Good relay testers do more than hook up their test-set, download the relay settings, reprogram the relay to create easy-to-test scenarios, and then test all the elements inside the relay. Element testing was important in electro-mechanical relays because electro-mechanical relays had limited features and operating characteristics that could be tweaked. Modern digital relays simply don’t fail that way, so we should not apply the same old test procedures.
Modern digital relays stop working when a component inside the relay fails, but the most common problems occur when they are programmed to do the wrong thing from the start, usually by accident. You are the last line of defense for finding problems. If you don’t find the problem today, when is the next time this relay will be tested? Three, six, or twelve years from now? Will the tests be as robust during maintenance intervals, or will everyone assume the relay was tested correctly the first time? If you don’t find the obvious problems today, you’ll likely hear about them when the relay does the wrong thing and allows catastrophic damage that could have been prevented when it was supposed to protect the personnel, equipment, or electrical system.
The most common relay problems can be found by a simple review of the site documentation and relay settings, which we’ll cover in this lesson. Watch this series of videos while I review a real-life scenario, and collect all of the information before I get to the job site. If I can get the problems corrected before I arrive, I can work as quickly as possible with no unnecessary delays.
I usually perform this procedure on a scrap notebook page in less than 10 minutes. Please remember that the next hour of videos is significantly longer than it normally would take because I am explaining the reasoning behind this procedure. There is no reason to make a formal analysis like the one depicted here. What’s important is that you review the entire application while looking for obvious errors that could cause problems for the application.
Download the flowchart we use in all of the lessons with this button.