Not long after I began contributing to Hagerty eight years ago, I wrote a detailed four-part piece on electrical relays and how they work in cars. You can still find the articles here (Part I: Why We ...

Many low and medium temperature single-phase compressors require some type of external relay to assist in the starting of its motor. The purpose of this relay is to remove the motor’s start winding, ...

A simple ohmmeter is all that is needed to troubleshoot a potential relay. After taking all of the connecting wires off of the potential relay, measure the resistance across the 1 and 2 terminals. The ...

Relays usually are driven using optocouplers, which offer isolation between analog and digital grounds to ensure that switching currents in the relay coils do not affect the noise margin of the ...

In Part 1 of this two-part series, we presented a 3-phase, 480VAC motor circuit with its associated controls (Figure). We stepped through a logical, systematic approach to troubleshoot the main power ...