UPS causing lights to flicker

[mcelweec@gmail.com]

I plugged an incandescent light into a UPS backed outlet and it's causing the bulb to flicker. This is a television studio with a 200kva UPS with a step down transformer 480v-120/208v.
When the same light is plugged into "dirty power" it works fine. Is this a sign of the transformer going bad?

 

[iceworm]

I plugged an incandescent light into a UPS backed outlet and it's causing the bulb to flicker. This is a television studio with a 200kva UPS with a step down transformer 480v-120/208v.
When the same light is plugged into "dirty power" it works fine. Is this a sign of the transformer going bad?

Which particular transformer?

 

[mcelweec@gmail.com]

The UPS transformer,the dirty power seems fine.

 

[iceworm]

The UPS transformer,the dirty power seems fine.

... a 200kva UPS with a step down transformer 480v-120/208v. ...

Ahhh .... Sloppy me. I could read a bit better.

I would not suspect the transformer. They tend to either keep the smoke in - or let it all out.

Look at the UPS circuitry that regulates the UPS output voltage.

Or possibly there is a load on the UPS that is cyclic and is pulling the voltage down (and up). The UPS may not be as stiff as the Bypass feed.

Do you have any monitoring equipment? Do you have the UPS IOM manual?

ice

 

[mcelweec@gmail.com]

I didn't really get into troubleshooting the unit. We were doing a small renovation in a conference rm and using the 120v for temp lighting when they started flickering. I'm just trying to figure out if there is an issue that's going to surface down the line.

 

[ATSman]

If the light flickers then the UPS output voltage is fluctuating. The voltage needs to be monitored as the next step in the T-shooting process. If you don't have a disturbance analyzer, hand held scope, then hook up A Fluke 87 DMM and use the record feature. It has a 100ms and 1ms resolution so it is fast enough to catch a light flicker. Could be a problem in the UPS circuitry. How are the other loads fed from the UPS behaving?