starters have the advantages of delivering high torque, mechanical simplicity and reliability. They eliminate the need for oversized, heavy storage batteries in prime mover electrical systems.

Basic airplane electric system & components

Alternator - an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature. Alternating current generating systems were known in simple forms from the discovery of the magnetic induction of electric current in the 1830s. The early machines were developed by pioneers such as Michael Faraday and Hippolyte Pixii.Faraday developed the "rotating rectangle", whose operation was heteropolar - each active conductor passed successively through regions where the magnetic field was in opposite directions.[4] William Stanley, Jr. demonstrated the first practical system for providing electric illumination with the use of alternating current in 1886.[5] Both DC generators and the "alternator system" were used from the 1870s on.[6] Large two-phase alternating current generators were built by a British electrician, J.E.H. Gordon, in 1882. Lord Kelvin and Sebastian Ferranti also developed early alternators, producing frequencies between 100 and 300 Hz. In 1891, Nikola Tesla patented a practical "high-frequency" alternator (which operated around 15 kHz).[7] After 1891, polyphase alternators were introduced to supply currents of multiple differing phases.[8] Later alternators were designed for varying alternating-current frequencies between sixteen and about one hundred hertz, for use with arc lighting, incandescent lighting A conductor moving relative to a magnetic field develops an electromotive force (EMF) in it, (Faraday's Law). This emf reverses its polarity when it moves under magnetic poles of opposite polarity. Typically, a rotating magnet, called the rotor turns within a stationary set of conductors wound in coils on an iron core, called the stator. The field cuts across the conductors, generating an induced EMF (electromotive force), as the mechanical input causes the rotor to turn.The rotating magnetic field induces an AC voltage in the stator windings. Since the currents in the stator windings vary in step with the position of the rotor, an alternator is a synchronous generator.The rotor's magnetic field may be produced by permanent magnets, or by a field coil electromagnet. Automotive alternators use a rotor winding which allows control of the alternator's generated voltage by varying the current in the rotor field winding. Permanent magnet machines avoid the loss due to magnetizing current in the rotor, but are restricted in size, due to the cost of the magnet material. Since the permanent magnet field is constant, the terminal voltage varies directly with the speed of the generator. Brushless AC generators are usually larger machines than those used in automotive applications.An automatic voltage control device controls the field current to keep output voltage constant. If the output voltage from the stationary armature coils drops due to an increase in demand, more current is fed into the rotating field coils through the voltage regulator (VR). This increases the magnetic field around the field coils which induces a greater voltage in the armature coils. Thus, the output voltage is brought back up to its original value.

Alternators used in central power stations also control the field current to regulate reactive power and to help stabilize the power system against the effects of momentary faults. Often there are three sets of stator windings, physically offset so that the rotating magnetic field produces a three phase current, displaced by one-third of a period with respect to each other. and electric motors.By excitation- There are two main ways to produce the magnetic field used in the alternators, by using permanent magnets which create their own persistent magnetic field or by using field coils. The alternators that use permanent magnets are specifically called magnetos. In other alternators, wound field coils form an electromagnet to produce the rotating magnetic field. All devices that use permanent magnets and produce alternating current are called PMA or permanent magnet alternator. A "permanent magnet generator" (PMG) may produce either alternating current, or direct current if it has a commutator. If the permanent magnet device makes only AC current, it is correctly called a PMA.

Direct connected DC generator- This method of excitation consists of a smaller direct-current (DC) generator fixed on the same shaft with the alternator. The DC generator generates a small amount of electricity just enough to excite the field coils of the connected alternator to generate electricity. A variation of this system is a type of alternator which uses direct current from the battery for excitation, after which the alternator is self-excited.

Transformation and rectification- This method depends on residual magnetism retained in the iron core to generate weak magnetic field which would allow weak voltage to be generated. The voltage is used to excite the field coils for the alternator to generate stronger voltage as part of its build up process. After the initial AC voltage buildup, the field is supplied with rectified voltage from the alternator.

