NETA 4 Exam Questions 7/2018

[MartyCoyne]

I took the NETA IV exam this Monday. There was maybe one or two questions from this entire site on the exam!!!

[ejbrewer]

I took the NETA IV exam this Monday. There was maybe one or two questions from this entire site on the exam!!!

How did it go? Do you have any info to share?

[MartyCoyne]

How did it go? Do you have any info to share?

I don't remember a lot of questions but I will post as they come back to me!!

[MartyCoyne]

I don't remember a lot of questions but I will post as they come back to me!!

1000kva 34.5kv to 480v secondary transformer 5% imp. apply 480v to primary side and short secondary to ground. What is primary fault current?

[Lestracy31]

1000kva 34.5kv to 480v secondary transformer 5% imp. apply 480v to primary side and ground secondary. What is primary fault current?

8.1A?

[MartyCoyne]

8.1A?

1000000/34500*1.732=16.73a
34500*.05=1725v
480 is to 1725 as X is to 16.73
480/1725=.2782 .2782*16.73=4.65a pri

[Lestracy31]

1000000/34500*1.732=16.73a
34500*.05=1725v
480 is to 1725 as X is to 16.73
480/1725=.2782 .2782*16.73=4.65a pri

thx forgot sqrt3 in my Ibase calculation

[3Ashockers]

1000kva 34.5kv to 480v secondary transformer 5% imp. apply 480v to primary side and ground secondary. What is primary fault current?

Assuming D-Y

Turns Ratio 34.5k to 277 = 124.5:1
Sec. phase voltage at 480 primary = 3.86V
Line Voltage from 480 primary = 6.68V
1,000,000VA / (1.732*6.7V) = 86.4kA
Secondary SC Current = 86.4/.05 = 1,729kA
Primary Current = 1,729,000 / 124.5 = 13.88kA SC

[1electricalguru]

I took the NETA IV exam this Monday. There was maybe one or two questions from this entire site on the exam!!!

The exams are all being rewritten to be more challenging as well as more fair in the information being tested. Ambiguous and "trick" questions (and the answer choices) are being eliminated. While I have not taken any of the practice questions on this site, I am going to assume that the questions are similar, not verbatim from previous exams. Obtaining a passing score on any of these NETA exams will require the ability to apply your industry knowledge and experience, not just rote memorization.

[Wanderer20001us]

Assuming D-Y

Turns Ratio 34.5k to 277 = 124.5:1
Sec. phase voltage at 480 primary = 3.86V
Line Voltage from 480 primary = 6.68V
1,000,000VA / (1.732*6.7V) = 86.4kA
Secondary SC Current = 86.4/.05 = 1,729kA
Primary Current = 1,729,000 / 124.5 = 13.88kA SC

Can someone explain to me how to differentiate between the wording of the test question and the two results other than looking at the magnitude of the answers? I have re-read the questions many times and cannot tell (other than answer choice) which method you would choose. They both appear to ask for the short circuit primary current, and short of the answers, I would get the answer of 4.65A as my answer. I mean, let's face it, if I hook up a 480 source to the primary with the secondary grounded, I'm going to get one or the other, not both.