RE: 33 x 20w on 1 ld11 ?

["Hawes,Timothy Edward (GEG)" <haweste@xxxxxxxxxxxxxxx>]

> -----Original Message-----
> From: Young, Jeff  Sent: 06 April 2004 17:39
>
> do you think that running 33 x 20w halogens off one LD11 (
> 700W ) would be
> too be cutting it to close ? especially with them all firing
> up at once .

Jeff,

I assume you talking about LV halogens and 20W is the bulb rating. I can't
seem to put my finger on a typical transformer efficiency ATM, but if
they're 95% efficient, you consume 21W of "mains" for every 20W
of "LV" you have. 33x 21W = 693W. If the LD11 is 700W +/-1%
(which seems very tight), that's you at the limit, or over it if the LD11
tolerance is worse. Long explanation, but my short answer would be yes, it
seems too close.

IIRC Keith blew something up because the bulbs were cold and their
resistance was lower compared to when they'd been running for a while and
warmed up (so they drew more than their rated current when cold). ISTR that
was a fully mains system though. Dunno if that helps or not :-)

Cheers,

Tim H.

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