66 Kv Single Face Distribution 2

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INDUSTRY PROFILE- ELECTRIC POWER INDIA

The electric power industry in India is both a supplier and a consumer of primary energy,

depending on the kind of energy used to turn the generators. Hydroelectric and nuclear

power plants add to the country's supply of primary energy. The total installed electricity

capacity in public utilities in 1992 was 69,100 megawatts, of which 70 percent was

thermal, 27 percent hydropower, and 3 percent nuclear. The total installed capacity was

programmed to reach around 100,000 megawatts by FY 1996 through a package of

government-supported incentives to the private sector.

Because they cannot always depend on public utilities, many larger industrial enterprises

have developed their own power generation systems. In 1992 there was a capacity of 9,000

megawatts outside the public utility system. Overall, the generation and transmission of

power in India--with an average 57 percent plant load factor in FY 1992 in thermal plants

and transmission losses of 22 percent--were inefficient. About 322 billion kilowatt- hours

of power were generated by utilities in FY 1992, approximately 8.5 percent shy of demand.

The resulting deficit led to acute shortages in some states. This trend continued the next

year when 315 billion kilowatt-hours were produced. Many factors contributed to the

shortfall of electric power in India, including slow completion of new installations, low use

of installed capacity because of insufficient maintenance and coal, and poor management.

In FY 1990, industry accounted for 45 percent of electricity consumed, agriculture 26

percent, and domestic use 16.5 percent. Other sectors, including commerce and railroads,

accounted for the remaining 12.5 percent.

Rural electrification in India made great progress in the 1980s; more than 200,000 villages

received electricity for the first time. In 1990 around 84 percent of India's villages had

access to electricity. Most of the villages without electricity were in Bihar, Orissa,

Rajasthan, Uttar Pradesh, and West Bengal. Villagers complain that government figures on

electrification of villages are artificially inflated. Actually, although lines have been run to

most villages, electricity is provided only sporadically (for example, only nine to twelve

hours per day), and villagers feel they cannot depend on electricity to operate pumps and


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other equipment. Electricity to cities also is sporadic; blackouts occur every day in most

cities.

India's first hydroelectric station was constructed in 1897 in Darjiling (then Darjeeling). In

FY 1990, installed capacity for hydroelectric power was 18,000 megawatts. The country

has a large economically exploitable hydroelectric potential, especially in the foothills of

the Himalayas, but no large increase in capacity is predicted for the mid-1990s.

Hydroelectric facilities have to be coordinated with other sources of electricity because

seasonal and annual variations in rainfall affect the amount of water needed to turn the

generators and consequently the amount of electricity that can be produced.

Hydroelectric power projects in India have not been without controversy.Indian Dams for

irrigation and power generation have displaced people and raised the specter of ecological

problems.


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ELECTRIC-POWER TRANSMISSION

Electric-power transmission is the bulk transfer of electrical energy, from generating

power plants to electrical substations located near demand centers. This is distinct from the

local wiring between high-voltage substations and customers, which is typically referred to

as electric power distribution. Transmission lines, when interconnected with each other,

become transmission networks. In the India , these are typically referred to as "power

grids" or just "the grid", while in the UK the network is known as the "national grid."

Historically, transmission and distribution lines were owned by the same company, but

starting in the 1990s many countries have liberalized the regulation of the electricity market

in ways that have led to the separation of the electricity transmission business from thedistribution business.

Transmission lines mostly use high-voltage three-phasealternating current (AC), although

single phase AC is sometimes used in railway electrification systems.High-voltage direct-

current (HVDC) technology is used for greater efficiency in very long distances (typically

hundreds of miles (kilometres), or in submarine power cables (typically longer than 30

miles (50 km). HVDC links are also used to stabilize against control problems in large

power distribution networks where sudden new loads or blackouts in one part of a network

can otherwise result in synchronization problems and cascading failures.

Electricity is transmitted at high voltages (110 kV or above) to reduce the energy lost in

long-distance transmission. Power is usually transmitted through overhead power lines.

Underground power transmission has a significantly higher cost and greater operational

limitations but is sometimes used in urban areas or sensitive locations.

A key limitation in the distribution of electricity is that, with minor exceptions, electrical

energy cannot be stored, and therefore must be generated as needed. A sophisticated

system of control is therefore required to ensure electric generation very closely matches

the demand. If supply and demand are not in balance, generation plants and transmission

equipment can shut down which, in the worst cases, can lead to a major regionalblackout.
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To reduce the risk of such failures, electric transmission networks are interconnected into

regional, national or continental wide networks thereby providing multiple redundant

alternate routes for power to flow should (weather or equipment) failures occur. Much

analysis is done by transmission companies to determine the maximum reliable capacity of

each line (ordinarily less than its physical or thermal limit) to ensure spare capacity is

available should there be any such failure in another part of the network.

We have worked on the project which distribute the single face electricity to Domestic

Supply.

DIAGRAM OF AN ELECTRICAL SYSTEM
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INTRODUCTION OF ALTERNATING CURRENT


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The competition between the direct current (DC) of Thomas Edison and the alternating

current (AC) ofNikola Tesla and George Westinghouse was known as the War of

Currents. At the conclusion of their campaigning, AC became the dominant form of

transmission of power. Power transformers, installed at power stations, could be used to

raise the voltage from the generators, and transformers at local substations could reduce

voltage to supply loads. Increasing the voltage reduced the current in the transmission and

distribution lines and hence the size of conductors and distribution losses. This made it

more economical to distribute power over long distances. Generators (such as hydroelectric

sites) could be located far from the loads.

