How to Check the Relay Operation

The electromagnetic relay is a mechanical device, and therefore subject to wear. Before installing it is necessary to check the circuit. To carry out this operation, you can use the equipment available at each home worker.

Discover pinout relay (e.g. 4 relay module). First of all, find out where he arranged the winding connections. Also find pinout groups of contacts: normally open (which closes when triggered) and normally closed (which opens when activated). If the English documentation on the relay, the phrase "normally open" means the normally open contacts, "normally closed" - normally closed. The so-called switching contacts can be presented in two groups, one of which is normally open, normally closed and the other, which are combined and one of the terminals such that their total number is reduced from four to three.

If the operation voltage of the relay is not known, and known only to the operating current, measure the resistance of the coil. Then multiply the measurement result on the operating current (pre-translating both values in SI units), and you get a response voltage in volts. Such a method is not applicable to test relays with AC coils.

If during the previous operation you have measured the relay coil resistance, at the same time you found out whether the winding intact. If such a measurement you have not yet carried out, spend it. During measurements do not touch the terminals of the winding and probe ohmmeter, so as not to get hit the self-inductance voltage.

On the AC winding serve only to alternating voltage. Diodes it does not shunt. Try to apply for a winding DC voltage equal to the voltage operation. If the relay (e.g. 8 channel relay board) is serviceable, it will work. Conclusions winding and source terminals at the same time and do not touch the same reason. Touching the live circuit in the presence of the diode cannot be all the same, since it can at any moment be destroyed.

Use an ohmmeter to check the condition of each group of contacts. When the voltage across the coil is not, normally open groups must be open, normally closed - closed. When removing the stress situation should be changed to the opposite.