1. Electronic brakes require extensive maintenance, adjustment, and periodic replacement of worn parts.
a. True
b. False
2. Three-phase electric braking reduces the heat buildup in the motor as compared to single-phase braking.
a. True
b. False
3. A self-contained transformer and rectifier provide the direct current required for braking.
a. True
b. False
4. DC and AC supplies must be connected to a motor at the same time.
a. True
b. False
5. The sudden stopping of a motor by mechanical brakes can often harm the motor or load.
a. True
b. False
Name: Class: Date:
Unit 51 Electric and Electronic Braking
6. It is sometimes difficult to install conventional electromechanical brakes on existing equipment without ____.
a. the use of magnetic switches b. overheating the motor
c. extensive rebuilding d. establishing an arc
7. Taps on current-limiting resistors provide a means of adjusting the ____ torque over a wide range.
a. down b. limit
c. polyphase d. braking
8. It is recommended that the motor starter ____ be included as an integral unit with the brake.
a. never b. sometimes
c. always d. in most cases
9. With dynamic braking for a wound rotor motor, the circuit may provide three braking options, coast stop, medium
stop, and ____ stop.
a. step b. rapid
c. successive d. steep
10. Dynamic braking can easily be demonstrated by applying direct current to an AC induction motor and turning the
____.
a. motor shaft by hand b. operator knob, not pushing it
c. switch to the off position d. transistor on and off several times
Name: Class: Date:
Unit 51 Electric and Electronic Braking