In India, early distribution systems used a voltage of 2.2 kV corner-grounded delta. Over

time, this was gradually increased to 2.4 kV. As cities grew, most 2.4 kV systems were

upgraded to 2.4/4.16 kV, three-phase systems. In three phase networks that permit

connections between phase and neutral, both the phase-to-phase voltage (4160, in this
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example) and the phase-to-neutral voltage are given; if only one value is shown, the

network does not serve single-phase loads connected phase-to-neutral. Some city and

suburban distribution systems continue to use this range of voltages, but most have been

converted to 7200/12470Y, 7620/13200Y, 14400/24940Y, and 19920/34500Y.

While power electronics now allow for conversion between DC voltage levels, AC is still

used in distribution due to the economy, efficiency and reliability of transformers. High-

voltage DC is used for transmission of large blocks of power over long distances, or for

interconnecting adjacent AC networks, but not for distribution to customers. Electric power

is normally generated at 11-25kV in a power station. To transmit over long distances, it is

then stepped-up to 400kV, 220kV or 132kV as necessary. Power is carried through a

transmission network of high voltage lines. Usually, these lines run into hundreds ofkilometres and deliver the power into a common power pool called the grid. The grid is

connected to load centres (cities) through a sub-transmission network of normally 33kV (or

sometimes 66kV) lines. These lines terminate into a 33kV (or 66kV) substation, where the

voltage is stepped-down to 11kV for power distribution to load points through a

distribution network of lines at 11kV and lower.

MODERN DISTRIBUTION SYSTEMS

The modern distribution system begins as the primary circuit leaves the sub-station and

ends as the secondary service enters the customer's meter socket. Distribution circuits serve

many customers. The voltage used is appropriate for the shorter distance and varies from

2,300 to about 35,000 volts depending on utility standard practice, distance, and load to be

served. Distribution circuits are fed from a transformerlocated in an electrical substation,

where the voltage is reduced from the high values used for power transmission.

Conductors for distribution may be carried on overhead pole lines, or in densely-populated

areas where they are buried underground. Urban and suburban distribution is done with

three-phase systems to serve both residential, commercial, and industrial loads.

Distribution in rural areas may be only single-phase if it is not economical to install three-

phase power for relatively few and small customers.
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Only large consumers are fed directly from distribution voltages; most utility customers are

connected to a transformer, which reduces the distribution voltage to the relatively low

voltage used by lighting and interior wiring systems. The transformer may be pole-

mounted or set on the ground in a protective enclosure. In rural areas a pole-mount

transformer may serve only one customer, but in more built-up areas multiple customers

may be connected. In very dense city areas, a secondary networkmay be formed with many

transformers feeding into a common bus at the utilization voltage. Each customer has an

"electrical service" or "service drop" connection and a meter for billing. (Some very small

loads, such as yard lights, may be too small to meter and so are charged only a monthly

rate.)

A ground connection to local earth is normally provided for the customer's system as wellas for the equipment owned by the utility. The purpose of connecting the customer's system

to ground is to limit the voltage that may develop if high voltage conductors fall on the

lower-voltage conductors, or if a failure occurs within a distribution transformer. If all

conductive objects are bonded to the same earth grounding system, the risk of electric

shock is minimized. However, multiple connections between the utility ground and

customer ground can lead to stray voltage problems; customer piping, swimming pools or

other equipment may develop objectionable voltages. These problems may be difficult to

resolve since they often originate from places other than the customer's premises.

AUTOMATION IN POWER DISTRIBUTION

The demand for electrical energy is ever increasing. Today over 21% (theft apart!!) of the

total electrical energy generated in India is lost in transmission (4-6%) and distribution (15-

18%). The electrical power deficit in the country is currently about 18%. Clearly, reduction

in distribution losses can reduce this deficit significantly. It is possible to bring down the

distribution losses to a 6-8 % level in India with the help of newer technological options

(including information technology) in the electrical power distribution sector which will

enable better monitoring and control.

HOW DOES POWER REACH US?
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Electric power is normally generated at 11-25kV in a power station. To transmit over long

distances, it is then stepped-up to 400kV, 220kV or 132kV as necessary. Power is carried

through a transmission network of high voltage lines. Usually, these lines run into hundreds

of kilometres and deliver the power into a common power pool called the grid. The grid is

connected to load centres (cities) through a sub-transmission network of normally 33kV (or

sometimes 66kV) lines. These lines terminate into a 33kV (or 66kV) substation, where the

voltage is stepped-down to 11kV for power distribution to load points through a

distribution network of lines at 11kV and lower.

The power network, which generally concerns the common man, is the distribution

network of 11kV lines or feeders downstream of the 33kV substation. Each 11kV feeder

which emanates from the 33kV substation branches further into several subsidiary 11kVfeeders to carry power close to the load points (localities, industrial areas, villages, etc.,).

