On 15/11/2017 11:30, whisky-dave wrote:
On Tuesday, 14 November 2017 16:53:40 UTC, John Rumm wrote:
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!

doesn't worry me in the least because I expected it.
That's the advantage of understanding both theory and the real world.

Hmmm Dunning Kruger at work perhaps...

If the wiring is underspecified, that would suggest that close to full
load it is running at over them maximum continuous conductor
temperature rating of the cable. So expect shortened cable life and
elevated fire risk.

If the voltage sags too far, then you get lower PSCC so can expect
slower operation of protective devices under fault conditions, so
increase electrocution risk, and catastrophic cable failure risk.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/