NETA 4 Exam Questions 1/2017

[ddd675]

I wrote my NETA 4 test today... and failed. Here are some tips.
Don't waste your time reading the NETA study material that they give you. I went through it all and did all the Tech Quizzes.... I don't think anything I studied was on the test. NETA updated the exam but didn't update any of the study material. Some of it is outdated and wrong as well.

The study material focuses on Approach Boundaries, testing levels, expected results, NETA ATS & MTS info etc. NONE OF THIS WAS ON THE EXAM.

Here are some of the questions I could remember:

1. What kind of test do you perform on a fibre optic cable?
a. Time domain reflectometry
b. Light domain reflectometry

2. What test value would you use while testing fibre optic cable?
a. dBs

3. At what elevation do ohm readings get effected?
a. 1000m

4. When testing insulation resistance on a MV Motors, at what voltage does it become ambiguous?

5. On a main incoming of a 480V switchgear, what class powermeter should be installed?
a. II
b. III
c. IV
d. V

6. A DCS is sending an auto speed signal for 30HZ via a 0-20mA transducer. The VFD is only outputting 1-3HZ. The mA measured by a mutimeter at the VFD is 10mA. What is the likely issue?
a. High resistance in Auto Speed circuit?
b. AC Component on DC signal

7. A primary injection is to be performed on a transformer 138kV/25kV, 2500kva, 8%Z using a 480V generator connected to the high side with the low side grounded. The expected current in the high side is?

8. A harmonic filter bank consists of a capacitor bank at XXuF and XXXmH. Which harmonic is this bank eliminating?

9. According to ANSI Standards if you can not physically place a lock on a device what extra step needs to be taken to ensure safety.

10. In insulating oil, what gas would indicate partial discharge in the oil?

11. Two 1mH inductors are connected in parallel and in series with two 45uF capacitors connected in parallel. What is the total impedance of the circuit?

12. There is 60 amps measured on the line of a delta transformer secondary. How many amps are in the delta?

13. Two loads are connected to the same soure. Load 1: 1250KVA @ 0.85PF. Load 2: 600KW, 300KVAR. What is the combined load in KVA & PF.

14. What is meant by double insulation?

15. In a 480V solidly grounded system you must _________.
a. Have automatic ground fault tripping
b. Not have automatic ground fault tripping

16. Which SCADA communication is only appropriate for short distances?
a. RS232
b. RS485
c. CAT6
d. Fibre

17. A battery bank has batteries where the terminals are bulged and the seals broken. This is likely from:
a. Improper charging
b. Increasing plate growth
c. Decreasing plate growth

18. Two parallel feeder cables with individual 400:5 CT’s per parallel run are connected to one overcurrent relay per phase. The proper connection would be:
a. Parallel additive with relay set to 800:5
b. Parallel subtractive with relay set to 800:5
c. Series additive with relay set to 400:5
d. Series subtractive with relay set to 400:5

19. A substation has zone ground fault protection. Which statement is true?
a. The main will trip before the feeder breakers
b. The feeder breakers send a block to the main and tie so they don’t trip
c. The feeder breakers send a block the main and tie so they don’t trip until their designated tripping time.
d. The main will trip and block tripping to the other side of the bus

20. Before using a ground and test device you must perform what test every time before use?

21. Which statement is true about a DCS System?
a. Replaces many electromechanical devices

22. A CT circuit with a CT resistance of 15mohm goes to a SEL-751 (.27VA @ 5A) through 125ft of #12 SIS (.988 ohms per 100ft). What is the appropriate CT class?
a. C10
b. C50
c. C100
d. C200

23. What is the IEC 61850 naming structure?

24. What is true about Natural esters oil?
a. Cannot be mixed with mineral oil
b. Has a higher PF than mineral oil

25. What would a reactor placed at the end of a long transmission line be for?

26. What is a wavetrap for?

27. A DC drive with a high carrier frequency could cause issues with
a. AC ripple
b. Pulse width modulation

28. What kind of fault on a transformer is shown on the given waveform?
a. B to ground internal
b. Single phase to ground on high side

29. According to ANSI a newly installed battery bank should be load tested after:
a. 1 year
b. 2 years
c. 4 years
d. 5 years

30. Three single phase transformers feed a load and one faults. Connected in open delta how much load can the 2 units support?
a. 57.7%

31. While testing a 100KVAR 480V 3 phase wye connected capacitor. What would the expected uF be across A-B terminals.

[runewinn]

Just took it today and passed. These study tips were crucial. Thanks a ton.

