1. Rated working voltage

It refers to the voltage required by the coil of a relay during normal operation, which is the control voltage of the control circuit. Depending on the model of the relay, it can be AC voltage or DC voltage.

2. DC resistance

It refers to the DC resistance of the coil in the relay, which can be measured through a multifunctional meter.

3. Pickup current

It refers to the minimum current that a relay can generate for the suction action. During normal use, the given current must be slightly greater than the suction current in order for the relay to operate stably. For the working voltage applied to the coil, it is generally not allowed to exceed 1.5 times the rated working voltage, otherwise a large current will be generated and the coil will be burned out.

4. Release current

It refers to the maximum current generated by the release action of a relay. When the current in the energized state of the relay decreases to the specified level, the relay will return to the non energized release state. At this point, the current is much smaller than the suction current.

5. Contact switching voltage and current

It refers to the voltage and current that the relay is allowed to load. It determines the magnitude of the voltage and current that the relay can control, and should not exceed this value during use, otherwise it is easy to damage the relay contacts.

1. Measuring contact resistance

Using the resistance range of a multifunctional meter, measure the resistance between the normally closed contact and the moving point. The resistance value should be 0 (using a more accurate method, the contact resistance value can be measured within 100 milliohms); The resistance between the normally open contact and the moving point is unlimited. This can distinguish which is a normally closed contact and which is a normally open contact.

2. Measure coil resistance

The resistance value of the relay coil can be measured using the R × 10 Ω range of the multifunctional meter to determine whether there is an open circuit phenomenon in the coil.

3. Measure the pull-in voltage and current

Find an adjustable voltage regulator and ammeter, input a set of voltage to the relay, and connect an ammeter in series in the power supply circuit for monitoring. Slowly increase the power supply voltage, and when you hear the sound of the relay closing, record the closing voltage and current. For accuracy, you can try multiple times and calculate the average value.

4. Measure release voltage and release current

Also, connect the test as mentioned above. After the relay is engaged, gradually reduce the power supply voltage. When the relay releases again, record the voltage and current at this time. You can also try multiple times to obtain the average release voltage and current. In general, the release voltage of a 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 voltage), it cannot be used normally, which poses a threat to the stability of the circuit and makes its operation unreliable.