| Abbreviation |
Nomenclature |
Description |
Switch Symbol |
| SPST |
Single pole, single throw |
Two terminals connected together or not connected. |
 |
| SPDT |
Single pole, double throw |
A simple change form switch: Common is connected
either to L1 or to L2. |
 |
| SPCO |
Single pole changeover
or Single pole, centre off |
Identical to SPDT. Suppliers may use SPCO
for switches which are stable in off position while
position the center and SPDT for those
which do not. |
| DPST |
Double pole, single throw |
Identical to two SPST switches
mechanical connected. |
 |
| DPDT |
Double pole, double throw |
Identical to two SPDT switches mechanically
connected. |
 |
| DPCO |
Double pole changeover
or Double pole, centre off |
Identical to two DPDT. Suppliers may use DPCO
for switches which are stable in off position while
position in the center. |
