Thermal Motor Protection; Thermal Motor Models - Siemens SINAMICS S120 Function Manual

10.2

Thermal motor protection

The thermal motor protection monitors the motor temperature and responds to
overtemperature conditions with alarms or faults. The motor temperature is either measured
with sensors in the motor, or is calculated without sensors, using a temperature model from the
operating data of the motor. Combinations of temperature measurement and taking into
consideration a motor temperature model are possible. As soon as critical motor temperatures
are determined, measures to protect the motor are initiated.
For thermal motor protection with temperature sensors, the motor temperature is directly
measured in the motor windings. The temperature sensors are either connected to the Control
Unit, the Motor Module or supplementary modules. The determined temperature values are
sent to the Control Unit, which then responds according to the parameter settings. When
switching on again after a power failure, the actual motor temperatures are immediately
available.
With thermal motor protection without temperature sensors, different thermal motor models are
used for calculation. The temperatures according to the motor temperature model are
calculated from the motor operating data. Whereby, the masses of the motor parts and the type
of ventilation, for the I
operating time is taken into consideration in the calculation. For motor temperature protection
without a temperature sensor, p0600[0...n] = 0 is set or p0601[0...n] = 0 is set. In addition to
motor temperature protection without a temperature sensor, a motor temperature model must
be activated with p0612.00 = 1, p0612.01 = 1 or p0612.02 = 1.
If you are using motors from the motor lists, or with integrated DRIVE-CLiQ connection, the
relevant motor data is automatically transferred to the Control Unit.
In the VECTOR control mode, the drive response to a detected motor overtemperature can be
parameterized using p0610 (motor overtemperature response). The motor may either be
switched off immediately – or continue to operate at reduced power, reduced load, under
adapted conditions.
10.2.1

Thermal motor models

Motor temperature measurements using temperature sensors protect the motor against
overheating. If temperature sensors are not being used, then instead, the thermal motor model
can be used as motor protection. Thermal motor models respond more dynamically than
temperature sensors, and therefore provide better protection relating to brief overload
conditions.
Depending on the particular temperature model, the temperature rise is either assigned to
various motor parts (stator, rotor) or is calculated from the motor current and the thermal time
Drive functions
Function Manual, 06/2019, 6SL3097-5AB00-0BP2
t model (for synchronous motors), the motor current in relation to the
2
Monitoring functions and protective functions
10.2 Thermal motor protection
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