At these load points, a transformer further reduces the voltage from 11kV to 415V to

provide the last-mile connection through 415V feeders (also called as Low Tension (LT)

feeders) to individual customers, either at 240V (as single-phase supply) or at 415V (as

three-phase supply). A feeder could be either an overhead line or an underground cable. In

urban areas, owing to the density of customers, the length of an 11kV feeder is generally up

to 3 km. On the other hand, in rural areas, the feeder length is much larger (up to 20 km). A

415V feeder should normally be restricted to about 0.5-1.0 km. Unduly long feeders lead to

low voltage at the consumer end.

BOTTLENECKS IN ENSURING RELIABLE POWER

Lack of information at the base station (33kV sub-station) on the loading and health status

of the 11kV/415V transformer and associated feeders is one primary cause of inefficient

power distribution. Due to absence of monitoring, overloading occurs, which results in low

voltage at the customer end and increases the risk of frequent breakdowns of transformers

and feeders. In fact, the transformer breakdown rate in India is as high as around 20%, in

contrast to less than 2% in some advanced countries.

In the absence of switches at different points in the distribution network, it is not possible

to isolate certain loads for load shedding as and when required. The only option available


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in the present distribution network is the circuit breaker (one each for every main 11kV

feeder) at the 33kV substation. However, these circuit breakers are actually provided as a

means of protection to completely isolate the downstream network in the event of a fault.

Using this as a tool for load management is not desirable, as it disconnects the power

supply to a very large segment of consumers. Clearly, there is a need to put in place a

system that can achieve a finer resolution in load management.

In the event of a fault on any feeder section downstream, the circuit breaker at the 33kV

substation trips (opens). As a result, there is a blackout over a large section of the

distribution network. If the faulty feeder segment could be precisely identified, it would be

possible to substantially reduce the blackout area, by re-routing the power to the healthy

feeder segments through the operation of switches (of the same type as those for loadmanagement) placed at strategic locations in various feeder segments.


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Typical Power Transmission and Distribution Scenario with DA components


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LIST OF COMPONENTS

Step-down Transformer

Neon Lamp

SPST

Insulator

Feeder cabling

Single face wiring


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CIRCUIT DIAGRAM


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WORKING PRINCIPAL

Systems that comprise those parts of an electric power system between the sub

transmission system and the consumers' service switches. It includes distribution

substations; primary distribution feeders; distribution transformers; secondary circuits,

including the services to the consumer; and appropriate protective and control devices.

The sub transmission circuits of a typical distribution system deliver electric power from

bulk power sources to the distribution substations. The sub transmission voltage is usually

between 34.5 and 138 kV. The distribution substation, which is made up of power

transformers together with the necessary voltage-regulating apparatus, bus-bars, and

switchgear, reduces the sub transmission voltage to a lower primary system voltage forlocal distribution. The three-phase primary feeder, which usually operates at voltages from

4.16 to 34.5 kV, distributes electric power from the low-voltage bus of the substation to its

load center, where it branches into three-phase sub feeders and three-phase and

occasionally single-phase laterals. Most of the three-phase distribution system lines consist

of three-phase conductors and a common or neutral conductor, making a total of four wires.

Single-phase branches (made up of two wires) supplied from the three-phase mains provide

power to residences, small stores, and farms. Loads are connected in parallel to common

power-supply circuits.


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ELECTRIC POWER TRANSMISSION

There is transport of generator-produced electric energy to loads. An electric power

transmission system interconnects generators and loads and generally provides multiple

paths among them. Multiple paths increase system reliability because the failure of one linedoes not cause a system failure. Most transmission lines operate with three-phase

alternating current (ac). The three-phase system has three sets of phase conductors. Long-

distance energy transmission occasionally uses high-voltage direct-current (dc) lines.


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The electric power system can be divided into the distribution, sub transmission, and

transmission systems. With operating voltages less than 34.5 kV, the distribution system

carries energy from the local substation to individual households, using both overhead and

underground lines. With operating voltages of 69-138 kV, the sub transmission system

distributes energy within an entire district and regularly uses overhead lines. With

operating voltage exceeding 230 kV, the transmission system interconnects generating

stations and large substations located close to load centers by using overhead lines.

OVERHEAD ALTERNATING-CURRENT TRANSMISSION

Overhead transmission lines distribute the majority of the electric energy in the system. A

typical high-voltage line has three phase conductors to carry the current and transport the

energy, and two grounded shield conductors to protect the line from direct lightning strikes.

The usually bare conductors are insulated from the supporting towers by insulators attached

to grounded towers or poles. Lower-voltage lines use post insulators, while the high-

voltage lines are built with insulator chains or long-rod composite insulators. The normal

distance between the supporting towers is a few hundred feet.

Transmission lines use ACSR (aluminum cable, steel reinforced) and ACAR (aluminum

cable, alloy reinforced) conductors. In an ACSR conductor, a stranded steel core carries themechanical load, and layers of stranded aluminum surrounding the core carry the current.

An ACAR conductor is a stranded cable made of an aluminum alloy with low resistance

and high mechanical strength. ACSR conductors are usually used for high-voltage lines,

and ACAR conductors for sub transmission and distribution lines. Ultrahigh-voltage

(UHV) and extra high-voltage (EHV) lines use bundle conductors. Each phase of the line is

built with two, three, or four conductors connected in parallel and separated by about 1.5 ft

(0.5 m). Bundle conductors reduce corona discharge.

