Previous in Forum: How to Build 0-200Hz Square Wave Generator Next in Forum: Circuit Breaker
Power-User

Join Date: Apr 2010
Location: Asia/India
Posts: 365

# Cable Copper Thickness

06/12/2010 7:54 AM

I want to know how the thickness of a 60 HP slip ring induction motor cabling for overhead crane from 1.5MVA transformer is done. What are the parameter to be considered, i have a slight idea that we should consider short circuit current. Please explain with formulae.

Pathfinder Tags: cable Copper current
Interested in this topic? By joining CR4 you can "subscribe" to

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Anonymous Poster
#1

### Re: Cable Copper thickness

06/12/2010 9:36 AM

is this motor directly connected to Transformer?...The main parameters to be considered is the thickness of overhead crane, height of the crane should be less than the height of transformer. Short circuit current means the current in the short length of the circuit. Measure the length of the circuit and consider it.

Formulae:- Sc= L x I/ZxY.

Guru

Join Date: Oct 2008
Posts: 42293
#2

### Re: Cable Copper thickness

06/12/2010 10:19 AM

Hire a competent electrician. Having a slight idea about 45 Kw will get someone killed. And, unfortunately, it might be someone other than just you.

This is not a DIY project.

Power-User

Join Date: Apr 2010
Location: Asia/India
Posts: 365
#3

### Re: Cable Copper thickness

06/12/2010 10:48 AM

I want to learn its just a study.I am asking your help to learn nobody authorise me to do it. I didnt hide my identity.I am facing a lot of problems just because i am straight forward?

Guru

Join Date: Oct 2008
Posts: 42293
#4

### Re: Cable Copper thickness

06/12/2010 11:08 AM

I quote from one of your earlier characteristically elementary questions,

"How does a tester work? I have done checking phase and myself as ground but Ii never understand why I'm not getting shocked.The circuit is closed now, is it the resistance in series or vacuum in bulb or a positive charge is developed from ground? Please help I'm a graduate EE."

What did you learn in school?

Power-User

Join Date: Apr 2010
Location: Asia/India
Posts: 365
#5

### Re: Cable Copper thickness

06/12/2010 11:18 AM

We didnt learn about a tester we have to understand it from what ever higher circuit numericals we do.I was deliberatly in need of answer and i want to bring the situation going on here to the public.I know you people mean the very designation as Engineer now please forgive me and be kind to help me sir.

Guru

Join Date: Mar 2007
Location: Rosedale, Maryland USA
Posts: 5198
#6

### Re: Cable Copper Thickness

06/12/2010 11:24 AM

They extrude single strands of copper size depending on how much flexibility the final cable needs to have. Then the twist them together into a stranded wire to handle amperage in excess of the load of the motor at the working voltage. They then cover the strands with insulation which would have the flexibility needed and the insulating properties to the working voltage. Parameter are amperage, voltage and flexibility. Short circuit current is what breakers are for in distribution panels to protect the wires. Motors are protected with fuses or thermal overloads. There is not just one formula for all you wish to know. Each manufacture of cable has his own. They maybe similar but there may be some differences. Could just be twists per foot.

Not quite the answer you expected?

__________________
Life is not a journey to the grave with the intention of arriving in a pretty, pristine body but rather to come sliding in sideways, all used up and exclaiming, "Wow, what a ride!"
Power-User

Join Date: Apr 2010
Location: Asia/India
Posts: 365
#7

### Re: Cable Copper Thickness

06/12/2010 11:49 AM

Thank you Mr. Ozzb i was expecting a general formula.whatever you said is what happens in a manufacturing unit right. So what you mean the twisted cable can withstand short circuit current even though we wired it for specific current only.In fault conditions the breakers (MCBs) takes some time know and i wonder how the wire could withstand it ? We use HRC fuses here i hope that is for cable protection and its rated capacity is high.

Anonymous Poster
#8

### Re: Cable Copper Thickness

06/12/2010 11:52 AM

Dont question us. Just beleive what we americans say.

