IEA designed and built a 16,000 kW (16 MW) diesel standby generating plant for a customer’s world headquarters. The facility is comprised of ten 1,600 kW capacity generators, each with its own 5 kV generator output breaker.  The two sets of 5 generators are tied to two separate generator bus’s, connected to a common emergency bus via a 5kV to 12.5 kV step-up transformer and 15kV class switchgear to two incoming independent 12.5 kV utility feeds via Tie circuit breakers.  The system controls both of the utility 15kV breakers to allow for either extended parallel operation with the utility or isolated operation. 

The customer’s internal switchgear is configured to allow the entire facility to be connected to a single utility source.  However, this is not the normal mode of system operation. In the event of an outage of one of the two utility sources, internal customer owned switchgear will automatically transfer loads to the available utility source.  The generating system will only initiate standby mode of operation upon failure of both utility sources, and is designed to operate on both or only one of the utility sources.

Local utility regulations do not allow the interconnection of either of the two independent utility feeds.  The generating system is designed  to connect to only one source at time.  Normal paralleling operations occur through one of two utility feeders. 

This generator facility has three primary operating modes;

• Standby mode: loss of utility source.

• Import mode: extended parallel operation while maintaining a designated import level across a utility source.

• Isolated mode: operating isolated from all utility sources, while both sources are available.

All operations are controlled by a system PLC (Allen Bradley Compact Logix series). The system is designed to operate in Standby mode in the event of a failure of the system PLC. 

Every month, a loaded system test is conducted to confirm operability while carrying full customer load. The system has been successfully used by the customer in response to sporadic utility outages, as well as extended continuous runs of over 100 hours in response to severe weather. In addition, the equipment is called upon to support the local utility interruptible program.