Brushless alternators- A brushless alternator is composed of two alternators built end-to-end on one shaft. Smaller brushless alternators may look like one unit but the two parts are readily identifiable on the large versions. The larger of the two sections is the main alternator and the smaller one is the exciter. The exciter has stationary field coils and a rotating armature (power coils). The main alternator uses the opposite configuration with a rotating field and stationary armature. A bridge rectifier, called the rotating rectifier assembly, is mounted on the rotor. Neither brushes nor slip rings are used, which reduces the number of wearing parts. The main alternator has a rotating field as described above and a stationary armature (power generation windings).

Varying the amount of current through the stationary exciter field coils varies the 3-phase output from the exciter. This output is rectified by a rotating rectifier assembly, mounted on the rotor, and the resultant DC supplies the rotating field of the main alternator and hence alternator output. The result of all this is that a small DC exciter current indirectly controls the output of the main alternator.

By number of phases- Main articles: Single-phase generator and Polyphase coil Another way to classify alternators is by the number of phases of their output voltage. The output can be single phase, or polyphase. Three-phase alternators are the most common, but polyphase alternators can be two phase, six phase, or more.

By rotating part- The revolving part of alternators can be the armature or the magnetic field. The revolving armature type has the armature wound on the rotor, where the winding moves through a stationary magnetic field. The revolving armature type is not often used. The revolving field type has magnetic field on the rotor to rotate through a stationary armature winding. The advantage is that then the rotor circuit carries much less power than the armature circuit, making the slip ring connections smaller and less costly; only two contacts are needed for the direct-current rotor, whereas often a rotor winding has three phases and multiple sections which would each require a slip ring connection. The stationary armature can be wound for any convenient medium voltage level, up to tens of thousands of volts; manufacture of slip ring connections for more than a few thousand volts is costly and inconvenient.Alternators are used in modern automobiles to charge the battery and to power the electrical system when its engine is running.Until the 1960s, automobiles used DC dynamo generators with commutators. With the availability of affordable silicon diode rectifiers, alternators were used instead.Diesel electric locomotive alternatorsIn later diesel electric locomotives and diesel electric multiple units, the prime mover turns an alternator which provides electricity for the traction motors (ac or dc).The traction alternator usually incorporates integral silicon diode rectifiers to provide the traction motors with up to 1200 volts dc (dc traction, which is used directly) or the common inverter bus (ac traction, which is first inverted from dc to three-phase ac).The first diesel electric locomotives, and many of those still in service, use DC generators as, before silicon power electronics, it was easier to control the speed of DC traction motors. Most of these had two generators: one to generate the excitation current for a larger main generator.

Optionally, the generator also supplies head end power (HEP) or power for electric train heating. The HEP option requires a constant engine speed, 900 rpm for a 480 volt 60 Hz HEP application, even when the locomotive is not moving.

Marine alternators- Marine alternators used in yachts are similar to automotive alternators, with appropriate adaptations to the salt-water environment. Marine alternators are designed to be explosion proof so that brush sparking will not ignite explosive gas mixtures in an engine room environment. They may be 12 or 24 volt depending on the type of system installed. Larger marine diesels may have two or more alternators to cope with the heavy electrical demand of a modern yacht. On single alternator circuits, the power is split between the engine starting battery and the domestic or house battery (or batteries) by use of a split-charge diode (battery isolator) or a mechanical switch. Because the alternator only produces power when running, engine control panels are typically fed directly from the alternator by means of an auxiliary terminal. Other typical connections are for charge control circuits.

Radio alternators- High frequency alternators of the variable-reluctance type were applied commercially to radio transmission in the low-frequency radio bands. These were used for transmission of Morse code and, experimentally, for transmission of voice and music. In the Alexanderson alternator, both the field winding and armature winding are stationary, and current is induced in the armature by virtue of the changing magnetic reluctance of the rotor (which has no windings or current carrying parts). Such machines were made to produce radio frequency current for radio transmissions, although the efficiency was low..

