Synchronous Motor Excitation Panel

[burntcoil]

We have a 27000HP Synchronous motor operating at 13.2kV. The motor excitation control panel have redundant DESC200 Excititation Controller from Basler. During normal operation, if the Master fails, the excitation control will automatically transfer to backup controller. The motor was tripped on Loss of Excitation (although exciter circuit was checked and found healthy). When the motor was started with backup conrtoller, its working fine. After the startup when we shifted the motor to master controller, it tripped again. Now the motor is on backup controller. I am interested to know if we can test the Master to Backup and Backup to Master transfer without running the motor? Do anyone have such previous experience?

 

[DTR2011]

How is this transfer implemented? Is it hard wired via an Alarm contact or is it implemented via software to a larger control system?

Assuming you have ruled out any problem in the sensing and control circuits ahead of time and that the settings/logic for both devices agree, I offer the following suggestion. Given the size of the motor, a simulation of the motor via volts and amps may help sort things out.

If you have access to a modern relay test set, you could probably accomplish what you want.
Use the test set to both produce the voltages & currents, but also to measure any trips (when & what) that occurred or simulate various status points, control logic,etc. To simplify things, wire the same current in series with the two units and parallel the voltages between them.

The DECS may have a COMTRADE file, which can be played back with the test set.

Have you checked for simple things like the V/I into the master controller are accurate and match the backup unit? Again the COMTRADE or event log file may help to solve that without a test set.

If you don't have the equipment, it may be best to hire a service company (with their test equipment) for a day.

 

[burntcoil]

Thanks DTR2011

Can you tell me how I can test the Auto Tracking feature of these Redundant DESC200 units. I want to make sure that the backup unit is auto tracking the master to maintain the required excitation and both the units are communicating togather.