1. In order to prolong the using life, it should measure regularly whether the voltage of power supply, operating current and insulation resistance are normal, if find one of the following phenomena, the pump should be shut immediately, after the malfunctions are removed, operation can be available.

•  Under the operation of rated working parameters, the current increases to 120% of rated value.

•  Variable water level drops to impellor of each stage, intermittent water outlet.

•  The electric pump generates fierce vibration and noise.

•  The voltage of power supply lower than 340 V.

•  The fuse connected according to requirement is broken frequently.

•  Pipeline damaged, water leakage occurs.

•  Start equipment damaged or relaying protection trips frequently.]

•  The insulation resistance in thermal state lower than 0.38 megohms.

2. Overhaul should be made each a year for the electric submersible pump, overall check should be made each a season during the operation stage.