TCC Curves - Mapping the Long Time Delay

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adamscb

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EE
Forum,

I have a question regarding drawing TCC curves, given the different settings, especially when I2t is on for either the short time delay or the long time delay. I understand that when I2t is on, the TCC line becomes sloped and joins the different segments of the curves together. However, is there a magic rule of thumb or formula that says what the slope is of these line segments, when I2t is on?

Also on a slightly different note, when I2t is turned on, what does the "seconds" refer to? I believe it refers to seconds at 6x the long time trip in which the breaker will open, but I could be mistaken.

Any help is appreciated.
 
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