Transmission lines are subject to environmental adversities, including wide variations of

temperature, high winds, and ice and snow deposits. Typically designed to withstand

environmental stresses occurring once every 50100 years, lines are intended to operate

safely in adverse conditions.


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Variable weather affects line operation. Extreme weather reduces corona inception voltage,

leading to an increase in audible noise, radio noise, and telephone interference. Load

variation requires regulation of line voltage. A short circuit generates large currents,

overheating conductors and producing permanent damage.

The power that a line can transport is limited by the line's electrical parameters. Voltage

drop is the most important factor for distribution lines; where the line is supplied from only

one end, the permitted voltage drop is about 5%.

Conductor temperature must be lower than the temperature which causes permanent

elongation. A typical maximum steady-state value for ACSR is 212F (100C), but in an

emergency temperature 1020% higher are allowed for a short period of time (10 min to 1

h).

Corona discharge is generated when the electric field at the surface of the conductor

becomes larger than the breakdown strength of the air. The oscillatory nature of the

discharge generates high-frequency, short-duration current pulses, the source of corona-

generated radio and television interference. Surface irregularities such as water droplets

cause local field concentration, enhancing corona generation. Thus, during bad weather,

corona discharge is more intense and losses are much greater. Corona discharge alsogenerates audible noise with two components: a broad-band, high-frequency component,

which produces crackling and hissing, and a 120-Hz pure tone.

Transmission-line conductors are surrounded by an electric field which decreases as

distance from the line increases, and depends on line voltage and geometry. At ground

level, this field induces current and voltage in grounded bodies, causes corona in grounded

objects, and can induce fuel ignition.

Lightning strikes produce high voltages and traveling waves on transmission lines, causing

insulator flashovers and interruption of operation. Steel grounded shield conductors at the

tops of the towers significantly reduce, but do not eliminate, the probability of direct

lightning strikes to phase conductors.


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The operation of circuit breakers causes switching surges that can result in interruption of

inductive current, energization of lines with trapped charges, and single-phase ground fault.

Modern circuit breakers, operating in two steps, reduce switching surges to 1.52 times the

60-Hz voltage.

Line current induces a disturbing voltage in telephone lines running parallel to transmission

lines. Because the induced voltage depends on the mutual inductance between the two

lines, disturbance can be reduced by increasing the distance between the lines and shielding

the telephone lines.

AC POWER TRANSMISSION

AC power transmission is the transmission of electric power by alternating current. Usually

transmission lines use three phase AC current. In electric railways, single phase AC current

is sometimes used in a railway electrification system. In urban areas, trains may be

powered by DC at 600 volts or so.

Overhead conductors are not covered by insulation. The conductor material is nearly

always an aluminum alloy, made into several strands and possibly reinforced with steel

strands. Improved conductor material and shapes are regularly used to allow increased

capacity and modernize transmission circuits. Thicker wires would lead to a relatively

small increase in capacity due to the skin effect, which causes most of the current to flow

close to the surface of the wire.

Today, transmission-level voltages are usually considered to be 110 kV and above. Lower

voltages such as 69 kV and 33 kV are usually considered sub-transmission voltages but are

occasionally used on long lines with light loads. Voltages less than 33 kV are usually used

for distribution. Voltages above 230 kV are considered extra high voltage and requiredifferent designs compared to equipment used at lower voltages.

Overhead transmission lines are uninsulated wire, so design of these lines requires

minimum clearances to be observed to maintain safety.


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THE DISTRIBUTION GRID

For power to be useful in a home or business, it comes off the transmission grid and is

stepped-down to the distribution grid. This may happen in several phases. The place where

the conversion from "transmission" to "distribution" occurs is in a power substation. A

power substation typically does two or three things:

It has transformers that step transmission voltages (in the tens or hundreds of

thousands of volts range) down to distribution voltages (typically less than 10,000

volts).

It has a "bus" that can split the distribution power off in multiple directions.

It often has circuit breakers and switches so that the substation can be

disconnected from the transmission grid or separate distribution lines can be

disconnected from the substation when necessary.

A typical small substation

The box in the foreground is a large transformer. To its left (and out of the frame but

shown in the next shot) are the incoming power from the transmission grid and a set of

switches for the incoming power. Toward the right is a distribution bus plus three voltage

regulators.


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PROJECT DESCRIPTION

STEP-DOWN TRANSFORMER: (MANY TURNS: FEW TURNS).

The step-up/step-down effect of coil turn ratios in a transformer (Figure: above) is

analogous to gear tooth ratios in mechanical gear systems, transforming values of speed

and torque in much the same way: (Figure: below)

Torque reducing gear train steps torque down, while stepping speed up.

Step-up and step-down transformers for power distribution purposes can be gigantic in

proportion to the power transformers previously shown, some units standing as tall as a

home. The following photograph shows a substation transformer standing about twelve feet

tall:

Substation transformer


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A transformer is a device that transfers electrical energy from one circuit to another

throughinductively coupled conductorsthe transformer's coils. A varying current in the

first orprimary winding creates a varyingmagnetic flux in the transformer's core and thus

a varying magnetic field through the secondary winding. This varying magnetic field

induces a varying electromotive force (EMF), or "voltage", in the secondary winding. This

effect is calledinductive coupling.

