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Sakeen Farhan
Participant

Join Date: Feb 2011
Posts: 2

Circuit Breaker

02/22/2011 5:44 AM

What is the meaning of "Icu,Icw,Ics,Isc" and What are the differences between them

Best regards
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lyn
Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#1

Re: Circuit Breaker

02/22/2011 5:50 AM

Using the same skills that brought you here, search for these terms on the internet.

Once you learn to search for yourself, you will no longer have to ask other people to do your work, and your thinking, for you.

Best regards.
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Anonymous Poster
#2
In reply to #1

Re: Circuit Breaker

02/22/2011 6:51 AM

Hey now...be careful throwing crazy advice like that out there. You're about to upset a bunch of political parties with such notions!

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Anonymous Poster
#7
In reply to #1

Re: Circuit Breaker

02/22/2011 10:35 AM

CR4 ADMIN: Deleted Post

Abuse/Attack: This post was deleted because it was an attack on another user. Please review the CR4 Site FAQ and the CR4 Rules of Conduct.
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Anonymous Poster
#10
In reply to #7

Re: Circuit Breaker

02/22/2011 11:43 AM

Guest,

I understand your irritation and I have also scolded responses which consisted of "look it up". And perhaps Lynlynch's response was a little lacking in tact. But your own response was utterly devoid of it.

It seems to me that lately there's been an increase in questions which are phrased in such a way they can be read that the OP hasn't bothered to do their own research. Maybe this is a misperception on my part, maybe it's due to language barriers, maybe it's correct. I can see Lynlynch's thought process when he read the OP's question. Had it been worded differently then his answer would have probably been quite a bit better.

Of course that's no excuse for poor CR4 ettiquite on his part - or yours. Or mine, for that matter. So let's all take a moment to think about civility and make CR4 a better place, shall we?

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lyn
Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#11
In reply to #10

Re: Circuit Breaker

02/22/2011 11:50 AM

Until you register and distinguish yourself from the insulting guests who hide behind the cloak of anonymity, your opinions are as meaningless as the rest of the drivel spouted by most "Guests".

It just sounds like you're talking to yourself.
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Anonymous Poster
#12
In reply to #11

Re: Circuit Breaker

02/22/2011 12:27 PM

Yes well, until I see anyone else here with my exceedingly high intellect I guess talking with myself will just have to do.

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lyn
Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#13
In reply to #12

Re: Circuit Breaker

02/22/2011 12:34 PM

Try to do it quietly then, so as not to disturb us feeble minded members.
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Anonymous Poster
#15
In reply to #11

Re: Circuit Breaker

02/22/2011 1:52 PM

Since you responded in a somewhat intelligent manner, I would call this a true conversation.
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Anonymous Poster
#17
In reply to #11

Re: Circuit Breaker

02/22/2011 2:09 PM

CR4 ADMIN: Deleted Post

Abuse/Attack: This post was deleted because it was an attack on another user. Please review the CR4 Site FAQ and the CR4 Rules of Conduct.
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lyn
Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#18
In reply to #17

Re: Circuit Breaker

02/22/2011 2:33 PM

CR4 ADMIN: Deleted Post

Irrelevant This post was deleted because it is related to a deleted post and would otherwise be taken out of context.
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Anonymous Poster
#14
In reply to #10

Re: Circuit Breaker

02/22/2011 1:51 PM

This is the place to do research. This is an open forum, where they get together, crack a few beers, and talk out their technical to-do list. When someone walks up to the group with a beer and asks a simple question and is told to pack sand, that's just plain rude. And very dick-like.

Normally this would not be practiced in human form, but some douches on the board like to throw their imaginary weight around and just tell people to shove off.
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67model
Guru

Join Date: Dec 2010
Posts: 1686
Good Answers: 116
#3

Re: Circuit Breaker

02/22/2011 7:14 AM

These apply to the parameters of circuit breakers and contactors.

