What Contacts Are Needed for a HAND-OFF-AUTO Selector Switch?
What you need to know
For a standard HAND-OFF-AUTO (HOA) arrangement using a Schneider Electric Harmony 9001KS43 or 9001SKS43 3-position selector switch, use a 9001KA1 contact block.
With the C cam configuration:
- HAND (left): NC contact closed
- OFF (center): NO contacts closed
- AUTO (right): NO contact closed
This provides two independent contact functions for the traditional HAND/OFF/AUTO control arrangement.
HAND-OFF-AUTO selector switch configuration
The 9001KS43 is a Harmony 9001K 30 mm, 3-position, maintained selector switch head supplied without a contact block. Schneider Electric identifies it as compatible with the 9001KA1 contact block.
For standard HOA arrangement:
- Use a 9001KA1 contact block.
- The selector switch uses a C cam.
- The left position corresponds to HAND.
- The center position corresponds to OFF.
- The right position corresponds to AUTO.
Contact operation by selector position
| Selector position | Operating mode | NC contact | NO contact |
|---|---|---|---|
| Left | HAND | Closed | Open |
| Center | OFF | Open | Open |
| Right | AUTO | Open | Closed |
This arrangement ensures that HAND and AUTO are independent operating selections, while neither contact is closed in the OFF position.
Schneider Electric references
| Function | Schneider Electric reference | Product description |
|---|---|---|
| Selector switch head | 9001KS43 | Harmony 9001K metal selector switch head, 30 mm, 3 positions, maintained/stay-put, supplied without contact block. |
| Selector switch head | 9001SKS43 | Harmony 9001SK selector switch referenced for the equivalent HAND/OFF/AUTO arrangement in the source FAQ. |
| Contact block | 9001KA1 | Contact block used with the C-cam selector switch to achieve the traditional HAND/OFF/AUTO contact arrangement. The Harmony 9001K documentation identifies 9001KA1 as a compatible contact block for these selector-switch configurations. |
Launch Product Selector on se.com to configure a 9001selector switch according to your requirements or contact Schneider Electric Technical Support to check a configuration against your control scheme.