Recent content by Cram For The PE

You can read about real life events on the situation you are describing here: https://www.nrc.gov/reactors/operating/ops-experience/open-phase-electric-systems.html A famous example of this occurred on Jan. 30, 2012, Unit 2 at the Byron Station. A single phase left open can go undetected...

I have created a live CBT test. Each test will consist of 80 questions which is sampled at random from a question bank. For the morning and afternoon session, you will get a total of 8 hours with a lunch break. Remember to set aside at least 9 hours before clicking to start the test. Most of the...

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Send me an email Ill give you a discount :)

They give it in the reference handbook. The problem listed above is very different though. It is asking this: "If I have a single line to ground fault occurs on the wye side of the transformer, what does it look like on the delta side"? This requires a little bit of thinking and is not simply...

You are mixing up turns ratio and PU. These fault values are well known for protection engineers. No matter what the turns ratio of the transformer is- if you have a line to ground fault on the wye side the 1pu appears as 0.577 pu on the delta secondary side. You are also missing an important...

You got it.

Congrats!

This is incorrect.

First person to solve this in the comments section will get one or all of my books for a 30% discount. You must show how you got the answer. Solve in comment section here. A three-phase circuit with ABC rotation is show below. If both transformers are ideal and have subtractive polarity, how...

Yes that’s correct

Yes that is correct.

Question now states: A 50Hz generator is going to supply power to a 50Hz motor through a transformer designed for 60Hz. Which of the following statements is true?

You are correct. I have it backwards. Typo has been fixed.

That is incorrect.