Fused Switch - Short Circuit Tab

The interrupting rating of the fused switch (ANSI).

The breaking capacity of the fused switch (IEC).

Test X/R ratio of the circuit. ANSI Standard test ratios might be different for the same fuse depending on the voltage level at which the fuse is applied.

This comes directly from the device library and cannot be changed.

When selected, this fills in computed values for the Test X/R and Fused Interrupting fields, based on the device library entry for Mfr, Type, Style, and the base kV. You can override these values by clearing the checkbox and typing in different numbers. This also causes the appropriate Testing Standard to be displayed for your information.

Note: The short circuit rating of low voltage fuses is not returned from the device library look up if the applied voltage exceeds the fuse rated voltage.

TCC Defaults

Data entered in this section is used to place tick marks representing short circuit values on the TCC plot.

You can clip the time current curve (TCC) for the breaker at the specified current in kA. Select <None> to avoid clipping of TCC.

• For ANSI, select Momentary (1/2 cycle), 5-cycle or 30-cycle.
• For IEC, select Initial, Breaking, or Steady State.

Select the appropriate check boxes to display the tick mark on the TCC plot.

• For ANSI, you can display Momentary, Interrupting and 30 Cycle short circuit values. Enter the corresponding short circuit values in kilo amps in their respective edit fields for phase short circuit.
• For IEC, Select Initial, Breaking, or Steady State. If you select Breaking, you can select the breaking values. The options are Global, 0.02, 0.05, 0.1, or > 0.25. Global is derived from the Short Circuit Options on the Control tab.