Multi-gen Plant Cyclic Failure


Thread Starter



My apologies for having to ask a question with out contributing to other discussions first.

I recently took charge of a power plant that is outside of the United States. The plant configuration is 20 high speed diesel generators, variety of Cat and Cummins from 1300 to 1600 kw continuous rating. The plant operates 24/7. Each plant utilizes woodward DSLC-2's for generator control, and buss tie breakers are controlled by MSLC's. The control system is operating on a closed system. SCADA is SEL WonderWare. Gen protection is GE-489's.

My issue. 99.404677 days after plant commissioning the SCADA system registered loss of communication from the DSLC-2's and the PLC's. This caused the entire plant to open all breakers. The engines did not shut down and the lock devices did not operate. This has happened every 99.404 days until last year when the time was reduced to approximately 49.702 days. We have no other unplanned outages.

Currently, the contractor that installed the control system is stating that this is a known issue with the DSLC's; and that because of the large plant a DSLC processor over is being experienced on every DSLC at the exact same moment on a cyclic time rate.

Their current suggestion is to program a 10 sec breaker open delay in the PLC's when a breaker open signal is received with out an unload command.

Essentially, allowing the plant to operate with out DSLC control for 10 secs during the next outage.

The last 3 outages were estimated with in 3 minuets.

My questions.
- What could cause a failure that is this predictable?
- Any recommendations to mitigate other than breaker open delay?

Thank you for any and all help.