Off Topic (Score 7)
Power-User

Join Date: Apr 2010
Location: Asia/India
Posts: 365
#9

### Re: Cable Copper Thickness

06/12/2010 12:06 PM

I believe mathematics. Who said "what is most important is not to stop asking" ? I Believe Americans are good people, they feel happy to share knowledge.

Power-User

Join Date: Sep 2010
Location: Thrissur, Kerala, India
Posts: 177
#18

### Re: Cable Copper Thickness

09/12/2010 8:58 AM

Hmmmmmmmmmmmmm

__________________
If you can't find a way, make one........
Off Topic (Score 5)
Guru

Join Date: Dec 2008
Location: Long Island NY
Posts: 15250
#10

### Re: Cable Copper Thickness

06/12/2010 3:15 PM

GA ozzb.

The thing is that many of the things that has to be considered in an appropriate choice of any cable are critical parameters that cannot quantified. (i.e. flexibility, insulation durability to abrasion, ultra-violet radiation, chemical exposure, temperature extremes, icing) This is why a continuous function equation, linear or non-linear, cannot be made. So regional code standards have been made that have look up tables that must be translated by a knowledgeable person.

__________________
"Don't disturb my circles." translation of Archimedes last words
Power-User

Join Date: Apr 2010
Location: Asia/India
Posts: 365
#11

### Re: Cable Copper Thickness

06/13/2010 8:18 PM

But atleast for understanding the Amp. rating there will be a calculation?

Guru

Join Date: Dec 2008
Location: Long Island NY
Posts: 15250
#12

### Re: Cable Copper Thickness

06/13/2010 10:37 PM

No, not even the amperage rating of a certain conducting area of copper can be calculated. Given a copper wire sheathed in teflon with a cross sectional area of "x" that is able to safely and continuously dissipate the power created by amperage "J" will only require a smaller fraction of the same cross sectional area "x/y" copper wire if the insulation of the same thickness is Kapton reinforced by fiberglass. For the Kapton and fiberglass insulation will not deform and short out the wiring at the same temperature. If one were to immerse the cable in an insulating and also heat removing oil bath then even less wire thickness is required for safe continuous duty. Also the duty cycle of the current can play greatly into this problem. I have a device that regularly delivers hundreds of amperes of current through wire no greater than one millimeter square in cross sectional area suspended in a vacuum chamber with absolutely no additional cooling provided. It's done for only 20 micro seconds and no more often than four times an hour but it is regularly done without failure.

__________________
"Don't disturb my circles." translation of Archimedes last words
Power-User

Join Date: Apr 2010
Location: Asia/India
Posts: 365
#14

### Re: Cable Copper Thickness

06/14/2010 3:58 AM

What a logic :-)!!:-)!!:-). 0 where did you learn this attitude of making it very simple.

Power-User

Join Date: Mar 2010
Posts: 105
#13

### Re: Cable Copper Thickness

06/14/2010 3:45 AM

Dear Mr.Hithuanand,

I am following all the questions posted by you in this forum.

As one of the readers has pointed out you as EE !!, I still do not know why you

Torment OR torture us with your stupid questions. I am sure that some basic

qualifications is to be included in this forum so that people like you will not show

up OR pose as Qualified technocart or a Dumbfool.Sorry for my comments- it

is too harsh !.

Manroop Chennai.

Power-User

Join Date: Apr 2010
Location: Asia/India
Posts: 365
#15

### Re: Cable Copper Thickness

06/14/2010 5:17 AM

I am sorry i quit the forum but i was genuine with my intentions to know. I should learn first electrician job believe it i completed my graduation with full dedication.see you.

Anonymous Poster
#16

### Re: Cable Copper Thickness

06/14/2010 2:19 PM

Vulgar/Rude/Improper Behavior: This post was deleted because it did not adhere to the behavioral policies of the site. Please review Section 14 of the CR4 Site FAQ about rules for posting.

Off Topic (Score 5)
Guru

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 30461
#17

### Re: Cable Copper Thickness

06/15/2010 3:37 AM

→ British Standard 7671.

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Interested in this topic? By joining CR4 you can "subscribe" to