02-09-2019  (1076 lectures) Categoria: Electronics

SPST - SPDT - SPCO - SPTT - DPST - DPDT - DPCO

Electronics specification and abbreviation Expansion
of
abbreviation
British
mains
wiring
name
American
electrical
wiring
name
Description Symbol
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-Switch.svg
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. SPST-NC-Switch.svg
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. SPDT-Switch.svg
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. DPST-symbol.svg
DPDT Double pole, double throw

Equivalent to two SPDT switches controlled by a single mechanism. DPDT-symbol.svg
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. Crossover-switch-symbol.svg
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. 2P6T-symbol.svg

 

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