02-09-2019 (3215 lectures) | Categoria: Electronics |
Electronics specification and abbreviation | Expansion of abbreviation | British mains wiring name | American electrical wiring name | Description | Symbol |
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SPST | Single pole, single throw | One-way | Two-way | A simple on-off switch: The two terminals are either connected together or disconnected from each other. An example is a light switch. | ![]() |
SPST-NO
Form A[4] |
Single pole, single throw, normally open | A simple on-off switch. The two terminals are normally disconnected (open) and are closed when the switch is activated. An example is a pushbutton switch. | |||
SPST-NC
Form B[4] |
Single pole, single throw, normally closed | A simple on-off switch. The two terminals are normally connected together (closed) and are open when the switch is activated. An example is a pushbutton switch. | ![]() |
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SPDT
Form C[4] |
Single pole, double throw | Two-way | Three-way | A simple break-before-make changeover switch: C (COM, Common) is connected either to L1 or to L2. | ![]() |
SPCO SPTT, c.o. |
Single pole changeover or Single pole, centre off or Single Pole, Triple Throw |
Similar to SPDT. Some suppliers use SPCO/SPTT for switches with a stable off position in the centre and SPDT for those without.[citation needed] | |||
DPST | Double pole, single throw | Double pole | Double pole | Equivalent to two SPST switches controlled by a single mechanism. | ![]() |
DPDT | Double pole, double throw | Equivalent to two SPDT switches controlled by a single mechanism. | ![]() |
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DPCO | Double pole changeover or Double pole, centre off |
Schematically equivalent to DPDT. Some suppliers use DPCO for switches with a stable center position and DPDT for those without. A DPDT/DPCO switch with a center position can be "off" in the center, not connected to either L1 or L2, or "on", connected to both L1 and L2 at the same time. The positions of such switches are commonly referenced as "on-off-on" and "on-on-on" respectively. | |||
Intermediate switch | Four-way switch | DPDT switch internally wired for polarity-reversal applications: only four rather than six wires are brought outside the switch housing. | ![]() |
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2P6T | Two pole, six throw | Changeover switch with a COM (Common), which can connect to L1, L2, L3, L4, L5, or L6; with a second switch (2P, two pole) controlled by a single mechanism. | ![]() |
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