Test method for electromagnetic relay

There are many kinds of relays, and there are more than ten kinds according to the working principle or structural characteristics of the relays. However, in the amateur production and conventional applications, electricians are more exposed to electromagnetic relays.

Here is a brief description of the electromagnetic relay test method:

1. Measuring coil resistance: The resistance value of the relay coil can be measured by the universal electric meter R×10Ω file, thereby judging whether there is an open circuit phenomenon in the coil. The resistance of the relay coil has a very close relationship with its operating voltage and operating current. The operating voltage and operating current can be calculated from the resistance of the coil.

2, measuring contact resistance: using the multimeter's resistance file, measuring the normally closed contact and the point resistance, its resistance should be 0, such as large or unstable resistance, indicating contact contact is bad; and normally open contact and movement The resistance of the point is infinite. If there is a resistance value, the contact is stuck. This makes it possible to distinguish between a normally closed contact, a normally open contact and a good relay (especially a used relay).

3. Measure the pull-in voltage and pull-in current: use the adjustable power supply and current meter to input a set of voltage to the relay, and connect the current meter in the power supply circuit for monitoring. Slowly increase the power supply voltage. When you hear the relay's pickup sound, record the pull-in voltage and pull-in current.

Measuring the release voltage and release current: It is also connected test as described above. When the relay is closed, the supply voltage is gradually reduced. When the relay is heard again, record the voltage and current at this time. Under normal circumstances, the release voltage of the relay is about 10 to 50% of the pull-in voltage. If the release voltage is too low (less than 1/10 of the pull-in voltage), it will not be used normally, which will threaten the stability of the circuit. Make work unreliable.