Electrical Repair Flashcards

1
Q

How fast, approximately, does a SI engine need to spin to start?

A

40-60rpm.

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2
Q

How fast, approximately, does a CI engine need to spin to start?

A

80-100rpm

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3
Q

What are the major components of the starting system?

A

Battery, ignition switch, starter relay, starter motor, and ring gear.

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4
Q

What are the common types of ignition switch systems?

A

Key start, remote starting, push button, stop/start, or hybrid

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5
Q

How does a key start system work?

A

When the key is turned, it sends voltage to terminal 30 on the starter, which allows the battery to send voltage to terminal 50, which causes the starter to turn.

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6
Q

How does remote starting work?

A

The remote starting system is similar to the basic system, although it has an ECU, and when the engine speed rises above cranking speed, the ECU cuts the voltage to the starter relay.

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7
Q

How does push button start work?

A

The push button start system usually utilises the remote starting system, although it uses a button instead of a key.

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8
Q

What happens if a conductor is placed between the N and S poles of a permanent magnet?

A

The lines of magnetic force from the conductor and magnet interfere, causing the magnetic flux to increase at the bottom of the conductor and decrease at the top.

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9
Q

How is strength of EMF (electromagnetic force) calculated?

A

F = B (density of flux) * I * t (length of conductor)

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10
Q

What does the commutator do in a motor?

A

It swaps the polarity of the conductor so that it will continue to rotate in the correct direction as it passes the top or bottom of a cycle.

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11
Q

How does a series wound DC motor work?

A

The field coil and armature coil are connected in series. Current flows through the armature coil and field coil in a single series circuit.

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12
Q

How does a shunt wound DC motor work?

A

The field coil and armature coil are connected in parallel. Current flows through the armature coil and field coil via separate parallel circuits.

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13
Q

How does a compound DC motor work?

A

This motor uses a combination of series and parallel circuits to connect the field coil and armature coil.

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14
Q

What beneficial characteristic does a series wound DC motor have for a starter motor?

A

It draws high current and develops large torque at low speed.

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15
Q

What are the characteristics of a reduction starter motor?

A

It uses a motor which puts out less torque than a conventional motor, although it achieves the same torque by using gear reduction. The plunger of the magnetic switch acts directly on the pinion as it’s on the same axis.

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16
Q

What are the characteristics of a conventional type starter motor?

A

The armature and pinion gear are on the same axis and spin at the same speed. A drive lever attached to the magnetic switch plunger pushes the pinion.

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17
Q

What are the characteristics of a planetary type starter motor?

A

It is similar to the conventional type, although it uses a planetary gear set to increase drive torque so that a smaller armature can be used.

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18
Q

What are the characteristics of a planetary reduction segment conductor type starter motor?

A

This starter motor is very similar to the planetary type, although uses permanent magnets instead of field coils.

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19
Q

What are the major components of a starter motor?

A

Magnetic switch, armature, yoke sub-assembly, brush and brush holder, overrunning clutch, and pinion gear and helical spline.

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20
Q

What does the magnetic switch in a starter motor do?

A

It operates engagement of the pinion gear and controls the flow of electricity through the motor, it works the same as a solenoid.

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21
Q

What does the armature do in a starter motor?

A

It generates the rotation of the motor,

22
Q

What does the yoke sub-assembly do in the starter motor?

A

It produces a magnetic field for the motor to operate. It also acts as an outer case for the field coils.

23
Q

What do the brushes do in the starter motor?

A

They maintain a fixed direction of current flow between the armature and coil. The brush springs help the armature to stop spinning after the engine stops due to frictional characteristics.

24
Q

What does the overrunning clutch do in a starter motor?

A

It prevents damage to the pinion when the engine starts by using rollers which transmit torque in one direction.

25
Q

What kind of design does the pinion gear / ring gear have for easy engagement?

A

Chamfered edges.

