Hi Sargent york:
really appreciate your reply,
yes I believe the motor is a RAM motor,
one of my customers in Vietnam has five YK chillers in their plant, all the five chillers are equiped with RAM motor, just in 8 years, they have 3 motors burned,
and on the job site I currently work, there are another two same type chillers, their motor current also fluctuates, but no so serious, only have 2 or 3% differentials,
I am not sure if I can give advice to the customer to replace the motor, because the motor had been working well for years, it seems the quality of RAM motor is so bad that it will eventually has problem someday.