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CDTA Technical Training Center
ELECTRICAL
CDTA Technical Training Center
ATOMIC STRUCTURE
Protons – positive charge
Electron – negative charge
Neutron - neutral
Electricity is the movement of electrons from atom to atom
CDTA Technical Training Center
ELECTRON FLOW
CONDUCTOR - Materials which have extra electrons that will move freely Gold, silver, copper, lead
INSULATOR - Materials that do not allow for free electron movement Glass, plastic, rubber
SEMI-CONDUCTOR - Material which has some properties of a conductor and some properties of an insulator An example would be a diode
CDTA Technical Training Center
BASIC PROPERTIES OF ELECTRICITY
LIKE CHARGES REPEL
OPPOSITE CHARGES ATTRACT
CDTA Technical Training Center
ELECTRICAL THEORY
ELECTRON THEORY – Electrons flow negative to positive
CONVENTIONAL THEORY – Electrons flow positive to negative
CDTA Technical Training Center
Electron Theory
Conventional Theory
+_
Current Flow Theories
CDTA Technical Training Center
ELECTRICAL MEASUREMENTS
VOLTAGE – Force that causes electron flow
EMF, push, pressure, potential difference
Symbol – E
Unit of measurement – V
Checking – voltmeter ; use leads in parallel with source.
CDTA Technical Training Center
ELECTRICAL MEASUREMENTS
AMPERAGE – Rate of current flow through a conductor.
Intensity, flow, current
Symbol – I
Unit of measurement – A
Checking – ammeter ; use leads in series with circuit (or inductive pick-up)
Note; wire gauge is determined by amperage draw.
CDTA Technical Training Center
ELECTRICAL MEASUREMENTS
RESISTANCE – The opposition to current flow through a conductor. Symbol – R Unit of measurement –
ohms Checking – ohmmeter;
connected in a series loop of an isolated circuit or component. Note – circuit must
contain no voltage when checking resistance
CDTA Technical Training Center
ELECTRICAL MEASUREMENTS
RESISTANCE – The opposition to current flow through a conductor
Infinity – open circuit; no current flow
Low resistance – short; high current flow
High resistance – corrosion; low current flow
CDTA Technical Training Center
LAWS OF ELECTRICITY
VOLTS = AMPS x OHMS (Ohms Law)
ELECTRONS TAKE THE PATH OF LEAST RESISTANCE
ELECTRON FLOW THROUGH A CONDUCTOR WILL CREATE A MAGNETIC FIELD
WATTS = AMPS x VOLTS
CDTA Technical Training Center
Types of Current
Direct current – (DC) electron flow in one direction only
Alternating current – (AC) electron flow changes direction many times per second
CDTA Technical Training Center
CURRENT FLOW
TYPES OF CIRCUITS
Series circuit
Parallel circuit
Series – parallel circuit
CDTA Technical Training Center
CURRENT FLOW
SERIES CIRCUIT
All controls and current consuming devices are connected in a single line.
One path from source through loads to ground.
+-
12 Volt
CDTA Technical Training Center
OHMS LAW
If two values are known in a circuit, the remaining value can be found using ohms law
E=IxR
I=E/R
R=E/I
E
I R
CDTA Technical Training Center
CURRENT FLOW
SERIES CIRCUIT LAWS
Connecting loads in series
Voltage drops across loads
Amperage remains constant
Resistances are added
CDTA Technical Training Center
Series Circuit
+-
12 Volt
Fuse
1 OHM 3 OHM
CDTA Technical Training Center
CURRENT FLOW
PARALLEL CIRCUITS
Devices are connected in a parallel line providing several current paths to ground.
+-
12 Volt
Fuse
CDTA Technical Training Center
CURRENT FLOW
PARALLEL CIRCUIT LAWS
Loads connected in parallel
Voltage remains constant
Amperages are added
Resistance is divided
CDTA Technical Training Center
Parallel Circuit
+-
12 Volt
Fuse
1
OHM
3
OHM
CDTA Technical Training Center
CURRENT FLOW
SERIES–PARALLEL CIRCUITS
Combination of each type of current path
Rules of each circuit apply
+-
12 Volt
Fuse
Rheostat
(Variable resistor)
CDTA Technical Training Center
OHM’S LAW VISUALIZEDAmperage and Resistance
12V
High
Resistance
Voltage
Constant
Low
Current Flow
CDTA Technical Training Center
OHM’S LAW VISUALIZEDAmperage and Resistance
12V
Low
ResistanceVoltage
Constant
High
Current Flow
CDTA Technical Training Center
OHM’S LAW VISUALIZEDAmperage and Voltage
16V
Resistance
Constant
High
Voltage
High
Current Flow
CDTA Technical Training Center
OHM’S LAW VISUALIZEDAmperage and Voltage
9V
Resistance
Constant
Low
Voltage
Low
Current Flow
CDTA Technical Training Center
CIRCUIT MALFUNCTIONS
OPEN CIRCUIT
SHORT CIRCUIT
GROUNDED CIRCUIT
CDTA Technical Training Center
CIRCUIT MALFUNCTIONS
OPEN CIRCUIT
SHORT CIRCUIT
GROUNDED CIRCUIT
+-
12 Volt
Fuse
CDTA Technical Training Center
CIRCUIT MALFUNCTIONS
OPEN CIRCUIT
SHORT CIRCUIT
OHMS
4
Fluke
OHMS
1
Fluke
CDTA Technical Training Center
CIRCUIT MALFUNCTIONS
OPEN CIRCUIT
SHORT CIRCUIT
GROUNDED CIRCUIT
+-
12 Volt
Fuse
CDTA Technical Training Center
CIRCUIT MALFUNCTIONS
Shorted or grounded components can damage circuits due to additional current flow.
