FES Ammonia Screw Compressor 1

[wrsharper]

I hope somebody may have ran into this problem in the past. The electrical side of the compressor is in good shape. The compressor motor experiences higher than normal inertial load during start. During run the motor is working 10% harder than it should. I suspect something with the slide valve. One thing I noticed was when the slide valve was at 90% the motor was pulling 480A. Increasing the slide valve to 100% caused the motor to pull 625A. Motor FLA is 570A. There are no gas obstructions both upstream and downstream of the compressor. The refrigeration man ensures me that the compressor bearings are in good shape. The slide valve dial indicator indicates correctly. I think that the 10% increase of the slide valve should not have caused such a large increase of motor current and this may be indicitive of the problem. Any ideas?

 

[wrsharper]

Nobody responded to my post so it must have been red flagged but I will supply the recently found answer in case anyone else encounters this potentialy dangerous situation. It was not electrical but the liquid ammonia injection cooling valve. It was jacked all the way open allowing liquid ammonia to enter the compressor when it should not have been allowed. The screw compressor was starting with liquid ammonia around the screw. As you already know this compressor is only designed for gas. This also drastically lowered the oil level in the tank below it. I am only responsible for the electrical side and our only experienced refrigeration man found it. He told me there was no reason for this valve to be jacked open.