Teach You How To Repair A Submersible Pump

The submersible pump is composed of an asynchronous motor and a water pump. It is widely used in agricultural drainage and industrial water supply industries. There are several types such as dry type, oil-immersed type, and water-cooled type. Due to the fact that the pump body works underwater for a long time, combined with poor water quality in some areas, poor power grid quality, and insufficient maintenance experience, the failure rate is high and the maintenance workload is large. 1. Common faults of submersible pumps 1) Electric leakage Electric leakage is the most common fault of submersible pumps and is also one of the most dangerous factors endangering personal safety. The fault phenomenon is that when the switch is closed, the leakage protection device in the transformer distribution room trips (if there is no leakage protection device, it will be extremely dangerous and may cause the motor to burn out). This is mainly because water enters the pump body, causing the insulation resistance of the motor winding to decrease, resulting in the action of the protection device. At this time, using a multimeter or a universal meter with the R×10kΩ setting, measure the leakage resistance between the motor winding and the casing. The pump is used for a long time, causing severe wear of the mechanical seal end face, and water seeps in, wetting the motor winding to form electric leakage. The submerged pump motor can be placed in an oven or dried with a 100-200W incandescent bulb; when the insulation resistance is infinite, replace the mechanical seal and reinstall the pump to put it back into use. 2) Oil leakage The leakage of submersible pumps is mainly due to severe wear of the sealing box, causing oil leakage from the oil chamber of the sealing box or poor sealing at the outlet box. When oil leakage occurs in the oil chamber of the sealing box, oil stains can be seen at the water intake section. There is an oil filling hole at the water intake section, unscrew the screw and observe whether the oil chamber is filled with water. If the oil chamber is filled with water, it indicates poor sealing, and the sealing box should be replaced to prevent severe oil leakage into the motor. If there is oilization at the root of the submersible pump cable, it belongs to internal leakage of the motor. Generally, it is caused by poor sealing of the rubber plug or unqualified leads after rewinding the motor; some are caused by the rupture of the pump connection board. After checking and determining, replace with qualified new products. Also measure the insulation degree of the motor, if the insulation is not good, it should be dealt with in time, and the oil in the motor should be replaced. 3) After power-on, the impeller does not rotate After powering on, the pump has a buzzing AC sound, but the impeller does not rotate. Cut off the power supply, and move the impeller at the water intake section. If it cannot be moved, it indicates that the rotor is stuck. The submerged pump can be disassembled for inspection. Whether the lower end bearing ball of the rotor is crushed due to damage can cause the rotor to be stuck; if the impeller can be moved but does not rotate after power-on, the fault may be caused by severe wear of the bearing, and the magnetic field generated by the stator when powered on attracts the rotor and cannot rotate. Replace the bearing and reassemble the pump, and the impeller can rotate flexibly, and the fault can be resolved. 4) Weak water output and low flow rate When the pump is taken out, check that the rotor rotates flexibly and can rotate after power-on. When disassembling the submerged pump for inspection, it is found that the shaft at the lower end of the pump is loose between the bearing and the shaft, and the rotor moves downward. Therefore, the rotor rotates weakly and the output power is small. Use an appropriate washer to pad between the rotor and the bearing to make the rotor move upward, install and test the pump, and the fault can be eliminated. 2. Maintenance precautions for submersible pumps 1) The disassembly method should be correct Before disassembling, mark the joint of the front and rear end covers and the base with a chisel. Because the assembly of the motor when it leaves the factory is quite reasonable, if not assembled in the same way after repair, it may cause slight errors and make the shaft less flexible. During disassembly, carefully observe the degree of damage to the winding, preliminarily analyze the cause of the damage, and pay attention to minor scratches such as scuffing and broken balls. When disassembling and repairing the damaged winding, pay attention to protecting the iron core and plastic guard ring. If the method is inappropriate, it may cause the iron core to expand outward and damage, and the motor may vibrate due to electromagnetic effect when powered on, causing the insulation paper and electromagnetic wire of the winding to be damaged. The method of cutting the wire is to use an oblique mouth pliers to cut from one end and pull out from the other end. 2) The homemade wire mold should be appropriate, and the wiring should be correct. After embedding one phase, embed the other phase, forming a three-layer plane at the end, and the end must be tightly wrapped to prevent scratches during assembly. 3. Adjust the position of the limit screws. During the adjustment process, be meticulous and ensure that the rotor rotates freely and the no-load current is minimized. Then, tighten the locking nut. 4. Handle the waterproof and insulation of the connectors properly. Remove the insulation and sheath from the connector, clean the paint and oxide layer on the copper wire surface, and solder after winding. Then, remove the sharp corners, burrs, and soldering fluid. Wrap a polyethylene tape in half layers, and then wrap a polypropylene adhesive tape in half layers as the mechanical protection layer. 5. Prepare for the power-on test. Before the test, the motor cavity must be filled with clean water or rust-proof buffer agent. The purpose is to cool the windings and lubricate the bearings. Otherwise, the motor windings will be burned out quickly. When not in use in winter, drain the water from the motor to prevent the pump body from cracking due to freezing. 6. Use the QYW type polyethylene insulated nylon sheathed water-resistant wire produced by a regular manufacturer for the submersible pump.