OT: Short Circuit Current Calculation To Satisfy EN60204

[osmanmom]

www.systemseurope.be/products/nap.en.php

 

[Badger]

Listen up. The earth has to withstand the maximum value that the supply can attain.

 

[JRB]

http://www1.cooperbussmann.com/pdf/a71ecbc4-b8c6-4655-a22f-725e47e5a8d4.pdf

http://www.cooperindustries.com/con...le_Industrial_Control_Panel_SCCR_Tutorial.pdf

 

[Kidblue]

1. the power frequency may be 50 hz.
2. the three phase power will more than likely be 380 volts
(sqrt of 3 times 220). 220 volts is the single phase

1. The frequency definitely will be 50Hz if derived from the national supply
2. The harmonised European voltage for 3 phase is 400V (+/- 10%)
3. Single phase, harmonised voltage is 230V (+/- 6%)

Just clarifying for the benefit of non European posters!

Rob

 

[kamenges]

Originally posted by Badger:

Listen up. The earth has to withstand the maximum value that the supply can attain.

While I agree that the earth conductor needs to be properly sized its unreasonable that the size of the earth conductor is the only factor I need to worry about. Under that rationale I could connect a control panel designed with a 10kA Icw to a supply with a prospective fault current of 100kA and, as long as the earth conductor is sized right, I will be fine. That doesn't make sense.

I think part of the issue is the EU's general philosophy of flexibility with responsibility. There are many ways to reach a single goal and it is up to the user to determine the most appropriate way to reach that goal. So components have multiple ratings to satisfy the multiple methods available. But for an occasional user like myself it is hard to find the information about how to correctly apply these ratings.

I have purchased a copy of IEC61912-1. I'm hoping I can get some useful information out of that. UL508A is the U.S. standard for control panel assemblies. Supplement B of that document describes in pretty good detail what needs to be done to calculate the short circuit current rating of an industrial enclosure. I'm hoping to find a similar document for use in Europe.

Keith

 

[marcius]

I think you are looking at a wrong standard.
Take a look at IEC 61439.

Chapter 8 in this paper by ABB

 

[Dariusch]

Hi kamenges,

For building a controlcabinet for a machine, you also have to use the standard EN 60439-1 (Low-voltage switchgear and controlgear assamblies - Part 1: Type tested and partially type-tested assemblies) - Chapter 4 "Electrical charateristics of assemblies" It defines what kind of voltage/current ect. that has to be taken in consider when assamble a cabinet. These are the fundamentales.

Also look at chapter 7.5 "Short-circuit and short-circuit withstand strength.

Among other things you have to informe about the Short-circuit rating of the equipment. Ikmax (Icc/Icf) The maximum short-circuit there can be at the incoming place (where the maincable is connected).
You have to find the weakest part (a circui breaker, contactor, earthcable, etc.) that will define the Icc/Icf of you cabinet.

ex.
You have a cabinet with a mainswitch (no backup function for breakers etc.) and the wires go straight in to a RCCD witch is marked 6kA. your earthcables etc. are a big square, so this is not to be consider.
You have to state the cabinet to Icc/Ifc 6kA.

ex. 2
The cabinet has an circuit breaker in the incoming with a breaking capacity of 25kA and downstream it has numbers of circuit breakers with a breaking capacity of 6kA. according to the manufacturer this combination can make the hole system 15kA. So now your cabinet can be labelled 15kA Icc/Icf.

ex. 3
Almost the same as no. 2.
The cabinet has an circuit breaker in the incoming with a breaking capacity of 25kA and downstream it has numbers of circuit breakers with a breaking capacity of 6kA. according to the manufacturer this combination can make the hole system 15kA. But you mainwires in cabinet has a min. square and the calculation shows they can only tolerate a 9kA.
You have to label the cabinet 9kA Icc/Icf.

If the customer did not indicate any rated short-circuit at the installed place, then it is the installer (customer) responsibility that the cabinet can be installed at the place with your stated Icc/Icf.

So in short form, you do not need to do any complicated calculations. Find the weakest component in the cabinet and that is the max. allowable short-circuit at the installed placed.

I hope this is what you had in mind? Else I misunderstod your thread :-(

Best regards
Dariusch.

