NETA Circuit Breaker Maintenance 2

Question 1

During a circuit breaker contact resistance test, a high resistance reading typically indicates:

Accepted Answer

Worn, pitted, or corroded contacts

Answer

High contact resistance in a circuit breaker indicates degraded contacts due to wear, pitting from arcing, corrosion, or inadequate contact pressure.

Question 2

The purpose of a circuit breaker timing test is to verify:

Accepted Answer

The opening and closing times meet manufacturer specifications

Answer

Timing tests verify that breaker opening and closing operations occur within the manufacturer's specified time windows, ensuring coordination with other protective devices.

Question 3

What does a dielectric withstand test (hi-pot test) on a circuit breaker verify?

Accepted Answer

Insulation integrity between phases and to ground

Answer

A dielectric withstand (hi-pot) test applies elevated AC or DC voltage to verify that insulation between phases, between phases and ground, and across open contacts can withstand the required voltage without breakdown.

Question 4

Minimum oil circuit breakers (MOCBs) use oil primarily for:

Accepted Answer

Arc interruption only, with separate solid insulation

Answer

Minimum oil circuit breakers use oil only in the interrupter chamber for arc quenching, while the main insulation is provided by solid insulating materials, using less oil than bulk oil breakers.

Question 5

During circuit breaker maintenance, what is the significance of checking the minimum pickup of the trip unit?

Accepted Answer

It verifies the minimum current at which the breaker will trip

Answer

Minimum pickup (or pickup current) is the minimum fault current level at which the trip unit will initiate a trip. Verifying this ensures the breaker provides proper protection.

(NETA) InterNational Electrical Testing Association Certified Technicians Practice Test

(NETA) InterNational Electrical Testing Association Certified Technicians Practice Test

NETA Circuit Breaker Maintenance 2