Icu VS Ics

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Abdel Rahman Mohamed

Abdel Rahman Mohamed

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Riyadh,KSA
one of the most important factors in evaluate the circuit breaker the ratio between ultimate and service short circuit current(Icu,Ics) is there a fixed no of tripping identifying the both values.
 
I for one have no idea what the terms you are asking about mean. They are not terms that are common in the US.
 
don_resqcapt19 said:
I for one have no idea what the terms you are asking about mean. They are not terms that are common in the US.
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http://blog.schneider-electric.com/...l-risk-insurance-for-circuit-breakers-part-2/

[h=3]Icu and Ics: essential to operational reliability[/h]Across both categories, circuit breakers must deliver reliability. The two IEC 60947-2 requirements which ensure that reliability are:
? Ultimate breaking capacity (Icu)
? Service breaking capacity (Ics)
Icu is the maximum short-circuit current that a circuit breaker can break without damage. That maximum might be 6,000 or 10,000 amps. Or when it comes to MCCBs, as high as 200kamps. However, in a sense, Icu is essentially as statement of quality for a specific voltage rating.
And that?s where Ics comes in. It is expressed as a percentage ratio of Icu and tells you the maximum short-circuit current if a circuit breaker can break three times and still resume normal service. The higher the lcs, the more reliable the circuit breaker.
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Sajid khan said:
Is it mandatory that circuit breaker will interrupt 3 time only or it can interrupt more than that.
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It can interrupt more than 3 times, but the official rating will be based on the highest short circuit current that it can interrupt three times without damage.
If the manufacturer cuts the tests as close as possible to maximum performance, that number may not be good for 4 times on a typical production sample.
 
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