Chapter 10

Question 1

1. Technician A says that an ac electric motor converts electrical energy into mechanical torque. Technician B says that when mechanical torque is applied to an ac motor, it can output electrical energy. Who is correct?
   A. Technician A only
   B. Technician B only
   C. Both A and B
   D. Neither A nor B

Answer 1

C both

Question 2

2. What is currently the common method of cooling a traction motor in most EV drive trains?
   A. Natural convection
   B. Forced-air cooling circuit
   C. Forced-liquid cooling circuit
   D. EV electric motors do not have to be cooled

Question 3

3. What is the advantage of using multi-phase over single-phase ac traction motors in EVs?
   A. More efficient operation
   B. Lower operating temperatures
   C. Alternating current frequency ripples can be smoothed out
   D. All are correct.

Answer 3

C alternating current frequncy ripples can be smoothed out

Question 4

4. Technician A says that EV traction motors typically have higher power ratings than the ICEs used in an equivalent vehicle. Technician B says that the peak torque ratings for EV traction motors tend to be lower than those used in an equivalent ICE by a significant margin. Who is correct?
   A. Technician A only
   B. Technician B only
   C. Both A and B
   D. Neither A nor B

Answer 4

A tech A

Question 5

5. What is used to quantify electromotive force (EMF)?
   A. Amps
   B. Volts
   C. Ohms
   D. Watts

Answer 5

B volts

Question 6

6. When electrical energy is transferred without physical contact, which of the following terms best describes what has occurred?
   A. Conduction
   B. Grounding
   C. Induction
   D. Pulsing

Answer 6

A conduction

Question 7

7. What type of traction motor is used in a current Chevrolet Bolt?
   A. Direct current series-wound
   B. Synchronous permanent magnet
   C. Asynchronous
   D. Single-phase ac

Answer 7

B synchronous permanent magnet

Question 8

8. Technician A says that the traction motors used in EV drive trains must be mounted transversely. Technician B says that the front and rear axle traction motors used in a 2020 Tesla Model 3 are identical. Who is correct?
   A. Technician A only
   B. Technician B only
   C. Both A and B
   D. Neither A nor B

Answer 8

D neither

Question 9

9. What results when a conductive wire is wound around a rod and current flows through it?
   A. Source voltage is increased.
   B. Source voltage is decreased.
   C. Magnetic field is intensified.
   D. Magnetic field is weakened.

Answer 9

C magnetic field is intensified

Question 10

10. Which of the following terms means the same thing as stall torque?
    A. Locked rotor torque
    B. Breakdown torque
    C. Torque rise rpm
    D. Motor overrun torque

Answer 10

A locked rotor torque

Question 11

11. Which of the following is likely to reduce ac conductor skin effect in wiring required to conduct a fixed value current?
    A. Using thicker wire
    B. Using multiple separate wires
    C. Using thicker insulation
    D. Using aluminum in place of copper wire

Answer 11

B multiple wires

Question 12

12. Technician A says that a direct-drive traction motor with fixed ratio reduction gearing is commonly used in EV drive trains. Technician B says that some EVs use a pair of transverse-mounted motors at each axle end to provide traction torque. Who is correct?
    A. Technician A only
    B. Technician B only
    C. Both A and B
    D. Neither A nor B

Answer 12

B tech b

Question 13

13. Assuming similar powertrain output requirements, which of the following electric drive train technologies would enable the use of smaller sectional sizes of wire to be used to connect a power management electronics (PME) module to a traction motor?
    A. Permanent magnet motors
    B. Three-phase traction motors
    C. Six-phase traction motors
    D. Nine-phase traction motors

Question 14

14. Technician A says that an advantage of a nine-phase over three-phase traction motor is higher torque output. Technician B says that a disadvantage of six- and nine-phase traction motors is less efficient use of the wiring that connects the power management electronics (PME) module to the motor. Who is correct?
    A. Technician A only
    B. Technician B only
    C. Both A and B
    D. Neither A nor B

Answer 14

C both

Question 15

15. Which of the following electric powertrain layouts would provide the most energy efficient torque transfer between the traction motor(s) and drive wheels?
    A. Single longitudinal-mounted motor, transmission, differential, axle shafts
    B. Single longitudinal-mounted motor, differential, axle shafts
    C. Single transverse-mounted motor, axle shafts
    D. Twin transverse motors mounted at each drive axle wheel-end