ABB 5VHK250 1200A 4160V Breaker Trip
ABB 5VHK250 1200A 4160V Breaker Trip
(OP)
I have a single line that shows a 87 differential relay from the primary breaker of the XFMR and the Secondary main CKT into the 4160V ABB SWGR. I have not been able to find an overcurrent relay for the 4160V Main Breaker. My question is what is tripping that main 4160 Breaker? There are 3 CTs at the back of the Main Breaker compartment that connects to the differential relay, but doesn't the main bkr need to have overcurrent protection or does the differential relay take care of that? Confused? Please advise.






RE: ABB 5VHK250 1200A 4160V Breaker Trip
RE: ABB 5VHK250 1200A 4160V Breaker Trip
RE: ABB 5VHK250 1200A 4160V Breaker Trip
RE: ABB 5VHK250 1200A 4160V Breaker Trip
If it is tripping, what targets or flags, if any are you getting on the 87?
Like David said, there are three phase relays that have the conplete package built in and you should be getting trip targets. It should also be labelled other than just an 87.
Alan
Democracy is two wolves and a sheep deciding what to have for dinner. Liberty is a well armed sheep!
Ben Franklin
RE: ABB 5VHK250 1200A 4160V Breaker Trip
Zogzog: I realize that a picture is worth a thousand words so I am attaching the one-line I have for this power system. The 5A and 5B breakers are the main breakers to the 4160 dual bus arrangement. According to the oneline I only see CTs conneted to the load side of the main breakers that go to an 87 differential Relay. I have not seen the 87 relay to determine if overcurrent functions are integral with the relay but I intend on looking into this soon based on Mr. Beach's recommedation. Thank you all for your responses. I look forward to any other recommendations you may provide.
RE: ABB 5VHK250 1200A 4160V Breaker Trip
RE: ABB 5VHK250 1200A 4160V Breaker Trip
Read NEC Sec. 384-16(c)it's about sizing your circuit breaker. Usually, Calculate the current:
I= KW x 1000
----------------.
1.73 x Volts x PF
Convert HP to KW in your case to apply
this formula .
On top of my head,Circuit breaker trip will be sized 80% of the rated current.
Son
www.electrical-designer-guide.com
RE: ABB 5VHK250 1200A 4160V Breaker Trip
RE: ABB 5VHK250 1200A 4160V Breaker Trip
Alan
Democracy is two wolves and a sheep deciding what to have for dinner. Liberty is a well armed sheep!
Ben Franklin
RE: ABB 5VHK250 1200A 4160V Breaker Trip
RE: ABB 5VHK250 1200A 4160V Breaker Trip
I have come across such a practice in some of the major utilities.
However, it is important to have separate Earth fault protection on the transformer secondary side as the Dy transformer cannot have zero sequence currents in primary phases when fault is on secondary side of the transformer.
RE: ABB 5VHK250 1200A 4160V Breaker Trip
Alan
Democracy is two wolves and a sheep deciding what to have for dinner. Liberty is a well armed sheep!
Ben Franklin
RE: ABB 5VHK250 1200A 4160V Breaker Trip
I found a three line drawing that showed the overcurrent protection for the main breakers. You were right the oneline just showed how the powered flowed although some relays were shown as well. Thanks for the tips to dig deeper! I had to put away my hand trowel and use a bigger shovel.