TCC Setting

[schan05]

Most TCC charts that I have seen so far have upper limits of 10,000A and 1,000 seconds on the current and time axies respectively. Is there particular reason for this? If I need to model a power breaker with higher short time and instantaneous rating (say 3000a or 5000a power circuit breaker), how can i model the range beyong 10,000A? I am using SKM Power Tool. Thanks.

 

[davidbeach]

Right click on the TCC, select TCC Settings, then on the Layout Tab, change the number in Current Scale x 10^.

With a 0, the 0.5A to 10,000A is just that; with a 1, the range becomes 5A to 100,000A; with a 2 the range becomes 50A to 1,000,000A. Those should give you enough range to work with. For what ever reason, TCC plots have historically been 4.5 x 5 decades with current shifted as necessary. 1000 seconds is essentially forever from a protection standpoint that plots rarely go above that, and unless you are concerned with sub-cycle clearing times (current limiting) the standard 0.01 seconds at the bottom of the plot is a short enough time. I have seen 6 and 7 decades of time (0.01 to 10,000 or 0.001 to 1000, or 0.001 to 10,000 seconds) but they aren't very common.

 

[schan05]

It worked as your described, really appreciate your help.

 

[cflatters]

By right-clicking on the TCC in CAPTOR you can change all the ranges on either time or current scales, or even the reference voltage level plus lots of other settings.

As david says, a range of 0.01 - 1,000 secs is usually more than adequate but I frequently use 1A - 100,000A for current range since LV currents are commenly in excess of 50kA.

It is also important to recognise and appreciate what fault current conditions exist on site and what you are modelling in Captor using the fault current tab (again right-click in CAPTOR)