Battery - a device that is placed inside a machine (such as a clock, toy, or car) to supply it with electricity.The usage of "battery" to describe a group of electrical devices dates to Benjamin Franklin, who in 1748 described multiple Leyden jars by analogy to a battery of cannon[3] (Benjamin Franklin borrowed the term "battery" from the military, which refers to weapons functioning together.Alessandro Volta described the first electrochemical battery, the voltaic pile in 1800.[5] This was a stack of copper and zinc plates, separated by brine soaked paper disks, that could produce a steady current for a considerable length of time. Volta did not appreciate that the voltage was due to chemical reactions. He thought that his cells were an inexhaustible source of energy,[6] and that the associated corrosion effects at the electrodes were a mere nuisance, rather than an unavoidable consequence of their operation, as Michael Faraday showed in 1834.Although early batteries were of great value for experimental purposes, in practice their voltages fluctuated and they could not provide a large current for a sustained period. The Daniell cell, invented in 1836 by British chemist John Frederic Daniell, was the first practical source of electricity, becoming an industry standard and seeing widespread adoption as a power source for electrical telegraph networks.[8] It consisted of a copper pot filled with a copper sulfate solution, in which was immersed an unglazed earthenware container filled with sulfuric acid and a zinc electrode.These wet cells used liquid electrolytes, which were prone to leakage and spillage if not handled correctly. Many used glass jars to hold their components, which made them fragile. These characteristics made wet cells unsuitable for portable appliances. Near the end of the nineteenth century, the invention of dry cell batteries, which replaced the liquid electrolyte with a paste, made portable electrical devices practical. Batteries convert chemical energy directly to electrical energy. A battery consists of some number of voltaic cells. Each cell consists of two half-cells connected in series by a conductive electrolyte containing anions and cations. One half-cell includes electrolyte and the negative electrode, the electrode to which anions (negatively charged ions) migrate; the other half-cell includes electrolyte and the positive electrode to which cations (positively charged ions) migrate. Redox reactions power the battery. Cations are reduced (electrons are added) at the cathode during charging, while anions are oxidized (electrons are removed) at the anode during discharge.[11] The electrodes do not touch each other, but are electrically connected by the electrolyte. Some cells use different electrolytes for each half-cell. A separator allows ions to flow between half-cells, but prevents mixing of the electrolytes.

Each half-cell has an electromotive force (or emf), determined by its ability to drive electric current from the interior to the exterior of the cell. The net emf of the cell is the difference between the emfs of its half-cells.[12] Thus, if the electrodes have emfs \mathcal{E}_1 and \mathcal{E}_2, then the net emf is \mathcal{E}_{2}-\mathcal{E}_{1}; in other words, the net emf is the difference between the reduction potentials of the half-reactions.The electrical driving force or \displaystyle{\Delta V_{bat}} across the terminals of a cell is known as the terminal voltage (difference) and is measured in volts.[14] The terminal voltage of a cell that is neither charging nor discharging is called the open-circuit voltage and equals the emf of the cell. Because of internal resistance,[15] the terminal voltage of a cell that is discharging is smaller in magnitude than the open-circuit voltage and the terminal voltage of a cell that is charging exceeds the open-circuit voltage.An ideal cell has negligible internal resistance, so it would maintain a constant terminal voltage of \mathcal{E} until exhausted, then dropping to zero. If such a cell maintained 1.5 volts and stored a charge of one coulomb then on complete discharge it would perform 1.5 joules of work.[14] In actual cells, the internal resistance increases under discharge[15] and the open circuit voltage also decreases under discharge. If the voltage and resistance are plotted against time, the resulting graphs typically are a curve; the shape of the curve varies according to the chemistry and internal arrangement employed.The voltage developed across a cell's terminals depends on the energy release of the chemical reactions of its electrodes and electrolyte. Alkaline and zinccarbon cells have different chemistries, but approximately the same emf of 1.5 volts; likewise NiCd and NiMH cells have different chemistries, but approximately the same emf of 1.2 volts. The high electrochemical potential changes in the reactions of lithium compounds give lithium cells emfs of 3 volts or more.Primary batteriesMain article: Primary cellPrimary batteries, or primary cells, can produce current immediately on assembly. These are most commonly used in portable devices that have low current drain, are used only intermittently, or are used well away from an alternative power source, such as in alarm and communication circuits where other electric power is only intermittently available. Disposable primary cells cannot be reliably recharged, since the chemical reactions are not easily reversible and active materials may not return to their original forms. Battery manufacturers recommend against attempting to recharge primary cells.In general, these have higher energy densities than rechargeable batteries,[23] but disposable batteries do not fare well under high-drain applications with loads under 75 ohms (75 ). Common types of disposable batteries include zinccarbon batteries and alkaline batteries.

