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emergency power for an elevator.. 3 phase..

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Posted by danny burstein on October 19, 2006, 5:17 am

Our building has two elevators, 3 phase power. I haven't
been able to verify the motor size but I'm guessing
at 10 horsepower or so.

That would give us a nominal 10 kw of demand, with
a higher starting surge.

Now... a three phase 50 kw generator is pretty expensive,
so I'm wondering if there's any way to, for example,
take two Honda EU 3000 generators ganged together
(nominally rated at 6 kw, but with a bit more
when Scotty needs it...) in some wierd wiring configuration?

(or perhaps a slightly larger generator setup if
needed. The advantage of the EU 3000 is, of course,
that it's portable, and after we patch it in
to the elevator,we can move the two of them
to other places).

The purpose is _only_ for the 30 seconds or so to power
up the service during a blackout and get the cab to
the next floor, so a bit of overheating and motor
unhappiness is ok (as long as it's not way out of line).

I suspect being able to do this is about as likely
as getting an honest statement from a used car salesman,
but I figured someone might have some experience that
could give us a clue.


Knowledge may be power, but communications is the key
[to foil spammers, my address has been double rot-13 encoded]

Posted by Anthony Matonak on October 19, 2006, 5:37 am

danny burstein wrote:

Maybe you don't need to power the motors. After all, you
are only interested in making sure the elevator stops at
a floor, any floor, and opens the doors. You might be able
to get the elevators to descend automatically when the power
fails. If the motors can be wired to do it, they might act
like brakes to slow the decent of the elevators without
actually using any power. You would only need to provide
power for lights, controls and the motors that open the

This would, of course, require some redesign of the elevator
controls and would be more complex than just trying to give
them enough juice to run.


Posted by danny burstein on October 19, 2006, 6:25 am

That's close to the emegency technique used by
elevator mechanics.

When power fails the brakes lock onto the motor and cable,
so nothing moves. They manually release them allowing
the cab to move a bit.

Note that elavators are counterweighted to roughly 3/4
the rated capacity, so if there's only one person
on baord it'll actually float _upwards_ a bit.

They'll watch the cable moving, and after a foot or
three or five, they'll stop it again figuring the
cab is close enough to floor level to (once the doors
are manually opened) let the people out.

We'd like to make the process more automatic with
less highly skilled manual involvement (and doubly
so since the elevator control and motor room is
a 20 flight walkup...)

Knowledge may be power, but communications is the key
[to foil spammers, my address has been double rot-13 encoded]

Posted by Bughunter on October 19, 2006, 10:25 pm

Honda EU3000 generators are single phase. My EU3000 will not even start my
2hp table saw.

There are lots of used 3 phase generators out there. Check military
auctions. Presuming your
budget is $k (the cost of two Eu3000's), you should be able to find a
serviceable old 3 phase unit that should run long enough to move an elevator
1 floor.

my $.02.

Posted by mgkelson on October 20, 2006, 7:24 am

danny burstein wrote:

EU3000 generators would be a bad choice even if they would work. They
are very expensive because they are quiet and fuel efficient. Since you
will only be using it for "30 seconds or so", you could care less about
fuel efficiency or noise.

I think your best bet is to try to find a good deal on a used, 30-50KW
generator or find a non-electrical solution to the problem.

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