Normally-open and Normally-closed Switch Contacts

Electrical switch contacts are either normally-open or normally-closed, depending upon the open or closed status of the contacts under “normal” conditions.

But what exactly defines “normal” for a switch? The answer is not complicated, but it is often misunderstood because of the ambiguous nature of the common word.

The “normal” state of the switch is the state of electrical contacts in the state of non-physical regeneration. One way to think of a “normal” situation is to think of a change in relaxation.

With the change of the temporary contact button, this may be the status of the switch contact if it is not pressed. Electric switches are always designed with scheme drawings in their “normal” conditions, regardless of the type of operation.

The “normal” state of the switch (closed) is actually an abnormal state of the internal process (low flow), for the simple reason that the switch should be stimulated and not rested while the process is running. as it should.

Below listing of “normal” definitions for various process switch types:

  • Limit switch: target not contacting the switch
  • Proximity switch: target far away
  • Pressure switch: low pressure (or even a vacuum)
  • Level switch: low level (empty)
  • Temperature switch: low temperature (cold)
  • Flow switch: low flow rate (fluid stopped)

Symbols of electrical switches

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