If a load is connected to the secondary, current will flow in the secondary winding, and

electrical energy will be transferred from the primary circuit through the transformer to the

load. In an ideal transformer, the induced voltage in the secondary winding ( Vs) is in

proportion to the primary voltage (Vp) and is given by the ratio of the number of turns in the

secondary (Ns) to the number of turns in the primary (Np) as follows:

By appropriate selection of the ratio of turns, a transformer thus enables an alternating

current (AC)voltage to be "stepped up" by making Ns greater thanNp, or "stepped down"

by makingNs less thanNp.

In the vast majority of transformers, the windings are coils wound around a ferromagnetic

core,air-core transformers being a notable exception.

Transformers range in size from a thumbnail-sized coupling transformer hidden inside a

stagemicrophone to huge units weighing hundreds of tons used to interconnect portions of

power grids. All operate on the same basic principles, although the range of designs is

wide. While new technologies have eliminated the need for transformers in some electronic

circuits, transformers are still found in nearly all electronic devices designed forhousehold("mains") voltage. Transformers are essential for high-voltage electric power transmission,

which makes long-distance transmission economically practical.
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Basic principles

The transformer is based on two principles: first, that an electric current can produce a

magnetic field (electromagnetism) and second that a changing magnetic field within a coil

of wire induces a voltage across the ends of the coil (electromagnetic induction). Changing

the current in the primary coil changes the magnetic flux that is developed. The changing

magnetic flux induces a voltage in the secondary coil.

An ideal transformer is shown in the adjacent figure. Current passing through the primary

coil creates a magnetic field. The primary and secondary coils are wrapped around a core

of very high magnetic permeability, such as iron, so that most of the magnetic flux passes

through both the primary and secondary coils. If a load is connected to the secondary

winding, the load current and voltage will be in the directions indicated, given the primary

current and voltage in the directions indicated (each will be alternating current in practice).

NEON LAMP

A neon lamp (also neon glow lamp) is a miniature gas discharge lamp that typically

contains neon gas at a lowpressure in a glass capsule. Only a thin region adjacent to the

electrodes glows in these lamps, which distinguishes them from the much longer and

brighterneon tubes used for signage. The term "neon lamp" is generally extended to lamps

with similar design that operate with different gases. Neon glow lamps were very common
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in the displays of electronic instruments through the 1970s; the basic design of neon lamps

is now incorporated in contemporaryplasma displays.

DESCRIPTION

A small electric current, which may be AC orDC, is allowed through the tube, causing it to

glow orange-red. The formulation of the gas is typically the classic Penning mixture,

99.5% neon and 0.5% argon, which has lowerstriking voltage than pure neon. The applied

voltage must initially reach the striking voltage before the lamp lights up. At the striking

voltage, the lamp enters a breakdown mode and exhibits a glow discharge. Once lit, the

voltage required to sustain the discharge is significantly (~30%) lower than the striking

voltage. This is due to the organization of positive ions near the cathode. When driven from

a DC source, only the negatively charged electrode (cathode) will glow. When driven from

an AC source, both electrodes will glow (each during alternate half cycles). These

attributes make neon bulbs (with series resistors) a convenient low-cost voltage testers;

they determine whether a given voltage source is AC or DC, and if DC, the polarity of the

points being tested. Neon lamps operate using a low currentglow discharge. Higher power
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devices, such as mercury-vapor lamps or metal halide lamps use a higher current arc

discharge.

Graph showing the relationship between current and voltage across a neon lamp.

Once the neon lamp has reached breakdown, it can support a large current flow. Because of

this characteristic, electrical circuitry external to the neon lamp must limit the current

through the circuit or else the current will rapidly increase until the lamp is destroyed. For

indicator-sized lamps, a resistortypically limits the current. Largerneon sign sized lamps

often use a specially constructed high voltage transformerwith highleakage inductance or

otherelectrical ballast to limit the available current.

When the current through the lamp is lower than the current for the highest-current

discharge path, theglow discharge may become unstable and not cover the entire surface of

the electrodes. This may be a sign of aging of the indicator bulb, and is exploited in the

decorative "flicker flame" neon lamps. However, while too low a current causes flickering,

too high a current increases the wear of the electrodes by stimulating sputtering, which

coats the internal surface of the lamp with metal and causes it to darken.

The potential needed to strike the discharge is higher than what is needed to sustain the

discharge. When there is not enough current, the glow forms around only part of the

electrode surface. Convective currents make the glowing areas flow upwards, not unlike

the discharge in aJacob's ladder. Aphotoionization effect can also be observed here, as the

electrode area covered by the glow discharge can be increased by shining light at the lamp.
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In comparison with incandescent light bulbs, neon lamps have much higher luminous

efficacy. Incandescence is heat-driven light emission, so a large portion of the electric

energy put into an incandescent bulb is converted into heat. Non-incandescent light sources

such as neon light bulbs, fluorescent light bulbs, and light emitting diodes are therefore

much more energy efficient than normal incandescent light bulbs. Green neon[clarification needed]

bulbs can produce up to 65 lumens per watt of power input, while white neon bulbs have an

efficacy of around 50 lumens per watt. In contrast, a standard incandescent light bulb only

produces around 13.5 lumens per watt

APPLICATIONS

Most small neon (indicator-sized) lamps, such as the common NE-2, break down at

between 90 and 110 volts. This feature enables their use as very simple voltage regulators

orovervoltage protection devices. In the 1960s General Electric (GE), Signalite, and other

firms made special extra-stable neon lamps for electronic uses. They even devised digital

logic circuits,binarymemories, and frequency dividers using neon lamps.[7][8][9][10][11][12][13][14]

Such circuits appeared in electronic organs of the 1950s, as well as some instrumentation.

