Quiz #3 Flashcards
A low-voltage protection circuit is used in electric motor starting equipment to __________.
prevent the motor from restarting automatically on restoration of voltage
Low Voltage Release protection as used in some shipboard motor starter and control equipment will have which of the following characteristics?
They allow the motor to restart upon restoration of normal voltage.
The main difference between a motor control circuit containing low voltage release and low voltage protection is that the latter contains __________.
a momentary-contact start button
BONUS: Which of the listed items will stop a motor due to a reduction in voltage and automatically restart it when the voltage is restored to normal? A Renewable link fuse B Non-renewable link fuse C Low voltage protection circuit D low voltage release circuit
D low voltage release circuit
BONUS: What is the name of the type of motor control circuit that will not permit automatic restarting after power is restored, following a power failure? A low voltage protection B overload lockout C reduced voltage restart D low voltage release
A low voltage protection
An across-the-line starter is typically used for which of the following applications?
Full-voltage starting of motors
Across-the-line starters are used with AC motors to provide __________.
high starting torque
If the contacts of a motor starter or controller fail to drop out when the ‘stop’ button is depressed the __________.
stop contacts have become welded together
If a three-phase induction motor malfunctions and drops to a single-phase (one supply line open) __________.
the motor will continue to run if it is not heavily loaded
When troubleshooting a motor controller, all indications are that a relay coil should be energized. If there were no magnetic pull, with rated voltage measured across the coil, the most probable cause would be that the
coil is open
The wiring diagram for the motor starting circuit shown in illustration EL-0007 indicates __________.
low voltage protection
If the illustrated motor (EL-0007) fails to start and gives a loud hum when the start button is pushed, the problem is __________.
one of the phases to the motor is not energized because of an open motor lead
If the motor fails to start and a voltmeter reading between 1 and 6, as illustrated (EL-0007), indicates line voltage, your next step should be to.
reset and determine the cause of the overload
The motor starts when the start button in the illustration (El-0007) is pushed, but stops when the button is released the trouble is __________.
a faulty holding relay contact ‘Ma’
The illustrated motor (EL-0007) fails to start and gives a loud hum when the start button is depressed, your first action should be to __________.
push the stop button to de-energize the “M” coil
