Hi all,

I have an unusual starting issue that maybe someone can give some advise on.

I have an SZ24 mini screw that sounds terribly labourous and draws excessive current on the star start but runs normally on delta. The star contactor has been replaced in recent years and is in good condition. The voltages over the windings on star start are normal and the amps are ballanced. Electricly the starters and conductors cannot be faulted. The discharge pressure on start is normal. Both discharge and suction check valves are holding and operate. The load slide is at minimum at starting. This skid is on R22 and works as a stand alone system with 3 others that are the same on a cool store. No issues with the others. This system has no oil pump. The motor starts in the correct direction. The system is about 30 years old and I think this motor is orriginal.
There is a economiser side load connected but is isolated.

We have to disconnect the compressor and lift it to open the coupling to be able to run the motor with nothing connected so this has not been done.......yet.

Where I'm heading is either a issue with the electric drive motor, something strange with the poles maybe but you would think that if it was a motor issue then the delta run would be effected.

Or is it possible to oil log a compressor to this extent? The compressor sits about 5ft off the ground, way above the vertical oil separator oil level. I think the compressor has some sort of oil resivour as it has a low oil level float internally.

Any bright ideas?

Thanks