What could cause this?

[VisokiNapon]

The panel is 208/120 panel and it appears that the peak voltage is being clipped. Also, the user reported that dimmer switch that was installed would not work on A phase but it worked on B or C. Voltage readings were normal as you can see from the graph.

 

[wayne440]

It looks a lot like the waveform discussed here-

http://www.eng-tips.com/viewthread.cfm?qid=292193&page=1

 

[Skogsgurra]

I see nothing abnormal. Flat top - caused by SMPS in computers and the like - some mild notching, probably dimmers. No probs at all.

Is the light source dimmable? Some aren't.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[VisokiNapon]

The issue is that this is a country club, they have a lot of lights but not that many computers. Could dimmers really cause this much voltage drop at peak?

Yes, the light source was dimmable. It worked on B or C phases.

 

[Skogsgurra]

Dimmers do not flatten the sine, the notches are probably the result of dimmers (or thyristor controlled drives - very unlikely). Modern appliances flatten sine waves. They also have lots of switch-mode power supplies. Does this country club have their own transformer? Or are there other consumers connected?

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...