At least some of these lamps had a glow concentrated into a small spot on the cathode,

which made them unsuited to use as indicators. These were sometimes called "circuit-

component" lamps, the other variety being indicators. A variant of the NE-2 type lamp, the

NE-77, had three parallel wires (in a plane) instead of the usual two. It was also intended

primarily to be a circuit component.

Small neon lamps are used as indicators in electronic equipment. Called "tuneons" in 1930s

radio sets, they were fitted as tuning indicators, and would give a brighter glow as the

station was tuned in correctly. Larger lamps are used in neon signage. Neon lamps, due to

their low current consumption, are used as nightlights. Because of their comparatively fast

response time, in the early development of television neon lamps were used as the light

source in many mechanical-scan TV displays. They were also used for a variety of other

purposes; since a neon lamp can act as a relaxation oscillatorwith an added resistor and

capacitor, it can be used as a simple flashing lamp oraudiooscillator. (See Pearson-Anson

effect.)
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Neon lamps with several shaped electrodes were used as alphanumerical displays known as

Nixie tubes. These have since been replaced by other display devices such as light emitting

diodes, vacuum fluorescent displays, and liquid crystal displays.Novelty glow lamps with

shaped electrodes (such as flowers and leaves), often coated with phosphors, have been

made for artistic purposes. In some of these, the glow that surrounds an electrode is part of

the design.

In AC-excited lamps, both electrodes produce light, but in a DC-excited lamp, only the

negative electrode glows. Thus a neon lamp can be used to distinguish between AC and DC

sources and to ascertain the polarity of DC sources.

Colour

Neon indicator lamps are normally orange, and are frequently used with a coloured filter

over them to improve contrast and change their colour to red or a redder orange, or less

often green.

They can also be filled with argon, krypton, orxenon rather than neon, or mixed with it.

While the electrical operating characteristics remain similar, the lamps light with a bluish

glow (including some ultraviolet) rather than neon's characteristic reddish-orange glow.

Ultraviolet radiation then can be used to excite a phosphorcoating inside of the bulb and

provide a wide range of various colors, including white.[15] A mixture of neon and krypton

can be used for green glow, but nevertheless "green neon" lamps are more commonly

phosphor-based.

STEP-UP TRANSFORMER

A step-up transformer is one whose secondary voltage is greater than its primary voltage.

This kind of transformer "steps up" the voltage applied to it. For instance, a step up

transformer is needed to use a 220v product in a country with a 110v supply.
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'RATING'

This depends entirely on the products you will be using it with. Give the electrical retailer a

detailed list of all the products you will be using with it - and also their maximum outputs.

From this information he/she will be able to advise the correct transformer rating needed.

A transformer converts alternating current (AC) from one voltage to another voltage. It has

no moving parts and works on a magnetic induction principle; it can be designed to "step-

up" or "step-down" voltage. So a step up transformer increases the voltage and a step down

transformer decreases the voltage.

HOW DOES A STEP UP TRANSFORMER WORK?

A transformer is made from two or more coils of insulated wire wound around a core made

of iron. When voltage is applied to one coil (frequently called the primary or input) it

magnetizes the iron core, which induces a voltage in the other coil, (frequently called the

secondary or output). The turns ratio of the two sets of windings determines the amount of

voltage transformation.

An example of this would be: 100 turns on the primary and 50 turns on the secondary, a

ratio of 2 to 1.

Transformers can be considered nothing more than a voltage ratio device.

With a step up transformer or step down transformer the voltage ratio between primary and

secondary will mirror the "turns ratio" (except for single phase smaller than 1 kva which

have compensated secondaries). A practical application of this 2 to 1 turns ratio would be a

480 to 240 voltage step down. Note that if the input were 440 volts then the output would

be 220 volts. The ratio between input and output voltage will stay constant. Transformers

should not be operated at voltages higher than the nameplate rating, but may be operated at

lower voltages than rated. Because of this it is possible to do some non-standard

applications using standard transformers.


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Single phase transformers 1 kva and larger may also be reverse connected to step-down or

step-up voltages. (Note: single phase step up or step down transformers sized less than 1

KVA should not be reverse connected because the secondary windings have additional

turns to overcome a voltage drop when the load is applied. If reverse connected, the output

voltage will be less than desired.)

STEP UP TRANSFORMERS AND HAVE A LONG LIFE.

The primary components for voltage transformation are the transformer's core and coil. The

insulation is placed between the turns of wire to prevent shorting to one another or to

ground. This is typically comprised of mylar, nomex, kraft paper, varnish, or other

materials.

