Are you concerned about the arc flash safety of your facility?
Do you want to know how to carry out a competent arc flash study?
This is your guide to a detailed arc flash analysis! Have a look at the infographic to have a quick review of the seven steps. Read the blog to find out the systematic way in which a proper arc flash study is performed.
It is important to have a clear understanding of the process of arc flash analysis before beginning the actual work. The following steps are employed to perform an arc flash analysis of a facility. After understanding these seven steps, you can have a clear concept of the process of a detailed arc flash study.
Hello there! We previously wrote a blog about Importance of Arc Flash Hazard Analysis. If this peaks your interest, check it out and let us know what you think
[7 Steps] - The details of every step go as follows:
After setting up the goal of the any sort of analysis (Arc Flash Study in our case), the first and foremost step is to gather information. It is crucial to identify all the required data, the sources of the data and the means of acquiring it.
In the regard of arc flash, the required data is the ratings and settings of ALL the equipment present in the facility, from the utility to the smallest of the circuit breaker! It also includes the single-line diagrams of the facility.
The power systems engineer collects this data from the existing facility documents which include Bill of Materials, nameplates of the equipment, documented single line diagrams and all sorts of paperwork which contains such information.
The data collection can be done by visiting the site or the power systems engineer can contact the facility's owner to send in the required documents. The former arc flash study reports can also be useful in performing the latest study.
After identifying the ratings and settings of all equipment like panelboards, cables, loads etc., the power systems engineer then models the system. A graphical layout is drawn on specialized software. That graphical layout is actually the one-line model of the facility.
The equipment drawn are modeled using the ratings gathered in Step 1. It is mandatory to check that the settings (manufacturer, type, ratings and more) of all the equipment in the facility match the actual settings provided in Step 1.
There are number of software available for power systems analysis and design. Some of them are: ETAP, SKM, CYME, Power World etc.
Modeling of the power system on the software is followed by two studies which are the pre-requisites of performing an arc flash analysis of the facility. One of these studies is the short circuit study. As the name suggests, it has to do something when a short circuit conditions occur in the power system.
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.
A short circuit study aids in ensuring the safety of the equipment and personnel by establishing appropriate interrupting ratings of protective devices (protective relays, circuit breakers and fuses).
To evaluate these ratings, the power systems engineer determines the short circuit current rating (SCCR) of all the panelboards, switchboards, switchgears and other feeders. All of this calculation is done using the simulation in the software which also includes other parameters like full load currents, fault currents and impedances in faulty situations.
The outcome of this study is:
Read our blogs titled Short Circuit Study – Most Frequently Asked Questions in 2019 and Simple Method for Basic Short Circuit Current Calculations for in-depth knowledge on Short Circuit Study.
The second study required to perform arc flash analysis is the protective device coordination study. In the wake of a short circuit or any other fault condition, a protective device is used to disrupt the power flow in the faulty feeder. That feeder may be of any panelboard, switchboard or even a switchgear.
Due to this disruption the electrical components downstream of that feeder will shut down. However sometimes fault current may exceed a certain limit and can affect other feeders too, which were not supposed to be shut down. This is where a coordination study is done.
As the name suggests, there should prevail a coordination between the protective devices that only the affected feeder should be turned off and others remain in operation. This increases the reliability of the system. It also prevents damage to electrical equipment by selecting the appropriate rating of each protective device.
The power systems engineer performs a coordination study by using the results of the short circuit study to determine whether a faulty condition would lead to power outage in other unfaulty feeders. Time current characteristic curves are generated using the simulation software to examine the effects of protective devices and to ensure coordination.
The outcome of this study is:
Read the blog Importance of Achieving Selective Coordination for Critical Power Systems for knowing the significance of a selective coordination study.
Finally, after carrying out short circuit and coordination studies, the power system engineer has gathered all the required parameters to run the arc flash study on the software. This is the fifth step from the 7 steps of arc flash study.
The methodology goes like this: selecting all the busses (panelboards, switchboards and switchgears) present in the facility and then running the arc flash analysis.
The software outputs the incident energy level, arcing current, time duration of arc fault and arc flash boundary at each electrical point (bus) in the facility.
The power systems engineer then uses the results of Step 5 to determine the minimum working distance, PPE level and requirements at all the electrical points. These may also be determined using the software. Arc flash labels are also generated.
In case of a very high and dangerous incident energy level, the power systems engineer provides recommendations on how to reduce the level. He may provide new ratings of the protective devices or recommend an additional protective device.
The last step is the implementation step in which the power systems engineer reports the arc flash study results and recommendations to the facility for their on-site application. He submits his findings, results and recommendations in a documented form to the facility owner.
The facility owner then directs his employees to apply arc flash labels on all the electrical points in the facility. This is a very essential part of the implementation phase.
An arc flash label contains all the necessary information like incident energy measurements, safety parameters and PPE category so that the personnel is fully aware before going near the electrical point for any purpose. It is mandatory for the employer to ensure all the electrical points are labeled. Click here to find out more about arc flash labels.
Another optional but useful sub-step in this final step is arc flash training for, but not limited to, the personnel involved in maintenance, installation, and troubleshooting of low and medium voltage electrical control and distribution equipment.
The personnel should be fully trained and qualified as per the codes and standards to ensure a safe and secure working environment. Some internationally accepted standards include OSHA, NFPA 70, IEEE and NEC standards.
We at AllumiaX strive hard to provide the best to our customers by performing a systematic and clear arc flash study. What separates us from the others in the market is our precise and methodical arc flash report.
We document each of the steps and our methodologies of performing each step in a way that can be useful for the facility and for the other personnel who views the report. To read more about our services, visit https://arcflashstudys.com/services
So yes, a report is the deliverable that marks the successful completion of the 7 steps to perform arc flash study!
About The Author
Abdur Rehman is a professional electrical engineer with more than eight years of experience working with equipment from 208V to 115kV in both the Utility and Industrial & Commercial space. He has a particular focus on Power Systems Protection & Engineering Studies.