[slts1991]

Thanks for the input. Here are some answers

Please correct me if I'm wrong:

1.A (Optic time domain reflectometry)

5.C

7. You did not specify the xfmr connection but assuming it is Delta/Wye my calculation is 3007.12 A primary

8. 5th Harmonic

10. Acetylene

11. 0.41 miliohms

12. Not enough info but after assumptions 103.92 A???

13. 1825.8 @ 0.91 PF

14. Requires no connection to ground (earth)

15.B (not required, NEC 700.6(D))

16.C (most likely since CAT6 length limit is 100 m)

17.B

18.A

19.C

20. Dielectric withstand @ 75% of Factory acceptance testing value (IEEE C37.20.6)

22.D (C200 since i came up with a burden of aprox 1.25 ohms which exceed the error limit of a C100)

24.B (0.89 vs 0.92)

25 The line reactor compensates for line capacitance, mitigates voltage transients and limits the fault currents. I don't know what the answers were there.

26. They are used in PLC (Power Line Carrier) to trap the high frequency communication signals typical of 400 Hz

29.D maybe? (Lead-acid is 5 years and VRLA 12-18 months so we need more info here)

31. 2.3 micro-farad

[slts1991]

Question 2 correct answer db/km
Question 14 correct answer is double layer insulation

[slts1991]

Passed my level 4 yesterday and your questions were very helpful. I will post a couple of the questions as soon as my card is issued (4-6 weeks)

Thank you very much !

[slts1991]

Here are some more questions:

1. Which order harmonic would be effectively removed from a power system by applying a single-tuned filter with a 0.55 μF capacitor and a 500 mH inductor?
(A)3
(B) 5th –correct
(C) 7th
(D)13

2. When attaching a lock to a disconnecting means is not possible and a tag is
used, which one of the following requirements applies?
(A) At least one additional safety measure must be employed to reduce hazard

3. The trip area of an mho, loss-of excitation relay primary resides in which quadrants of an R-X diagram?
(A) +R, +X and -R, +X
(B) +R, -X and -R, -X - CORRECT
(C) +R, -X and +R, +X
(D) -R, +X and -R, -X

4. In a directional comparison blocking (DCB) scheme, why is a communications signal transmitted?
(A) To communicate to the remote end that the fault is in the reverse direction of the local end - CORRECT
(B) To communicate to the remote end that the fault is in line and to trip instantly

5. What is the purpose of a preventive transformer? (Read LTC functionality)

6. Which of the following statements is correct with regards to ground-fault protection for a 480 V, 1200 A, solidly grounded emergency system? (READ NEC)
(A) Automatic ground-fault tripping is prohibited
(B) Automatic ground fault tripping is required
(C) An audible and visual signal is required - CORRECT

7. For a 480 V system, the arcing-fault magnitude relative to the available bolted- fault magnitude is approximately:
(A) 25%
(B) 50%
(C) 75%
(D) 90%

8. How is a transformer with a cooling class listed ONAN/OFAF cooled?
http://electrical-engineering-portal...ooling-classes


9. According to NETA-ATS, a required insulating gas analysis on a SF6 switch is:
(A) naturalization number
(B) interfactial tension
(C) moisture content - CORRECT
(D) flash point

10. On an outage that included two medium voltage contactors, one supplies the motor and one a transformer. The fuses are E and R rated, which one goes where?