Secondary batteriesMain article: Rechargeable batterySecondary batteries, also known as secondary cells, or rechargeable batteries, must be charged before first use; they are usually assembled with active materials in the discharged state. Rechargeable batteries are (re)charged by applying electric current, which reverses the chemical reactions that occur during discharge/use. Devices to supply the appropriate current are called chargers. The oldest form of rechargeable battery is the leadacid battery. This technology contains liquid electrolyte in an unsealed container, requiring that the battery be kept upright and the area be well ventilated to ensure safe dispersal of the hydrogen gas it produces during overcharging. The leadacid battery is relatively heavy for the amount of electrical energy it can supply. Its low manufacturing cost and its high surge current levels make it common where its capacity (over approximately 10 Ah) is more important than weight and handling issues. A common application is the modern car battery, which can, in general, deliver a peak current of 450 amperes.

Master Switch - Most often actually two separate switches, the Battery Master and the Alternator Master. The Battery Master activates a relay (sometimes called the battery contactor) which connects the battery to the aircraft's main electrical bus.Master Switch - Most often actually two separate switches, the Battery Master and the Alternator Master. The Battery Master activates a relay (sometimes called the battery contactor) which connects the battery to the aircraft's main electrical bus. The alternator master activates the alternator by applying power to the alternator field circuit. These two switches provide electrical power to all the systems in the aircraft.Throttle - Sets the desired power level. The throttle controls the mass flow-rate of air (in fuel-injected engines) or air/fuel mixture (in carburetted engines) delivered to the cylinders.Propeller Control - Adjusts the Constant Speed Unit, which in turn adjusts the propeller pitch and regulates the engine load as necessary to maintain the set R.P.M.Mixture Control - Sets the amount of fuel added to the intake airflow. At higher altitudes, the air pressure (and therefore the oxygen level) declines so the fuel volume must also be reduced to give the correct air/fuel mixture. This process is known as "leaning".Ignition Switch - Activates the magnetos by opening the grounding or 'p-lead' circuit; with the p-lead ungrounded the magneto is free to send its high-voltage output to the spark plugs. In most aircraft the ignition switch also applies power to the starter motor during engine start. In piston aircraft engines, the battery does not generate the spark for combustion. This is accomplished using devices called magnetos. Magnetos are connected to the engine by gearing. When the crankshaft turns, it turns the magnetos which mechanically generate voltage for spark. In the event of an electrical failure, the engine will continue to run. The Ignition Switch has the following positions:Off - Both magneto p-leads are connected to electrical ground. This disables both magnetos, no spark is produced.Right - The left magneto p-lead is grounded, and the right is open. This disables the left magneto and enables the right magneto only.Left - The right magneto p-lead is grounded, and the left is open. This disables the right magneto and enables the left magneto only.Both - This is the normal operating configuration, both p-leads are open, enabling both magnetos.Start - The pinion gear on the starter motor is engaged with the flywheel and the starter motor runs to turn the engine over. In most cases, only the left magneto is active (the right p-lead is grounded) due to timing differences between the magnetos at low RPMs.[1]Tachometer - A gauge to indicate engine speed in revolutions per minute (RPM) or percentage of maximum.Manifold Pressure (MP) Gauge - Indicates the absolute pressure in the intake manifold.Oil Temperature Gauge - Indicates the engine oil temperature.Oil Pressure Gauge - Indicates the supply pressure of the engine lubricant.Exhaust Gas Temperature (EGT) Gauge - Indicates the temperature of the exhaust gas just after combustion. Used to set the fuel/air mixture (leaning) correctly.Cylinder Head Temperature (CHT) Gauge - Indicates the temperature of at least one of the cylinder heads. Used to set the fuel/air mixture.Carburetor Heat Control - Controls the application of heat to the carburetor venturi area to remove or prevent the formation of ice in the throat of the carburetor as well as bypassing the air filter in case of impact icing.Alternate Air - Bypasses the air filter on a fuel-injected engine.

