Submersible sewage pumps are among the most common types of submersible pumps encountered in daily life. Even with products from the same manufacturer, the service life can vary significantly depending on the user—a phenomenon particularly evident with submersible pumps. Users who maintain their equipment well may enjoy over a decade of trouble-free operation, whereas others—neglecting maintenance or even running the pump without water—can cause the motor to burn out in mere minutes. Such instances are very common. Both manufacturers and customers desire long-lasting, stable product performance; this depends not only on the manufacturer's quality standards but also heavily on the customer's maintenance practices. Today, pump our engineering team will briefly explain how to maintain submersible sewage pumps, in the hope that this information proves helpful.
1. Ensure the correct motor rotation direction. It is crucial to verify the motor's rotation direction. While many modern submersible sewage pumps can discharge water during both forward and reverse rotation, reverse rotation results in reduced flow and higher current; prolonged reverse operation can damage the motor windings.
2. Prevent startup under abnormal voltage conditions. Low-voltage supply 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 fails to reach 70% of the rated RPM, 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 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 a submersible sewage pump, the power cable should be suspended overhead, and the power line should not be excessively long. Do not subject the cable to tension when lowering or retrieving the pump, as this can cause the power line to crack or break. Do not allow the submersible pump to sink into the mud during operation; doing so impairs motor heat dissipation and can burn out the motor windings. During installation, the motor's insulation resistance should be no less than 0.5 megohms.
4. Installation of a residual current device (RCD): An RCD is also known 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 electric shock accidents. If an RCD is installed, it will cut off the power supply to the pump whenever the leakage current exceeds the device's trip threshold (typically no more than 30 mA), thereby ensuring safety and preventing both 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. Because the starting current is very high, frequent starting can also damage the submersible sewage pump's motor windings.
6. Avoid prolonged overload operation. To prevent the submersible sewage pump from operating under overload conditions for extended periods, 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 excessively high, stop the pump for inspection. Additionally, do not run the pump dry 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 cover or damaged/ineffective rubber sealing rings are found, replace or repair them promptly to prevent water from entering the pump.
Paying attention to the use of protective devices and performing routine maintenance can significantly extend the service life of submersible sewage pumps.
We hope the information above has been helpful to you regarding the maintenance of submersible sewage pumps. —