How to choose an AC contactor: utilization categories AC-1/AC-3/AC-4, coil voltage, and why the same contactor has different ratings.
A contactor is rated by current, but the number on the label only means something once you state the duty. The same 25 A contactor might be allowed 25 A for a heater and only 9 A for a directly started motor — the utilization category is the difference.
| Category | Load | Typical use |
|---|---|---|
| AC-1 | Resistive, non-inductive | Heaters, ovens, lighting banks |
| AC-3 | Squirrel-cage motor, start + run | Pumps, fans, conveyors (most common) |
| AC-4 | Motor, frequent start/plug reverse | Cranes, hoists, presses |
AC-3 and AC-4 make and break motor current including the starting surge, so their allowed current is far lower than AC-1 for the same contactor. Picking AC-1 data for a motor under-rates the device and welds the contacts.
The coil must match the control supply: 24 V DC, 110 V AC, 230 V AC are common. A 230 V coil on a 24 V PLC output will not pull in; a 24 V coil on 230 V burns out. Keep the coil supply derived from the same source the PLC or pushbuttons use.
ELEHPD AC contactors, household contactors, overload relays, motor protectors and starters cover AC-1 through AC-4 duties.
Because the rating depends on the utilization category: AC-1 (resistive) allows the full current, while AC-3 and AC-4 make and break motor starting current — a 25 A contactor may only be allowed 9 A for a directly started motor.
AC-3 — squirrel-cage motor starting and running, the most common duty for pumps, fans and conveyors. AC-4 is for frequent start and plug reversing such as cranes and presses.
Match the control supply: 24 V DC, 110 V AC or 230 V AC. A 230 V coil on a 24 V PLC output will not pull in, and a 24 V coil on 230 V burns out — derive the coil supply from the same source as the PLC and pushbuttons.
Send the ratings, dimensions and quantities you are working to and we will confirm the closest match from the ELEHPD catalogue, the compliance documents available for it and the lead time. OEM branding, private model numbering and buyer-specific cartons are available on qualified volumes.