Bus Bar - is a strip or bar of copper, brass or aluminium that conducts electricity within a switchboard, distribution board, substation, battery bank, or other electrical apparatus. Its main purpose is to conduct a substantial current of electricity, and not to function as a structural member.In electrical power distribution, a busbar (also spelled bus bar, or sometimes as bus bar or bussbar, with the term bus being a contraction of the Latin omnibus, "for all") is a strip or bar of copper, brass or aluminium that conducts electricity within a switchboard, distribution board, substation, battery bank, or other electrical apparatus. Its main purpose is to conduct a substantial current of electricity, and not to function as a structural member.

The cross-sectional size of the busbar determines the maximum amount of current that can be safely carried. Bussbars can have a cross-sectional area of as little as 10 mm2, but electrical substations may use metal tubes 50 mm in diameter (20 cm2) or more as busbars. An aluminium smelter will have very large busbars used to carry tens of thousands of amperes to the electrochemical cells that produce aluminium from molten salts.

Busbars are typically either flat strips or hollow tubes, as these shapes allow heat to dissipate more efficiently due to their high surface area to cross-sectional area ratio. The skin effect makes 5060 Hz AC busbars more than about 8 mm (5/16 in) thickness inefficient, so hollow or flat shapes are prevalent in higher current applications. A hollow section has higher stiffness than a solid rod of equivalent current-carrying capacity, which allows a greater span between busbar supports in outdoor switchyards.

A busbar must be sufficiently rigid to support its own weight, as well as forces imposed by mechanical vibration and possibly earthquakes, as well as accumulated precipitation in outdoor exposures. In addition, thermal expansion from temperature changes induced by ohmic heating and ambient temperature variations, and magnetic forces induced by large currents must be considered.

Busbars are typically contained inside switchgear, panel boards, or busway enclosures. Distribution boards split the electrical supply into separate circuits at one location. Busways, or bus ducts, are long busbars with a protective cover. Rather than branching from the main supply at one location, they allow new circuits to branch off anywhere along the route of the busway.

A busbar may either be supported on insulators, or else insulation may completely surround it. Busbars are protected from accidental contact either by a metal earthed enclosure or by elevation out of normal reach. Power neutral busbars may also be insulated. Earthing (safety grounding) busbars are typically bare and bolted directly onto any metal chassis of their enclosure. Busbars may be enclosed in a metal housing, in the form of bus duct or busway, segregated-phase bus, or isolated-phase bus.

Busbars may be connected to each other and to electrical apparatus by bolted, clamped, or welded connections. Often, joints between high-current bus sections have precisely-machined matching surfaces that are silver-plated to reduce the contact resistance. At extra high voltages (more than 300 kV) in outdoor buses, corona discharge around the connections becomes a source of radio-frequency interference and power loss, so special connection fittings designed for these voltages are used.

