The transformer data is: 7.5MVA, Delta-Wye, 8.23% Z, 138kV/4.16kV. Channel two was attached to 'B' phase. The way this particular PT is set up is phase B is actually grounded and it uses phases A and C as reference to 'assume' the voltage on phase B. That all being said, it is curious that...
Here's the report I received from the utility. I'm not sure I fully understand it.http://files.engineering.com/getfile.aspx?folder=a1c051b9-004e-4f58-9086-4a9c25883966&file=Wilburton_Harmonic_Study.pdf
Skogsgurra,
Most recently when we latched them in and latched in 300kVAR they did not blow up or blow any fuses. They were only latched in for only a minute or so.
The bank is fused externally, two sets of 300kVAR. I don't know if any tests were done or not, but the manufacturer did replace the blown caps under warranty, but the strange sound still exists with the new bank.
jghrist,
I realized that afterward. The relay can sense the arc fault, but doesn't have a breaker to trip; there's primary pole fusing and internal transformer fusing.
Jraef,
You are correct; I mis-read my print. There is an in-line contactor and a separate bypass contactor. The motors are Mitsubishi / Toshiba Induction motors.
Skogsgurra,
Definitely came from the capacitor cabinet. We didn't hear the sound until the caps were latched in. Thanks for the paper, although I admit, I am not sure I really understand it. If this is the issue, however, what would be the recommended solution?
Thanks for all the posts. To answer a few questions, we have a contactor upstream of the capacitors to latch them out when any motors are 'ramping up' to speed or when only one motor is running. This is controlled via PLC and it was verified after we blew the capacitors. They blew shortly...
jghrist, it is a 12470/480V transformer, 1000kVA. I added the VAMP 221 relay as suggested above into my power tools software and remarkably it lowered it from a category 4 to a category 1.
I have a power factor correction capacitor bank rated 600kVAR. It is in parallel with three 1250hp motors on soft start systems used for gas compression. The bank has a contactor that closes only when 2 or three motors are running and is unlatched when the soft start is ramping up the motors...
I need some help in understanding and possibly mitigating an issue that I have seen in several locations. It seems that every time I have low fault current available from the utility, I always end up with a category 4 or worse on the secondary side / line side of the breaker downstream. I'm not...
I have been studying for the PE for the last couple of months. I got an email from Testmasters for a review for the PE that guarantees passing. My work won't pay for the course, which is $1600 and I have to take (4) vacation days, and spend (4) weekend days taking the course. I also will have to...
