Checkout Current Transformers (CTs) and check resistance across each one while it is disconnected. All resistances should be within 10% of one another. Also do a diode test on the CT inputs on each compressor module. (The diode test is described in RTAA-SVB10B-EN.)
[pdf] Heat generated during compression can cause air expansion before intake is completed. Poor cooling performance—whether due to inefficient oil cooling or water cooling —raises internal temperatures and reduces overall intake volume. Air displacement is directly proportional to rotor speed.
[pdf] Air compressor oil is standard or synthetic oil made specifically for air compressors. Unlike motor oil, air compressor oil does not contain detergent and typically has lower amounts of carbon, sulfur, an.
[pdf] 
