NETA 4 Exam Questions 1/2017

[Ninjaneer]

Just wanted to thank everyone for the input in this thread. Has for sure helped in my studying, me and the PE of the company are taking the test tomorrow, and two of our other guys have taken it this month. I was told to look out for lots of questions on fiber optics, especially optical time domain reflectometry, good amount on batteries and calculating transformer load, and a random question on knowing when Bellville washer is bad, which I haven't found too much info on. Here's a good article for transformer through fault testing I found helpful, and about FR3

http://blog.fauske.com/blog/primary-...r-transformers

https://static1.squarespace.com/stat...3-insulect.pdf

[randyw8483]

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. Methane (Duval's Triangle)

11. 0.41 miliohms

12. 60A / sqrt(3) = 34.64A
On a Wye connection your phase current is equal to your line current but in a delta it is divided by 1.732

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

[SecondGen]

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

Cat IV is is for 3 phase at utility connection.

[SecondGen]

23. What is the IEC 61850 naming structure?

Relay1/XCBR1$ST$Loc$stVal

Relay1 = Logical Device
XCBR1 = Logical Node
ST = Functional Constraint
Loc = Data
stVal = Attribute

http://www.ucaiug.org/Meetings/Austi...0-Tutorial.pdf

[ElectricalTestTech]

Just keep in mind, the new structure of the test recognizes which questions continuously get correct answers. The new structure throws out those questions and inputs different ones so the test can continuously change. While it is good to know the questions put up on this forum, do not expect them to be on your test.

[testguy]

Just keep in mind, the new structure of the test recognizes which questions continuously get correct answers. The new structure throws out those questions and inputs different ones so the test can continuously change. While it is good to know the questions put up on this forum, do not expect them to be on your test.

This is an excellent point. It cant be emphasized enough that when taking the practice exam its important to focus on the subject matter rather than the actual question and answer. We are looking into implementing a similar feature that stops showing you questions after answering them correctly a certain number of times. This way users who frequently take exams will continue to see fresh questions in subsequent exams.

[SecondGen]

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

Here are the max distances for each:

RS232 (50 feet)
RS485 (1220 meters)
CAT6 (100 meters)
Fiber (2000 meters)

[MartyCoyne]

Three coils with a resistance of 4 ohms and impedance of 13 ohms each are connected in wye to a 120/208 Volt panel. What will each wattmeter indicate if three single-phase wattmeters are used to measure the power?

Help: What will each wattmeter indicate?

[young_dad]

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

Using E^2/R = P, you can manipulate to get Xc = E^2/Q (or P).

Plug that in to C=1/(2*pi*f*Xc) gives C = Q/(2*pi*f*E^2) to get phase capacitance of 1151uF. If you used 1/3 of bank KVAR (33.3kVar) and phase voltage (277), you would get a similar result. Both of these will give you a per phase uF.

To me, the straight forward solution is to look at the WYE and solve E^2/R = P. and plug R into Xc formula to get 1152uF.

Caps in series act like resistors in parallel, so take half of that to get the capacitance measure between A-B = 576

I also found this reference which helped me decided which method I will use on the test.

https://www.se.com/us/en/faqs/FA323640/

[young_dad]

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

IL = 1.732IP in a delta, so solving for IP (in the delta) I get 34.6A.