Control Tab (IEC)

To set short circuit options, from the Short Circuit focus, click SC Options. You can also access the options from within the Database Edit focus by selecting Tools > Options > Analysis Options > Short Circuit.

Select the Control tab to specify various parameters for controlling the behavior of a short circuit study.

Figure 1: Control Tab of Short Circuit Options Dialog Box

Option Descriptions
Option Description
Fault Type for 3PH buses

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.

Fault Type for 1PH buses

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).
"Fault All" Filters Enables you to specify a specific bus Area, Zone, and kV Range that to fault and report when you fault multiple or all buses.

Include Single Phase Buses

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

Equipment Duty Threshold

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.

Compare 1PH Device Rating to Device/Bus Current

  • 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.

Voltage Sensitivity Threshold

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.

IEC (GB/T) DC Driving Point Voltage

DC short circuit calculations use this voltage per unit.

IEC-60909 (GB/T 15544) Settings

C factor

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.

Voltage Range

Voltage C Factor table

Voltage Level

Cmax

Cmin

Low Voltage ( < 1 kV)

1.05

0.95

High Voltage ( > 1 kV)

1.1

1

Breaking

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.

Peak Calculation Method

Peak currents are calculated based on method B or method C as described in IEC 60909. Worst case uses the higher current after comparing method B and C.

For unbalanced faults, use 3-phase peak ratio

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.

Default

In the Short Circuit Options Defaults dialog box, you can specify which default short circuit option settings you want to use. This affects the settings in the entire dialog box and is not limited to only the currently selected tab. These default settings are used for all new one-lines.

The options are:

  • Store Current Options as Default Settings: This stores all of the current short circuit options in your equipment defaults file.

  • Reset Current Options to Default Settings: This updates all of the current short circuit options based on those you stored previously in your equipment defaults file.

  • Reset Current Options to Factory Settings: This updates all of the short circuit options to match the defaults that are included in the initial installation of the EasyPower program.

Default settings specified here only affect IEC settings.

More Information