That is, a common terminal connects to either of two others, never connecting to both at the same time. Including two for the coil, such a relay has a total of five terminals. DPST – Double-Pole Single-Throw relays are equivalent to a pair of SPST switches or relays actuated by a single coil.
Accordingly, what is NO and NC contact?
NO is normally open i.e. the contacts are normally open and close when the switch is actuated. NC is normally closed i.e. the contacts are normally closed and open when the switch is actuated. 1NO1NC is generally used to describe contactors (industrial power relays) and manual switches like emergency stop buttons.
What is a normally closed contact?
Normally Open/Closed. When a momentary switch is not actuated, it's in a “normal” state. Depending on how the button is constructed, its normal state can be either an open circuit or a short circuit. When a button is open until actuated, it's said to be normally open (abbreviated NO).