Executive Summary

There have been various instances in an industrial facility when a connection is established by accident or intention between two points in an electrical circuit. This excessive electric current potentially causes circuit damage, overheating, magnetic stress, arcing, fire or explosion. Therefore, a comprehensive protection scheme to provide the necessary safeguard from such electrical hazards is of paramount importance.

A Short Circuit Analysis will aid in ensuring the safety of the equipment and personnel by establishing appropriate interrupting ratings of protective devices (circuit breaker and fuses).

Objective

The main objective of Short circuit analysis is to provide necessary over current protection devices in the distribution system that will prevent injury to personnel, minimize damage to system components, and limit the extent and duration of service interruption during equipment failures, overload or short circuit conditions.

Study Methodology

Maximum available short-circuit current is a central parameter for all power networks as it provides the necessary information to ensure equipment is being utilized within its rating and the system is running smoothly and reliably. A comprehensive modelling of the system is first done by using the data acquired from the existing facility documents. The next step is to calculate the continuous full load current rating for each electrical point in the system.

The short circuit currents can then be calculated on the basis of the impedance represented by the “equivalent circuit”. This impedance may be calculated after separately summing the various resistances and reactance’s in the fault loop, from (and including) the power source to the fault location. After obtaining the impedance, it is used to divide the Full load Amperes at the specified electrical point in order to evaluate the short circuit current.

Study Outcomes & Recommendations

Short circuit studies will be 100% in compliance with the latest IEEE, NEC & NFPA standards. Study outcomes and recommendations are expected to improve your facility in the following areas:

• Identification of critical areas in the power system
• Contingency plans for emergency shutdowns
• Improved protection for switchgears and switchboards
• Significant reduction in power blackouts following severe fault conditions
• Proper ratings of the protective devices installed at each feeder
• Adequate protection for the working personnel against electrical hazards

Study Deliverables

Our team of certified professional engineers have the expertise to investigate short circuit conditions and provide innovative engineering solutions for your power system’s protection. We work closely with our clients in gathering data, modeling the system, simulating faults and abnormalities, documenting fault magnitudes & recommending solutions in compliance with the latest industrial standards.

AllumiaX, LLC provides independent and third-party engineering support by presenting comprehensive deliverable reports backed by industry standards and best practices, analysis work based on industry-leading software (ETAP), and proven results based on accurate modelling and calculations. The reports are expected to include the following deliverables:

• A comprehensive model of the facility in modern power systems software
• Evaluation of the system under short circuit conditions for normal and emergency scenarios
• Design parameters of the protective devices that are required for optimal protection
• Comparisons between the existing protective device ratings and the available fault current
• Recommendations for the protection of equipment and personnel
• Recommendations for the corrective action of the protective devices for protection against high fault currents
• Providing the necessary information for NEC and NFPA standard labels

References

• NFPA 70, “National Electric Code” ,2017
• NFPA70E, “Standard for Electrical Safety in the Workplace”, 2017
• IEEE Std 551™-2006, “Recommended practice for Calculating AC Short Circuit Currents in Industrial and Commercial Power Systems”