INSULATOR

A true insulator is a material that does not respond to an electric field and completely

resists the flow of electric charge. In practice, however, perfect insulators do not exist.

Therefore, dielectric materials with high dielectric constants are considered insulators. In

insulating materials valence electrons are tightly bonded to their atoms. These materials are

used in electrical equipment as insulators or insulation. Their function is to support or

separate electrical conductors without allowing current through themselves. The term also

refers to insulating supports that attach electric power transmission wires to utility poles or

pylons.

Some materials such as glass, paperor Teflon are very good electrical insulators. Even

though they may have lower bulkresistivity, a much larger class of materials are still "good
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enough" to insulate electrical wiring and cables. Examples include rubber-like polymers

and most plastics. Such materials can serve as practical and safe insulators for low to

moderate voltages (hundreds, or even thousands, ofvolts).

PHYSICS OF CONDUCTION IN SOLIDS

Electrical insulation is the absence of electrical conduction. Electronic band theory (a

branch of physics) says that a charge will flow if states are available into which electrons

can be excited. This allows electrons to gain energy and thereby move through a conductor

such as a metal. If no such states are available, the material is an insulator.

Most (though not all, see Mott insulator) insulators have a large band gap. This occurs

because the "valence" band containing the highest energy electrons is full, and a large

energy gap separates this band from the next band above it. There is always some voltage

(called the breakdown voltage) that will give the electrons enough energy to be excited into

this band. Once this voltage is exceeded, the material ceases being an insulator, and charge

will begin to pass through it. However, it is usually accompanied by physical or chemical

changes that permanently degrade the material's insulating properties.

Materials that lack electron conduction are insulators if they lack other mobile charges as

well. For example, if a liquid or gas contains ions, then the ions can be made to flow as an

electric current, and the material is a conductor. Electrolytes and plasmas contain ions and

will act as conductors whether or not electron flow is involved.

BREAKDOWN

Insulators suffer from the phenomenon of electrical breakdown. When the electric field

applied across an insulating substance exceeds in any location the threshold breakdown

field for that substance, which is proportional to the band gap energy, the insulator

suddenly turns into a resistor, sometimes with catastrophic results. During electrical

breakdown, any free charge carrierbeing accelerated by the strong e-field will have enough

velocity to knock electrons from (ionize) any atom it strikes. These freed electrons and ions

are in turn accelerated and strike other atoms, creating more charge carriers, in a chain
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reaction. Rapidly the insulator becomes filled with mobile carriers, and its resistance drops

to a low level. In air, "corona discharge" is normal current near a high-voltage conductor;

an "arc" is an unusual and undesired current. Similar breakdown can occur within any

insulator, even within the bulk solid of a material. Even a vacuum can suffer a sort of

breakdown, but in this case the breakdown orvacuum arc involves charges ejected from

the surface of metal electrodes rather than produced by the vacuum itself.

USES

Insulators are commonly used as a flexible coating on electric wire and cable. Since air is

an insulator, in principle no other substance is needed to keep power where it should be.

High-voltage power lines commonly use just air, since a solid (e.g., plastic) coating is

impractical. However, wires which touch each other will produce cross connections, short

circuits, and fire hazards. In coaxial cable the center conductor must be supported exactly

in the middle of the hollow shield in order to prevent EM wave reflections. Finally, wires

which expose voltages higher than 60V can cause human shock and electrocution hazards.

Insulating coatings help to prevent all of these problems.

Some wires have a mechanical covering which has no voltage rating; e.g.: service-drop,

welding, doorbell, thermostat. An insulated wire or cable has a voltage rating and amaximum conductor temperature rating. It may not have an ampacity (current-carrying

capacity) rating, since this is dependent upon the surrounding environment (e.g. ambient

temperature).

In electronic systems, printed circuit boards are made from epoxy plastic and fibreglass.

The nonconductive boards support layers of copper foil conductors. In electronic devices,

the tiny and delicate active components are embedded within nonconductive epoxy or

phenolic plastics, or within baked glass or ceramic coatings.

In microelectronic components such as transistors and ICs, the silicon material is normally

a conductor because of doping, but it can easily be selectively transformed into a good

insulator by the application of heat and oxygen. Oxidized silicon is quartz, i.e. silicon

dioxide.
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In high voltage systems containing transformers and capacitors, liquid insulator oil is the

typical method used for preventing arcs. The oil replaces the air in any spaces which must

support significant voltage without electrical breakdown. Other methods of insulating high

voltage systems are ceramic or glass wire holders, gas, vacuum, and simply placing the

wires with a large separation, using the air as insulation.

SINGLE-PHASE ELECTRIC POWER

In electrical engineering, single-phase electric power refers to the distribution of

alternating current electric powerusing a system in which all the voltages of the supply

vary in unison. Single-phase distribution is used when loads are mostly lighting and

heating, with few large electric motors. A single-phase supply connected to an alternating

current electric motordoes not produce a revolving magnetic field; single-phase motors

need additional circuits for starting, and such motors are uncommon above 10 or 20 kW in

rating.

In contrast, in a three-phase system, the currents in each conductor reach their peak

instantaneous values sequentially, not simultaneously; in each cycle of the power

frequency, first one, then the second, then the third current reaches its maximum value. The

waveforms of the three supply conductors are offset from one another in time (delayed in

phase) by one-third of their period.