Schnieder Electric are one of the biggest makers of this kind of device for distribution boards, motor starters - with brand names like Telemecanique.

http://www.schneider-electric.com/sites/corporate/en/home.page

If you delve into their website for contactors, like I did, you should find that they have technical information and memoranda which explain these terms (and much more). For example "Cahier Technique No. 150 - Development of Circuit Breakers to IEC 947-2".

One has to keep trying different menus and documents till the right area is found.....

It is like the food Supermarket - At Tesco, I learned, in time, that (there being no "tinned meat" or "canned meat sign) "tinned meat" was (with the tinned vegetables) under the sign "Canned Vegetables" - it appears "Canned" was the important word in the mind of the planner.
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Anonymous Poster
#4

Re: Circuit Breaker

02/22/2011 7:46 AM

Icu = Rated Ultimate Short Circuit Breaking Capacity of a Circuit Breaker - This implies the maximum RMS value of short circuit current that the Circuit Breaker can safely break for a operating duty cycle O-CO. After clearing the rated Icu twice, the breaker becomes unusable again.

Ics = Rated Service Short Circuit Breaking Capacity of a Circuit Breaker - This implies the maximum RMS value of short circuit current that the Circuit Breaker can safely break for a operating duty cycle O-CO-CO. After clearing the rated Ics thrice, the breaker can be used as a Switch till replacement is received. But, no more short circuit clearings. Ics can be either 25% or 50% or 75% or 100% of Icu.

Icw = Rated Short Time Withstand Current - This implies the maximum RMS value of short circuit current that the breaker can safely carry for a given duration (e.g.) 50kA for 1sec. This is an important specification, because in co-ordinated networks, all the breakers may have to continue carrying the fault current till cleared by the uppermost stream breaker - in case the down stream breakers fail to clear the fault.

The above three are very important specifications for an LV Circuit Breaker.

Isc = Short Circuit Current (more system related)
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electricalexpert65
Guru

Join Date: Oct 2009
Posts: 2061
Good Answers: 169
#5
In reply to #4

Re: Circuit Breaker

02/22/2011 7:48 AM

Forgot to login. The previous answer was given by yours obediently "ee65"
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Anonymous Poster
#8
In reply to #4

Re: Circuit Breaker

02/22/2011 10:36 AM

Thank you.
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67model
Guru

Join Date: Dec 2010
Posts: 1686
Good Answers: 116
#16
In reply to #4

Re: Circuit Breaker

02/22/2011 2:00 PM
  1. So what is a duty cycle O-CO? Or O-CO-CO? Does "O" mean overcurrent, off or open? Does "C" mean clear or close? Or something else?
  2. Seems like a code Icu or Ics defined using two other codes O and CO.
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kvsridhar
Guru
India - Member - New Member

Join Date: Sep 2009
Location: Temporarily at Ashburn, VA
Posts: 2744
Good Answers: 164
#21
In reply to #16

Re: Circuit Breaker

02/22/2011 9:55 PM

IEC 60947 definitions : Open - 3 minutes - Close/Open (without intentional delay between the C and O)

CB requires to clear O-CO at Icu and O-CO-CO at Ics.

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loadshare
Power-User
Engineering Fields - Electrical Engineering - New Member Engineering Fields - Mechanical Engineering - New Member

Join Date: Jan 2011
Location: Jakarta
Posts: 162
#6

Re: Circuit Breaker

02/22/2011 9:58 AM

Every one has the right to ask and answer...Go 4 Piece

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 One system
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Anonymous Poster
#9
In reply to #6

Re: Circuit Breaker

02/22/2011 10:37 AM

Amen, brother.
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wareagle
Guru
United States - Member - New Member

Join Date: Jun 2008
Location: Alabama
Posts: 1604
Good Answers: 63
#19

Re: Circuit Breaker

02/22/2011 2:41 PM

Lyn

Maybe Next time I am on Phoenix for the BCS game I can stop by for a free meal and a beer.
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lyn
Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#20
In reply to #19

Re: Circuit Breaker

02/22/2011 2:50 PM

Come on over.
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Users who posted comments:

67model (2); Anonymous Poster (10); electricalexpert65 (1); kvsridhar (1); loadshare (1); lyn (5); wareagle (1)

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