What KAIC stands for? If there is a number before the word KAIC, what does it mean, say, 14 KAIC?

Thanks..

Killo Amp interrupting capacity

14KAIC this meas that your CB is capable to handle 14kiloampered fault current with out damging your cercuit breaker..

Exactly.

The value is a rating of electrical overcurrent devices that if a fault exceeds it can result in catastrophic failure, or blow up into shrapnel.

To size this value, a short circuit coordination study needs to be done. Along with the impedance of transformers and copper wire due to distances, and voltages and current ratings, will either raise or lower the value equipment must be able to withstand.

This is a serious engineering task sometimes ignored.

Along with this info and additional detail, an Arc Flash study can and should be done.

Any body who knows the standard on the number of maximum operation of a circuit breaker under a fault condition?

Quote:

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Originally Posted by danar

Any body who knows the standard on the number of maximum operation of a circuit breaker under a fault condition?

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The ratings as I remember them are only for one operation at full rating. If this occurs, the circuit breaker should be replaced. Also in the discussions above, I found no comments on the asymetrical fault duty for the circuit breaker. This should also be considered.

Does this mean that after a cb is trip on earth or line to line fault it is not allowed to swith on again after clearing the fault?

Ratings for circuit breaker interrupting capability may be different for different voltage, current and circuit parameters. For most in home, 240/120 volt circuit breakers rated for 200 amps on down to 15 amp circuit breakers, if they have an AIC rating for 10,000 amps symmetrical or asymmetrical. If a short circuit to ground or phase to phase or line to line develops and due to system parameters (voltage, impedance, X/R ratio, etc.) the current level reaches 10,000 amps, the circuit breaker is designed to successfully interrupt this current for one time. It should be replaced with a new CB at that time.

Since most faults are well below the AIC rating of the CB, it is OK to reset it and reuse to protect the circuit. The ratings are based on how much energy the CB can mechanically and electrically withstand and may be measured by the cumulative amount of IIt, or I squared multiplied by the time it takes for the current to reach zero. So if the CB is designed to interrupt the full fault of 10,000 amps in 0.0333 seconds then a total of 3.3 million amp-seconds of energy are what it is designed to handle. If we assume most short circuits seen in a home are on the average of 1500 amps, you could say the CB can be used 2,222 times successfully.

This same application of total energy is used for 12 kV through 500 kV circuit breakers used by most power companies. In their case however, the circuit breaker is overhauled in accordance with the manufacturer’s recommendation or an internal procedure developed through operating experience and performance.

I hope this helped.

Quote:

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Originally Posted by danar

Any body who knows the standard on the number of maximum operation of a circuit breaker under a fault condition?

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for KAIC rating we have what we called Icu/Ics.. Icu-ultimate, Ics-service
for ex you have a kAIC rating of 15/7.5 (Icu/Ics)

if there's a short circuit or major fault along the system >=15,000A, then the CB will trip to protect the ckt and needs to be replaced after.

But, if there's a fault along the system >= 7500A , then the CB will trip to protect the system too. Take note that CB can still be used for 3 times (up to 10 times for some, it depends on the manufacturer) under the same condition.

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Kaic means a circuit breaker can withstand without damaging with fault occur on it.

When

Kaic means kiloamps interrupting capacity, 1000amps is equivalent of 1 kaic, ex. When have a CB 50AT, 220V, 3 pole 60hz. 18 kaic, this means your CB is able to withstand or capable to handle up to 18kiloampered fault current without damaging its mechanism. However this will still depend on the manufactures recommendation.