How to troubleshoot a Relay

George Merchant introduces the topic of troubleshooting relays, emphasizing that the principles apply universally across different systems. He starts by illustrating a simple latching circuit with a stop switch, start switch, relay coil, and relay contact, explaining its operation with 24 or 120 volts.

The video delves into the physical components of a relay, highlighting the coil (a copper winding) and the contacts. It demonstrates how the contacts move when the relay is energized, clarifying that most relays have normally open (NO) and normally closed (NC) contacts, along with a common terminal for incoming voltage. It also explains that a relay's contacts can switch a different voltage than the coil, often used for isolation between control voltage (e.g., 24V DC) and higher power circuits (e.g., 480V 3-phase for a motor).

The core of troubleshooting begins by checking if voltage is reaching the relay coil. Users are advised to use a multimeter set to the appropriate voltage type (AC or DC) and measure across the A1 and A2 terminals of the coil. If voltage is present but the coil isn't energizing (no indicator, no pulling in), the coil itself or its base connections may be faulty. Safety precautions are noted, especially when dealing with live circuits.

The next step focuses on testing the relay contacts. The video explains checking the voltage passing through the contacts, specifically looking for voltage drops. A significant voltage drop (e.g., 24V incoming but only 18V outgoing) indicates a problem with the contacts, often due to dirt, arcing, or carbon buildup over time. Such issues can prevent proper power delivery to the next device in the circuit.

The video concludes by summarizing the troubleshooting steps for relays and invites viewers to explore more resources on their website, improvemaintenance.com, and subscribe for more how-to videos to help train the next generation of technicians or sharpen existing skills.