Standard frequencies of single-phase power systems are either 50 or 60 Hz. Special single-

phase traction power networks may operate at 16.67 Hz or other frequencies to power

electric railways.

In some countries such as the United States, single phase is commonly divided in half to

create split-phase electric powerfor household appliances and lighting.
http://en.wikipedia.org/wiki/Silicon_dioxidehttp://en.wikipedia.org/wiki/High_voltagehttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Capacitorshttp://en.wikipedia.org/wiki/Electrical_breakdownhttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Utility_frequencyhttp://en.wikipedia.org/wiki/Hertzhttp://en.wikipedia.org/wiki/Traction_power_networkhttp://en.wikipedia.org/wiki/Split-phase_electric_powerhttp://en.wikipedia.org/wiki/High_voltagehttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Capacitorshttp://en.wikipedia.org/wiki/Electrical_breakdownhttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Utility_frequencyhttp://en.wikipedia.org/wiki/Hertzhttp://en.wikipedia.org/wiki/Traction_power_networkhttp://en.wikipedia.org/wiki/Split-phase_electric_power


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Splitting out

Single phase polemount stepdown transformer

No arrangement oftransformers can convert a single-phase load into a balanced load on a

polyphase system. A single-phase load may be powered from a three-phase distribution

system either by connection between a phase and neutral or by connecting the load between

two phases. The load device must be designed for the voltage in each case. The neutral

point in a three phase system exists at the mathematical center of an equilateral triangle

formed by the three phase points, and the phase-to-phase voltage is accordingly times

the phase-to-neutral voltage.[1]For example, in places using a 415 volt 3 phase system, the

phase-to-neutral voltage is 240 volts, allowing single-phase lighting to be connected phase-

to-neutral and three-phase motors to be connected to all three phases.

In North America, a typical three-phase system will have 208 volts between the phases and

120 volts between phase and neutral. If heating equipment designed for the 240-volt three-

wire single phase system is connected to two phases of a 208 volt supply, it will only
http://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Polyphase_systemhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Ground_and_neutralhttp://en.wikipedia.org/wiki/Single-phase_electric_power#cite_note-0http://en.wikipedia.org/wiki/Single-phase_electric_power#cite_note-0http://en.wikipedia.org/wiki/Split_phasehttp://en.wikipedia.org/wiki/Split_phasehttp://en.wikipedia.org/wiki/File:Single-phase-pole-transformer-d335.jpghttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Polyphase_systemhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Ground_and_neutralhttp://en.wikipedia.org/wiki/Single-phase_electric_power#cite_note-0http://en.wikipedia.org/wiki/Split_phasehttp://en.wikipedia.org/wiki/Split_phase


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produce 75% of its rated heating effect. Single-phase motors may have taps to allow their

use on either 208 V or 240 V supplies.

On higher voltage systems (on the order of kilovolts) where a single phase transformer is in

use to supply a low voltage system, the method of splitting varies. In North American

utility distribution practice, the primary of the step-down transformer is wired across a

single high voltage feed wire and neutral, at least for smaller supplies (see photo of

transformer on right). Rural distribution may be a single phase at a medium voltage; in

some areas single wire earth return distribution is used when customers are very far apart.

In Britain the step-down primary is wired phase-phase.
http://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Ruralhttp://en.wikipedia.org/wiki/Single_wire_earth_returnhttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Ruralhttp://en.wikipedia.org/wiki/Single_wire_earth_return


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CONCLUSION AND FUTURE SCOPE

Single-phase power distribution is widely used especially in rural areas, where the cost of a

three-phase distribution network is high and motor loads are small and uncommon. We

used single phase distribution in our project where with the help of single phase we pass

the current to Domestic Supply.


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REFERENCES

1. http://earth2tech.com/2009/06/05/why-the-smart-grid-wont-have-the-innovations-

of-the-internet-any-time-soon/

2. http://earth2tech.com/2009/04/21/ciscos-latest-consumer-play-the-smart-grid/

3. en.wikipedia.org/wiki/Powerhouse

4. electronics.howstuffworks.com/circuit

5. www.electrical-installation.org/wiki/
http://earth2tech.com/2009/06/05/why-the-smart-grid-wont-have-the-innovations-of-the-internet-any-time-soon/http://earth2tech.com/2009/06/05/why-the-smart-grid-wont-have-the-innovations-of-the-internet-any-time-soon/http://earth2tech.com/2009/04/21/ciscos-latest-consumer-play-the-smart-grid/http://earth2tech.com/2009/06/05/why-the-smart-grid-wont-have-the-innovations-of-the-internet-any-time-soon/http://earth2tech.com/2009/06/05/why-the-smart-grid-wont-have-the-innovations-of-the-internet-any-time-soon/http://earth2tech.com/2009/04/21/ciscos-latest-consumer-play-the-smart-grid/


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CONTENTS

Electric Power India

Electric-power transmission

Diagram of an electrical system

Introduction of alternating current

List of Components

Circuit Diagram

Working Principal

Project description

Step-down transformer

Neon Lamp

Step Up Transformer

Insulator

Single-phase electric power

Conclusion and Future Scope

References


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Documents

66 Kv Single Face Distribution 2