SAFETY ALERT, Perspex cased BMU (Balanced mains unit)

[Firebottle]

I have found a serious safety problem with an encased BMU. DO NOT OVERLOAD YOUR BMU, this applies equally to any transformer.

The unit in question is a perspex cased BMU, I stress that this transformer has been subject to OVERLOAD.

The enclosed 1kVA transformer was held in place with glue and expanded foam packing, with no ventilation or method of heat transfer whatsoever.
Every power transformer has a specified temperature rise (above ambient) at full rating, usually 55 degrees Centigrade.

Think about that.. 55 degrees above ambient. Usually a transformer has free air around it that conducts heat away from it.

This is what I found:



I don't know what loading had been used on this BMU but the transformer became so hot that (1) the foam packing has melted, plus most worryingly (2) the transformer insulation and the input wiring PVC insulation has melted, causing a short circuit. The input wiring was held against the top of the transformer by the frankly shocking construction employed.

The unit was causing a trip to operate in the consumer unit (mains supply).



The melting point of PVC insulation is >140 degrees C, so not a great situation.
Unfortunately due to the construction method a visual inspection of similar units is nearly impossible.

The minimum advice for anyone using one of these would be to operate it at nowhere near maximum rating.

[Wakefield Turntables]

WTF!

[hifinutt]

thanks so much for highlighting , nearly bought one of these in past .

[Beobloke]

Shocking (sorry…)

Frankly I’m not surprised. I’ve seen pictures of the inside of one of his ‘Statement’ products and it was appalling.

[southall-1998_mk2]

Jesus fucking wept! You could destroy earth with that thing.

S.

[Radford Revival]

Oops, wrong kind of insulation

[Firebottle]

Having received feedback from the manufacturer it is confirmed that the design principle is one of containment under fault conditions.

It is considered not to present a fire hazard but my advice of under-running the unit stands.

[Beobloke]

Looking at the pictures, my advice would be to not plug it in under any circumstances!

[legb4rsk]

Having received feedback from the manufacturer it is confirmed that the design principle is one of containment under fault conditions.

It is considered not to present a fire hazard but my advice of under-running the unit stands.

Sounds very familiar. cladding?

[Firebottle]

A statement from the manufacture:

'Our current BMU comes with the option of a thermal cut out and we speak to each potential purchaser about the calculations required to check the power consumption of the equipment that they want to use the BMU with. The BMU is rated at 1Kva. We recommend that you do not use beyond 70% of that capacity. If we are not satisfied that the BMU will be used within that limit, we won't sell it to you.'

Bear this in mind if you buy one second hand.