Hi, how are you? We have an GE MS6001FA 69MW with an SFC for 88.118 MVA Generator
Brand: Ansaldo Sistemi Industriali
Schema Elementary: FN290800C02
Manufactured Date: 2001
We are having a problem at startup time, when TNH reach 64%, unit trip for a problem in SFC (CURRENT DIFFERENTIAL BETWEEN RECTIFIER-INVERTER BRIDGES I''DC < I'DC), according manual:

The protection verifies that there is no difference between the converter input and output currents, in this case the protection trips if the output current is lower than the input one, the tripping threshold can be customised through R76 (X23 -X24) resistance.
Differential acknowledge calibration 15% Idcn (Idcn :drive rated current);
it is possible to delay the protection tripping with R101 (X29 - X30) resistance.

Could you help me with a checking path to try to resolve this problem? (We have )
I was thinking to start checking thyrtisors. How can I do this?
Any suggestion is good!

Best Regards

 

Hi
I am doing well Thank you for asking
How are you ?

Could you reply to followings questions:

OEM of the SFC (Alstom??)

Can you tell us when the problem started ?

I would advise to review PLC /Automation cell program software for the control & protection ..

James

 

Hi ControlsGuy25, thanks for your quick reply.

• OEM of the SFC (Alstom??)
  • I have added some pictures.
• Can you tell us when the problem started ?
  • Unit tripped due to alarm "Motor Brush Fault", brushes wheel was changed.

Generator Relay is OK, AVR is OK, NO alarms. For the time being, unit trips around 62%, when happen this:


Pictures SFC








Sequence in SFC before/after trip.

 

Hi

Thank you for sharing these datas

I am not familiar with Ansaldo controls & protection equipment for that SFC

I would advise to monitor the mentionned currents at start up

You can trends also other datas /values for the specified SFC

Are you able to connect and communicating a pc /laptop with the equipment?

If so trends and event records can be monitored to troubleshoot the issue and specially if you can have access to the installed software/program of this device

James

 

Try to read the Ansaldo device manual it can help you