TCC options can be used in the coordination focus to select the type of fault, the short circuit values, the calculation type, and the output pictures in the TCC plots. When the TCC window is open, click TCC Options from the TCC ribbon.
Figure 1: SC Control Tab of TCC Options Dialog Box
Fault Type: Four different types of faults are available during a short circuit analysis. The default is 3 Phase, which is generally used to determine the highest available currents for equipment duty comparisons, and relaying. You can also select 3 Phase fault by clicking 3-Phase on the TCC ribbon. The other types, Line to Ground , Double Line to Ground, and Line to Line are generally used for specialized relaying applications or system trouble shooting. The green dots in the buttons indicate the ground fault type.
TCC Short Circuit Currents: The short circuit currents used in the TCC can be calculated from short circuit or user-specified.
Driving Point kV PU: System fault point voltage in per-unit. This value defaults to 1.0 per-unit.
X/R Calculation Type: Short circuit calculations are based on one of three methods:
IDC = Ö2 IAC RMS SYM exp (-p /|X/R|)
After each dc component is determined and totaled, the equivalent X/R ratio is found from the equation below.
Equivalent X/R = -p/ ln (S IDC / S IAC RMS SYM / Ö2)
The CCM method provides a conservative approach to obtain the fault point X/R ratio and appears to do the best overall job without being over-conservative.1Parise G., “A new approach to calculate the decaying AC contributions to short-circuit: the ‘characteristic’ currents method”; IEEE Transactions on Industry Applications, Vol. 31, No. 1, January/February 1995.
The contents of the One-line Output tab of the TCC Options dialog box are the same as those described for Short Circuit Options dialog box. See One-line Output Tab for more information.
Coordination with PowerProtector™ | |
One-line Output Tab |