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

Monitoring and protective functions

8.5 Thermal motor protection

8.5 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. For a 3-mass model, the masses of the motor
parts and the type of ventilation, for the I
in relation to the operating time is taken into consideration in the calculation. For motor
temperature protection without temperature sensor, p0600[0...n] is set to 0, p0612.00 to 1
and p0612.01 to 1. (For more information, see Chapter, Temperature model.)
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 control type "Vector Control", using p0610 the reaction of the drive to a detected motor
overtemperature can be parameterized. The motor may either be switched off immediately –
or continue to operate at reduced power, reduced load, under adapted conditions.
8.5.1

Thermal motor models

Thermal motor models are used so that thermal motor protection without a temperature
sensor or with temperature sensor deactivated (p0600 = 0) is guaranteed. The simultaneous
use of temperature sensors and a thermal motor model also make sense. For example, a
very fast temperature increase, which is not detected by the sensors in sufficient time, can
potentially damage motor. This situation can occur for motors with a low thermal capacity.
Depending on the particular model, the temperature rise is either assigned different motor
parts (stator, rotor), or is calculated from the motor current and the thermal time constant. A
combination of motor temperature model with additional temperature sensors can also be
used.
534
t model (for synchronous motors), the motor current
2
Function Manual, (FH1), 01/2013, 6SL3097-4AB00-0BP3
Drive functions