Innovative rupture disc designs improve safety and optimize medium-voltage switchgear

SITUATION

It was an ordinary day at the lab. The new medium-voltage transformer was close to being signed off, with just a few safety tests to go. That's when it all went wrong. During the leak-testing process there was a sudden bang, a barely-felt sensation of something small and fast whistling past, then at almost the same time the sound of smashing and clattering - from the other side of the lab!

When the manufacturer of the gas-insulated switchgear equipment investigated what had happened, they found the rupture disc had fragmented violently, damaging equipment up to 19 feet away. They found this to be due to two factors:

• The o-ring seal between the disc and the hold down ring had allowed the disc to slip so that it was no longer seated correctly and could not withstand the pressure as intended.
• The hold down ring itself had also deflected over time,reducing the hold down force on the disc

It was during the leak test.During the leak-testing process, the rupture disc on the equipment fragmentedThis story begins when, during leak testing on a medium voltage transformer, the rupture disk fragments violently, causing damage to equipment 19 feet away. The GISmanufacturer investigated the causes for this and found that: