English
Français
Türkçe
Español
Русский
The duty type states for how long and at what intervals the nameplate power can be delivered. IEC 60034-1 classifies these duties as S1–S10; the three-phase motors in our catalogue are rated for S1 continuous duty.
| Duty | Meaning | Example |
|---|---|---|
| S1 | Continuous operation at constant load until thermal equilibrium | Pumps, fans, compressors, conveyors |
| S2 | Short-time operation followed by full cooling | Gate and damper actuators |
| S3 | Intermittent periodic duty; starting heat neglected | Machines working in cycles |
| S4 / S5 | Intermittent duty where starting (and in S5 braking) heat is taken into account | Lifting and positioning duties with frequent starts |
| S6 | Continuous running with periodically varying load | Cutting machines with cyclic load |
In practice the key point is this: an S1 motor can deliver the same power in intermittent duty; only a high number of starts needs separate assessment. The reverse does not hold. If an old nameplate says something like S3 40%, that power applies only at that duty ratio; replacing it with an S1 motor of the same kW is on the safe side, but replacing an S1 motor with an S3-rated motor of the same kW is not correct.