⚡ Testing the Alarm & Trip Signals of the Buchholz Relay in Oil-Filled Transformers In this reel, our engineer demonstrates how to safely test the alarm and trip functions of the Buchholz relay — one of the most critical protection devices in oil-filled transformers. The test starts by locating the Buchholz relay’s built-in test button. With a half-press, the relay sends an alarm signal, confirming the first stage protection is active and responsive. This alarm stage is designed to detect early