Normally Open Contact Relay

Previous picture shows what this looks like in practice.

Normally open contact relay.

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. Normally closed nc contacts allow current through when the relay or contactor is not energized. Normally open relays default in the open position meaning that when they re not in use there is no contact between the circuits. 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.

As relay diagrams show when a relay contact is normally open no there is an open contact when the relay is not energized. Relays control one electrical circuit by opening and closing contacts in another circuit. The following is a description of the four basic types of time delay relay contacts. First two relays are defined as normally open and the other two as normally closed.

First we have the normally open timed closed notc contact. Form a contacts make contacts are normally open contacts. Relays and contactors have two types of contacts each suited for different applications. 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.

Relay act as switch which is operated by a small amount of current. 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. 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. Relays are switches that open and close circuits electromechanically or electronically.

Unlike open contacts with normally closed contacts signal will interrupt a contact or turn a relay off. 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. First relay 00 has a signal and closes its contacts. All relays react to a signal.

In other words when voltage is applied to the relay contactor terminals this contact closes.