Medium Voltage Power Conversion Equipment Standards
Medium Voltage Power Conversion Equipment Standards
(OP)
Has anyone seen a copy of the Underwriter's Laboratory (UL) standard 347A Medium Voltage Power Conversion Equipment, and if so can you comment on its' usefulness? Most of the medium voltage drive manufacturers list conformance to this standard in their drive specifications, but I have not had any success with UL in trying to obtain a copy. From what I gather, this standard may be in a preliminary status, and thus is not available for purchase.





RE: Medium Voltage Power Conversion Equipment Standards
Who's listing conformance to a standard that does not exist?
RE: Medium Voltage Power Conversion Equipment Standards
I didn't think this was being applied to drives however, I was under the impression that it was for soft starters. It started off when Benshaw went to get the first UL listing on their MVRVSS starters a few years ago, but ran into the fact that UL had no standards for MV soft starter testing, so they made one up as described above. Then other manufacturers complained to UL that they cannot give one manufacturer an exclusive listing, so UL started a project to develop the standards.
The problem was, there are only a few manufacturers of that equipment, most of which approach it in very different ways. So for UL to arbitrarily create a standard based on one of them would be devastating to all the others. The result is, UL came to those few manufacturers and asked them for input and expertise, including reviewing the input of the others. As you might imagine, that is going to be a long bloddy battle. Last I heard, the project was not complete and accepted. So for your case, if you are one of the existing manufacturers working with UL to make an acceptable standard, you know what it is. If you are someone attempting to get in on the action, you are probably going to have to wait it out.
RE: Medium Voltage Power Conversion Equipment Standards
By reading the first few paragraphs in the scope of the standards I read that UL347 is for motor starter applications up to 7.2kV and UL347B is for motor starter applications from 7.2kV to 15kV. UL347B is also for applications involving static switching elements for use from 1.5kV up to 15kV. I believe this means using SCR switches aka soft-starters.
The UL347B Outline document reads like a standard but I'd guess it's an Outline because it's still not a completed accepted standard. Online I can even download other documents related to the standards. For example, UL508 has around 30 documents on-line.
Jraef is quite correct that UL347B would have been started by Benshaw looking for UL approval on their 15kV class of soft-starters. The Benshaw 5kV starters have been UL listed for many years now (I'd think at least 10 years now).
RE: Medium Voltage Power Conversion Equipment Standards
http://www.ul.com/controlequipment/standards.html
I have seen reference to this standard from at least four manufacturers of medium voltage drives (only two indicate the standard is in some preliminary state). I would have thought if it is being referenced for compliance, then it should be available for review. Oh well.
RE: Medium Voltage Power Conversion Equipment Standards
Part 4: General Requirements—Rating Specifications for a.c. Power Drive Systems above 1000 V a.c. and Not Exceeding 35 kV).
It is referenced in the test section under short circuit withstand capability.
RE: Medium Voltage Power Conversion Equipment Standards
Go here;
http://www.comm-2000.com
Click on the UL Standards tab at the top and then click on the big UL that appears in the window. This page lets you look at the list of available Standards, Outlines and CSDS proposals amoung other stuff. Read the more info descriptions of what the outlines and CSDS's are. There should be either a proposal or outline for 347A if it's being worked on.
UL347A would be driven by some of the medium voltage drive manufacturers.
UL347B was driven by Benshaw wanting UL approval on their 15kV starters. Benshaw doesn't manufacture any VFDs.