NETA - InterNational Electrical Testing Association Certified Technicians Power Cable Test Methods Questions and Answers

Question 1

A NETA technician is preparing to perform an acceptance test on a newly installed 15 kV, 100% insulation level, shielded power cable.
According to NETA standards, which Very Low Frequency (VLF) withstand test parameters are correct?

Accepted Answer

19 kV rms for 30 minutes

Answer

10 kV DC for 15 minutes

Answer

22 kV rms for 15 minutes

Answer

34 kV DC for 10 minutes

Question 2

A technician performs a Tan Delta (or Power Factor) test on a service-aged, medium-voltage XLPE cable. The results show a significant increase in the Tan Delta value as the test voltage is stepped up. What is this phenomenon called and what does it most likely indicate?

Accepted Answer

Tip-Up; it indicates widespread degradation such as water treeing.

Answer

Polarization Index; it indicates good insulation.

Answer

Capacitive Discharge; it indicates the test was performed too quickly.

Answer

Sheath Fault; it indicates a break in the cable's concentric neutral.

Question 3

A client requests a DC high-potential (Hipot) test on a 20-year-old, 15 kV XLPE insulated feeder cable during a plant shutdown. Which of the following is the MOST critical reason for a NETA technician to advise against this test and recommend an alternative like VLF?

Accepted Answer

DC testing can induce a space charge in the aged insulation, leading to failure after the cable is returned to service.

Answer

DC test sets are typically too large and heavy for field use.

Answer

The test is likely to cause an immediate cable failure during the test.

Answer

DC Hipot testing is unable to detect common insulation defects in XLPE.

Question 4

During a maintenance insulation resistance test on a medium-voltage cable, a technician records a reading of 800 megohms at 1 minute and a reading of 2000 megohms at 10 minutes. What is the Polarization Index (PI), and how should it be classified according to NETA standards?

Accepted Answer

PI = 2.5; Good/Acceptable

Answer

PI = 0.4; Unacceptable

Answer

PI = 1200; Data Error

Answer

PI = 1.6; Questionable

Question 5

An underground medium-voltage cable has failed a VLF withstand test during commissioning. Which of the following test methods is specifically designed to pre-locate the physical position of the fault along the cable's length?

Accepted Answer

Time-Domain Reflectometry (TDR)

Answer

Tan Delta Test

Answer

Partial Discharge Test

Answer

Sheath Voltage Test

Question 6

An offline Partial Discharge (PD) test is being performed on a newly installed cable system. This test is most effective at detecting which of the following types of defects?

Accepted Answer

Small voids or contaminants introduced into a splice during assembly.

Answer

High resistance in a bolted connection.

Answer

Incorrect phasing of the terminations.

Answer

Overall moisture content evenly distributed along the cable.

A NETA technician is preparing to perform an acceptance test on a newly installed 15 kV, 100% insulation level, shielded power cable.According to NETA standards, which Very Low Frequency (VLF) withstand test parameters are correct?

A NETA technician is preparing to perform an acceptance test on a newly installed 15 kV, 100% insulation level, shielded power cable.
According to NETA standards, which Very Low Frequency (VLF) withstand test parameters are correct?