The WQ-series submersible sewage pump is widely used in wastewater treatment; proper use of protective devices and routine maintenance can significantly extend the pump's service life. So, how should the pump be maintained? Experts from Shenyin Pump Industry—a manufacturer of submersible sewage pumps—are here to explain the maintenance procedures for the WQ-series pump.
1. Ensure the correct motor rotation direction. It is crucial to verify the motor's rotation direction. While many submersible sewage pumps can discharge water during both forward and reverse rotation, reverse rotation results in lower flow rates and higher current; prolonged reverse operation can damage the motor windings.
2. Prevent operation during abnormal voltage conditions. Low-voltage power lines are often long, frequently resulting in low voltage at the terminal end. When the phase voltage drops below 198V or the line voltage below 342V, the motor speed decreases. If the speed falls below 70% of the rated speed, the starting centrifugal switch remains engaged, causing the starting winding to remain energized for an extended period; this generates heat that can burn out the windings and capacitors. Conversely, excessively high voltage causes the motor to overheat and burn out the windings. Therefore, operators must constantly monitor the power supply voltage during operation. If the voltage deviates by more than 10% from the rated value (either too low or too high), the motor should be stopped immediately to identify and rectify the fault.
3. Cable installation and insulation resistance requirements. When installing the pump, the cable should be suspended overhead, and the power cord should not be excessively long. Avoid placing tension on the cable when lowering or lifting the pump to prevent the power cord from cracking. Do not allow the pump to sink into the mud during operation, as this impedes heat dissipation and can burn out the motor windings. During installation, the motor's insulation resistance should be no less than 0.5 MΩ.
4. Installation of a leakage protection device. A leakage protection device is often referred to as a "life-saving device," a name that clearly indicates its function. Since submersible sewage pumps operate underwater, they are prone to electrical leakage, which can result in energy loss or even fatal electric shock accidents. If a residual current device (RCD) is installed, it will cut off the power supply to the submersible sewage pump whenever the leakage current exceeds the device's trip threshold (typically no more than 30 mA). This ensures safety while preventing electrical leakage and energy waste.
5. Avoid frequent switching: Do not switch the submersible pump on and off frequently. When the electric pump stops, backflow occurs; restarting it immediately forces the motor to start under load, causing an excessive starting current that can burn out the windings. Since the starting current is high, frequent starts can damage the motor windings.
6. Do not allow the submersible sewage pump to operate under overload for extended periods: To prevent prolonged overloading, avoid pumping water with high sand content and regularly monitor the current to ensure it stays within the values specified on the nameplate; if the current is excessive, stop the pump for inspection. Additionally, avoid running the pump without water (dry running) for too long, as this can cause the motor to overheat and burn out.
7. Pay attention to routine maintenance: Regularly inspect the motor. If issues such as cracks in the lower casing or damage/failure of the rubber sealing ring are found, replace or repair the parts promptly to prevent water from entering the pump.
How should WQ-series submersible sewage pumps be maintained?