Elevator on UPS 2

[AusLee]

Hello,

I have an elevator bank of 100 kVA. I intend to put it on a 150kVA UPS. Will that be enough? and could you please tell me, when the mains power is not present, what does the UPS do with the regenerated power when the empty car are going Up due to the descent of the the heavier counter weight?

 

[bjenks]

I would assume the power room is Locked and only accessible by maintenance. So the need to worry about someone dropping the power is confusing. If they can get a key to the power room they can get an elevator key.

Anyways, although I have a good understanding of VFD's I will express some ignorance as it purtains to elevators. If the VFD has a power factor corrected IGBT front end AND you are ramping up the freqency so that you don't exceed 150% then I would feel comfortable with 200% oversized UPS. However, if you have a full bridge rectifier it will produce harmonics back into the electronic inverter of the UPS which will require much larger oversizing. Since you can control the rate of change of the frequency over time I am thinking that an elevator in a large building would ramp the frequency up much faster so that your start up current would go over 150% maybe up to 200%. So if you have both of these issues I still am thinking 300%.

I once installed some UPS systems for an escalator. It worked, but we never rolled it out to other locations as the cost didn't justify the problem. Also we UPS a Toshiba UPS which at the time was the only company using IGBT transistor on their inverter.