Time delayed relay sequencer and alarm reset for a gas turbine local maintenance controller

摘要

The majority of a number of relays is held in a quiescent state, without power, in a local maintenance controller preparatory to assumption of control of a gas turbine power plant. Control transfer may be manually requested or may occur automatically in response to failure of the plant's primary control system. Regardless of the cause of transfer, a time delay relay is utilized to allow the quiescent relays sufficient latching time. The time delay period is chosen to reflect the maximum period of time for which a lack of trip availability can be safely tolerated.PPThe relay sequencing arrangement is adapted so that when the quiescent relays are energized, alarm circuitry for predetermined plant parameters is automatically reset for on-line transfers, thereby allowing more rapid and efficient transfer and minimizing the need for operator intervention. Alternative means for manually resetting the alarm circuitry is also provided.