Fuse - is a type of low resistance resistor that acts as a sacrificial device to provide overcurrent protection, of either the load or source circuit. Its essential component is a metal wire or strip that melts when too much current flows through it, interrupting the circuit that it connects. Short circuits, overloading, mismatched loads, or device failure are the prime reasons for excessive current. Fuses are an alternative to circuit breakers.In 1847, Breguet recommended use of reduced-section conductors to protect telegraph stations from lightning strikes; by melting, the smaller wires would protect apparatus and wiring inside the building.[2] A variety of wire or foil fusible elements were in use to protect telegraph cables and lighting installations as early as 1864. A fuse was patented by Thomas Edison in 1890[4] as part of his electric distribution system.A fuse consists of a metal strip or wire fuse element, of small cross-section compared to the circuit conductors, mounted between a pair of electrical terminals, and (usually) enclosed by a non-combustible housing. The fuse is arranged in series to carry all the current passing through the protected circuit. The resistance of the element generates heat due to the current flow. The size and construction of the element is (empirically) determined so that the heat produced for a normal current does not cause the element to attain a high temperature. If too high a current flows, the element rises to a higher temperature and either directly melts, or else melts a soldered joint within the fuse, opening the circuit.The fuse element is made of zinc, copper, silver, aluminum, or alloys to provide stable and predictable characteristics.[citation needed] The fuse ideally would carry its rated current indefinitely, and melt quickly on a small excess. The element must not be damaged by minor harmless surges of current, and must not oxidize or change its behavior after possibly years of service.The fuse elements may be shaped to increase heating effect. In large fuses, current may be divided between multiple strips of metal. A dual-element fuse may contain a metal strip that melts instantly on a short-circuit, and also contain a low-melting solder joint that responds to long-term overload of low values compared to a short-circuit. Fuse elements may be supp Speed[edit]The speed at which a fuse blows depends on how much current flows through it and the material of which the fuse is made. The operating time is not a fixed interval, but decreases as the current increases. Fuses have different characteristics of operating time compared to current, characterized as, according to time required to respond to an overcurrent condition. A standard fuse may require twice its rated current to open in one second, a fast-blow fuse may require twice its rated current to blow in 0.1 seconds, and a slow-blow fuse may require twice its rated current for tens of seconds to blow.

Fuse selection depends on the load's characteristics. Semiconductor devices may use a fast or ultrafast fuse as semiconductor devices heat rapidly when excess current flows. The fastest blowing fuses are designed for the most sensitive electrical equipment, where even a short exposure to an overload current could be very damaging. Normal fast-blow fuses are the most general purpose fuses. The time delay fuse (also known as anti-surge, or slow-blow) are designed to allow a current which is above the rated value of the fuse to flow for a short period of time without the fuse blowing. These types of fuse are used on equipment such as motors, which can draw larger than normal currents for up to several seconds while coming up to speed.

The I2t rating- is related to the amount of energy let through by the fuse element when it clears the electrical fault. This term is normally used in short circuit conditions and the values are used to perform co-ordination studies in electrical networks. I2t parameters are provided by charts in manufacturer data sheets for each fuse family. For coordination of fuse operation with upstream or downstream devices, both melting I2t and clearing I2t are specified. The melting I2t, is proportional to the amount of energy required to begin melting the fuse element. The clearing I2t is proportional to the total energy let through by the fuse when clearing a fault. The energy is mainly dependent on current and time for fuses as well as the available fault level and system voltage. Since the I2t rating of the fuse is proportional to the energy it lets through, it is a measure of the thermal damage and magnetic forces that will be produced by a fault.

Breaking capacity- The breaking capacity is the maximum current that can safely be interrupted by the fuse. Generally, this should be higher than the prospective short circuit current. Miniature fuses may have an interrupting rating only 10 times their rated current. Some fuses are designated High Rupture Capacity (HRC) and are usually filled with sand or a similar material. Fuses for small, low-voltage, usually residential, wiring systems are commonly rated, in North American practice, to interrupt 10,000 amperes. Fuses for larger power systems must have higher interrupting ratings, with some low-voltage current-limiting high interrupting fuses rated for 300,000 amperes. Fuses for high-voltage equipment, up to 115,000 volts, are rated by the total apparent power (megavolt-amperes, MVA) of the fault level on the circuit.

Voltage rating of the fuse must be equal to, or greater than, what would become the open circuit voltage. For example, a glass tube fuse rated at 32 volts would not reliably interrupt current from a voltage source of 120 or 230 V. If a 32 V fuse attempts to interrupt the 120 or 230 V source, an arc may result. Plasma inside the glass tube may continue to conduct current until the current diminishes to the point where the plasma becomes a non-conducting gas. Rated voltage should be higher than the maximum voltage source it would have to disconnect. Connecting fuses in series does not increase the rated voltage of the combination, nor of any one fuse.