To protect circuits, fuses or circuit breakers are used
CDTA Technical Training Center
CIRCUIT PROTECTION
FUSE – A thin metal strip designed to break (open) at a specific current draw.
Once a fuse is blown (opens) it must be replaced
Fuses come in various amperage ratings –USE CORRECT FUSE
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FUSE TYPES
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FUSE RATING
CDTA Technical Training Center
CIRCUIT PROTECTION
CIRCUIT BREAKER – Uses a heat sensitive bi-metallic strip designed to break contact in an overload condition.
Circuit breakers can be manual reset or auto reset.
When replacing a circuit breaker use correct rating.
CDTA Technical Training Center
WIRE GAUGE RATING
A.W.G. – American Wire Gauge
The higher the number the smaller the diameter of the wire.
Large diameter = less resistance
Smaller diameter = more resistance
10 Gauge 18 Gauge
CDTA Technical Training Center
ELECTRICAL COMPONENTS
BATTERIES
Purpose
Energy for cranking
Supply current when demand exceeds output of charging system
Stabilize voltage/dampen voltage spikes
CDTA Technical Training Center
ELECTRICAL COMPONENTS
BATTERIES
SAFETY
While charging, batteries produce hydrogen gas that WILL EXPLODE if exposed to open flame or spark
Acid will burn – Protect eyes, skin, and clothing
CDTA Technical Training Center
CDTA Technical Training Center
ELECTRICAL COMPONENTS
BATTERIES Construction
Hard plastic case
Plates; made of lead alloy Positive plate –
lead peroxide
Negative plate –sponge lead
Separator plate -PVC
CDTA Technical Training Center
ELECTRICAL COMPONENTS
BATTERIES
Cell Construction
Negative and positive plates alternate; there is one more negative plate to occupy the exposed end of each group.
4D battery has 19 plates per cell.
8D battery has 27 plates per cell.
Each cell is filled with electrolyte
CDTA Technical Training Center
ELECTRICAL COMPONENTS
BATTERIES
Construction
Electrolyte; a solution that consists of sulfuric acid in water
64% water + 36% acid = electrolyte
CDTA Technical Training Center
ELECTRICAL COMPONENTS
BATTERIES
Each cell will produce approximately 2.2 volts
Six cells connected in series will produce a 12 volt battery (13.2 volts)
CDTA Technical Training Center
ELECTRICAL COMPONENTS
BATTERY RATINGS Cold Cranking Amps (CCA) – cranking
current available at 0 degrees 8D battery = 900 CCA
4D battery = 550 CCA
Amp Hours (AH) – Amp hours is determined by placing a specific load on a battery and measuring the time required for it to discharge
CDTA Technical Training Center
ELECTRICAL COMPONENTS
BATTERY CHARGING
Restores the active chemicals of the plates and the electrolyte to their original condition, by feeding direct current to the cell.
CDTA Technical Training Center
ELECTRICAL COMPONENTS
BATTERY CHARGING
Connecting a charger
Red clamp to positive terminal
Black clamp to negative terminal
NOTE – when disconnecting batteries remove negative cable first; when connecting cables connect negative last.
CDTA Technical Training Center
ELECTRICAL COMPONENTS
Battery Tests
Specific gravity
Load test
CDTA Technical Training Center
ELECTRICAL COMPONENTS
Specific Gravity
The weight of a substance in relation to that of water
Affected by temperature
For every 10* F above 80* add .004 pts.
For every 10* F below 80* subtract .004 pts.
Measured at each cell with hydrometer
Indicates a cell’s STATE OF CHARGE
CDTA Technical Training Center
ELECTRICAL COMPONENTS
BATTERY TESTING
Hydrometer; An instrument that measures the specific gravity of electrolyte
1.280 is full charge at 80* F
.025 difference between cells indicates a defective battery.
