... .can connect to two Pumps,stable performance.3.with sensor,alarm unit. Auto-Water Level Detecting Equipment Water level switch sensorDescription ... pump to pump water out and can give sound-light alarm !1.Technical information:Power supply:24V ±10%Quiescent current:<200mAWorking ... do not connect the wires inversely,it will make alarm unit broken; Alarm unit which is built-in buzzer can give sound ...