Medium-voltage fuses rated for a few thousand volts are never used on low voltage circuits, because of their cost and because they cannot properly clear the circuit when operating at very low voltages.

A voltage drop across the fuse is usually provided by its manufacturer. There is a direct relationship between a fuse's cold resistance and its voltage drop value. Once current is applied, resistance and voltage drop of a fuse will constantly grow with the rise of its operating temperature until the fuse finally reaches thermal equilibrium or alternatively melts when higher currents than its rated current are administered over sufficiently long periods of time. This resulting voltage drop should be taken into account, particularly when using a fuse in low-voltage applications. Voltage drop often is not significant in more traditional wire type fuses, but can be significant in other technologies such as resettable fuse (PPTC) type fuses orted by steel or nichrome wires, so that no strain is placed on the element, but a spring may be included to increase the speed of parting of the element fragments.

Circuit Breaker an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and interrupt current flow. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city.An early form of circuit breaker was described by Thomas Edison in an 1879 patent application, although his commercial power distribution system used fuses.[1] Its purpose was to protect lighting circuit wiring from accidental short-circuits and overloads. A modern miniature circuit breaker similar to the ones now in use was patented by Brown, Boveri & Cie in 1924. Hugo Stotz, an engineer who had sold his company to BBC, was credited as the inventor on DRP (Deutsches Reichspatent) 458392.[2] Stotz's invention was the forerunner of the modern thermal-magnetic breaker commonly used in household load centers to this day. Interconnection of multiple generator sources into an electrical grid required development of circuit breakers with increasing voltage ratings and increased ability to safely interrupt the increasing short circuit currents produced by networks. Simple air-break manual switches produced hazardous arcs when interrupting high currents; these gave way to oil-enclosed contacts, and various forms using directed flow of pressurized air, or of pressurized oil, to cool and interrupt the arc. By 1935, the specially constructed circuit breakers used at the Boulder Dam project use eight series breaks and pressurized oil flow to interrupt faults of up to 2,500 MVA, in three cycles of the AC power frequency.All circuit breaker systems have common features in their operation, although details vary substantially depending on the voltage class, current rating and type of the circuit breaker.The circuit breaker must detect a fault condition; in low voltage circuit breakers this is usually done within the breaker enclosure. Circuit breakers for large currents or high voltages are usually arranged with protective relay pilot devices to sense a fault condition and to operate the trip opening mechanism. The trip solenoid that releases the latch is usually energized by a separate battery, although some high-voltage circuit breakers are self-contained with current transformers, protective relays and an internal control power source. Once a fault is detected, contacts within the circuit breaker must open to interrupt the circuit; some mechanically-stored energy (using something such as springs or compressed air) contained within the breaker is used to separate the contacts, although some of the energy required may be obtained from the fault current itself. Small circuit breakers may be manually operated, larger units have solenoids to trip the mechanism, and electric motors to restore energy to the springs.

The circuit breaker contacts must carry the load current without excessive heating, and must also withstand the heat of the arc produced when interrupting (opening) the circuit. Contacts are made of copper or copper alloys, silver alloys and other highly conductive materials. Service life of the contacts is limited by the erosion of contact material due to arcing while interrupting the current. Miniature and molded-case circuit breakers are usually discarded when the contacts have worn, but power circuit breakers and high-voltage circuit breakers have replaceable contacts.When a current is interrupted, an arc is generated. This arc must be contained, cooled and extinguished in a controlled way, so that the gap between the contacts can again withstand the voltage in the circuit. Different circuit breakers use vacuum, air, insulating gas or oil as the medium the arc forms in. Different techniques are used to extinguish the arc including:

Lengthening / deflection of the arcIntensive cooling (in jet chambers)Division into partial arcsZero point quenching (Contacts open at the zero current time crossing of the AC waveform, effectively breaking no load current at the time of opening. The zero crossing occurs at twice the line frequency, i.e. 100 times per second for 50 Hz and 120 times per second for 60 Hz AC)Connecting capacitors in parallel with contacts in DC circuits.

