Overload Protection - Siemens 3RK1308‑0 00‑0CP0 Series Equipment Manual

Functions

6.5 Overload protection

6.5 Overload protection
Description
The approximate temperature of the motor is calculated using the measured motor currents
and device parameters "Rated operating current" and "Tripping class". This indicates
whether the motor is overloaded or is functioning in the normal operating range.
Ensuring overload protection
Do not connect more than one motor to one motor starter to ensure overload protection.
Response of the thermal motor model on restart
You set the response of the thermal motor model on restart with this parameter:
● Retention of the thermal motor model on restart
If the motor starter has been disconnected from the 24 V power supply, the thermal motor
model is at the same motor temperature rise state when the power supply is restored as it
was before disconnection. This behavior protects the motor against overload in the case
of brief failures of the 24 V power supply. With this setting, you can therefore specify that
the motor starter retains the thermal motor model when the power supply is restored.
● Deletion of the thermal motor model on restart
If the motor starter has been disconnected from the 24 V power supply for a longer
period, for maintenance purposes, for example, the saved values can result in an
incorrect interpretation of the motor state. With this setting, you can therefore specify that
the motor starter deletes the thermal motor model when the power supply is restored.
In ATEX operation, fail-safe motor starters can only be parameterized to "Retention of the
thermal motor model on restart", however.
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CAUTION
Motor starter (3RK1308‑0**00‑0CP0)
Equipment Manual, 11/2019, A5E34821005002A/RS-AC/003