Show:
CIRCUITS
CIRCUITS
CIRCUITS
CIRCUITS
CIRCUITS
100
What provides undervoltage protection?
undervoltage coil
100
What provides protection when ground circuit continuity is open?
ground monitor relay
100
What provides protection when a phase wire contacts a grounded frame?
ground trip relay
100
What provides protection when two phase wires contact each other?
Instantaneous magnetic unit
100
What provides overload protection?
Thermal element
200
What is commonly used to provide remote tripping?
Shunt trip coil
200
What should be adjusted according to cable size?
instanateous magnetic unit
200
What is commonly used in conjunction with a C.T. which encircles the phase conductors?
ground trip relay
200
What must be energized before the CB can be reset?
undervoltage coil
200
What do the initials C.T. stand for?
current transformer
300
What do the initials P.T. stand for?
Potential transformer
300
What is not an approved method of testing circuit breakers?
Break continuity of a phase conductor
300
Dual element fuses provide protection over single element fuses by providing?
Time delay and overload
300
What source book shouild be used in order to obtain information concerning over current and short circuit protection for feeder wires and motors?
NEC
300
One of the protections provided by the thermal overload relays in the line starter of an AC circuit is... a. short circuit b. undervoltage c. single phase d. over voltage
Single phase
400
The purpose of a fail safe ground check circuit is what?
To monitor conintuously the grounding circuit
400
An undervoltage realy in an AC circuit breaker may be safely inspected by how? a. disconnecting the cable coupler and attempting to reset the circuit breaker b. energizing the trailing cable and lifting up on the cable coupler c. shunting a phase to ground on the equipment served by the breaker
A. disconnecting the cable coupler and attempting to reset the circuit breaker
400
The same rules or laws concerning overload and short circuit protection apply to feeder circuits and trailing cables alike. True or false?
False
400
A grounded current carrying neutral conductor should be fused? True or false?
False
500
What are ten things you should visually examine on or around you section power center?
1. roof and ribs 2. accumulations of water 3. excess dust 4. restraining clamps 5. lid bolts 6. physical damage to the enclosure 7 labeling 8. bridged relays, unplugged relays 9. safe from moving equipment, excess heat 10. insulating mats 11. fire protections equipment 12. magnetic trip settings
500
Describe one method of checking the grounding resistor in the section power box
Open and lockout the visible disconnect outby the power center and check the resistor with an ohmmeter. Disconnect any parallel paths while testing.
500
Describe the proper method of testing the undervoltage relay in a circuit breaker.
Open the circuit breaker, remove the cable coupler, and attempt to reset the circuit breaker. The circuit breaker handle should not latch in the down position.
500
Describe the proper method of testing the ground monitor circuit for a piece of mobile machinery.
Open and lockout the visible disconnect for the equipment and disconnect the pilot or filter ground at the machine. Attempt to reset the circuit breaker.
500
Describe a safe method of testing the ground trip realy for a piece of mobile equipment having series connected contacts.
Unplug the relay if you can do so without any unsafe exposure to energized conductors. The circuit breaker should open. Parallel connnected contacts. Manually operate the contacts if you can do so without any unsafe exposure. Built in testing circuits are avavilable from most manufacturers and rebuilders.