How to use a multimeter to detect submersible pump circuit faults
How to troubleshoot line faults? For open circuits, we can use the multimeter to adjust to the Fengming setting, which is the diode setting to measure the resistance of each group of coils. Generally, the resistance values of the three submersible pumps are close. If there is no resistance in one of the measured The resistance value means that the coil is blocked, that is, the circuit is open.
There is another kind of leakage. For this fault, we need to use a megger. The megger has two wires. We connect one to any group of coils and the other to the iron sheet. Then turn the handle of the megger and see. The direction in which the screen pointer swings. If the pointer swings towards 500, it means that the coil is not leaking and it is normal. If it swings toward 0, it means the coil is leaking and needs repair.
Use a megger to measure the resistance between each of the three sets of coils and the ground to determine the quality of the line.
Also, when lifting the submersible pump out of the water, check whether the pump body is bumped or damaged. Is the sealing gasket damaged? If there is a problem, it should be replaced immediately to avoid secondary damage caused by water entering the pump body after being put into the water.
If you are inspecting the circuit, start with the main circuit, then check the control circuit, and perform maintenance according to the drawings.
If you want to check the fault of the water pump itself, it is not enough to rely on a multimeter. The multimeter can measure the resistance of the water pump motor winding, but because the voltage of the multimeter itself is very low, it cannot accurately measure whether the insulation of the water pump motor is qualified. For For submersible pumps, insulation damage should be a common fault.
To check the insulation of the motor, a low-voltage megger with an insulation level of 500 volts is required. Connect one end of the oscillator to the shell 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 oscillator at a speed of 120 revolutions per minute. If the measurement If the value is smaller than the normal value, it means that the motor insulation of the water pump has been damaged and can no longer be used.
