SP, PD, ST, DT em interruptores eletrônicos

When customers ask us about electronic switches such as button switches and rocker switches. We often ask customers whether they want SPST, SPDT, DPST, DPDT or 3PST, 3PDT. This involves the concepts of extreme numbers and throwing.

SP and DP refer to single pole and double pole respectively, ST and DT refer to single throw and double throw respectively.

The number of poles refers to the number of circuits controlled by the switch: an SP switch only controls one circuit. A DP switch controls two independent circuits (like two identical switches mechanically connected). Don’t confuse “pole” with “terminal”. For example, a DPST switch has four terminals, but it is a DP, not a 4P switch.

Throw refers to the extreme position of the actuator: the ST switch closes the circuit in only one position. Another position for the handle is closed. The DT switch closes the circuit in the Up position and Down position (On-On). DT switches can also have a center position (usually On-Off-On).

Single pole/throw and double pole/throw switches are by far the most common switches, but triple and quadruple configurations are also available. They are usually represented as 3PST, 3PDT, 4PDT, etc..

Functional differences of SP, PD, ST, and DT
In electronic switches, SP, PD, ST, and DT refer to the number of circuits and positions a switch can control:
SP: Single pole, which means the switch controls one electrical circuit
PD: Double pole, which means the switch controls two electrical circuits
ST: Single throw, which means the switch has two positions, such as on and off
DT: Double throw, which means the switch has three positions, such as on, off, and on

The most common types of switches are:
SPST: Single pole single throw, which has two terminals and is ideal for on-off applications
SPDT: Single pole double throw, which has three terminals
DPST: Double pole single throw, which has four terminals
DPDT: Double pole double throw, which has six terminals
A switch’s poles and throws define its internal circuit structure and contact form.

SP and DP refer to single pole and double pole, ST and DT refer to single throw and double throw.

The number of poles refers to the number of circuits the switch controls: SP switches control only one circuit. DP switches control two separate circuits (and act like two identical switches mechanically connected). Don’t confuse “poles” com “terminals.” For example, a DPST switch has four terminals, but it’s a DP, not a 4P switch.

The throws refer to the extreme positions of the actuator: ST switches close the circuit in only one position. The other position of the handle is Off. DT switches close the circuit in the Up position and the Down position (On-On). DT switches can also have a center position (usually On-Off-On).

SP/Throw and DP/Throw switches are by far the most common switches, but triple and quadruple configurations are also available. They are often denoted as 3PST, 3PDT, 4PDT, etc..