Control Tab (IEC)

For 3-phase faults, there are four different types of faults 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. The other types, Line to Ground, Double Line to Ground, and Line to Line are generally used for specialized relaying applications or system troubleshooting. You can specify the phases to fault for each fault type. During short circuit analysis, the program automatically changes the display phases if the phases selected appear on the one-line do not match these fault values.

Note: Your phase descriptions may be different than described here if they have been customized in Tools > Options > Terminology.

For single-phase faults, there are three different types of faults available during a short circuit analysis. You can specify the phases to fault for each fault type. The options are as follows:

• 1PH-3W: For single-phase-3-wire faults, the options are line-to-neutral (LN) or line-to-line (LL).
• 1PH-2W Line to Neutral: For single-phase-2-wire line-to-neutral faults, the option is line-to-neutral (LN). This is for reference and cannot be changed.
• 1PH-2W Line to Line: For single-phase-2-wire line-to-line faults, the options are double-line-to-ground (DLG ) or line-to-line (LL).

Selects whether single-phase buses are included when bus faults are performed. By default, this option is selected.

Sets the lower limit for flagging breaker violations in SmartDuty™. If the threshold is set to -10 percent, SmartDuty™ flags all equipment which has short circuit duties within 10 percent of their maximum rating (greater than 90% of their rating).

Note: The ability to automatically check equipment duties during analysis is only available if you have purchased the SmartDuty™ option to EasyPower.

Note: You must click Equipment Duty from the Short Circuit focus for this field to have any effect on the one-line result output. 
For this field to have any effect for text result output, you must select the Create Equipment Duty Report check box in the Text Output tab of the Short Circuit Options dialog box.

For more information on IEC equipment duty calculations, see IEC Equipment Duty Calculations.

• Device: This applies the 1-phase fault type and compares the device ratings with the fault currents through the 1-phase devices (see the options under Fault Type for 1PH buses). This applies to protective devices that appear in the one-line view. Devices within panels and MCCs are compared to the bus current.
• Bus: This choice applies the types of fault available at the bus. 3-phase buses can have the faults 3-phase, single-line-to-ground, double-line-to-ground, or line-to-line. You can choose the fault type for 3-phase buses from the Short Circuit Options or from the short circuit menu. 1PH-3W buses can have a line-to-ground fault or a line-to-line fault. For 1PH-3W, you can choose the fault type only from within this dialog box.

For more information, see Equipment Duty for Single-Phase Devices.

You can set a threshold for remote bus voltages. Buses that violate this threshold are highlighted. You can control the highlighting for high voltage and low voltage buses using Short Circuit Options > One-line Output > Voltage Sensitivity Highlighting. This is applicable only for single bus faults.

DC short circuit calculations use this voltage per unit.

IEC-60909 (GB/T 15544) Settings

This is the voltage correction factor (commonly referred to as C Factor). The C Factor is used for modifying equipment impedances and the driving point voltage. IEC recommends calculations for minimum and maximum short circuit currents. Selecting C Factor for Max or Min enables the desired type of calculation. You can perform calculations for only one of the two at any time. The C Factors differ by voltage levels. The default values in the Options dialog box are those recommended by IEC-60909, and are summarized below. You can change these values if needed.

One of the four breaking currents (0.02s, 0.05s, 0.1s, 0.25s) can be chosen as a global default for TCC clipping and tick marks in LV breakers and fuses. You can change the individual settings of the breakers and fuses in their respective dialog boxes.

Select this option to ensure unbalanced faults such as single-line-to-ground, line-to-ground, and double-line-to-ground use the X/R ratio of the 3 phase fault to calculate the peak current in method C. If this option is not selected, the X/R of the unbalanced fault is used for peak current calculations.