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Author Topic: 240v / 208v question  (Read 3481 times)

Ted Christensen

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240v / 208v question
« on: August 08, 2014, 06:15:06 pm »

So how important is it when you have 240v and one leg reads 122.4 and another leg reads 123.7 .. same with 208 where all 3 legs reads something different.  I have heard conflicting things.  Im believing more its rare to find matching voltages and the myth is different voltages can cause weird things especially with digital consoles. Just wanted to see what the general consensus is.

Thanks!
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Ivan Beaver

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Re: 240v / 208v question
« Reply #1 on: August 08, 2014, 08:00:05 pm »

So how important is it when you have 240v and one leg reads 122.4 and another leg reads 123.7 .. same with 208 where all 3 legs reads something different.  I have heard conflicting things.  Im believing more its rare to find matching voltages and the myth is different voltages can cause weird things especially with digital consoles. Just wanted to see what the general consensus is.

Thanks!
I would be more concerned that the voltage is high-rather than the difference between the legs.

Now if you run into a situation like I did last weekend and the voltage was 75V-THEN you have an ISSUE!!!!!
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
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Mike Sokol

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Re: 240v / 208v question
« Reply #2 on: August 08, 2014, 08:08:53 pm »

So how important is it when you have 240v and one leg reads 122.4 and another leg reads 123.7 .. same with 208 where all 3 legs reads something different.  I have heard conflicting things.  I'm believing more its rare to find matching voltages and the myth is different voltages can cause weird things especially with digital consoles. Just wanted to see what the general consensus is.

Thanks!

I would say that's a myth that has no basis in fact. Since nothing you would be using uses 3-phase power (except for really big movie projectors, I think), each leg can be treated as a separate power source. And even with 3-phase supplies, I think voltage differences that small wouldn't be an issue.

I'm also pretty sure that 3-phase motors wouldn't care about such small deviations in voltage on different legs since I used to run them all the time on conveyor belts and such with a lot more variation than that.

What's the basis of the rumors? Is it supposed to cause the board to lock-up? Sound bad? Lose memory? Something else? I'm really curious.
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Ted Christensen

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Re: 240v / 208v question
« Reply #3 on: August 08, 2014, 08:25:03 pm »

I would say that's a myth that has no basis in fact. Since nothing you would be using uses 3-phase power (except for really big movie projectors, I think), each leg can be treated as a separate power source. And even with 3-phase supplies, I think voltage differences that small wouldn't be an issue.

I'm also pretty sure that 3-phase motors wouldn't care about such small deviations in voltage on different legs since I used to run them all the time on conveyor belts and such with a lot more variation than that.

What's the basis of the rumors? Is it supposed to cause the board to lock-up? Sound bad? Lose memory? Something else? I'm really curious.


He never said exactly.  Just that it can cause digital gear to do weird things :/

He never specified how drastic of a voltage difference though :/

My ilive took a dump on me Thursday but worked a ok last week. It did  not get used or turned on between then. Powered up everything Thursday and I had no output but everything was connected fine and showing input and output on the board. Yes I know it was the output section of the mixrack and yes I know everything was assigned properly.
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Mike Sokol

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Re: 240v / 208v question
« Reply #4 on: August 08, 2014, 08:37:30 pm »


My ilive took a dump on me Thursday but worked a ok last week. It did  not get used or turned on between then. Powered up everything Thursday and I had no output but everything was connected fine and showing input and output on the board. Yes I know it was the output section of the mixrack and yes I know everything was assigned properly.

For the last few years I've been specifying that digital boards are powered from a UPS since just a few cycles of voltage drop-out can cause them to lock up. And even a 30-second reboot is an eternity when you're doing a live show.

I know that Goose-Juice makes a nice line of UPS units. Any other brands that you guys use?  If you like I can break that discussion out into a separate thread.
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Ted Christensen

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Re: 240v / 208v question
« Reply #5 on: August 08, 2014, 09:02:45 pm »

For the last few years I've been specifying that outboards are powered from a UPS since just a few cycles of voltage drop-out can cause them to lock up. And even a 30-second reboot is an eternity when you're doing a live show.

I know that Goose-Juice makes a nice line of UPS units. Any other brands that you guys use?  If you like I can break that discussion out into a separate thread.

So in my case since I have a mix rack and surface would I need one at foh and mix rack position?  i dont see how that would help my output cards from quiting but I could be wrong just as easily. Ups is not my forte.  I do see how it would prevent what you mentioned cause it would keep power while everything else got cut for whatever reason.
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Stephen Swaffer

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Re: 240v / 208v question
« Reply #6 on: August 08, 2014, 10:34:23 pm »

Drop outs are one thing-voltage differences another.  Since most digital gear now is using switch mode power supplies-and probably in many cases universal voltage power supplies (most lamp ballasts I have installed lately are happy with anything from 100 VAC to 277 VAC) I would be shocked to see a minor voltage difference -anything less than 4 or 5 volts-create a problem. 

A difference of more than a few volts probably indicates a poor/loose/dirty connection that will eventually lead to dropouts/brownouts-say about 30 minutes into a show after everything is working hard-and THAT will lead to issues unless you have a UPS and the issues are minor enough that it can cover for them.
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Steve Swaffer

Tim McCulloch

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Re: 240v / 208v question
« Reply #7 on: August 09, 2014, 02:25:28 am »

Ted, the problem with your mixer is almost certainly NOT related to voltage differences between phase legs, as you are only using ONE leg and the neutral to power your mixer.  It can't "see" the other legs.  There are some things that could spew harmonics into the neutral, but I doubt the quality of electrical service is the cause of an audio component failure.

It sounds to me like the mixer needs a trip to Dr. Console.  If it's out of warranty you can open it up and re-seat ribbon cables and look for things obviously wrong.  If you find nothing and wiggling the connectors doesn't fix it, the Dr. should be consulted.
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Guy Holt, Gaffer

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Re: 240v / 208v question
« Reply #8 on: August 09, 2014, 08:10:03 am »

My ilive took a dump on me Thursday but worked a ok last week. It did not get used or turned on between then. Powered up everything Thursday and I had no output but everything was connected fine and showing input and output on the board.

Ted,  was your ilive powered off the house in the first instance the week before and a generator when it took the dump?

Guy Holt, Gaffer
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Ted Christensen

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Re: 240v / 208v question
« Reply #9 on: August 09, 2014, 10:05:34 am »

Ted,  was your ilive powered off the house in the first instance the week before and a generator when it took the dump?

Guy Holt, Gaffer
ScreenLight & Grip
rentals@screenlightandgrip.com

No. The last 3 shows went generator.  Wall. Wall.
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Re: 240v / 208v question
« Reply #9 on: August 09, 2014, 10:05:34 am »


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