PDA

View Full Version : What should this panel ammeter read?


moshi666
July 12, 2015, 08:24 PM
A 4160V circuit is equipped with 200/5 CTs, at full scale what should the panel ammeter read if the circuit was operating with a power factor of 0.8%?
madMAX
July 13, 2015, 04:55 PM
what was your answer? key part of this question are the 200/5 cts
Mmfz85
July 13, 2015, 07:41 PM
200 because that's full scale
Biscuit
July 14, 2015, 11:23 AM
If a circuit is supplied with 200 A CT's then the most you will be able to sense is 200 A.
jlogan
August 11, 2015, 08:52 PM
Could someone please explain the answer to me, i'm a little confused here.
Biscuit
August 12, 2015, 03:57 AM
A CT can only sense the amount of current it's rated for (200A CT can only sense 200A, 400A CT can only sense 400A, etc.) before it becomes saturated. Back in the day of analog meters you would install a meter based on the CT installed on the circuit. So if you had a circuit with 200A CT's you would install a 0-200A meter, if it had 400A CT's you would install a meter that reads 0-400A. Same principles apply with modern microprocessor meters except you program the scale -- it is all based on the size of the CT's installed.
jlogan
August 13, 2015, 08:09 PM
I understand the workings of a ct but what I don't understand is how the.8 power factor comes into play or the equation that needs to be done to figure out the answer.
Mmfz85
August 13, 2015, 08:15 PM
The answer is 200. The power factor had nothing to do with the question. They add that to try to throw off a person who doesn't know.
jlogan
August 17, 2015, 07:34 PM
HA !!! well it worked, I see how tricky they try to be with their questions, thanks for pointing that out since I didn't know.
GeorgeGuthrie
March 1, 2021, 01:36 PM
A 4160V circuit is equipped with 200/5 CTs, at full scale what should the panel ammeter read if the circuit was operating with a power factor of 0.8%?

200 amps