26
Q

What causes the pinion gear to engage with the ring gear?

A

A combination of the rotating force of the armature, the pull-in force of the magnetic switch, and the thrust force of the helical spline.

27
Q

What causes the pinion gear to disengage with the ring gear?

A

When the engine starts running, the overrunning clutch allows the pinion to spin freely which releases pressure, also, the compressed return spring pulls the pinion back when the magnetic force is no longer applied.

28
Q

Why is it important to have a brake mechanism in the starter?

A

If the engine is attempted to be cranked again while the pinion is still spinning from inertia, it could damage the teeth on the pinion gear.

29
Q

How does a brake mechanism work on a starter?

A

When the return spring retracts the pinion gear, the brake spring and lock plate pull the armature against the brush holder.

30
Q

What is the reduction ratio of a planetary starter motor?

A

1:5

31
Q

What type of magnets are used in a PS starter?

A

Main magnets and interpolar magnets.

32
Q

What is the charge warning light’s job in the charging system?

A

The light will turn on if the ignition switch is in the “on” position, but either no voltage, or too much voltage is being supplied.

33
Q

How does a hybrid charging system work?

A

A hybrid system uses the inverter/converter assembly to generate a 12v supply to non-HV systems and the 12v battery.

34
Q

What happens if you push a conductor through magnetic flux?

A

EMF will be created in the conductor.

35
Q

What is electromagnetic induction?

A

When a conductor passes through a magnet and creates EMF in the conductor.

36
Q

What is Fleming’s right hand rule?

A

If you bend your right hand’s middle finger and point out your thumb and pointer finger. The thumb is the direction of motion, the pointer finger is the direction of flux, and the middle finger is the direction of current.

37
Q

What is the formula for EMF created from passing a conductor through a magnet?

A

EMF = N (number of lines of flux cut through) / t (seconds)

38
Q

What three things impact EMF created through electromagnetic induction?

A

Size of magnetic field, speed of conductor movement, and number of conductors (coil windings).

39
Q

How does an alternator regulate voltage?

A

The electromagnet alters the amount of magnetic flux in accordance with engine rpm.

40
Q

How far apart are the coils spaced in an alternator’s rotor?

A

120 degrees.

41
Q

What type of electricity does an alternator produce?

A

Three-phase AC.

42
Q

How many diodes are used in an alternator’s rectifier, and what is the conversion called?

A

It uses 6 diodes, and it creates full wave rectification.

43
Q

In reference with rectifiers, what is the danger of reversing battery polarity?

A

Excessive current will be placed on the diodes and destroy them.

44
Q

How many pairs of magnetic poles does an alternator’s rotor utilise?

A

6 pair, 12 poles total.

45
Q

What component in an alternator generates the most heat? And where is the heat transferred to?

A

The stator, and the heat is transferred to the drive-end frame.

46
Q

What components are in a rectifier?

A

Output terminal, holder fin (heat shrink), and diodes.

47
Q

Why is the holder fin so important in a rectifier?

A

The diodes in the rectifier create a lot of heat, and the semi-conductor material is sensitive to heat, so the holder fin needs to pull the heat away from the diodes.

48
Q

What does the IC regulator consist of?

A

The hybrid integrated circuit, heat-releasing fins, and the connector.

49
Q

What are the two types of IC regulators used?

A

Battery sensing type, and alternator sensing type.

50
Q

The IC regulator, as well as regulating voltage, gives warning when certain conditions arise, what are those conditions?

A

Open/short in rotor coil, S terminal disconnected, B terminal disconnected, Over-voltage condition.

51
Q

What is a “zener diode” and how does it work?

A

It was used on older regulators and was used when there was too much charge, it only allows current to flow when high enough voltage is applied. So if the voltage was too high, the zener diode would allow current flow and would disrupt the rest of the circuit, limiting field coil current.

52
Q

What is the current IC regulator design called?

A

MIC - monolithic integrated circuit.