Circuit Design Help

[ezekiel]

Sorry for this but need some help on learning and calculating circuit design-

I pretty much have a grasp of the procedure correct if wrong -
ib - in - inst method - corret factors - select cable - calc volt drop - check efli ?

Having trouble finding relevant sections in regs and my college notes are not very clear was wondering if any one has or can give a full working example, including pages to find relevant info in iee or onsite guide, would be very much appreciated

 

[pompeygit]

I've got a worked example in word format but not sure if it will come out on here as it uses lots of symbols. If you want me to email it let me have your mail

 

[Spark123]

If you look at appendix 5 in the IEE regs (17th edition - p256) there is an explaination in there.
(also appendix 4 in the 16th ed)

 

[ezekiel]

thanks for help guys,

the word file would be great my email is ***removed*** if its no trouble thanks

 

[ezekiel]

oops forgot profile updated if you can send info ta

 

[pompeygit]

Sorry for delay have only just got back in.......check your mailbox for word file

 

[ezekiel]

? never recieved email

 

[ezekiel]

can anyone help?

 

[ezekiel]

pulling hair out now, just cant find my way round tables in regs to get info i need so can someone work this out and give me answers with page numbers in regs for me to follow pleeeease.

6.5kw heater @230v in pvc flat twin (thermo 70degree c) 20m long protected by bs3036 fuse with ambient temp 35 degrees c and grouped with 3 circuits.
find ib ok
find in (can only guess cant find table)
apply corrections (think i got it but would like pages)
it to find (cable selection table?)
apply volt drop

sorry to be a pain but if i get one good walkthrough im sure i be able to get it.

 

[ban-all-sheds]

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http://www.kevinboone.com/cableselection_web.html - skip down to "3. Example of selecting cable size"
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http://www.tlc-direct.co.uk/Book/4.3.1.htm
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[GaryMo]

pulling hair out now, just cant find my way round tables in regs to get info i need so can someone work this out and give me answers with page numbers in regs for me to follow pleeeease.

6.5kw heater @230v in pvc flat twin (thermo 70degree c) 20m long protected by bs3036 fuse with ambient temp 35 degrees c and grouped with 3 circuits.
find ib ok
find in (can only guess cant find table)
apply corrections (think i got it but would like pages)
it to find (cable selection table?)
apply volt drop

sorry to be a pain but if i get one good walkthrough im sure i be able to get it.

Assume clipped direct and no thermal insualtion

6.5kW @ 230v = 28.3A (Ib)
Chosen BS3036 fuse would be 30A (In)

Factors
Ca = 0.97 (ambient temp) table 4C2
Cg - 0.70 (grouping) table 4B1
Cr = 0.725 (BS3036) Known as Cc in the 17th edition

It = 60.94A table 4D5A

Chosen cable = 10mm2 t&e (rated 64A)

4.4 mV/A/m

VD = (4.4x28.3x20)/1000
VD = 2.5v so complies as it's less than 9.2v at full load