component of electrics

8/20/2019 Component of Electrics

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Automotive Electrical Systems

Basic electrical system

Components

Matthew Whitten

Brookhaven College


Basic circuit components

Power supply

Circuit protection

Conductor

Load

Switch


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Power source

Automobiles use twobasic sources forelectrical power.

Battery: uses chemicalreactions to produce avoltage used duringKOEO ,engine startingand high load KOER.

Alternator: usesrotational force fromthe engine to producevoltage to operate the

automobile whilerunning and rechargethe battery.


Conductors

The conductors are usedto transfer the electricalpower to the loadsthroughout theautomobile.

Various conductorsinclude: copper wiring,

vehicle frame, vehiclebody, powertrain, andmodule casings.

There are situationswhere high resistanceconductors arenecessary: blower motorresistors and cooling fanresistors.


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Circuit protection

Provides a limiter forsituations where toomuch amperage mayflow through theconductors.

Rated in AMPS.

Types:

Fuses

Circuit breaker

Fusible link Thermal limiters


Fuses

Fuses have a thin strip ofmaterial that onceheated by highamperage it meltscreating an open circuit.

Common types used: Standard Blade

Auto-fuse Miniature Blade

Mini-fuse

High amperage Maxi-fuse

Mega-fuse Fusible link cartridge


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Circuit Breaker

Circuit Breakers are usedon circuits thatcommonly see highamperage. (not normal)

Types: Non-cycling circuit

breakers once theamperage exceeds a setamount the breakeropens the circuit untilthe operator resets it.

Cycling circuit breakerwill reset once thebreaker cools. If thecircuit is still in fault thebreaker will reopenupon the high amperage


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Fusible link

Slow circuit protection. Excessively high amperage loads are needed for the link

to create an open circuit. Short term short circuits are not enough to create an

open circuit. (ie. Wrench grounding to frame) Also used in situations where high amperage might be

common for short periods of time.


Fusible link


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Stepped Resistors

Stepped resistorsallow two or morefixed value resistors tobe placed in series tocontrol load operation(speed or illumination)

Selecting differentswitch positions on thecontrol panel adds orsubtracts resistors in

series.


Potentiometer

A potentiometer uses avariable resistor toprovide a voltage signalto indicate the wiper’sposition to a module orcomputer

Not in series with a load.

Circuits associated:A. VREF (normally 5 volts.

B. Signal (varies 0 to 5volts)

C. Signal Return (basicallya monitored Ground)


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Rheostat

Variable resistorused in series withloads to control theamount of voltagesupplied to theload. (continuouslyvariable)


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Diodes

Semiconductor used tocontrol the flowelectricity.

One way electricalvalve

Diodes are used to “clamp voltage spikes”for circuit protection.

Diodes are used to “rectify” AC voltageproduced by thealternator. Converts

AC to DC for vehicleoperation.


Electric motors

Electrical motorsconvert electricalenergy intomechanical action.

The motors use theforces involvedwith magneticfields to create arotational torque.


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Change of magnetic poles


Ignition coil/ AC clutch coil

An ignition coil is used to create high voltage spikesfor spark during ignition operation. Converts @13vto 40Kv.

AC clutch coil is used to produce a magnetic field toapply a clutch plate onto a clutch pulley. It converts@13v into @300 volts.


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Switches

Switches are used tocontrol circuitoperation.

Types: Single pole single

throw Single pole double

throw Ganged switch Momentary contact Temperature

activated Pressure activated Position activated


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Mercury Switches

Contains a capsule partially filled withmercury which makes or brakescontact when switch is tipped.



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Solenoids.

Solenoids are use to perform somemechanical function.

Will also produce voltage spikes due tothere design.


Relays

Relays are used to control a high amperagecircuit with a low amperage control from amodule or switch.

The low amperage circuit is used to create

a magnetic field to close or open contactson the high amperage circuit.

Types:

Standard mini-ISO 5pin relay

Micro-ISO 5 pin

Symmetrical 4 pin

* International Standards Organization


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Relays


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