Voltage Regulator - designed to automatically maintain a constant voltage level. A voltage regulator may be a simple "feed-forward" design or may include negative feedback control loops. It may use an electromechanical mechanism, or electronic components.A simple voltage regulator can be made from a resistor in series with a diode (or series of diodes). Due to the logarithmic shape of diode V-I curves, the voltage across the diode changes only slightly due to changes in current drawn or changes in the input. When precise voltage control and efficiency are not important, this design may work fine.Feedback voltage regulators operate by comparing the actual output voltage to some fixed reference voltage. Any difference is amplified and used to control the regulation element in such a way as to reduce the voltage error. This forms a negative feedback control loop; increasing the open-loop gain tends to increase regulation accuracy but reduce stability. (Stability is avoidance of oscillation, or ringing, during step changes.) There will also be a trade-off between stability and the speed of the response to changes. If the output voltage is too low (perhaps due to input voltage reducing or load current increasing), the regulation element is commanded, up to a point, to produce a higher output voltageby dropping less of the input voltage (for linear series regulators and buck switching regulators), or to draw input current for longer periods (boost-type switching regulators); if the output voltage is too high, the regulation element will normally be commanded to produce a lower voltage. However, many regulators have over-current protection, so that they will entirely stop sourcing current (or limit the current in some way) if the output current is too high, and some regulators may also shut down if the input voltage is outside a given range (see also: crowbar circuits).In electromechanical regulators, voltage regulation is easily accomplished by coiling the sensing wire to make an electromagnet. The magnetic field produced by the current attracts a moving ferrous core held back under spring tension or gravitational pull. As voltage increases, so does the current, strengthening the magnetic field produced by the coil and pulling the core towards the field. The magnet is physically connected to a mechanical power switch, which opens as the magnet moves into the field. As voltage decreases, so does the current, releasing spring tension or the weight of the core and causing it to retract. This closes the switch and allows the power to flow once more. If the mechanical regulator design is sensitive to small voltage fluctuations, the motion of the solenoid core can be used to move a selector switch across a range of resistances or transformer windings to gradually step the output voltage up or down, or to rotate the position of a moving-coil AC regulator.

Early automobile generators and alternators had a mechanical voltage regulator using one, two, or three relays and various resistors to stabilize the generator's output at slightly more than 6 or 12 V, independent of the engine's rpm or the varying load on the vehicle's electrical system. Essentially, the relay(s) employed pulse width modulation to regulate the output of the generator, controlling the field current reaching the generator (or alternator) and in this way controlling the output voltage produced. The regulators used for DC generators (but not alternators) also disconnect the generator when it was not producing electricity, thereby preventing the battery from discharging back into the generator and attempting to run it as a motor. The rectifier diodes in an alternator automatically perform this function so that a specific relay is not required; this appreciably simplified the regulator design. More modern designs now use solid state technology (transistors) to perform the same function that the relays perform in electromechanical regulators.To control the output of generators (as seen in ships and power stations, or on oil rigs, greenhouses and emergency power systems) automatic voltage regulators are used. This is an active system. While the basic principle is the same, the system itself is more complex. An automatic voltage regulator (or AVR for short) consist of several components such as diodes, capacitors, resistors and potentiometers or even microcontrollers, all placed on a circuit board. This is then mounted near the generator and connected with several wires to measure and adjust the generator. How an AVR works: In the first place the AVR monitors the output voltage and controls the input voltage for the exciter of the generator. By increasing or decreasing the generator control voltage, the output voltage of the generator increases or decreases accordingly. The AVR calculates how much voltage has to be sent to the exciter numerous times a second, therefore stabilizing the output voltage to a predetermined setpoint. When two or more generators are powering the same system (parallel operation) the AVR receives information from more generators to match all output.

Coil-rotation AC voltage regulator- Basic design principle and circuit diagram for the rotating-coil AC voltage regulator. This is an older type of regulator used in the 1920s that uses t