What Is Duty Cycle (S1–S9)

The duty cycle of an electric motor describes the relationship between the operating time,load conditions,starting frequency and resting periods during motor operation.

Motor manufacturers classify duty cycles according to international standards such as IEC 60034-1 Which defines duty types from S1 to S9.Selecting the correct duty cycle is essential.

Among all motor duty classifications,S1 continuous duty is the most widely used and easiest to understand.According to IEC 60034-1,an S1 motor is designed to operate continuously at rated load without exceeding its permitted temperature rise.

S2 short time duty is one of the motor duty classifications defined by IEC 60034-1.Different S1 continuous duty motor,S2 motor operates for a limited period of time and then stops for sufficient cooling period.

The motor is designed to operate a higher load than continuous duty motor.S2 duty motors are commonly used in machines that operate only occasionally.

S3 intermittent periodic duty is motor duty classification defined by IEC60034-1.S3 motor does not operate continuously.The motor temperature rises during operation and decreases during rest periods.S3 motors are widely used in equipment requiring repeated but not continuous movement.

S6 continuous operation with intermittent load is a motor duty classification defined by IEC60034-1.It describes motor that operate continuously but with alternating periods of load and no-load operation.

S7 continuous operation with starting and braking duty motors are designed for highly dynamic applications.

S8 continuous operation with periodic speed changes motors are designed for modern variable speed industrial applications.

S9 Non-periodic duty is the most advanced motor duty classification among the IEC 60034-1 duty.S9 represent the highest level of dynamic motor operation.