How to do a good job in relay testing to achieve accuracy

a. Measure contact resistance. Use the resistance profile of the universal meter to measure the resistance of the normally closed contact and the moving point. The resistance value should be 0, while the resistance value of the normally open contact magnetic latching relay and the moving point is infinite. It can be distinguished which is a normally closed contact and which is a normally open contact.

b. Measure the coil resistance. The resistance value of the relay coil can be measured with the resistance profile of a universal meter to determine whether there is an open circuit in the coil.

c. Measure the pull-in voltage and pull-in current. Find an adjustable regulated power supply and ammeter, input a set of voltage to the relay, and connect an ammeter in the power supply loop for monitoring. Slowly increase the power supply voltage. When you hear the pick-up sound of the relay, write down the pick-up voltage and current. For accuracy, you can try several times and find the average.

d. Measure the release voltage and release current. When the relay is pulled in, gradually reduce the power supply voltage. When you hear the relay release sound again, write down the voltage and current at this time. Generally, the release voltage of the relay is about 10-50% of the pull-in voltage. If the release voltage is too small (less than 1/10 of the pull-in pressure), it cannot be used normally, which will threaten the stability of the circuit and make the work unreliable.