This is a solidly grounded star on the primary and open corner delta, with resistor in the delta, on the secondary grounding transformer on a 12.6 kV delta system. The transformer permits 15A 3Io current in the star ground. There are a few feeders with negligible capacitance but two of the...
The reactor is 12.9 kV; 600 amp; (13.4 MVA) X=5% I would like to obtain a typical X/R ratio, but could not find an answer anywhere. Could someone please help me.
Thank You
When a 400 amp 10 second grounding resistor is subjected to fault currents above 400 amp, how can I calculate the time this resistor can stand at the higher fault currents
Thank you again Lionel and jraef. I didn't receive the necessary information on motor protection. It is obvious that the motor protection should be on the 480 volt side. I assumed the motor was protected because the utility's problem was fuse coordination on the 12.5 kV side. The 300 KVA...
Thank you "jraef" and "itsmoked" for the valuable answers. I think they have a problem with the 350 KVA soft start limit, because the company observed about 900 Amp staring current. Of course this might be due to the motor trying to drive a stuck pump, and the rotor was completely stopped until...
When the start of a 250HP 480Volt pump motor is limited to 350KVA soft start, what would be the starting current? Should I calculate this current as the current for a 350KVAR inductive load, or there is a power factor involved? For how long would this current last? I want to select a fuse to...
ABB has offered optical current transducers. They are an integrated part of the MACH 2 control and protection system for HV Series Capacitors.
Any comments on this system wuold be welcome.
Thank you for your reply. I took the information from a drawing where the manufacturer was not mentioned. I wonder what would be the approximate X/R ratio for a similar series reactor?
Thanks,
kingi
I have two questions:
1. Where can I find the X/R ratio of a 3ph, 12.6 kV, 5%, 600A reactor?
2. I calculated the MVA rating of this reactor as follows:
1.73x12.6x600/1000=13.1 MVA. Is this correct?
Thanks,
kingi
Is there any information somewhere on the Internet about practical cable impedances? I need approximate impedances for 12 kV, 5 kV and 600 volt cables for short circuit calculations.
Where do I find information on the present state of the art on "Emergency Diesel Generator Protection"? I don't mean relay application bulletins, I am looking more for recent IEEE standards on the subject, or for reference to a relay protection book that treats the subject in detail.
I am to...
This is an old diesel generator. 4.16 kV, 350 kW, 80% Power factor. For setting the negative sequence overcurrent protection I need information on the negative sequence current capability of the generator. The manufacturer does not exist any longer. I would be greatful for some approximate data...
