Voltage Drop After Plugging In Load

Are these installed racks, or tour racks?

Might be a bad connection in the wiring to your fixture... (loose 6ckt soca connector...?)

Might be a long run?  and need bigger gauge wire..

yea, we have @ 200' of soca on each output.  I'm thinking this is line loss.  Can the CEM+ be tweaked to increase its output voltage?

touring racks, in a TV studio situation.  

Yes, it can, with one caveat.  I'm sure you know this but I'll mention it to get it on record in this thread.

While you can adjust the upper end of the voltage scaling, the dimmer cannot manufacture voltage.  You will only get out what is put in at the rack (i.e. if you are putting in 120VAC, you cannot get the dimmer to output 125VAC.)

This info is all in the CEM+ manual, but short form (with possible incorrect menu names,) access is in the Dimmer Setup menu (you may need to log in as a Power User,) select the Scaling or Scale Voltage screen, select the dimmer or dimmer range you wish to adjust, and the look for the min scale and max scale options, and adjust as necessary.  This may take several tries to get right.  There is also a section for load percentage, which is used to factor the scaling based on average load of a dimmer.  I believe the default is 35%.  Adjusting this may affect the far end voltage as well.

Good luck.

Can you confirm what type of meter you are reading this on? Make a model is fine. If it is not a true RMS meter, the values can't really be trusted with SCR dimmers.

I'm using a Greenlee CM 450.  Stated as True RMS.

Yea, I read the manual on scaling.  We are at Kaufman Astoria Studios and all the racks are theirs.   They are running 3.1.1 CEM +

Yea, I read the manual on scaling.  We are at Kaufman Astoria Studios and all the racks are theirs.   They are running 3.1.1 CEM +

Note that they are setup under Basic/Portable rack setup.   I  think I have to change them all to Full Feature to access the Scaling feature.  True?  And under Basic/Portable is there a default output for dimmers.  115vac possibly?

Yeah, I think you'd have to change them to full feature.  I know Basic/Portable removes a lot of configuration options.

Good luck.

Ted:

So the math is in the right range for voltage drop if starting at 115v. We went throughout this, as well. Last season it would be most apparent when putting hard-line blondes next to those that were dimmed through the outlets, or when running 20ks through dimmers using 220v lamps instead of 208v, when next to a hard-patched 10k. The 10ks color temp made them appear much brighter, but good luck getting KAS to switch those for you.

I set all the racks as full feature, and then networked (that was 13 racks on Stage G). They also ran on sACN. This offered several advantages, key among them:

You could adjust the scale voltage for the whole system using Web Connect. It is pretty painful trying to do it in the CEM+ for 13 racks/450 dimmers.

Also with the racks networked and using sACN, you could change the scale voltage settings from the Ion "About" screen. This would give you a chance to "see" the changes from the console, or do an A/B test with someone standing at the light and you in your chair rather than bent over the CEM+. Going from 115v to 125v certainly helped, but still not possible to get 120v on those socapex runs, except when KAS runs really hot. Some days I would come in and the racks were reporting 130v on each phase.

Of course with the hard-line lights getting brighter with the higher voltage as well, you end up chasing your tail. I lobbied hard to stop using hard line stuff (with 900 dimmers between the stages you would think there wouldn't be a need), but as you know that sounds easier than it actually is.

James