Abstract: In the control of prime movers, automatic and manually generated input signals should be able to be entered into the control system without undue control disturbance or perturbation. Likewise should an automatic signal fail, the switch to a last valid signal prior to entry into a manual mode is also desirable. An analog-digital hybrid circuit is described which includes a memory, storage, timing and manual input portions as well as certain select A or B circuits which allow for bumpless transfer between automatic manual and memory modes of operation.

Abstract: The useful life of a turbomachine part is affected by cyclic stresses which occur in the turbomachine part as a result of heating and cooling the turbomachine part. Each thermal cycle is comprised of a maximum heating stress and a maximum cooling stress which may occur during turbomachine start-up, load changes, shut-downs, or boiler excursions. The maximum heating stress and the maximum cooling stress for each cycle may be combined to define a stress range. The actual stress range for each cycle is compared with a calculated stress range curve for the turbomachine part to determine the amount of life expended during the cycle for the turbomachine part. This value may be expressed as a percent of life expended for the cycle. The life expended for each cycle is accumulated to provide an output indicative of the total percent life expended for the turbomachine part according to its operating history.