Points for attention when using frequency converters for submersible pumps

             Points for attention when using frequency converters for submersible pumps

1. Since the load of the submersible pump is heavier than that of the ordinary pump, the rated current of the matching 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. For those installed in relatively humid sites such as pump stations, the protection of the inverter should 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 submersible pump is generally about 100 meters deep, and the distance between the inverter and the pump is relatively long. Therefore, in the process of use, it is necessary to consider thickening the cable diameter to reduce line loss, selecting an output reactor to reduce line leakage current, and appropriately 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, and the no-load current is very large if it is not in the water.

4. the equipment is regularly inspected and maintained. For the pump unit, it is necessary to check whether the appearance is aging, whether the seal is leaking, and conduct insulation measurements. 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 can 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. For the sake of safety, the leakage protection switch is used in many places in rural areas. If the leakage protection is not properly adjusted, it will trip due to the influence of the leakage current of the frequency converter. 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.