How to use a multimeter for submersible pump circuit troubleshooting
How to troubleshoot circuit faults? For open circuits, we can use a multimeter to adjust to the Fengming mode, which is the diode mode, to measure the resistance of each group of coils. Generally, the resistance values of the three submersible pumps are close. If one of the measured circuits has no resistance value, it means that the coil is not connected and there is an open circuit.
There is another type of fault, which is leakage. We need to use a shaking table. The shaking table has two wires, one of which is connected to any set of coils, and the other is connected to a metal sheet. Then we turn the handle of the shaking table and see the direction in which the screen pointer swings. If the pointer swings towards 500, it means that the coil is not leaking electricity and it is normal. If it swings towards 0, it means that the coil is leaking electricity and needs to be repaired.
By using a shaking table to measure the resistance between each of the three sets of coils and the ground, the quality of the circuit can be determined
Also, when lifting the submersible pump out of the water, it is necessary to check whether the pump body is bumped or damaged. Is the sealing gasket damaged. Those with problems should be replaced immediately to avoid secondary damage caused by water ingress into the pump body after drainage.
If it is checking the circuit, then starting from the main circuit and then checking the control circuit, it is necessary to conduct maintenance according to the drawings.
If you want to check the fault of the water pump itself, relying solely on a multimeter is not enough. A multimeter can measure the resistance of the water pump motor winding, but due to the low voltage of the multimeter itself, it cannot accurately measure whether the insulation of the water pump motor is qualified. For submersible pumps, insulation damage should be a common fault.
To check the insulation of the motor, a low voltage megohmmeter with an insulation level of 500 volts is required. Connect one end of the shaking meter to the casing of the water pump and the other end to the three windings of the motor (the three windings need to be short circuited together in advance). Then, shake the handle of the shaking meter at a speed of 120 revolutions per minute. If the measured value is lower than the normal value, it means that the motor insulation of the water pump is damaged and cannot be used anymore.
