Understanding Generators 208 vs 240?

[Indrestudios]

So I did a gig a few weeks back, where we shared a generator with the video truck (not uncommon). His hook up was on camlocks: single phase, two hots, neutral, & ground.

Here's where I got confused...he told me he needed to see 208 across his two hots, and wound up turning down the output voltage on the genny to get there. In my basic knowledge about power, I thought that 208 was only for 3 phase systems, and that all single phase systems were based on 240.

I took our power feed from the big 50a twist lock connector & as expeceted got 208 across the two hots & 104 from each hot to neutral. We use a big Furman regulator, in high range mode, and it's pretty comfortable with anything from 190 to 260, so the gig went off with out a hitch, but I left totally confused.

I have another gig with this truck next week, and I'd like to find a good resource to explain all of this? Any suggestions? Did he make a mistake by running his truck at 208?

thanks,
Michael




2 x izRADAR 24
yamaha 02r96
48 channels Presonus digimax
aviom 48 ch digital snake

www.indrestudios.com

[Remoteness]

Michael,

I’m surprised no one chimed in on this one…

There’s the long reply and the short reply. Here’s the short form answer.

I believe audio, video and sound should always share the same power source be it shore power or a generator.
It’s a very common thing… or it should be.
E1016 Camloks are pretty much the standard in our industry. I’ve also seen and use the smaller E1015s but that’s a whole another story.

All three of our trucks are wired single phase 208V or 240V – That’s two hots and a ground. We float the neutral via our isolation transformers. Each of our transformers has three input taps – two of then being 208 & 240 volts. We set the input tap to the most applicable voltage setting and let our voltage regulator do the rest. You you have the extra bread, you can get a multiple tap isolation transformer with taps in +/- 10 volt steps so you can set the volts a lot closer to the voltage you’re getting this way the regulator doesn’t have to work so hard.

We should get into a discussion about the difference between Wye & Delta, step up/down transformers, buck/boost coils and such…

I’ll try to address this in another post. In the meantime maybe a lurking electrician or electrical design brainiac can enlighten us on the differentiation.

You really need to have a transformer on board taking in the voltage, setting it down when necessary and keeping it isolated from everyone else.

I would keep that Furman regulator in high range mode until you get your power needs more situated.

I hope to get more time to get into it more….

Here's a couple of pics of a three phase system with three six tap isolation transformers and stuff. Checkout the two voltage reguators on the left for their tech power...