On 60204-1 And Short Circuit Ratings In Europe

[Zivilin]

Hello,

I've been charged with calculating the Short Circuit Rating of a control panel, so that it can be presented on the panels naming plate, in compliance with standard 60204-1, p. 16.4. This has proven much more difficult then I have anticipated.

My main problem is that most, if not all, information on Short Circuit Ratings seems to originate from North American sources (where it is called SCCR - Short Circuit Current Rating). As I understand it, this is due to SCCR calculation and display becoming mandatory in the US a few years ago - obviously, numerous resources would appear for a mandatory task. However, this also means that all ways of SCR/SCCR calculation I can find invariably point towards UL and NEC standards as their foundation. There is absolutely none that I can find for 60204-1. When searching for SCCR for single devices, or combinations of devices, suppliers only seem to have UL certificates, which don't even include SCCR values for the typical European power supply, 3x400V. They usually have values for 480V and 600V, which, as I understand, are US and Canada-specific. Even the "default" values of SCCR for devices with no labels/certificates send me to UL508a Table SB4.1

Herein lies my dilemma - Is it permissible (necessary?) to use data provided by UL and NEC in order to comply with 60204? I assume that there is no problem with taking an SCCR value for 480V and applying it to a 400V application. Are there any European institutions that test the SCCR of a device or device-combination, or is this a niche dominated by UL? Or perhaps I'm barking up the wrong tree and 60204 Short Circuit Rating and NEC SCCR are different things?

Any help on this topic would be much appreciated.

 

[Marvo]

I'm not UK based so I'm not familiar with the BS requirements but I suspect the BS60204-1 and the ISO60204-1 are one and the same to all intents so for documentation requirements check this out

http://www.industry.usa.siemens.com/automation/us/en/industrial-controls/controls-news-and-events/Documents/Training%20IEC_CE%20panels%20and%20documentation_part%202.pdf

Are you just looking to calculate the PSSC rating of your panel for labeling purposes or do you need to get it independently tested and certified?

There's some good info on the UL 508a certification here;

German

English translation.

Here's a ISO60204 test sheet also for good measure;

http://cache.automation.siemens.com/dnl_iis/zA/zAxNjk2OQAA_78357602_HB/reference_manual_SCCR_of_industrial_control_panels_de-DE.pdf

Plus a BEAMA guide to BS60529 control panel verification.

And finally this guide has some good info on coordinating LV control switchgear for cascading and discrimination.

 

[Zivilin]

@Marvo
 
I am also not based in the UK, but in Poland, so IEC-60204 is exactly what I'm interested in.

I am interested in the rating for labeling purposes - 60204-1, p 16.4 states that a control panel must, among other things, have a marking stating its, I quote directly, "short circuit rating". Finding out what exactly is meant by "short circuit rating" is the thing that has been giving me a headache. The closest document which seemed relevant, IEC 61439-1, did little to help me - it defines a number of short circuit current parameters:

- Ipk - rated peak withstand current

- Icw - rated short-time withstand current

- Icc - rated conditional short-circuit current

but there is explicit explanation as to which is the "short circuit rating" required by 60204.

After much searching, I concluded that the best fit is the UL/NEC "Short Circuit Current Rating", which - from what I have read - had been partially inspired by IEC standards. However, this caused me a new problem - can I use UL/NEC standards to satisfy IEC standard requirements? For example, the UL508a has a helpful table SB4.1 with default values of SCCR for devices which have no such value printed on them or provided in their documentation. I can find no similar table based on IEC standard requirements. It is all very frustrating and confusing.

From Your first link, I think that the 61439 Icc parameter (rated conditional short-circuit current) is the one closest to SCCR, and probably what is supposed to be shown on the panel marking. The last two links are also of interest to me, thanks!

Unfortunately, I am not well enough versed in German to retrieve anything useful from Your other links, but thanks all the same for your time!

(By the way, the link called "English", "German" and "60204 test sheet" are all the same one, and they are all in German.)

My problem remains the same - If I calculate the SCCR of my control panel following NEC/UL instructions, will it satisfy IEC-60204-1 marking requirements? 

@Canoeboy

I'm moderately certain this is the case with some of our equipment. This is something our company is beginning to take note of - in all fairness, there is not much pressure on following standards from our clients, and I wouldn't be surprised if many of them don't even know what PSSC is, not to mention actually being able to give its value.

 

[NozSpark]

I don't get you original post...

Are you trying to determine the Short Circuit Rating of an existing panel or are you trying to determine the Short Circuit Rating for a panel that is going to be fitted?

If its for an existing panel then you'll have to use manufacturers data for the installed components

If its for a new panel design then you need to determine the Short Circuit Current and then design the panel with components that can cope with it

IMHO

 

[Zivilin]

@NozSpark

My apologies, I'm trying to be precise, but I suppose I'm not making myself clear.

The panel already exists. I am retroactively trying to determine its Short Circuit Rating.

