Normally Open Contact Relay

Relays are switches that open and close circuits electromechanically or electronically.

Normally open contact relay.

The national association of relay manufacturers and its successor the relay and switch industry association define 23 distinct forms of electrical contact found in relays and switches. First two relays are defined as normally open and the other two as normally closed. The following is a description of the four basic types of time delay relay contacts. Relay act as switch which is operated by a small amount of current.

Form a contacts make contacts are normally open contacts. In other words when voltage is applied to the relay contactor terminals this contact closes. First relay 00 has a signal and closes its contacts. Relays and contactors have two types of contacts each suited for different applications.

When power is introduced an electromagnet pulls the first circuit into contact with the second thereby closing the circuit and allowing power to flow through. Normally open no contacts allow current when the relay or contactor is energized. Relays control one electrical circuit by opening and closing contacts in another circuit. Normally open and normally closed electrical contacts make up electrical switches relays circuit breakers and most any other electrical component that switches something on off or can be switched on off.

Unlike open contacts with normally closed contacts signal will interrupt a contact or turn a relay off. Time delay relay contacts must be specified not only as either normally open or normally closed but whether the delay operates in the direction of closing or in the direction of opening. Previous picture shows what this looks like in practice. Normally closed nc contacts allow current through when the relay or contactor is not energized.

All relays react to a signal. The relay has two contacts normally open no normally close nc in the figure given below you can see there are two sides of a relay. Spst relay single pole single throw relay an electromagnetic switch consist of a coil terminals 85 86 1 common terminal 30 and one normally open terminal 87 it does not have a normally closed terminal like the spdt relay but may be used in place of spdt relays in all diagrams shown on this site where terminal 87a is not used. One is primary coil which acts as a electromagnet on passing current through it and other one is secondary side having no and nc contacts.

First we have the normally open timed closed notc contact.