(1) Too high pump speed;

(2) The specific gravity of the conveying liquid exceeds the original design value;

(3) High viscosity of conveying liquid;

(4) The size of the pump impeller is too large;

(5) The resistance of the pipeline system exceeds or is insufficient to the predetermined value;

(6) Too low lift rate and too large flow rate of the pump,

(7) Friction between rotor parts and stator parts:

(8) Bearing wear or damage;

(9) Excessive pressure of mechanical seal on sealing seat,

(10) Outlet pipeline is broken;

(11) Bent pump shaft;

(12) Uneven thermal expansion of different parts in the pump;

(13) Inaccurate dynamometer;

(14) The pump balancing device does not work.