How to measure the quality of contactor coil with multimeter
The multimeter generally measures the DC resistance value. If it is a small high-voltage coil, it is generally hundreds of thousands or a maximum of several megaohms, and the accuracy is not high. The measured value can be compared with the design value or other equivalent coils without faults. The coil is generally at the milliohm level, and the exact resistance value cannot be measured with a multimeter (the error is very large), and a dedicated direct resistance tester is required.
However, it cannot be said that the measured value is the same as or similar to the design value, and it can be concluded that the coil is good. Sometimes the inter-turn or inter-layer insulation damage of the coil cannot be measured with a multimeter, and a frequency multiplier tester such as a 3-fold frequency generator set is required. Wait for the fault to be found.
Use a digital multimeter to measure the coil in the ohm range below 2K to see if the coil is open circuit. If the circuit is open, the coil is broken.
Use a multimeter ohm gear 200 to measure the normally closed and normally open (measure the normally open by pressing and holding it with your hand or energized) and the auxiliary contact cannot be connected. If the contact is not in good contact, the measurement resistance is very large at this time.
Indicates that the contact is not in good contact. If the auxiliary contact is connected to a load, the voltage will not reach the rated voltage when measuring the voltage.
Use a multimeter to measure the normally open and normally closed terminals to see if they are normal. It is not easy to measure the coil with a multimeter. The best way is to directly add the rated voltage to test the action.
