Thermal Motor Models - Siemens SINAMICS G130 Operating Instructions Manual

9.4.5.6

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 makes
sense. For example, a very fast temperature increase that is not detected by the sensors in
sufficient time can potentially damage a 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
deployed.
NOTICE
Material damage caused by overheating for motor operation without sensor
A thermal motor model cannot fully replace a sensor. The thermal model cannot protect the
motor if incorrectly installed, for increased ambient temperatures or if errors were made in
the parameter settings. Without temperature sensors, thermal motor models are not in a
position to identify or take into account the ambient temperatures or the initial motor
temperature. This can cause motor overheating and so material damage.
• Do not deploy thermal motor models when a higher environment temperature or a
Thermal motor model 1 (for permanent-magnet synchronous machines)
By deploying the thermal I2t motor model, the temperature rise of the motor windings as a
result of dynamic motor loads is also determined in addition to data acquired using a
temperature sensor.
The model motor temperature is indicated in r0632. It is calculated from the following values:
● Absolute value of the actual current, unsmoothed (r0068[0])
● Motor stall current (p0318)
● I2t motor model thermal time constant (p0611)
● Measured motor temperature (r0035) or motor ambient temperature (p0625) for operation
without temperature sensor
● Motor temperature at rated load (p0605, for expansion p0627)
Inverter chassis units
Operating Instructions, 07/2016, A5E00331449A
higher initial temperature of the motor can occur.
Functions, monitoring, and protective functions
9.4 Monitoring and protective functions
485