Should be in the mage-ohms (you need an isolation tester / high voltage ohm meter for this). Check the voltage when the compressor is running. If the voltage drop significantly when the compressor starts/runs, you have a bad connection somewhere. Check all relays, fuses and electrical connections.
[pdf] The JX-100APMX is a single-stage screw air compressor engineered for maximum reliability, even in critical applications. It ensures minimal oil emissions, with exhaust levels not exceeding 3 parts per million. Powered by a robust 75 HP (55 kW) motor, it achieves an impressive speed of 3000 RPM.
[pdf] The Variable Frequency Rotary Screw Air Compressor is an energy efficient solution for industrial air compression requirements. The motor output frequency is intelligently matched to air consumption, making it more energy efficient and longer lasting than traditional air compressors.
[pdf] 
