Question 1

Which of the following methods of charging a CEV from the grid is contact-free?

Accepted Answer

A)   Inductive
B)   Overhead pantograph
C)   Stationary pantograph
D)   CCS type 2 coupler A

Question 2

How many NMC cells are required to produce a pack voltage of over 80 VDC?

Accepted Answer

A)   1
B)   8
C)   12
D)   22 D

Question 3

When a regenerative braking cycle is engaged in a vehicle with an electric powertrain, which of the following should be true?

Accepted Answer

A)   The driveshaft turns in reverse.
B)   The ICE compression retarder is actuated.
C)   The traction motor generates AC.
D)   The traction motor generates DC. C

Question 4

Technician A says that the peak torque ratings for CEV traction motors exceeds that used in an equivalent ICE by a significant margin. Technician B says that CEV traction motors typically have higher power ratings than the ICEs used in an equivalent vehicle. Who is correct?

Accepted Answer

A)   Technician A only
B)   Technician B only
C)   Both A and B
D)   Neither A nor B

Question 5

When a li-ion battery is charged, which of the following is true?

Accepted Answer

A)   lithium ions move from the cathode to the anode
B)   lithium ions move from the anode to the cathode
C)   lithium ions are discharged into the ground circuit
D)   a thermal runaway is likely

Question 6

Which of the following li-ion cells has proven to be the most thermally stable?

Accepted Answer

A)   LFP
B)   NCA
C)   LTO
D)   NMC

Question 7

Technician A says that using multiple battery banks in parallel increases the electrical energy density. Technician B says that CEVs use multiple battery banks in series to increase the nominal operating voltage. Who is correct?

Accepted Answer

A)   Technician A only
B)   Technician B only
C)   Both A and B
D)   Neither A nor B

Question 8

What device performs the high speed switching required in a solid state inverter?

Accepted Answer

A)   FET
B)   IGBT
C)   Diode
D)   Electromechanical rotary wheel

Question 9

Technician A says that that some CEVs are driven by a single, longitudinally-mounted (inline) traction motor directly coupled to drive wheels. Technician B says that a CEV drive axle can use a pair of in-axle traction motors coupled to reduction gearing in each wheel assembly. Who is correct?

Accepted Answer

A)   Technician A only
B)   Technician B only
C)   Both A and B
D)   Neither A nor B

Question 10

What would be the advantage of using a 9-phase traction motor over a 3-phase motor in a CEV?

Accepted Answer

A)   Lower cable operating temperatures
B)   Use of lower sectional area wiring
C)   Increased power
D)   All of the above

Question 11

Which of the following cities was the first to eliminate diesel engines from its transit bus fleet?

Accepted Answer

A)   Chicago
B)   Houston
C)   Los Angeles
D)   New York City

Question 12

Which of the following is true of the traction motor/generator used in a CEV?

Accepted Answer

A)   It generates multi-phase AC power.
B)   It requires the use of an inverter.
C)   Output must be rectified to DC to be stored battery banks.
D)   All of the above.

Question 13

Which of the following correctly describes a typical CEV traction motor?

Accepted Answer

A)   Series-wound 600 volt DC motor
B)   Series-wound 24 volt DC motor
C)   Synchronous 24 volt single phase AC motor
D)   Synchronous 600 volt 3-phase AC motor

Question 14

Where is a CEV string control unit (SCU) normally located?

Accepted Answer

A)   Engine ECM
B)   Inverter module
C)   Battery disconnect unit (BDU) 
D)   Chassis management module

Question 15

What frequency AC is used on the North American grid?

Accepted Answer

A)   600 hertz
B)   120 hertz
C)   60 hertz
D)   24 hertz

Question 16

Technician A says that li-ion packs are arranged in parallel to form a string. Technician B says that battery strings are arranged in series to form a bank. Who is correct?

Accepted Answer

A)   Technician A only
B)   Technician B only
C)   Both A and B
D)   Neither A nor B

Question 17

Technician A says that a CEV pantograph can be a permanent station fixture. Technician B says that a CEV stationary pantograph can uses a flexible parallelogram to enable its contact rails to connect with contactors on the vehicle. Who is correct?

Accepted Answer

A)   Technician A only
B)   Technician B only
C)   Both A and B
D)   Neither A nor B

Question 18

Which of the following best describes the source of the energy recovered during regenerative braking in an electric powertrain?

Accepted Answer

A)   Battery banks
B)   Inverter module
C)   Traction motor
D)   Vehicle momentum (kinetic energy)

Question 19

Where would you most likely find a pantograph on a CEV transit bus?

Accepted Answer

A)   In the forward engine compartment
B)   In the rear engine compartment
C)   Below the floor deck
D)   On the roof

Question 20

Technician A says that although the voltage is high in a CEV, there is usually insufficient available current to cause an injury. Technician B says that the RESS in a CEV can output HV exceeding 600 volts. Who is correct?

Accepted Answer

A)   Technician A only
B)   Technician B only
C)   Both A and B
D)   Neither A nor B

Exam 41: Electric Powertrains

Which of the following methods of charging a CEV from the grid is contact-free?

How many NMC cells are required to produce a pack voltage of over 80 VDC?

When a regenerative braking cycle is engaged in a vehicle with an electric powertrain, which of the following should be true?

Technician A says that the peak torque ratings for CEV traction motors exceeds that used in an equivalent ICE by a significant margin. Technician B says that CEV traction motors typically have higher power ratings than the ICEs used in an equivalent vehicle. Who is correct?

When a li-ion battery is charged, which of the following is true?

Which of the following li-ion cells has proven to be the most thermally stable?

Technician A says that using multiple battery banks in parallel increases the electrical energy density. Technician B says that CEVs use multiple battery banks in series to increase the nominal operating voltage. Who is correct?

What device performs the high speed switching required in a solid state inverter?

Technician A says that that some CEVs are driven by a single, longitudinally-mounted (inline) traction motor directly coupled to drive wheels. Technician B says that a CEV drive axle can use a pair of in-axle traction motors coupled to reduction gearing in each wheel assembly. Who is correct?

What would be the advantage of using a 9-phase traction motor over a 3-phase motor in a CEV?

Which of the following cities was the first to eliminate diesel engines from its transit bus fleet?

Which of the following is true of the traction motor/generator used in a CEV?

Which of the following correctly describes a typical CEV traction motor?

Where is a CEV string control unit (SCU) normally located?

What frequency AC is used on the North American grid?

Technician A says that li-ion packs are arranged in parallel to form a string. Technician B says that battery strings are arranged in series to form a bank. Who is correct?

Technician A says that a CEV pantograph can be a permanent station fixture. Technician B says that a CEV stationary pantograph can uses a flexible parallelogram to enable its contact rails to connect with contactors on the vehicle. Who is correct?

Which of the following best describes the source of the energy recovered during regenerative braking in an electric powertrain?

Where would you most likely find a pantograph on a CEV transit bus?

Technician A says that although the voltage is high in a CEV, there is usually insufficient available current to cause an injury. Technician B says that the RESS in a CEV can output HV exceeding 600 volts. Who is correct?