1. Continuous duty system -- S1

The load is constant and the system operates continuously for a long time.

Run until thermal stability is achieved (the temperature no longer rises).

Typical applications: water pumps, fans, compressors, conveyor belts.

Features: Can operate at full load for extended periods without interruption.

2. Short-time work system -- S2

The machine should be shut down for cooling if it fails to reach thermal stability within the specified time.

Standard times: 10, 30, 60, 90 min.

The shutdown time is long enough for the motor to cool to room temperature.

Typical applications: gates, valves, lifting platforms.

3. Intermittent periodic duty cycle -- S3

Constant load + power outage, repeated periodically.

One cycle is ≤10 minutes, and it is not thermally stable.

Note: Duty Cycle FC% (e.g., 15%, 25%, 40%, 60%).

Typical applications: cranes, winches, machine tool auxiliary motion. 

4. Including the intermittent periodic duty cycle with start-up -- S4

Same as S3, but includes the startup process.

The starting current has a significant impact on heat generation, and the temperature rise must be taken into account.

Typical applications: lifting and conveying equipment that requires frequent starts and stops.

5. Intermittent duty cycle including electric braking -- S5

Similar to S4, but with the addition of an electric braking phase.

Braking heat should also be taken into account.

Typical applications: cranes and machine tools that require rapid braking.

6. Continuous periodic duty system -- S6

Constant load operation + no-load operation, repeated periodically.

No power outages or shutdowns, cycle time ≤ 10 minutes.

Note: Duty cycle.

Typical applications: metal cutting machine tools, woodworking machinery.

7. Continuous duty cycle including electric braking -- S7

Similar to the S6, but with the addition of start-up and electric braking.

Without stopping, the cycle repeats from load to braking to no-load.

Typical application: Continuous production lines that require frequent start-up and braking.

8. Includes continuous cycle duty system with variable speed and load -- S8

The rotational speed and load change simultaneously within the cycle.

Multiple cycles with different speeds and different loads.

Typical applications: rolling mills, hoists, and continuous equipment requiring speed regulation.

9. Non-periodic load and speed duty cycle -- S9

The load and speed fluctuate irregularly and non-periodically.

Frequent variations within the rated range are permitted.

There is no clearly stable operating segment.

Typical applications: excavators, rolling mills, test benches, traction equipment.

10. Discrete constant load duty cycle -- S10

It includes no fewer than four discrete constant loads (which may include no-load/stop loads).

Each load segment ran for a sufficiently long time to reach thermal stability.

There is no significant impact on starting and braking.

Typical applications: graded loading test bench, multi-station stable load production line.

Minimalist mnemonic: 

S1 Continuous operation; S2 Operation for a while; S3 Intermittent operation; S4 Start-up; S5 Apply braking; S6 Unloaded operation; S7 Start-up and braking; S8 Variable speed load; S9 Random load changes; S10 Segmented stability.