Problem: What is the Short Circuit Rating? Specifically, the one mentioned by point 16.4 of the standard IEC-60204-1?

Is it the same as SCCR as defined by NEC?

If Yes: Can I use SCCR values provided by the UL 508a standard and in UL certificates to determine the 60204-1 SCR?

If Yes, Why? UL/NEC are, as far as I know, USA-only standards. IEC-60204 is an International Standard. I work in Poland. I am ultimately more interested in IEC and EN standard than UL/NEC ones. Why would it be permissible for me to use UL/NEC methods to calculate a IEC parameter? Is this justified?

Manufacturers, like Siemens, from what I see, use UL/NEC SCCR almost exclusively in their documentation. I can find no mention of the IEC-60204-1 SCR parameter practically anywhere but that one place in the 60204-1 document itself. Why?

 

[NozSpark]

Is this Short Circuit Rating not the same as the PFC / PSSC rating of the components used within the panel?

 

[Zivilin]

@NozSpark

To tell You the truth, I really have no idea.

Could You elaborate? What do You mean by PFC/PSSC ratings? I have yet to find such parameters in any standard I've read.

I believe PSCC is prospective short circuit current, which is a parameter characteristic to the site's supply. I have found no mention of a PSCC rating in any of the devices' documentations.

The only parameter which has an acronym of PFC that I know of is Power Factor Correction, and I am not certain how that would fit into this issue... although I do seem to recall the power factor has an influence on the peak value of short circuit current.

All I want is to label the panel in a 60204-1-compliant way, and be able to justify it. The only thing stopping me is deciphering what 60204-1 means by "Short Circuit Rating". The way I see it, If I slap an SCCR value on it (I certainly have enough data to do that) I'll have  UL508-compliant marking, not a 60204-1-compliant one.

 

[NozSpark]

Sorry... yes I meant PEFC & PSCC

 

[Marvo]

PFC - Potential Fault Current?

 

[Marvo]

I think determining the max fault current capability of a control panel can go far beyond just aligning it to the individual Icu ratings of the components or Icw ratings of busbars for example. Depending on the construction of the panels certain areas can be declared a fault free zones and as such are exempt for affecting the overall assembly ratings, see IEC 61641 for clarification.

 

[Zivilin]

Concerning PEFC and PSCC, according to my understanding those are values which characterize the site's power supply, informing potentially how high the short circuit current will reach if a short circuit occurred - the client should provide these values for us, the control panel manufacturer, to design a cabinet whose value of <sighs> SCR/SCCR/Icc is higher. However, I'm fairly certain this is not the information required by 60204-1 to be included on the control panel's rating plate.

 

[Zivilin]

@Marvo

IEC 61641 looks like a relevant standard, I'll have to acquire it. Although it seems to be exclusively about testing. I'm not certain if You noticed in my post earlier, but three of Your links seem to direct me to the same exact document. Since I'm interested in the content of the other two links, I was hoping You could repost them? 

However, this is still not what I was originally asking - I really do not know how to present this any clearer. I was hoping for answers like:

"Yeah, everybody uses SCCR values to satisfy that 60204-1 labeling requirement, this is justified because of such and such reason"

or

"SCR isn't SCCR at all, but actually a completely different parameter which You can read on in such and such document"

or even possibly:

"Actually no one knows what that parameter is, we usually just put in the SCCR value, nobody ever complained about mislabeling, there's no real justification, its just what we do"

Am I reading this incorrectly, or is there simply no deeper awareness of the 60204-1 marking requirements?

 

[Zivilin]

@Canoeboy

There'a an MCCB with a measly Interrupting Capacity of 6kA. So if 60204-1 SCR is equivalent to the UL508a SCCR, I have a clear answer to "What is the SCR of this control panel". I feel slightly silly for constantly repeating this, but that was never my question -my question is "What is SCR according to 60204-1, and how do You know that?".

 

[Marvo]

@Marvo.......I'm not certain if You noticed in my post earlier, but three of Your links seem to direct me to the same exact document. Since I'm interested in the content of the other two links, I was hoping You could repost them?

The links I posted were server cached search results and the must have expired, I couldn't find a direct link/URL to them and I also can't attach them because some of them are 3.6Mb and my forum permissions won't allow. If you send me a PM with a gmail address (or any other email that allows attachments at least 3.6mb) I can email them directly to you. 

 

[Zivilin]

@CanoeBoy

A bad place to double "C", I meant an MCB. 6kA not so surprising for those.

@Marvo

I'll risk embarrassing myself, but I can't find the PM option ANYWHERE. Not on Your posts, not on anyone's post, not in any of the forum settings - it's as if the option was nonexistent. Possibly because My membership "level" is too low? I also can't post links, even when those links are in a quote from someone else.

 

[Andy™]

you cannot send/receive a PM or post images / links yet

 

[Marvo]

No probs, send me an email to wellhungbigboy at gmail dot com.