Electrical Fundamentals - A Flashcards
Type 1 circuit breakers
Cycle off (open) when rating is exceeded, automatically reset when over load is removed from the system. Are a cycling breaker
Type 2 circuit breakers
Come with a heat-producing resistor and bi-metallic strip. The resistor heats up when exposed to high current and pushes the strip away opening circuit.
Are a non-cycling breaker
Type 3 circuit breakers
Are push button manual reset
Fusible link
Stretch of wire 4 awg smaller then the wire in the circuit where it is placed
Headlights must have what power source and breaker?
Low beams must be connected to the constant power terminal. Both high and low beam systems must use type 1 breakers
The daytime running light module sends what voltages out to the lights.
2-3 volts less then normal (9-10 at light)
Night running lights must be connected into what circuit?
Can only run when high beams are on
Clearance lights
Indicate the outer dimensions
Connected to constant power terminal
Marker Lights
Indicate the upper regions
Connected to constant power terminal
Tail Lights
Indicate the rear dimensions, must be red
Connected to the constant power terminal
Switch poles and throws
Poles - the number of power terminals in
Throws - the number of output options
Pulse width modulation
Signal is turned on and off to control the intensity
Turn signal flasher
Either a electromechanical device or a solid state electronic device. The electromechanical flasher will not typically work with the low current draw of LED’s
Solenoids
A electromagnetic device that changes electrical energy into linear energy
What are the 3 categories of solenoids?
Discrete
Proportional
Latching
Discrete Solenoids
A return spring holds the plunger in the relaxed position. Has 2 positions: fully retracted or fully extended
Proportional Solenoid
Provides an infinite number of plunger positions. Movement directly proportional to the voltage applied. Plunger works against a spring. Coil is designed to operate continuously; windings are made of many turns of fine-diameter copper conductors
Latching solenoid
Is a discrete solenoid that remains fixed at the end of its travel when the coil is de-energized. Not internally grounded and are controlled by a current-reversing circuit.
Self-induction
The process of producing a voltage in the coil circuit when current flow stops. Caused by the collapse of the magnetic field
What are the 2 way to prevent switch arcing from self-induction
Install a high value resistor in parallel with the solenoid coil.
Clamping diode is installed
Clamping diode
Self-discharge diode. Acts as a one way check valve, the solenoid coil can be energized normally, but when it produces a self-induced voltage, the current is not allowed to flow and the self-induced voltage will not rise
DC motors use what to create motion?
Electricity and magnetism
Counter electromotive force (CEMF)
The voltage produced by a operating dc motor. Is increased as the speed of the motor is increased, this allows less EMF to flow through. This balance is what governs the speed of the motor
Slow dc motor speed
Generates high levels of torque. The low levels of CEMF mean that high EMF current which generates high levels of heat
What prevents a dc motors generating effect from transmitting voltage
Blocking diode
Permanent magnet DC motors
Uses strong magnets to create stationary magnetic field. CEMF is the only factor that limits the motors speed. Used for high-load applications as they are low maintenance, reliable and provide constant torque
Permanent magnet motors are reversed how?
Changing the polarity of the input of the motor. ILM does this with a double pole double throw switch
Field wound dc motors
Field coils wrap around the pole shoes, which are wound in opposite directions. This creates a magnetic field in the housing
Parallel wound dc motor
Also called shunt motor. Field coils and armature are wound in parallel. This allows the field coils to maintain a even mag. field strength as the speed of the armature fluctuates. It also prevents CEMF from flowing through field
Field wound motor reversal
Requires connection changes inside of the motor. Must add extra switches and make internal motor wiring connections to change the current flow in either armature of field.
What are the 3 ways to control speed in a electric motor
Variable electrical resistance
Multiple shunt windings
Pulse width modulation
Variable resistance speed control
A resistor reduces the amount of voltage that is delivered to the motor. have a thermal fuse a current protection
Multiple Shunt windings
1 set of coils are small, 1 set of coils are large. Slow uses small coils, med. use large coils, high uses both coils to generate field strength
Pulse width modulation
Solid state module connected in series turns electrical current on and off. amount of time on (%) is the duty cycle. the longer the on time the faster the motor spins
What are the 3 ways to dis-engage the cruise control on a truck.
Step on brake pedal
Step on clutch/ auto trans. into neutral
Dash switch
Battery isolation switches
Disconnect main ground just before batteries
When by-passing the battery isolation switch what must be installed?
Fuses on both the positive and negative leads
What can you install to reduce or eliminate interference and static noise?
A series coil (filter choke) or a parallel-connected capacitor the the units power lead
If an entertainment or communication device requires a cable to transmit processed info, it must have?
A proper shield on the cable
What are the 3 most common truck position sensing systems?
Collision warning system (CWS)
Adaptive Cruise Control (ACC)
Collision mitigating system (CMS)
What sensor does a collision avoidance system use to detect that the vehicle is traveling around a curve?
Gyro sensor
Park contacts
A set of switch contacts located inside the motor, they supply power to motor after switch has been turned off until motor returns to park position.
