1. Ungrounded wire

It is a national mandatory standard to adopt protective grounding for Submersible Pumps. Only protective grounding can ensure personal safety during use. If there is no protective grounding, once the shell leaks electricity, the water at the outlet of the submersible pump and the water surface of the pump will be charged, endangering the safety of people and animals, and wasting a lot of electric energy. If the metal shell of the submersible pump is connected to the grounding body (grounding resistance is not greater than 4 Ω) that meets the national standard, when the submersible pump shell leaks electricity, the current forms a closed loop through the metal shell of the submersible pump, the protective grounding wire, the grounding body, the earth, the working grounding wire of the transformer and the power supply. When the leakage current is too large, especially when the live wire touches the shell, the protective device of the submersible pump will act (fuse fuse fusing or air switch tripping), and the power supply of the leakage submersible pump will be cut off.

2. No leakage protector is installed

When the submersible pump works in water, it is easy to cause electric energy loss or even electric shock due to leakage. If a leakage protector is installed, as long as the leakage value of the submersible pump exceeds the action current value of the leakage protector (generally not more than 30 MA), the leakage protector will cut off the power supply of the submersible pump.

3. Start up when the power supply voltage is abnormal

Too high and too low voltage will make the temperature rise of submersible pump too high, shorten the service life and even burn the submersible pump. Due to the long low-voltage power supply lines in rural areas, it is common for the terminal voltage of the lines to be too low and the starting voltage to be too high. Therefore, in the process of using the submersible pump, the operator must observe the power supply voltage at any time. If it is less than 10% lower than the rated voltage, more than 10% higher than the rated voltage, or the current is greater than 20% of the rated current of the submersible pump, the operator should immediately stop the machine and avoid starting the machine when the power supply voltage is abnormal.

4. The motor rotates in the opposite direction

At present, there are many types of submersible pumps that can discharge water both in forward and reverse rotation, but when reversing, the water output is small, the current is large, and the motor winding will be damaged if the reverse rotation time is long. Therefore, the submersible pump should be connected to the power supply to check whether the rotation direction is correct before entering the water. If the impeller of the three-phase submersible pump reverses, it shall be stopped immediately and the wiring of any two phases in the three-phase core wire in the cable shall be replaced.

5. Long term overload

To avoid long-term overload of submersible electric pump, do not use low lift pump for high lift work, do not pump water with large sand content (heavy mud), and observe whether the current value is within the specified range at any time. If excessive current is found, stop the machine for inspection. In addition, the submersible pump uses water as the cooling source, so the dewatering operation time of the submersible pump should not be too long.

6. Frequent switch

The submersible pump should not be started too frequently because it will generate backflow when it stops running. If it is started immediately, the motor will start with load, resulting in excessive starting current. Therefore, after the shutdown, it can only be started again after the return of the stored water in the pipe is completed. Generally, the interval is about 5min.

7. Use in muddy environment

If the submersible pump sinks into the mud during use, it will cause poor heat dissipation and burn out the motor winding. Therefore, the submersible pump must not be used in the muddy environment. In order to prevent the submersible pump from sinking into the sludge, the sludge in its working environment should be removed before the submersible pump is launched. If possible, the submersible pump should be covered with a fence shield to avoid the waste blocking the water inlet fence, resulting in motor heating and poor water outlet.

8. Put it in water for a long time after it is out of service

If the submersible pump is not used continuously after running in the well, it will rust for a long time, resulting in failure to start. Therefore, the disabled submersible pump should not be left in the water. It should be started up once a week for 5~10min. When it is not used for a long time, it is best not to soak in water for a long time. It should be put in clean water and powered on for a few minutes to clean the mud inside and outside the pump, then put forward to wipe dry the water surface, carry out a major inspection, disassemble all parts for maintenance, scrubbing, derusting and descaling, replace vulnerable parts, reassemble them, and put them in a dry, non corrosive gas warehouse after painting and rust prevention.