How to detect the fault of submersible pump circuit with multimeter
The circuit faults of submersible pump include open circuit (that is, there is no communication between lines) and electric leakage (the insulation layer of enameled wire is damaged or the coil is grounded).
How to troubleshoot the line fault? For the open circuit, we can adjust the multimeter to Fengming gear, that is, diode gear to measure the resistance value of each group of coils. Generally, the resistance values of submersible pumps of the three items are close. If there is no resistance value all the way, it is that the coils are blocked, that is, the open circuit.
There is also leakage. For this fault, we need to use a shaking table. The shaking table has two wires. We connect one to any group of coils and the other to the iron sheet, and then turn the handle of the shaking table to see the direction in which the screen pointer swings. If the pointer swings to 500, it means that the coil does not leak electricity, which is normal. If you swing to the zero side, it means that the coil is leaking, and it needs maintenance.
By measuring the resistance between each of the three groups of coils and the ground with a shaking table, the quality of the line can be judged.
Also, when lifting the submersible pump out of the water, check whether the pump body is bumped or damaged. Whether the gasket is damaged. If there is a problem, it should be replaced immediately to avoid secondary injury caused by water entering the pump body after launching.
If it is to check the line, then check from the main loop, and then check the control loop, which needs to be checked against the drawings.
If it is necessary to check the fault of the water pump itself, it is not enough to rely on the multimeter. The multimeter can measure the resistance of the winding of the water pump motor, but because the voltage of the multimeter itself is very low, it is impossible to 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 shaking table with insulation class of 500 volts is needed. Connect one end of the shaking table to the shell of the water pump and the other end to the three windings of the motor (the three windings need to be shorted together in advance). Then, shake the handle of the shaking table at a speed of 120 revolutions per minute. If the measured value is less than the normal value, it means that the motor insulation of the water pump has been damaged and cannot be used any more.
