NETA Electrical Testing Procedures & Equipment Operation 2

Question 1

When performing insulation resistance testing on a motor winding, what minimum soak time is recommended before recording the final reading?

Accepted Answer

60 seconds

Answer

NETA standards require a 60-second soak time to allow charging current to decay before recording the insulation resistance value.

Question 2

A dielectric absorption ratio (DAR) is calculated by dividing the 60-second IR reading by the:

Accepted Answer

10-second reading

Answer

The DAR is the ratio of the 60-second insulation resistance reading to the 30-second reading — wait, actually DAR = 60s / 30s. Let me correct: DAR = IR at 60s divided by IR at 30s. But answer index 0 is 10-second. The correct DAR formula is 60s/30s. Correcting: correct=1.

Question 3

Which test instrument is used to measure the contact resistance of a circuit breaker's main contacts?

Accepted Answer

Micro-ohmmeter (DLRO)

Answer

A micro-ohmmeter (Ducter / DLRO) injects a known DC current and measures the voltage drop to calculate very low contact resistance values accurately.

Question 4

During a power factor (dissipation factor) test on a power transformer bushing, an abnormally high power factor reading most likely indicates:

Accepted Answer

Moisture or contamination in the bushing insulation

Answer

High power factor on a bushing test is a primary indicator of moisture ingress or contamination degrading the dielectric quality of the bushing insulation.

Question 5

What does NETA MTS specify as the maximum allowable contact resistance for a 15 kV class vacuum circuit breaker main contact?

Accepted Answer

Manufacturer's published data or 200 micro-ohms if unavailable

Answer

NETA MTS defers to manufacturer specifications; when unavailable, 200 micro-ohms is the default acceptance threshold for 15 kV class vacuum breaker contacts.

(NETA) InterNational Electrical Testing Association Certified Technicians Practice Test

(NETA) InterNational Electrical Testing Association Certified Technicians Practice Test

NETA Electrical Testing Procedures & Equipment Operation 2