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Topic Title: Voltage Drop Calculation
Topic Summary: Check voltage Drop Answer
Created On: 03 March 2010 08:04 AM
Status: Read Only
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 03 March 2010 08:04 AM
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deleted_1_Martin57

Posts: 2
Joined: 02 March 2010

Could someone check my voltage drop calculation?

The voltage drop on a circuit supplied from a 230v source by 16mm two core copper cable 23m long, clipped direct and carrying a design current 33Amp.

Actual Voltage Drop = MV/A/M x Ib x Length then divided 1000. Therefore. 2.8 x 33 x 23 divided by 1000 = 2.12 volts (2.8 from table 4D2B page 277 BS7671)

The answer given in the book I am using is written this way..

Vc = mV x Ib x L divided 1000. Therefore. 28 x 33 x 23 divided 1000 = 21.25 volts


So where does the author get 28 for his calculation? I'm reading 2.8 in the IEE Regulations.

What is the answer? Is it 2.12 volts which is my understanding or the books author 21.25 volts?

Best Regards
Martin
 03 March 2010 08:22 AM
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sfchew

Posts: 589
Joined: 10 December 2002

You will get more replies if you post it in Wiring and the regulations.

By the way 21.25 volt drop does not look like the right answer.

Regards
Chris Chew
 03 March 2010 02:56 PM
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Robo

Posts: 15
Joined: 07 October 2004

Martin,

Your result looks OK to me. Looks like a typo in the book you have.

Just to confirm, voltage drop figures are given in mV/A/m, or in the case of 16mm sq = 2.8x10-3/A/m. So no need for the divide by a 1000 if you start off in mV.

Regards

Robo
 03 March 2010 09:11 PM
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57martin

Posts: 2
Joined: 03 March 2010

Thank you for your input "sfchew" I posted it into "Wiring and the regulations" with success.

Robo, thank you for your knowledge.

Regards
Martin
 19 March 2010 06:40 AM
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mohdyazel

Posts: 1
Joined: 19 March 2010

hello thre. i`m newbies here... anyone from you have a some picture for earthing installation for transformer.

thanks
 21 March 2010 09:49 PM
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Nedryerson

Posts: 38
Joined: 12 December 2009

Mohdyazel,

You must start a new thread and provide more information regarding the transformer.

Thanks
IET » Energy » Voltage Drop Calculation

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