You need to know what are those fuse types used for. In this case E @ XFMRand R @ contactor
11. What is an IRIG used for in SCADA?
Can't remember all the answer but correct one is Time Synchronization


11. What component of microprocessor power monitor is verified with metering comparison test?
A) CPU
B) SER
C) I/O module - CORRECT

12. What is the main reason to use shunt reactors in power lines?
A) To reduce power system harmonics - CORRECT

13. AC arc flash PPE category table what is the assumption that is listed for each equipment type?
A) Working distance - CORRECT
B) Presence of current limiting devices

14. Which standard addresses equipment grounding?
A) NFPA 70 -CORRECT (this is NEC)
B) NFPA 70B
C) NFPA 70E

15. Advantages of concrete encased grounding electrode

16. What is the maximum allowed frequency variation from nameplate for AC
induction motors?
A) 2%
B) 5%
C) 10% - CORRECT

17. On a LTC when increasing tap what happens to the voltage compared to the neutral posistion?
A) Lineary higher - CORRECT
B) Exponentialy higher
C) Lineary lower
D) Exponentialy lower

18. What is a Buchholz Relay.


READ ABOUT:

IEC 61850 (read about GOOSE as well)
DCS
UL listing
TDCG (oil tests in general)
Vectors (from polar to cartesian and vice-versa)
Infrared testing facts
Fiber optic
Transmission protection
Transmission protection communication facts and types (POTT, PUTT, DCB, DCUB, DTT, pilot wire)
SF6 gas testing
SCADA VFD LTC
Arrestors
Porcelain and polymer insulator advantages and disadvantages
Commissioning facts
Functional tests facts (especially for relays / solid state devices) Tranformer calculations, especially instrument transformers
CT facts and know how to calculate burden and what does the CT class represent
Battery maintenance and troubleshooting
Wavetrap facts (not just what it is)


PRO TIPS:
Consider taking over the counter lechitin capsules, one per day. Start about 2-3 weeks before your test. It doesn't do miracles but it is very cheap and it will help you retain some of the useless junk you will have to memorize for the test that you will never use in your testing career.

[tallyson71]

Thanks so much for posting this info. I had heard about the changes, so it is very nice to see some examples.

I do have some questions I was hoping you, or others could help with?

1. What kind of test do you perform on a fibre optic cable?
Could this be Optical time domain reflectometry

4. When testing insulation resistance on a MV Motors, at what voltage does it become ambiguous?
I couldn't find any information on this. Could the question have been at what IR value (Megohms) does P.I. become ambiguous? (5,000MOhms I think)

Thanks again for taking time to post this.

Shane

[Sanjayo]

4. When testing insulation resistance on a MV Motors, at what voltage does it become ambiguous?

I couldn't find any information on this. Could the question have been at what IR value (Megohms) does P.I. become ambiguous? (5,000MOhms I think)

I agree with your assesment.

If the IR value (at 40 °C) is greater than 5000 MΩ, the PI may be ambiguous and can be disregarded. http://electrominst.com/test-technol...on-resistance/

[joaogemal]

Found this on a NETA Handbook series II - Arc Flash vol. 2:
• Available bolted fault current – The punch behind the arc fault
magnitude. Recall that the magnitude of a low-voltage arcing
fault is approximately 43-57% of the bolted fault value. This implies
that systems with significant bolted fault currents will have
elevated arcing current levels.
Considering the options avilable I would say the best is 50%

[joaogemal]

Found this about question 17:

Positive Post Rise
As a battery ages, the positive grids corrode. This is also known as “growth” and it’s well understood in the industry. It is the primary determining factor in when it’s time to have a retirement party for a battery. In addition to this condition occurring as the battery approaches its end of life, the plates will eventually extend down to the bottom of the cell and at that point, there’s nowhere to go but up. Refer to Figure 4.

Here’s one reason why you’ll see the positive terminals pushing up out of the post seal, exposing an unusual amount of lead above the cover. In many cases, the post seal and surrounding area has limited flexibility to allow the added growth. As a result, the cell cover cracks. Don’t bother breaking out your ohmic testers or load banks.

Batteries that look like this are on death’s doorstep. What’s not expected is to see this occurring early in battery life. This condition can be accelerated with high operating temperatures, excessive and unnecessary cycling and over charging. (here: http://www.alber.com/Papers/TresslerPaperDONE2011_2.pdf)