Hey Harold,

I'd be surprised if there isn't a short delay in the transfer from
generator to utility, and not just an inter-lock. Except on very
expensive systems that do phase monitoring. In fact, even from
utility to generator during routine test. Actually, part of this is
occurs naturally as the switch gear is "centre-off" and not
centre-shorted. Common "timing" on emergency power is 13 seconds from
loss of utility, and at least two cycles for strictly resisitive
loads, but we required a 15 second advance warning of transfer to
shut-down to keep from damaging our MG sets.

They are pretty much gone now-a-days in favour of Robonic transfer
switches, but there were lots of fair size systems that had emergency
(called "auxiliary" today) systems where individual circuits were
hand-switched with three-pole-double-throw disconnect, where Up was
ON, Centred was OFF, and Down was ON. I've seen them from as small as
60 Amp up to 500 Amp. Mind you, I would not be too hasty to have to
throw the 500 myself!! With this system, the "load" is connected to
the "centre" or moving poles, and the "up" was normal or utility, and
"down" was the auxiliary. I even recall quite an elaborate system of
chains and pulleys, connected to various of these disconnects, to
"force" the operator to "do" the switching in a required sequence.

Take care.

Brian Lawson,
Bothwell,, Ontario.
XXXXXXXXXXXXXXXXXXXXX
On Tue, 22 Jun 2004 21:59:33 -0700, "Harold & Susan Vordos"
wrote:


"Jeff Wisnia" wrote in message
...
Ned Simmons wrote:

snipped

I do have a pair of 30A motor starting switches wired as
Jeff describes above to select either the rotary or static
converter. One switch is mounted upside down and a bar
between the handles prevents both from being on at the same
time.

Ned Simmons


Hey, thanks Ned! I thought I was going to get all sorts of jazz from
folks for that "interlock" suggestion.

My first thought was to recommend your "upside down" (and I presume
offset by one width.) trick, but I wasn't sure how much an upside down
disconnect switch would agitate an inspector. G

My commercially made MTS transfer panel works that way. It is impossible
to have our generator connected to the panel and still be connected to the
service. It's a slick way, and perfectly acceptable by code. They use a
Square D panel and add the interlock. Real slick system.

Harold