Eliminated from:
Inverter Drives 8400 TopLine from firmware version 12.00.00.00
Behaviour of the new version?
The rotor resistance is now adapted depending on the KTY temperature using the correct factor.
Which products are affected?
Inverter Drives 8400 TopLine with a firmware version lower than 12.00.00.00
What happens?
With an increasing motor temperature, the torque actuated is too low.
When does the problem occur
In the case of asynchronous motors in applications with a torque actuation and temperature feedback via a KTY in the servo control ASM control mode.
The increase of the stator resistance value is not calculated correctly. At the operating temperature of the motor, an error of up to 20 % can result.
Diagnostics options?
The error in the torque can usually only be detected using a torque metering shaft or a tension transducer.
Short-term measures/recommendations?
Compensation of the torque setpoint in the application depending on the motor temperature.
Evaluation:
The torque of ASM is not actuated correctly. This has an impact on the process (e. g. wrong web tension) for applications with torque actuation and, possibly, on the stability of the control in the case of a very dynamic speed control. In many applications, the restriction will only show a very low impact.
