NETA Electrical Testing Procedures & Equipment Operation 3

Question 1

The polarization index (PI) is calculated by dividing the insulation resistance measured at 10 minutes by the reading at:

Accepted Answer

1 minute

Answer

PI = IR at 10 minutes divided by IR at 1 minute; a value of 2.0 or above generally indicates acceptable insulation condition.

Question 2

Which safety precaution is mandatory before connecting a megohmmeter to a large capacitive load such as a cable run?

Accepted Answer

Verify the load is de-energized and fully discharged

Answer

Capacitive equipment stores dangerous charge; the equipment must be de-energized and discharged (verified with a voltmeter) before connecting the megohmmeter.

Question 3

In a transformer turns ratio (TTR) test, a ratio error exceeding what percentage typically triggers further investigation per NETA MTS?

Accepted Answer

0.5%

Answer

NETA MTS flags a turns ratio deviation greater than 0.5% from the nameplate ratio as requiring further evaluation for possible winding faults.

Question 4

When performing an AC high-potential (hipot) test on cable insulation, the test voltage is typically applied for:

Accepted Answer

1 minute

Answer

The standard AC hipot withstand duration for cable insulation per NETA MTS is 1 minute at the specified test voltage.

Question 5

A very low frequency (VLF) test on medium-voltage cable uses a test frequency of:

Accepted Answer

0.1 Hz

Answer

VLF testing uses 0.1 Hz (or 0.01–0.1 Hz range) to stress cable insulation at a fraction of the normal power frequency, reducing the required kVA from the test set.

(NETA) InterNational Electrical Testing Association Certified Technicians Practice Test

(NETA) InterNational Electrical Testing Association Certified Technicians Practice Test

NETA Electrical Testing Procedures & Equipment Operation 3