Relay Testing:
1. Testing contact resistanceUsing a multimeter in resistance mode, measure the resistance between the normally closed (NC) contact and the movable contact. The resistance should be 0 ohms (using a more accurate method, the contact resistance can be measured within 100 milliohms). The resistance between the normally open (NO) contact and the movable contact should be infinite. This can distinguish between the NC and NO contacts.
2. Testing coil resistanceUsing a multimeter in the R×10Ω range, measure the resistance of the relay coil to determine if there is an open circuit.
3. Measuring pull-in voltage and pull-in currentUse an adjustable power supply and an ammeter. Apply a set voltage to the relay and connect the ammeter in series in the power supply circuit for monitoring. Slowly increase the power supply voltage and note the voltage and current at which the relay pulls in. For accuracy, multiple attempts can be made and an average value can be obtained.
4. Measuring release voltage and release currentUsing the same setup as described above, after the relay pulls in, gradually decrease the power supply voltage. When the sound of the relay releasing is heard again, note the voltage and current at that time. Multiple attempts can also be made to obtain an average release voltage and release current. Generally, the release voltage of the relay is approximately 10-50% of the pull-in voltage. If the release voltage is too small (less than 1/10 of the pull-in voltage), it cannot be used properly, which can threaten the stability and reliability of the circuit.
Post time: Jun-20-2023