Voltage Sag Effect on Elevators

[boyaxski]

hi guys,

our elevators' programs reset whenever a voltage sag of significant magnitude occurs. our utility here explains that it normally happens when their overhead distribution lines get faulted. since the sags last for just a few msecs, it should not be a nuisance (chillers tripping off, programs resetting). how can my elevators ride through this disturbance? can i install a UPS for the program's power supply (is this feasible and had it been done?)?thanks in advance for your inputs.


boyaxski

 

[apowerengr]

You may be able to install a UPS or ferroresonant transformer to stabilize the input voltage to your elevator control for such ride-through support or ask the elevator manufacturer if they provide a modified power supply for this application.

 

[Skogsgurra]

A few ms? I guess a few 100 ms. Is this happenening often? I mean several times each year?

A utility that has so severe problems with their lines should do something about it. If it happens occasionally - once a year or so - your best bet is to just let it happen and do nothing about it.

A ferroresonant transformer has an energy "store" that can take your equipment through hundreds of milliseconds of power outage. And even longer brown-outs. But you need to know what the outage/brown-out looks like to know what size to choose. So you should do a power quality analysis, first thing.

Why ferroresonant? Because an UPS needs maintenance. And seldom gets it. So it probably doesn't work when you need it. Also, the kind of dips you have are handled very well by a ferroresonant.

Gunnar Englund

http://www.gke.org

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