How do you test your circuit protection?

[John Rumm]

A trip round Eaton's circuit protection testing facility:

If you ignore the cheesy presentation, the specialist kit they have to play with is really quite impressive.

[Chris J Dixon]

Indeed. I have been around similar work.

One of the most impressive bangs I saw was at Switchgear Testing Company in Trafford Park. Most of the adjacent GEC site, where I had once worked, had gone, and this remnant was a sad shadow of its former self, with weeds growing through the concrete. Looking at the mapping sites, it now looks as if all traces have been removed.

The device under test was a railway shoe fuse, as used on dc rolling stock. It consists of a bare copper strip in an open-sided fibreglass enclosure, which contains hidden metalwork to produce a magnetic blowout effect.

We did a trial shot at 10 kA, which merely caused a slight colour change. At 30 kA, I was very glad to be behind the ballistic glass. As the copper strip blew apart the shower of sparks was terrific.

We had some concerns about instrumentation details of a different test, which we had spent a day setting up, but the staff were confident that all was well. As the voltage was raised and tension increased in preparation for applying a short circuit, in the control room there was a loud bang and puff of smoke. A small RS box full of Metal Oxide Varistors had done what they were expected to when taken beyond their limits.

Chris

[tabbypurr]

The surge absorber section is misleading though, more applicable to the US.

NT

[spuorgelgoog]

I tested my circuit protection by cutting through the ring circuit with wire cutters.

As the fuse didn't I thought I'd update the consumer unit.

Owain