CDTA Technical Training Center
ELECTRICAL COMPONENTS
Load Test
A carbon pile load is connected to a fully charged battery for 15 seconds and minimum voltage is recorded
The load is equal to 1/2 the CCA rating of the battery
Minimum voltage is affected by temperature
Checks WORK CAPABILITY of the battery
CDTA Technical Training Center
ELECTRICAL COMPONENTS
Load Test Minimum Voltages Temp. Min. Volts
70* 9.6
60* 9.5
50* 9.4
40* 9.3
30* 9.1
20* 8.9
10* 8.7
0* 8.5
CDTA Technical Training Center
ELECTRICAL COMPONENTS
BATTERY MAINTENANCE
Check battery state of charge (hydrometer)
Clean terminals and battery casing
Check work capability (load test)
Check cables for stiffness
Check battery hold downs
CDTA Technical Training Center
WATTS LAW
Watts law is used to determine power availability and usage
Watts = Amps x Volts
CDTA Technical Training Center
WATTS LAW
Power sources connected in SERIES
Positive to Negative
Voltages are added
Amperage remains the same
12 Volt 12 Volt
400 AMPS 400 AMPS
24 VOLTS / 400 AMPS
24v x 400a = 9600 Watts
+- +-
= 9600 WATTS
CDTA Technical Training Center
WATTS LAW
Power sources connected in PARALLEL
Positive to positive; negative to negative
Voltage remains the same
Amperages are added
12 Volt 12 Volt
400 AMPS 400 AMPS
12 VOLTS / 800 AMPS
12v x 800a = 9600 Watts
+- +-
= 9600 WATTS
CDTA Technical Training Center
WATTS LAW
12 Volt 12 Volt
400 AMPS 400 AMPS
24 VOLTS / 400 AMPS
24v x 400a = 9600 Watts
+- +-
= 9600 WATTS
12 Volt 12 Volt
400 AMPS 400 AMPS
12 VOLTS / 800 AMPS
12v x 800a = 9600 Watts
+- +-
= 9600 WATTS
CDTA Technical Training Center
RELAYS
Another name for a relay is a magnetic switch
Relays are 12 or 24 volts
Relays normally have 5 posts and are 85,86,87,87a and 30.
85 and 86 is power and ground, 87 and 87a is the switch, 30 is power
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY OPERATION
+
12 Volt
-
85
86
30
8787a
CDTA Technical Training Center
RELAY
Relays are 12 or 24 volt
Determined by voltage placed on coil
+
12 Volt
-
85
86
30
8787a
24 Volt
12 Volt bulb
- +
+
12 Volt
-
85
86
30
8787a
24 Volt
12 Volt bulb
- +
CDTA Technical Training Center
ELECTRICAL COMPONENTS
CHARGING SYSTEM
ALTERNATOR; Theory & operation
REGULATOR; Theory & operation
CDTA Technical Training Center
ELECTRICAL COMPONENTS
CHARGING SYSTEM
CHECKING AND ADJUSTING ALTERNATOR OUTPUT
FULL FIELDING THE ALTERNATOR
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ALTERNATOR OUTPUT TEST
Carbon Pile Load
AMPS
F1 F2
12V Relay
ALTERNATOR
+
24 Volt12 Volt
-- +
F B I
REGULATOR
AMMETER
VOLTMETER
Ignition
27.5
CDTA Technical Training Center
50 “DN” ALTERNATOR
F2 Terminal
F1 Terminal
12 Volt relay terminal
CDTA Technical Training Center
VOLTAGE REGULATOR
Controls output of alternator by controlling the strength of the field coil
Constantly monitors system voltage & adjusts magnetic field accordingly
Stronger field – Higher output
Weaker field – Lower output
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“NOT” CHARGING
+
24 Volt12 Volt
-- +
30
87a 8785
86
F B I
REGULATOR
Alternator indicator light
10
1
CIR
CU
IT
F1 F2
12V Relay
ALTERNATOR
Climate Control
CB 100 Circuit
101
Circuit
To
12
Vo
lt circ
uits
24 V
12 V
GND
F1 F2
Neoplan - Off
CDTA Technical Training Center
CHARGING
+
24 Volt12 Volt
-- +
30
87a 8785
86
F B I
REGULATOR
Alternator indicator light
10
1
CIR
CU
IT
F1 F2
12V Relay
ALTERNATOR
Climate Control
CB 100 Circuit
101
Circuit
John Miller
To
12
Vo
lt circ
uits
24 V
12 V
GND
Neoplan - Charging
CDTA Technical Training Center
FLOW CHART
CDTA Technical Training Center
ELECTRICAL SYMBOLS
CDTA Technical Training Center
CURRENT FLOW
SERIES CIRCUITS
Connecting sources (batteries) in series
Voltages are added
Amperage remains constant
CDTA Technical Training Center
CURRENT FLOW
PARALLEL CIRCUITS
Connecting sources in parallel
Voltage remains constant
Amperage is added