Normally Open Relay Vs Normally Closed

In these systems normally closed relays act as.

Normally open relay vs normally closed.

Normally closed relay applications. Normally closed relays are used to keep ac unit blowers running even after the air compressor shuts off allowing the system to continue generating residual cool air without running the compressor. Relays and contactors have two types of contacts each suited for different applications. When it comes to electrical switches and contacts many people seem to be confused by the terms normally open no and normally closed nc the root of the problem seems to start with the fundamental concept of what it means to be open or closed this post attempts to clarify those concepts.

Gas valve control systems. A normally open is one that is an open circuit until you put voltage and a signal to it. Think of your relay as if it were two ends of as wire. Normally closed nc contacts allow current through when the relay or contactor is not energized.

In other words when voltage is applied to the relay contactor terminals this contact closes. Here are just a few systems that require normally closed relays.