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Short Circuit Analysis Module

Overview

The short circuit module helps you determine how the system will behave under fault conditions. The results of the analyses are key to designing and setting protective devices to protect your system and protect equipment and personel. Results of these analyses also form the basis for conducting protection coordination and arc flash studies.

General Short Circuit

Short circuit reports give the range of fault levels found on a selected feeder or system

The general short circuit analysis determines fault currents and impedances due to system faults. The results of the analysis include fault currents for all types of fault (phase-ground, phase-phase, 3-phase and phase-phase-ground) along with the Thevenin impedances of the faulted system.

The short circuit analysis gives results for maximum and minimum fault levels at each node included in the analysis. DESS allows you to specify both maximum and minimum source impedances when representing supplies from the transmission system and you can also choose whether to automatically exclude generation and motors when calculating minimum fault levels.

You can also choose to use values based on ANSI/IEEE C37 fault analysis or to use IEC 60909 correction factors when calculating fault values.

Specific Short Circuit

This analysis provides detailed information for system conditions during a specific fault condition. You choose the fault condition by specifying the location of the fault, the type of fault (phase-ground, three-phase, phase-phase, phase-phase-ground) and the faulted phases. You can also choose whether to calculate conditions for a bolted fault or for a specified fault impedance.

The analysis determines the fault paths and currents and voltages along these paths. If the system contains multiple sources of fault current (such as networked systems, large motors or distributed generation)then it shows the contributions from each source and the path of the current.

The fault current results can be used to set overcurrent and directional protection, and the voltage results can be useful for choosing settings for undervoltage relays.