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@vinothkumar asaithambi said:

Thanks for ur reply my frnd..

But i gotta too many questions..you gonna answer them pls..

consider the case i am having 10 DB`s each having 100A incomer MCB..and these DB`S ll be fed from SDP(Sub distribution Panel). where this SDP and the some other SDP`s (consider same size, say 10 each) connected to the MDB ( Main Distribution Board.).

Consider this is a Domestic load and load voltage 230/400V, 50Hz.Here is my Questions…

1. What Kind of Breakers we have to choose for each level(from DB- SDP – to MDB)??

2. What ll be the KA ratings for all these breakers (Incomer and Branches) ???

3. Is there any calculation behind this, choosing breakers and its KA ratings???

4.is there any Space Factors we have have to consider, when we are making all these panels???

5.Give me list of Busbar Sizes to carry all these for each level…

ThX n Advance,

So here is the deal,

First off, I see a big flaw in ur system consideration……..i will explain it you in steps……read carefully and understand in steps.

U have domestic loads, perhaps not exceeding than 63 A or may be 100 A or may be more, well we gotta select a perfect discrimination so that we are able to safeguard the whole system. Pls read and try to understand below system from BOTTOM (read dbs…..then sdps….and finally mdbs )

MDB -1

And finally….(HERE IS YOUR FLAW IN SYSTEM)…SO IF YOU HAVE 10 MORE SDPs……SO IF YOU TAKE BASICS AND CONSIDER THE BREAKER RATING …THEN IT COMES AS “1250×10 = 12500 A”…..DUDE…. THIS IS FUCKING HUGE….i mean wot is the rating of your transformer….. is it super duper ultra large transformer ?? ….:p …..THAT MEANS U HAVE TO BREAK OR BIFURCATE THE SYSTEM SOMEWHERE !!…AND ALSO… I AM SURE…. U MUST NOT HAVE 10. NOS OF SDPs….AND EVEN IF U HAVE…. THEN ITS A DIFFERENT SYSTEM

SDPs-10

As we now know when in full load we have 1000A drawn by your system (system below this) …so be safe…..consider 1250 A MCCB,

Lets take a breaking capacity of 36 or 50 kA…. no less available….and higher the better , if i was you ….. i wud have considered 50kA..

DBs-10

lets say a total mcbs are 10….so 100×10=1000 A

So this gives the breaker rating for SDP. now read up.

And as its a domestic load, to safeguard u can consider 10kA (more that enough)…u can find 6kA in market too….but…as u wish !

After MDB read here !!!…

So here is a better solution…..

MDB..1 Nos

2000 A ACB / SFU wid a breaking capacity of 50kA

SDBs..1+1 = 2

800 A mccb wid 36kA or 50kA breaking capacity

DBs..5 + 5 = 10

100 A mcb for each use and 5 for 1each sdb….this way u can hook up one system of 10 dbs with 2 sdbs..

I hope i was helpful

FLINT !

P.S : PLEASE CORRECT ME IF I AM SMALLEST BIT OF WRONG !!