How much current is there during an electrical fault and can my equipment handle it? These are the questions that are answered by the short circuit studies. Electrical faults, or shorts, can cause thousands of amperes of current to flow through equipment. If the electrical equipment’s withstand rating is lower than the fault current, it can cause dangerous situations where protective equipment fails to safely interrupt the fault, resulting in a catastrophic failure.  

A fault current analysis should be performed before any equipment is purchased and installed to ensure it has adequate withstand and interrupt ratings.  In addition, changes to the electrical system, either by the site itself or the utility provider, can cause the maximum fault current to change and equipment to become underrated.  It is recommended that the fault studies be re-evaluated periodically and before any major renovation.

The fault current calculations performed in the short circuit studies are a critical component of the arc flash analysis calculations.

The Process

The short circuit studies begin by gathering information from drawings, equipment submittals, on-site inspection, etc.  This information is then input into modeling software where it is organized into single line diagrams.  The software then calculates the various fault current types at every point in the modeled system and the studies specialist analyzes these calculations for accuracy and compares them with equipment ratings.  

The Deliverables

A complete report describing the fault current analysis would be provided.  This report would contain a discussion of the findings and will offer recommendations for correcting any deficiencies discovered. Appendices containing the developed single line diagram, the input data of the software model, the fault calculations output by the software and an equipment evaluation table showing the calculated values vs. equipment ratings will be included with the report.