Siemens S120 configurationmanual Intermittent duty S3, ෙW %

Configuring the motor 5.3 Short-time duty S2 and intermittent duty S3

Intermittent duty S3

With intermittent duty S3, periods of load time ΔtB with constant current alternate with periods of downtime ΔtS with no current feed. The motor heats up during the load time and then cools down again while at standstill. After a sufficient number of duty cycles with cycle duration ΔtSpiel = ΔtB + ΔtS, the temperature characteristic oscillates between a constant maximum value To and a constant minimum value Tu; see figure below.

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Figure 5-9 Current and temperature characteristic for intermittent duty S3

For currents IN < IM ≤ IMAX, the rms continuous current may not exceed the rated current:

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In this respect, the cycle duration should not exceed 10% of the thermal time constant tTH. If a longer cycle duration is necessary, please contact your local Siemens office.

Example

When the thermal time constant tTH = 180 s, this results in the following maximum permissible cycle duration:

tSpiel = 0.1 · 180 s = 18 s

1FW6 Built-in torque motors

Configuration Manual, 05/2009, 6SN1197-0AE00-0BP3 77