On 14/11/2017 11:03, Roger Hayter wrote:
John Rumm wrote:

On 13/11/2017 20:38, Roger Hayter wrote:

It seems he already has as much electrical heating as that
autotransformer will ever supply, and is probably exceeding its ratings.
Perhaps someone who knows where it is could have a quick look and see if
any smoke comes out when the voltage drops to 202V?

ISTR that bigclive did a tear-down on one of those voltage reduction
units. At some load point it actually had relays to bridge itself out of
the supply as a self protection mechanism. So you may find enough load
actually takes it out of circuit.

That sounds a sensible arrangement, But doesn't the marked voltage
drop make it a bit unlikely?

It would depend on where it bridged itself (if it does). It might
already have done that, in which case the measured voltage is even more
worrying!

(I remember once years ago we were installing a small network of
machines in the back of a converted mobile library to make a mobile
training setup. It was winter, so we had a rack of 8 systems running,
and a 2kW fan heater plus 1kW of halogen lighting on the mains supply to
the bus. I remember thinking that the fan heater was a bit feeble for
2kW, but then noticed we had an undervolt warning on the rack mount
UPSs. A quick measurement revealed we actually had something around
190V. It was then that the owner mentioned that he had plugged it into
his greenhouse sockets, since those were closest, and he had wired the
submain to the greenhouse in 50m of spare 1.0mm T&E he had laying about!)


--
Cheers,

John.

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