2 Incomer :1 Buscoupler Power Control Center (PCC)

[raj151857]

Dear All,

Am facing a problem with 2 IC:1BC PCC which am unable to rectify Request Please help.

1] Autochange over from BUS A is normal. (IC-1 trip on Undervoltage Buscoupler close).

2] Autochange over from BUS B is normal (with only 2 Motor running).(IC-2 trip on Undervoltage Buscoupler close).

3] If more than 3 Motors are running Bus transfer from IC-1 to BC is normal while
IC-2 to BC is creating problem. Buscoupler close & open frequently. Please
note UV in Motor relays are disable. None of the relays are registering any alarm
or fault. SEL-751 is used for IC & BC Feeder Protection.

4] I had checked the scheme , Relay Logic & Protections settings & found in line.
5] Some ACB open on surges without any fault on relays.
6] Am in opinion that Motor Residual Voltage is causing this problem but stuck up
for the cause of BC tripping.Am attaching BC tripping scheme for your reference, There are two trip commands,
a] K21 is BC relay & trip logic for same is 50P1T or 51P1T or 50N1T or 51N1T or G1T only.
b] K27 is Master trip & hand reset. There is no other source for tripping.

Any Suggestions.

[saurabhkumarsaxena]

Pls upload control wiring of PMCC, then I suggest u……

[raj151857]

how to attach file here?

[smzakaullah]

Hi Friend

Please send the control circuit diagram to me on my email (smzakaullah@yahoo.com) and I will try to help you.

[raj151857]

Thanks Mr.Smzakaullah I had solved the problem.

[orlyboy]

Thanks Mr.Smzakaullah I had solved the problem.

Hi raj151857,

Can you share the diagram along with the solution.

Thanks