LV breaker short time delay

[TWD82]

If I have the short time delay on a LV molded case circuit breaker set at .1 seconds, is this the total amount of time it will take the breaker to open? Does the .1 seconds include breaker operating time or is it just a delay before the breaker starts to operate?

 

[dpc]

It's normally the minimum response time, so you would have to add in the breaker clearing time and the tolerance. But the best way is to use the trip unit's published Time-current curve since the band shown on the curve accounts for everything.

A lot of short time delays are just described as "Min, Int, and Max" so you would definitely need the response curve for those.

 

[TWD82]

Thanks, I figured that was the case, but some of the manufacturers make it a pain to look up the device curves online