Forward: A master water pump repairman shares his experience!

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When handling faults in practice, the principle of first outside first and then inside should be followed based on specific problems and actual analysis, and do not operate blindly. first: The power supply should be checked: Is the connector connection secure? ； Is the switch contact tight? ； Is the fuse blown? ； Whether the three-phase power supply is equal or not. If there is an open circuit, poor contact, blown fuse, or phase loss, the cause should be identified and repaired in time. Secondly: Check whether it is a mechanical failure of the water pump itself. Symptom 1. Common causes of water pump failure to start: The packing is too tight or the space between the impeller and the pump body is blocked by accumulation of debris. ； The pump shaft, bearings and leakage reducing ring are rusted ； The pump shaft is severely bent, etc. Troubleshooting: Loosen the filler and clear the diversion channel ； Disassemble the pump body and remove debris and rust. ； Remove the pump shaft and correct or replace it with a new one. Symptom 2. Causes of insufficient flow: Most of them are leaks in the suction pipe and bottom valve. ； Water inlet blocked ； The water entry depth of the bottom valve is insufficient ； Water pump speed is too low ； The sealing ring or impeller is too worn ； The water absorption height exceeds the standard, etc. Troubleshooting: Check the suction pipe and bottom valve to block the source of air leakage ； Clear silt or blockage at water inlet ； The water entry depth of the bottom valve must be greater than 1.5 times the diameter of the water inlet pipe. Increase the water entry depth of the bottom valve. ； Check the power supply voltage, increase the water pump speed, and replace the sealing ring or impeller ； Lower the installation position of the water pump, or replace the high-lift water pump. Symptom 3: Causes of inability to absorb water: There is air in the pump body or air accumulation in the water inlet pipe, or the bottom valve is not closed tightly, the water diversion is not full, the vacuum pump packing is leaking badly, and the gate valve or flap door is not closed tightly. Troubleshooting: 1. Press up the water first, then fill the pump body with water, and then start it. At the same time, check whether the check valve is tight and whether there is air leakage in the pipelines and joints. If air leakage is found, apply lubricating oil or mixed paint to the joints after disassembly and tighten the screws. 2. Check the oil seal ring of the water pump shaft. If it is seriously worn, replace it with a new one. 3. The pipeline is leaking water or air. The nut may not be tightened tightly during installation. If the leakage is not serious, you can apply cement or cement slurry mixed with asphalt oil on the air or water leakage area. Temporary repairs can be done with wet mud or soft soap. If there is water leakage at the joint, you can use a wrench to tighten the nut. If the water leakage is serious, you must reassemble and replace the cracked pipe. ； Reduce the lift and press the nozzle of the water pump 0.5m underwater. Symptom 4. Causes of water pump failure: The pump body and suction pipe are not filled with water. ； The dynamic water level is lower than the water pump filter pipe ； Suction pipe rupture, etc. Troubleshooting: Troubleshoot the bottom valve and fill it with water ； Lower the installation position of the water pump so that the water filter pipe is below the moving water level, or wait until the moving water level rises to filter the water pipe before pumping water. ； Repair or replace the suction pipe. Symptom 5. Causes of severe vibration or noise of the pump body: The water pump is not installed firmly or the water pump is installed too high ； Damaged motor ball bearings ； The main shaft of the water pump is bent or is not concentric or parallel to the main shaft of the motor, etc. Treatment method: Install the water pump stably or lower the installation height of the water pump ； Replace motor ball bearings ； Correct the bent water pump spindle or adjust the relative position of the water pump and motor. Symptom 6: Causes of excessive power consumption: Water pump speed is too high ； The water pump main shaft is bent or the water pump main shaft and the motor main shaft are not concentric or parallel ； The pump lift is inappropriate ； The water pump sucks in sediment or is clogged ； Damage to the motor ball bearings, etc. Treatment method: Check circuit voltage and reduce water pump speed ； Correct the main shaft of the water pump or adjust the relative position of the water pump and motor ； Choose a water pump with appropriate lift ； Clear sediment or blockage ； Replace the motor's ball bearings. Symptom 7: Causes of overheating of drive shaft or motor bearings: Lack of lubricating oil or cracked bearings, etc. Treatment method: Add lubricating oil or replace bearings. These are common causes of "diseases" in water pumps. They are not all causes. In practice, when dealing with faults, the principle of first outside first and then inside should be followed, and do not operate blindly. Before analyzing water pump faults, we must also learn how to use a multimeter and a megohmmeter. Precautions for their use are:: 1. If the magnitude of the voltage or current to be measured cannot be estimated in advance, you should first measure it to the highest range, and then gradually reduce the range to the appropriate position depending on the situation. After the measurement is completed, the range switch should be moved to the highest voltage range and the power supply should be turned off. 2. When measuring voltage, the digital multimeter should be connected in parallel with the circuit under test. ； When measuring current, it should be connected in series with the circuit under test. When measuring DC flow, there is no need to consider the positive and negative polarity. 