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Duty Types (Duty Cycles)
The power output values specified in Catalogues and DataSheets (which can be downloaded from this website) are based on maximum power at continuous load at what the thermal stability of the motor winding is reached. The continuous load is referred to as S1 Duty Cycle. Electric motors can be used at various Duty Cycles, short-term or intermittent (S2, S3, S4, etc.). A higher power output may be achieved whilst used at short-term or intermittent duty. The main factor for determination of the maximum power output at a short-term or intermittent duties is the temperature rise, which when added to the (standard) ambient temperature of 40°C must not exceed the limit temperature of the insulation material used in the electric motor winding.

The Duty Cycles (S1 to S10) have been defined in IEC 60034-1 standard indicating the run cycles of electric motors and in case of the short or intermittent duty also the frequency of the run periods.

The most frequently Duty Cycles specified by our customers are:
Duty type S2 – Short-time duty
Duty type S3 – Intermittent periodic duty
Duty type S6 – Continuous-operation periodic duty

In order to determine the power at these Duty Cycles the following constants are needed:
T  - Thermal time constant
ko - Equivalent losses ratio (no-load/load)
h  - Heat dissipation ratio (ventilated/non-ventilated motor)

The motor data of MEZ IE1, IE2 and IE3 motors and the relevant constants have been loaded in this webpage and the calculation can obtained with a few clicks.

Please note that motors used for Short Term Duty have been excluded from ErP Directive so it is legal to display marking on these Short Term Duty motors nameplates and to install them in the European Union.

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Lower Farm Road
Moulton Park Industrial Estate
United Kingdom

Tel. +44 (0)1933 322113

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