Elev trips out on generator

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bwyllie

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MA
starting to look into a problem at a building when the elevator is running on generator power, the circuit breaker in the elev controller trips. The elev contracto measure a 10% voltage drop at the elev controller and supposedly this happens when the elev is leveling. I do not have excat specifications because I will not be on site till Monday. I have been told the elev is "old" and has not been load tested annualy. I also know the elev is a DC motor and had new SCR controls installed a few years ago and this is when the problems started. Can anybody suggest what I should be looking for and if anybody else has run across this problem.

Thank you
 
Re: Elev trips out on generator

Is it tripping on instantaneous current or overload?

You might want to consider adding line reactors to reduce the instantaneous current if the former.

DC drives can look like a near short circuit at times.

Line reactors can reduce the instantaneous current enough to eliminate this problem.

Assuming that is what your problem is.
 
DC drives can look like a near short circuit at times
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The inrush current of DC drives are not so severe as AC motors. The maximum is 2.5-3 times the FLC.

The elevator is tripping at leveleng phase (very low speed). The low speed in DC motors are controlled by the linear voltage or by the current/voltage in the field coils. Reduction of this current increases the linear current. Loosing the field coils current COULD TRIP the breaker.

So look into this circuits. It is possible that you can find some bad connection, or burnt resistor (old stuff) or contact.
 
Do these breakers have a shunt trip? Any chance that's causing the problem.

I would be wary of working on an elevator that hasn't been inspected. I know a lot of places don't do all the testing for emergency lights and other stuff like the code requires. But I have never heard of anyone bypassing elevator inspections.

Steve
 
the elev inspector shut down one of the elevators and thus why I am involved. Today we went out and tested the generator and when we transfered from normal power to generator power, the elevator tripped out. The elevator was not even moving, it was stopped on the 1st floor.
 
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