Safties for elevator hoist motor control having high gain negative feedback loop

摘要: A variable voltage hoist motor control wherein a pattern signal is compared with feedback in high gain closed loop and the signals at critical points are monitored to ascertain unsafe operating conditions. Indicated conditions alter either safe mode or shut down system. Monitored include error summing point for signals, rate of change signal, level power levels during period elevator car be stationary driven leveling speeds.