KA Rating of Lighting Panel

[Elekk]

Can MCB of 50kA be placed in a panel rated for 30kA?

 

[Sidewinder]

Ce?

 

[Elekk]

I mean that the available short circuit at the panel is 50kA. The MCB's are rated 50kA, which is good. But the Panel itself is rated 30kA. Is it acceptable?

 

[Sidewinder]

NO

 

[Sidewinder]

No mate it is Manuel speak!

When Basil has a rant!

:^O

 

[Elekk]

http://www.gepowercontrols.com/ex/resources/literature_library/catalogs/residential/downloads/d_pc_modular200_english_07.pdf

The breakers in this GE panel are rated 10kA. Can a cascading fuse be used upstream so that it can be used at the locations where the available short circuit current is 50kA?

 

[steptoe]

he comes from barcelona!?!

 

[septiclecky]

http://www.gepowercontrols.com/ex/resources/literature_library/catalogs/residential/downloads/d_pc_modular200_english_07.pdfThe breakers in this GE panel are rated 10kA. Can a cascading fuse be used upstream so that it can be used at the locations where the available short circuit current is 50kA?

May I ask where your getting these 50kA MCBs from as that is a mighty big PFC for a distrbution board?

That makes the Ze at the DB 0.0046ohms not even the transformer impedence is that low.

 

[Larnacaman]

I mean that the available short circuit at the panel is 50kA. The MCB's are rated 50kA, which is good. But the Panel itself is rated 30kA. Is it acceptable?

I don't quite understand, how you have a supply cable with an available PFC of 50KA supplying a DB that's rated at 30KA?? If what your saying is correct, then someone somewhere has made a real hush at the design stage !!!

As far as MCBs goes i've only seen them rated upto 25KA (Merlin Gerin) What's supplying this panel, as a standard UK/EU1000KVA transformer will normally only give a PFC of around 21 to 23ish KA depending on it's impedance. Then there's the impedance of the the cables /distances post transformer. So please give us a little more information of the installation your working on...

 

[Sidewinder]

I have fitted 35kA's.

The last BIG fault current job I did was 11kV supply to site,DNO transformer about 30m from my board down sub main.

DNO quoted PFC @ 23kA at their transformer.

At my board it was WELL below that.

Not trying to be funny Elekk, but if you are not sure then should you be playing with such high fault current levels?

You are talking about serious energy here, and lots of damage, possible plasma explosions even!

 

[Larnacaman]

Siemens do MCCB's much higher than 25kA, have a few at work on the shelf. From memory they are 35 and 50kA

I think there's a bit of a difference between MCBs and MCCBs, especially when it comes to breaking capacities!! ...But i think that was probably a typo mistake. haha!!!

Yes i'm aware there are much higher rated MCBs, and my mistake in not fully explaining what i was endeavouring to point out. Perhaps i should have stated while working in the UK, (as now i try to stick to all things UK style...lol!!) I was trying to make a point of it being somewhat unusual, to be using such high rated breaking capacities, even when close to a 1MVA distribution TX...

Now as far as i can remember, a 1.5MVA general distribution TX is about the largest size commonly used in the UK, especially when two are connected on a common MV/LV (Sorry HV...lol!!) Switchboard where a Buss coupler is incorporated to to keep the fault levels on the LV Switchboard to around 32 KA. Which is still nowhere near the OPs stated FL of 50KA!!

Now the only time i've had higher rated MCBs is on 2.5 and 3MVA 220/127v distribution TXs, in the combined substation and service building..... but those sort of instances are not going to be found in the UK, and certainly not at those voltages... lol!!!

 

[Sidewinder]

Larnacaman,

I missed the MCB bit, when the OP was talking about such fault levels I just read MCCB!

Yes the highest rated mcb I can recall is 10kA, perhaps 15 or 16.

The higher ratigns were as you say MCCB's!

Got to day now getting ready for the match...

 

[Larnacaman]

http://www.gepowercontrols.com/ex/resources/literature_library/catalogs/residential/downloads/d_pc_modular200_english_07.pdfThe breakers in this GE panel are rated 10kA. Can a cascading fuse be used upstream so that it can be used at the locations where the available short circuit current is 50kA?

This is basically very similar to the DNOs BS1361 fuses higher KA rating protecting the so called 16KA domestic CU fault level!! Most of which will have 6KA MCBs and RCBOs fitted... Obviously there's a bit more too it than that, but in answer to your question, ....Yes!!!

---------- Post Auto-Merged at 22:18 ---------- Previous post was made at 22:14 ----------

Larnacaman,I missed the MCB bit, when the OP was talking about such fault levels I just read MCCB!

Yes the highest rated mcb I can recall is 10kA, perhaps 15 or 16.

The higher ratigns were as you say MCCB's!

Got to day now getting ready for the match...

No .... you were right , the OP was talking MCBs, it was Canoeboy that mentioned MCCBs ...lol .... It's Friday mate ...Hae a Beer !!! lol!!

 

[Larnacaman]

Just been looking at the OPs link to GE breakers ....Sure do look like MG breakers and accessories to me!!! haha!!!

Don't know if any here have had anything to do with GE and or Westinghouse American style MCBs etc?? ....If you have, then you can understand why such large US companies will use European manufactured breakers and just rename them... there own would never pass first muster!! haha!!!

---------- Post Auto-Merged at 23:46 ---------- Previous post was made at 23:32 ----------

Did a 2MVa transformer job a couple of years ago, same factory is having another put in as we speak ( shame i missed out on the latest job though ! )

The LV Switchboard(s) must have cost them an arm and a leg, bracing levels must be around 45+KA. The old rule of thumb when costing switchgear/boards was, ....''For every 5kA over 22KA doubles the bracing costs'' ....Tends to get Expensive!! lol!!

Another reason WHY they tend to make full use of having two such rated TXs connected to a common MC Switchboard that always has a Buss coupler between then...