ACS800 VFD tripping with Motor Stall Fault
We are running the drive in DTC mode with speed feedback as internal. Encoder is mounted on the motor but we are not using its feedback for controlling the drive.
We often get motor Stall Fault while starting loaded kiln. Our current limit is 2700A, and torque limit is 300%. Pgain is 13.5% and Int time 1.19 sec.
We have observed that the drive current goes upto 2450A and drive drips with Motor stall fault. During this our motor doesn't rotate ( measured speed nearly Zero) but the drive shows rpm nearly 30-35 ( estimated speed).
Why the drive reads 30-35 RPM although motor doesn't rotate?
Why current doesn't go upto limit 2700A ?
We need to increase the gain upto 15.5% sometimes to overcome the motor stall fault.
Based on the information you provided, it appears that the load resisting torque is exceeding the motor torque of the motor.
To get a better point of view, I should know the complete programming of your inverter and the description of the system
The converter without encoder cannot give a more precise information about the number of turns you see, if you want to be sure that the display is correct, you must connect the encoder and make the encoder the speed control transducer
Since it seems to understand that once this combination of inverters plus motor worked, I can suggest you to check the idle operation of the motor, if it is possible to decouple the motor from the load. The first impression I have is that there is a mechanical overload in your system that prevents the motor from starting under load.
Alternatively, you can contact the ABB service closest to your geographical area and ask for their support.
In addition to the other answer, here are my comments:
First ensure that you don't have a real stall situation. This function will prevent the motor from damage !
Look in parameters for stall function 30.10...30.12
Stall protection has no direct relation with a current limits !
It is activated from stall torque limit (which is not user adjustable) AND stall freq AND time
You can vary the stall frequency and time.
As you can see, ACS800 uses output frequency for stall function, because internal speed estimation could not be so precise at low speeds.