3. When you misuse the AC voltage switch to measure DC voltage, or misuse the DC voltage switch to measure AC voltage, the display will display "000", or the low-digit numbers will jump. 4. It is forbidden to change the range when measuring high voltage (above 220V) or large current (above 0.5A) to prevent arcing and burning of switch contacts. 5. When "BATT" or "LOW BAT" is displayed, it means that the battery voltage is lower than the operating voltage. ▼ Question one: When the water pump is working, the motor is overloaded. Generally, the motor has a rated operating power, which is called rated power. The unit is Watt (W) or kilowatt (kW). If under certain circumstances, the actual operating power of the motor exceeds the rated power of the water pump, this situation is called motor overload. Motor overload has the following manifestations:: 1. The motor generates too much heat ； 2. The motor speed drops, or even drops to zero speed, which is manifested as the motor not rotating. ； 3. The motor makes a humming sound accompanied by large vibrations. ； 4. If the motor load changes drastically, the motor speed may rise and fall suddenly. List of problem causes and solutions ▼ Problem 2: When the water pump is running, the three-phase motor is missing a phase. When the three-phase motor is running, the driving power must be provided by three cables to achieve three-phase balanced operation. ； It can still operate if the power is provided by two power cords, but prolonged operation will cause the motor to burn out due to lack of phase. How to identify motor phase loss: 1. Use a multimeter to measure the voltage of the three power lines to see if there is no voltage drop in one phase. ； 2. Check the copper wires in the three power cords to see if two of them are black. The copper wire of one power cord is not black and remains the same. ； 3. Open the motor cavity. Generally, two phases of the three-phase motor will burn out, while the other phase will remain intact. List of problem causes and solutions ▼ Question 3: The power supply of the water pump motor suddenly trips. If the matching power protector matches the water pump motor, under normal circumstances, the protector will not trip. The main reasons for tripping of the protector are:: 1. Water pump motor overload ； 2. The water pump motor temperature rises too high ； 3. The running current of the water pump motor is too large ； 4. The power supply voltage of the water pump is too high. List of problem causes and solutions ▼ Question 4: Water has entered the water pump motor. Under normal circumstances, water is not allowed to enter the water pump motor (except for water immersion pumps). The following situations may occur when water enters the motor:: 1. Waterproof cable is damaged and water enters ； 2. The water pump motor power cord connection is not sealed properly and water enters. ； 3. The sealing structure at the inlet of the water pump motor is damaged and water enters. ； 4. Water pump mechanical seal is damaged and water enters ； 5. Water pump O-ring is damaged and water enters ； 6. The sealing bolts are not tightened, causing water to enter the motor. ； 7. Water pump parts are damaged and water leaks. List of problem causes and solutions ▼ Question 5: The water pump motor has leakage. Under normal circumstances, the water pump motor will not leak electricity, but under the following circumstances, the motor will leak electricity.: 1. Waterproof cable damage and leakage ； 2. The water pump motor power cord connection is not properly sealed and leaks. ； 3. Water pump motor leaks electricity ； 4. The water pump motor leaks electricity after being burned out. ； 5. Insulation resistance is too low causing leakage. In order to ensure the safety of people and property when the water pump encounters electric leakage from the motor, the grounding of the water pump must be correctly installed, and it is best to install a leakage switch. List of problem causes and solutions ▼ Question 6: The water pump motor cannot start. The water pump motor will not start (not rotating or the speed is too low). This is generally due to the following reasons.: 1. Water pump leakage ； 2. The supporting power supply voltage is too low ； 3. The water pump impeller is stuck due to foreign matter. ； 4. The bearing is damaged and stuck. ； 5. Motor overload operation (overload) ； 6. The three-phase power supply of the three-phase water pump is reversely connected. ； 7. Three-phase motor lacks phase ； 8. Motor sweep ； 9. The capacitor is damaged, reversely connected, and the capacity is too small. List of problem causes and solutions