After the unit is put into production, the pump will work for a period of time and a switch-on or trip-off problem will occur. After excluding the switchgear failure, according to the conventional method of checking the cable, the secondary circuit wiring and the relay and its rating are normal, start again often successful. Suspected to be dcs system soft failure caused, but the change in the control panel operation, there will still be this phenomenon. Under normal circumstances the main reasons for the pump trip: 　　 (1), the use of the pump head is lower than the pump lift too much lead to excessive current flow after the over-current solution to control the outlet valve opening to flow control small and the current down to allow the current range, or change the diameter of the impeller Lower the pump head. 　　 (2), water pump motor damp lead to excessive current. 　　 (3), pump motor quality problems. 　　 (4), the pump voltage is unstable. 　　 (5), pump control cabinet system problems.