Single Pole Double Throw Relay Wiring Diagram SP and DP refer to single pole and double pole, ST and DT refer to single throw and double throw. Pole refers to the number of circuits controlled by the switch: SP switches control only one electrical circuit. DP switches control two independent circuits (and act like two identical switches that are mechanically linked).
Single Pole Double Throw Relay Wiring Diagram Complete wiring diagram of double pole double throw switches from Battery all the way through to the motors 4 snowblower on a Craftsman tractor.
Single Pole Double Throw Relay Wiring Diagram A double pole single throw dpst switch controls the connections to two wires at once where each wire only has one possible connection. Below is the wiring schematic diagram for connecting a spst toggle switch. The switch is actually two spdt switches in one package with one switch bat. A double pole switch controls two separate circuits.
Single Pole Double Throw Relay Wiring Diagram The DPDT relay (Double Pole Double Throw) is quite interesting and can be used in various scenarious, including for changing the direction of a motor as you can see in the picture below. It has 2 terminals and 4 connectors and you can look at the DPDT relay as the equivalent of 2 Single Pole Double Throw SPDT relays.