A New Timing Method Based on PLC Scan Cycle Time and its Application in Automatic Marine Power Station

Abstract

For an established control system, scan cycle time of the PLC is almost constant during steady operation. Scan cycle time of PLC can be act as a timing unit and realize the function of timer by appropriate programming. The timing method based on PLC scan cycle time is practiced in judgment of start success of generator set and grasping of ACB (air circuit breaker of generator) closing opportunity in automatic synchronization control and achieved the desired results. Application of this timing method reduced the hardware of the control system, improved the reliability and economical efficiency. Several years of operation in training lab proved that this control method is reliable and steady.