Precautions for using frequency converter in deep well submersible pump

Precautions for using frequency converter in deep well submersible pump

Because ordinary deep well submersible pumps are not special frequency conversion motors, there are many restrictions and requirements when using frequency converters. 

Points to note when using frequency converters for deep well submersible pumps :

• The rated current of the motor

• Installation and use environment

• Thickening the cable diameter to reduce line loss

• Inspection and maintenance of equipment

• Good grounding

• Leakage protection switches

1.Since the load of the deep well submersible pump is heavier than that of the ordinary pump, the rated current of the supporting motor is relatively large. Therefore, when selecting a frequency converter, the selection should be made according to the rated current of the motor compared with the rated current of the frequency converter, not just power matching.

2. Pay attention to the installation and use environment. Well pumps are generally installed in relatively humid sites, so the protection of the frequency converter must be done well. For example, strengthen the insulation and protective paint treatment of PCB circuit boards, the protective treatment of screw and sheet metal parts, etc., and place them in the control box for use.

3. The deep well submersible pump is generally about 100 meters deep, and the distance between the inverter and the pump is relatively long. 

• Thickening the cable diameter to reduce line loss

• Selecting an output reactor to reduce line leakage current

• Increasing the selection of the inverter to compensate for power attenuation

   Especially if the non-clean water pump contains impurities, the selection should be increased.

4. Periodic inspection and maintenance of equipment. 

For well pumps, it is necessary to check whether the appearance is aging, whether the seal is leaking, and conduct insulation measurements, etc. The inverter should also be inspected and cleaned regularly to ensure that it can work well. For occasions where there is no need for intermittent use, a backup emergency control circuit should be prepared to prevent the inverter from shutting down due to a condition.

5. Good grounding is the basis for the stable and reliable operation of the inverter.

If there is no reliable grounding on site, it may be considered that the inverter is not grounded. It is strictly forbidden to share the neutral ground and connect the neutral wire to the ground terminal of the inverter as the ground wire. It is also not allowed to connect the ground of the motor and the ground of the frequency converter together.

6. Leakage protection switches are used in many occasions for safety. 

If the leakage protection is improperly selected and adjusted, it will trip due to the influence of the leakage current of the inverter. At this time, it can be considered to install a reactor at the input end or reduce the carrier frequency. If conditions permit, consider installing an output reactor to reduce the harmonic current.