Back to the startup systems. Star/delta (Y-D) is the most common system deployed in air compressors, or in industrial machines in general. It's simple, easy to understand, easy to troubleshoot and doesn't require expensive electronics. With Y-D starter we take advantage of the lower per-winding voltage when. .
Here we see a typical setup of a star-delta starter: *Typical setup of a star-delta starter. There are 6 cables going to the motor (white, at the bottom) .
The system always consists of 3 main contactors (big relais) in a typical configuration that is easy to recognize. The 3 contactors are: 1. Main/line contactor 2. Delta contactor 3. Star contactor
[pdf] 
The quickest way for direct results is to get my Air Compressor Troubleshooting Guide. You press the start button but nothing happens. Either an electrical problem, or the compressor has tripped on a safety device. Check supply power. Check for errors on display. Check emergency stop is out..
The quickest way for direct results is to get my Air Compressor Troubleshooting Guide. You press the start button but nothing happens. Either an electrical problem, or the compressor has tripped on a safety device. Check supply power. Check for errors on display. Check emergency stop is out..
Either an electrical problem, or the compressor has tripped on a safety device. Check supply power. Check for errors on display. Check emergency stop is out. Check and reset the overload relay. If it’s a new installation, check the phase sequence. Ambient temperature too high or not enough ventilation..
Symptoms: Decreased air pressure or the compressor running continuously. Inspect Hoses and Fittings: Check all hoses and fittings for leaks. Tighten connections or replace damaged hoses. Pressure Relief Valve: Test the pressure relief valve for proper operation. Replace it if it is leaking.
[pdf]