Class 2 Power (24v)

Rson

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Join Date
Jun 2017
Location
Michigan
Posts
517
So, I'm wanting to convert our control panels to class 2 systems whenever I get a chance.

The issue is, most of the time I only have 480VAC and 24VDC on a project - no 120VAC needed.

The one way I've found around this is using a Siemens selectivity module or a Murrelektronic Mico off a 10A power supply. It seems most manufacturers only offer a 10A or 20A supply (240W / 480W) - and in most cases I don't need more than 4A or so.

Does anyone know of any 480 to 24vdc power supplies that would deliver a class 2 power source or other ways to achieve this without having to overkill the power supply?

Thanks!
 
Phoenix contact make some three phase power supplies that are quite compact.

Also this one, which is two phase 400...500VAC input, 24VDC 3.75A output. Nice and compact.

I've only used a couple of phoenix power supplies, but I use their other equipment extensively and it's proven pretty much bulletproof.
 
Feeling this one.
I have to put 600 volt control transformers in mmost of my stuff since MOST of our supply is 600. The fancy little 500 V to 24VDC power supply let the smoke out when they meet the 600VAC.... I do know this for a fact.. LOL...

It sucks having to incorporate an XFMR into my builds simply to attain 24VDC, Like you, I do nothing but 24VDC builds so commonly, the only task of my XFMR is to create 120/240 for my DC power supply. I have yet to find a manufacturer that makes a 600 to 24VDC supply so I can eliminate the XFMR.
 
if this is an existing control panel, you might be ok.
NFPA79 - electrical standard for industrial machinery states control panels may not have control voltages above 120 volts. now I know I say control voltage, but the wording may have changed. I haven't been doing design in several years.

if I am wrong, someone please correct me.

you also need to pay attention to NFPA70E - arc flash guidelines.

james
 
So, I'm wanting to convert our control panels to class 2 systems whenever I get a chance.

The issue is, most of the time I only have 480VAC and 24VDC on a project - no 120VAC needed.

The one way I've found around this is using a Siemens selectivity module or a Murrelektronic Mico off a 10A power supply. It seems most manufacturers only offer a 10A or 20A supply (240W / 480W) - and in most cases I don't need more than 4A or so.

Does anyone know of any 480 to 24vdc power supplies that would deliver a class 2 power source or other ways to achieve this without having to overkill the power supply?

Thanks!
You can buy a Class 2 power supply with a 480V input but as you have likely noticed, they are not common. A-B has a couple, but only in the 1606-XLP line; 1606-XLP90E-2 (90W) and 1606-XLP100E-2 (100W). But also if your panel has a Neutral run to it from a 480/277V source, many of the power supplies with universal input will accept up to 300V, so 277V L-N works.

Or as you found you can ADD a Class 2 power limiting device down stream of a larger power supply like the Mico, although you must be sure to select one that is rated as Class 2. A-B offers those, as does Siemens, Puls and several others.
 

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