Try to turn the compressor by hand. It should be possible to turn it around. It should turn around smoothly, without any 'hickups' (be sure to completely shut down the air compressor!). Check the isolation of the motor windings.
[pdf] Uses a dedicated variable frequency drive (VFD) for permanent magnet synchronous motors, enabling stepless speed regulation, constant pressure air supply, and soft start. This eliminates idle power consumption and enables intelligent air supply.
[pdf] There are many advantages of rotary screw compressors. They are the compressor of choice for a wide range of compression applications across many industries: 1. Continuous airflow and pressurizati.
[pdf] 