 

[Dariusch]

... So all I can definitively state is the fault current limit that the installer needs to stay under in order to safely install the enclosure.

Keith

Yes, that is what you have to do.

/Dariusch

 

[goghie]

I think you have mixed several terms. There are:
-Rated short circuit making capacity (Icm),
-Rated short circuit breaking capacity,
-Rated ultimate short circuit breaking capacity (Icm),
-Rated service circuit breaking (or making) capacity (Ics),
-Rated short-time withstand current (Icw)...

Term you have used "short circuit current withstand capacity" is somehow wrong.

You are referring to EN 60204 which is about electrical equipment, documentation and marking on machinery, but in my humble opinion you need to read also IEC/EN 60947-2 to understand terms I mentioned.

Also to note one difference in America and Europe differences in standards. It is about responsibility regarding to safety of personal and equipment... In Europe you are generally responsible if you didn't provide enough safety measures, despite warning signs and similar, and despite it should be handled only by qualified personal.

 

[Dariusch]

Hi Goghie,

The standard IEC/EN 60947-2 ir not the standard you have to use, when building a control cabinet. You have to use the standard EN 60493-1 as mentioned.
The EN 60204-1 is general for Machines, but EN 60493-1 is for panels and in generel conserning the power.

The Standard IEC/EN 60947-2 is only for the manufacture of circuet breakers etc. to use.
Not the panelbuilder.

NB the Icu and Ics Is given up from the manufacture of the circuet breakers. etc. your responseble for given the Icc/Icf for the Panel. Icc is given when using cirbuit breakers for protecing the panel, and Icf is given if using fuses for protecting.

/Dariusch

 

[kamenges]

Thank you very much, Dariusch. That is definitely helpful. I will get a copy of this standard. It is a standard we really should have had already but unfortunately we don't.

Keith

 

[Dariusch]

Hi Keith,

Actually it is a set of standard - EN60439-1 to EN60439-5
EN60439-1 Is overall for cabinets - This one you need
EN60439-2 "Busbar trunking sytem" - Not relevant for machines cabinets
EN60439-3 "Distribution boards intended to be installes where unskilled persons have access for their use" - Could be usefull, but depends how you make you cabinet (if it also has some output for building installations).
EN60439-4 "Assemblies for construction sites (ACS)" - Not relevant for machine cabinet
EN60439-5 "Cable distribution cabinets (CDCs) for power distribution in networks intended to be installed outdoors in public places" - Not relevant.

Best regrds
Dariusch

 

[kamenges]

Thank you for the clarification. I ran into that as I was looking into the standard.

I read a short brochure on the ABB website that indicated that 60439-1 shouldn't be used alone but should be used in conjunction with one or more of the other sections. They also stated that 60439-2 would apply to anything not specifically covered by any of the other sections. Is that correct in your experience or can 60439-1 be used as a free-standing standard.

Also, should I be using the EN standard (60439) or the IEC equivalent (61439) or doesn't it matter?

Thanks,
Keith

 

[Dariusch]

Hi Keith,

The EN60439-1 is for general use so that has to be used. -2, -4,-5 is not relevant for your porpose. -3 however could maybe be relevant for you, but depends how you build the cabinet. Is the power and the control circuits in the same cabinet? Then you have to use -1 only. That is, that you mainly have to informe of the Icc/Icf, but you also need to informe of the lowest short circuit (Ikmin.). This is because, that the cabinet has to be protected against indirect contact. This can be made with RCCD, but some customers dont whant that because of faulttrip etc. so the whant to use fuses or circuit breakers. Than you have to inform of the lowest short circuit so the installer can make sure this is at the place.
There are also other information to give up. Those information has to be given according to the Machine directive, where you can use EN 60204-1.

I am not sure if/when the IEC will become relevant, but in the future it is likely that the IEC will take over EN60439.

But for now, if you use the EN60439-1 and EN 60204-1 + EMC + Safety standards, than you should not have any trouble installing the cabinet in the EU. What country is it going to?

PS. There can be some national requerements that also has to be meet.

Best regards
Dariusch

 

[kamenges]

Thank you again for the clarification. This machine will be installed in France.