600VAC and 575VAC

Hi, hopefully this is an easy one but just want to make sure.

Looking at a 24VDC Power Supply with 3 phase AC input.

The rated input voltage is 400..500VAC
The input voltage range is 340..575VAC
AC frequency range is 47..63Hz

Our facility has 600VAC and I actually measure around 602VAC. Am I okay to put 600VAC on that 24VDC Power Supply?

Thanks in advance!

whatplc,

i would say no.
the rated input voltage is 400 to 500 volts ac.
the variation of this voltage can be from 340 to 575 volts.
since you measured 602 volts thats the average, the variation could be as high as 662 volts (10%).

the electronics inside the unit most likely are not designed for that input voltage and would either be damaged or destroyed.

regards,
james

I think it will be OK. You are only 5% above the max input voltage.

the rated is only 500 so NO, you will need a transformer before this one.

nonuke said:

I think it will be OK. You are only 5% above the max input voltage.

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If you were only 7% above would that also be OK? How about 10%. It's called MAX for a reason ...

Thanks for the help, was thinking I couldn't but google search tends to hint towards 600V and 575V being the same thing so it was more wishful thinking. I was hoping to eliminate a transformer, but oh well.

Thanks again.

Skip the transformer. Buy a Power supply rated for the input voltage

i agree with sbaum.

buy the power supply rated for the input voltage and save a lot of grief and unnecessary labor.

james

whatplc said:

Thanks for the help, was thinking I couldn't but google search tends to hint towards 600V and 575V being the same thing so it was more wishful thinking. I was hoping to eliminate a transformer, but oh well.

Thanks again.

Click to expand...

So how that works is that there are in essence, two voltage "standards" for what we see, and what we use:

• The "Distribution Voltage" is what the power utilities deliver, and is required to be +-5% of the nominal value. Examples: 120V, 208V, 240V, 480V, 600V here in North America.
• The "Utilization Voltage" is what the equipment that will consume electricity is designed to and depending on the equipment, is typically at least +-10%. Corresponding examples, 115V, 200V, 230V, 460V, 575V.

The disparity is there on purpose to allow for imperfect conditions.

So in the case of 600V nominal systems in Canada, the PoCo is required to deliver 600VAC +-5% to the line terminals of your Service Entrance. What happens to it after that is your problem. 575V +-10% is what equipment mfrs design to for 600V systems, which allows for an expected voltage drop between the Service Entrance terminals and the connection of the equipment. So the PoCo can technically send you as much as 630VAC and still be in spec. If you have a 575V motor for example, it can tolerate up to 632.5VAC and still be in spec. That will not likely happen unless the motor is RIGHT NEXT to the service drop, but if it should, it's OK.

But this does not apply here because your power supply is designed for 500VAC nominal, and at 575V maximum, that means it is accepting +15%. That's fairly robust, especially considering that there are no 500VAC system, so it really means it is for a 480V +20%!

But it is going to be 575V +0%. You have already consumed the fudge factor at that point, so connecting it to a system that can officially climb another 55V above your maximum tolerance level is just begging for trouble.

sbaum said:

Skip the transformer. Buy a Power supply rated for the input voltage

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Yeah, no kidding. For something that small and cheap, just save it for another day and get the right one.