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

The breaker is operating at too high a voltage

Answer

The breaker trip mechanism is faulty

Answer

Excessive arc energy during normal operation

Question 2

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

Accepted Answer

The opening and closing times meet manufacturer specifications

Answer

The breaker's voltage rating is correct

Answer

The breaker can withstand short-circuit currents

Answer

The insulation resistance is adequate

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

Contact resistance and current-carrying capacity

Answer

The mechanical operation speed of the breaker

Answer

Proper calibration of the trip unit

Question 4

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

Accepted Answer

Arc interruption only, with separate solid insulation

Answer

Lubrication of mechanical components

Answer

Both arc interruption and insulation

Answer

Cooling of the current-carrying conductors

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

It ensures the breaker can carry maximum rated current

Answer

It confirms the breaker's interrupting rating

Answer

It measures the contact gap distance

Question 6

SF6 gas circuit breakers require which special precaution during maintenance?

Accepted Answer

SF6 gas must be recovered and reclaimed, not vented to atmosphere

Answer

The breaker must be energized during all tests

Answer

The breaker contacts must be replaced at every maintenance interval

Answer

Water must be added to the SF6 to improve arc interruption