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Short Circuit Study – Most Frequently Asked Questions in 2019!

Last updated: Oct 1, 2020

Are you having confusions regarding Short Circuit Study? Don't know how and when to carry it out? Or you just need a brief answer to your query? Go ahead and read the blog to know about this important power systems study all in all!

Hello there! On a related topic, we previously wrote a blog about Most Important Frequently Asked Questions Regarding Arc flash Study – What you need to Know! If this peaks your interest, check it out and let us know what you think


What is a Short Circuit Study OR Short Circuit Analysis?

“An examination of an electrical framework that decides the magnitude of the currents that flow during an electrical fault.”

Short circuit occurs when part of a current carrying conductor touches or comes in contact with another wire or part of the circuit and gives the electricity a path of less resistance to flow. This results in excessive current flow in the power systems through the path of low resistance and may even cause the power source to be destroyed in addition to causing more heat and fires

A Short circuit study holds crucial importance in power systems. Without performing a short circuit study, we cannot go for the arc flash study and it is a recommended practice for any power system facilities.

To put it simply, a short circuit study is the identification of the fault current levels at each electric point in the site and it is the first step in ensuring compliance with NEC requirements.



Why do we need a Short Circuit Study?

A Short Circuit Study is a major factor for safety, productivity, and economy of any electrical power system. It ensures site safety by calculating the interrupting ratings and identifying hazardous areas.

When a short circuit exceeds the interrupting rating of the protective device, the outcomes can be shocking, including damaged electrical equipment, and costly downtime.

On the off chance that you don't have a short circuit study performed, and you have underrated equipment, then this can potentially result in devastating outcomes and lost control over a more extensive region in the electric framework!

Under-rated equipment likewise risks getting harmed from bearing more fault current than it was rated for. This could mean spending more cash on replacing equipment or hardware much sooner than would normally be essential.

Short circuit studies are conducted to investigate the behavior of the system under fault conditions –various kind of failures and at different locations. The goals of these investigations are to determine Protective device settings and coordination, to design grounding system, to find the current interrupting capacity of circuit breakers and to calculate current limiting reactors if required.

That’s why it is necessary to perform a comprehensive short circuit study and use protective devices accordingly to counter short circuit currents in power systems.

AllumiaX aims to optimize power systems to a level that is safe, secure and reliable. A safe workplace is a successful workplace.

Danger Keep Off

Why a short circuit is dangerous?

The point at which Two Nodes of an Electric Circuit, planned to be at Different Voltages, Form an Abnormal Connection that causes:

  • Circuit Damage
  • Flames
  • Blasts
  • Overheating

A Short Circuit Fault is Thousand’s Time More Powerful as compared to Normal Current.


How can you perform a complete Short Circuit Study?

Short Circuit Study includes all the electric framework changes that happen after the underlying plan. Factors that usually change in the execution of a system are: the usefulness of accessible fault dimensions, estimate or potentially transformer impedance values, conductor length/type, expansion of motors, and the framework working parameters.

AllumiaX, work closely with our clients in gathering data, modeling the system, simulating faults and abnormalities, documenting fault magnitudes & recommending solutions by the latest industrial standards.

The following steps are required:

Data Collection: Information on all the components is obtained during a field visit and from electric utility and manufacturers, and then tabulated.

Study Cases: Perform Power systems studies based on normal and alternative operating scenarios to determine the worst case short circuit currents for power systems equipment.

One-line diagram: Provide clean One Line Diagrams with Title Blocks and clear component names in order to understand each model separately.

Equipment evaluation: Compare the short circuit ratings with protective device ratings and perform adjustments to the calculated short circuit rating.

Protective Device Recommendations: Improving the coordination between the protective devices, for reliable operation and correct any deficiencies bound in Short circuit, arc flash and coordination studies.

Self-Explanatory Time Current Curves (TCC):Provide an organized TCC Curve for every settable protective devices including circuit breakers and relays etc. for better understanding of coordination within the protective devices.

Electrical Safety Training: Provide customers with innovative, practical, and cost-effective System Overview Training and help your company efficiently disseminate vital knowledge to everyone who needs it.

Timely Report Submission: Rev#1 of our report consists of everything in order to get the client’s feedback then we solve additional queries of the client (if any) and provide the final report (Rev#2).


When do you require a Short Circuit Study and how often?

Short circuit analysis must be performed when a facility is in the designing stages. Some facility owners might consider it as the only instance, however you must keep in mind that this is not a one-time process. These studies are required to be conducted with any potential extension or with the expansion of any new electrical equipment i.e. circuit breakers, new transformers, cables etc. The best way is to have this study performed after the electrical equipment has been affirmed, yet before it has been sent to the site for installation and commissioning.

Usually, over the life of a facility, you may require a complete Arc Flash study every 5 years as recommended by the latest standard of NFPA 70E 2018 and OSHA requirements for the electrical safety of every employee in the field.


What is Short Circuit Analysis?

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

The main objective of Short circuit analysis is to provide necessary over current protection 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.

To learn more about it read our blog Importance of Short Circuit Analysis in Power Systems


How are short circuit currents calculated?

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.

A basic electrical theorem say that the short circuit current actually depends upon the two most important parameters:

  1. The total impedance from the source to the point of the fault
  2. The nominal voltage of the system

With the help of the basic formula, we can easily calculate the short circuit current at the fault location and with the help of those values, we can analyze the system and install protective devices and protect the facility from any major harm or damage.

To learn more about it read our blog Method for Basic Short Circuit Current Calculations


What are the outcomes and 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


What are the deliverables?

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 compliant with NEC, NFPA 70E 2018 and IEEE 1584-2018 standards.


What are the benefits of a short circuit study?

Beneficial things will result only when you have done short circuit studies on your facility! Some of the advantages are really obvious from the solution to our first inquiry above, however here is an organized rundown:

  • Electric equipment will be appropriately evaluated for the fault current it is encountering during a short circuit.
  • If short circuit analysis is performed before the installation of electrical equipment and modifications should be made, this allows you to make changes before it is past the no return or excessively costly.
  • Identifies issues and recommended answers for existing issues in the framework
  • Increased safety for employees and laborers.
  • Reduce loss of power to any electric facility
  • Risk of hardware being harmed, decreases
  • Increases the safety and reliability of the power system and guarantees execution under all working conditions

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