Understanding Relays

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NORMALLY DESIGN ID
Relays are either Normally Open or Normally Closed. Notice the position of the switches in the two relays shown below. Normally open relays have a switch that remains open until energized (ON) while normally closed relays are closed until energized. Relays are always shown in the de-energized position (no current flowing through the control circuit - OFF). Normally open relays are the most common in vehicles; however either can be use in automotive applications.