Power Supply Question

We use a couple different 24VDC power supplies to drive testing instrumentation we manufacture. Recently we've been told that using a
supply with "Automatic" voltage inputs (120V/230V) puts our equipment at risk when used on a 230V circuit and one leg drops, causing an "under voltage" situation, blowing up critical components because the supply cannot switch back to 120V fast enough. We have never experienced this and never had any of our international customers report this problem.
I am aware that power supply manufactures do make 120V or 240V input power supplies, but I am unsure as to what applications these apply to and cannot find any information pertaining to the above scenario.
Any help is appreciated.
Chad
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snipped-for-privacy@gmail.com wrote:

The only definitive answer is to ask the manufacturer of the power supplies concerned.
Lower-power power supplies (<1kW) with a wide input range typically do not "switch back to 120v" - their inverter electronics is simply designed to work over a very wide range of input voltage. It is very unlikely that any of these would be adversely affected by a sudden voltage drop where the new voltage was still within the design spec.
There are potential problems with supplies >~1kW but I doubt that applies to your instrumentation applications.
However, unless you can post the circuit diagram with values, the manufacturer is the one to ask.
--
Sue

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Usually I go by the "If it works, leave it alone" method. When confronted by a situation such as yours, I like to do a little research. While that may involve a question in a newsgroup, I prefer asking the manufacturer (as Palindrome suggested).
A switching power supply shouldn't much care what the voltage is, as long as it's within the rated spec. If it's a quality power supply, it'll automatically shut down when the voltage drops below safe levels.
If your really worried about it, look into getting a good UPS, which will protect your power supplies against both spikes and drops.
CS
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On Mon, 12 Nov 2007 12:50:57 -0800, snipped-for-privacy@gmail.com wrote:

Our supplies didn't have hard switches. They were what we called "auto-switchers, and would run from about 90 Volts all the up to 265 Volts. That is single phase, BTW, so there is no "one leg drops out" problem.
I have never seen a circumstance like that which you describe.
A 240 V capable input is meant for UK single phase applications, not US 3 conductor, dual phase (center tapped) systems.
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What do you mean by "dual phase" in regard to US scenario?
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On Mon, 12 Nov 2007 18:59:51 -0800, "Long Ranger"

Look at the parentheses. It is single phase, center tapped.
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wrote:

Yeah, I saw that. I thought there was some system out there I didn't know about. Thought I'd learn a new trick. So, what do you mean by "dual phase"?
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On Mon, 12 Nov 2007 19:51:25 -0800, "Long Ranger"

The same thing he meant by "drop a leg".
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wrote:

Hmmmmmmmmmmmmmmmmmmm.
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I've finally received full information pertaining to the workings of this issue. Our parent company is manufacturing custom linear power supplies for a couple of their applications, the engineer who developed this supply set the switching value at 190V. So when a "brown out" situation occurs on a 230V supply and drops to 190V, or below, the supply switches and blows the fuse. The custom supply configuration was not relayed to me initially and I was assuming this supply was a purchased part.
Thanks for the input,
Chad
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