自動控制上的SPST，SPDT，DPST和DPDT觸點配置圖解

SPST(Single Pole Single Throw)：單刀單擲開關(guān)。

SPDT(Single Pole Double Throw)：單刀雙擲開關(guān)。

DPDT(Double Pole Double Throw)：雙刀雙擲開關(guān)。

SPST-NO單刀單擲-常開線圈通電時閉合

SPST-NC單刀單擲-常閉線圈通電時斷開

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). Do not confuse ‘pole’ with ‘terminal’. The DPST switch, for example, has four terminals, but it is a DP, not a 4P switch.

Throw refers to the extreme position of the actuator: ST switches close a circuit at only one position. The other position of the handle is Off. DT switches close a circuit in the Up position, as well as the Down position (On-On). A DT switch can also have a center position (frequently 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 commonly denoted 3PST, 3PDT, 4PDT, etc.

SP 和 DP 指單刀和雙刀，ST 和 DT 指單擲和雙擲。

極數(shù)是指開關(guān)控制的電路數(shù)量：SP開關(guān)只控制一個電路。 DP 開關(guān)控制兩個獨立的電路（并且就像兩個機械連接的相同開關(guān)）。不要將“極”與“終端”混淆。例如，DPST 開關(guān)有四個端子，但它是 DP，而不是 4P 開關(guān)。

投擲是指執(zhí)行器的極限位置：ST 開關(guān)僅在一個位置閉合電路。手柄的另一個位置是關(guān)閉。 DT 開關(guān)在 Up 位置和 Down 位置 (On-On) 閉合電路。 DT 開關(guān)也可以有一個中心位置（通常是 On-Off-On）。

迄今為止，單刀/擲和雙刀/擲開關(guān)是最常見的開關(guān)，但也提供三重和四重配置。它們通常表示為 3PST、3PDT、4PDT 等。