Connection testing is also as described above. When the DC miniature relay is closed, the power supply voltage decreases gradually. When you hear the relay release sound again, record the voltage and current at that moment. You can also try several times to obtain the average release voltage and release current. Under normal circumstances, the release voltage of the relay is about 10-50% of the pull-in voltage. If the release voltage is too low (less than 1/10 of the pull-in voltage), it cannot be used normally, which will threaten the stability of the circuit and result in unreliable operation.

Electrical symbols and contact forms of relays

The relay coil is represented by a rectangular box symbol in the circuit. If a small signal relay has two coils, draw two parallel rectangular boxes. Meanwhile, mark the text symbol "J" of the relay in or next to the rectangular box. There are two ways to represent the contacts of the relay: one is to make them directly on the side of the rectangular box, which is more intuitive. The other is to pull each contact into its own control circuit according to the needs of circuit connection. Generally, the same symbol is marked next to the contacts and coil of the same relay, and the contact groups are numbered to show the difference.