For occasional manual switching, a manual on-load changeover switch is simple and safe. If the generator must take over by itself, use a motorised changeover with an automatic transfer controller (ATS). Size it at or above the incomer rating, and use 4 pole to switch the neutral too.
Why a changeover is essential
The changeover makes it impossible to connect the mains and the generator together. Without it, the generator could feed back into the supply line and endanger people working on it, and the generator could be damaged when the mains returns.
The three types
| Type | How it works | Suits |
|---|---|---|
| Manual off-load (rotary / cam) | Switch only after the load is off | Small loads, control circuits |
| Manual on-load changeover | Switches under full load: I – 0 – II positions | Shops, buildings, factories where someone changes over |
| Automatic (motorised + ATC / ATS) | Senses mains failure, starts the DG, changes over and back | Hospitals, data rooms, lifts, critical supplies |
Choosing the rating and poles
- Rate the changeover at or above the main incomer or generator current, whichever is higher.
- Use 4 pole for three-phase supplies with neutral, so the neutral is also switched between the two sources.
- Choose an on-load (AC-23) rated switch if it may be operated with the load connected.
- Enclosed versions save building a separate box.
Changeovers we supply
- All changeover switches & isolators
- Siemens SINOPLUS 3KJ (63–3150 A)
- L&T C-Line (manual and motorised)
- Schneider Acti9 and Compact INS
Need help choosing?
Send us the rating, the load or a photo of the nameplate on WhatsApp, and we will confirm the right model, availability and rate.
Values are typical guidance for Indian 230 V single-phase and 415 V three-phase supplies. Always follow the equipment nameplate, the manufacturer's instructions and your licensed electrician, who is responsible for the final selection and installation.