An arc flash study is a type of incident energy analysis that is used to establish safety protocols for qualified electrical people working on electrical equipment and circuit parts that cannot be placed in an electrically safe working environment.
The computed incident energy defines protocol such as required levels of PPE depending on both the shock and arc flash boundaries. A short circuit and coordination investigation, as well as updated facility electrical documentation, such as one-line diagrams and electrical equipment locations, are all advantages of engineered arc flash analysis services.
It’s critical to comprehend the arc flash analysis procedure and the “behind the scenes” nuances. My prior postings explain why Arc Flash Analysis services are important, how it saves lives, and how to get the proper information. A complete arc flash study requires the completion of the following seven procedures in general:
- Gather as-built documentation that already exists.
Gathering all existing electrical drawings that an Owner may have is a common beginning point for an Arc Flash Analysis. Typical examples would be:
Illustrations (such as floor plans)
One-line schematics of risers
If the documentation is missing, electrical one-lines must be built in the field, which necessitates a thorough field survey.
The electrical one-line diagram serves as a road map for the facility’s electrical distribution and is an important component of Arc Flash Analysis services.
- Observation in the field
The electrical drawings must be field validated before the data from them is loaded into the Arc Flash Analysis software. In order to develop a comprehensive and accurate one-line, a survey of each site is required to validate one-line documentation and capture any missing information.
Protective device (PD) manufacturer/types/sizes/settings, cable type/lengths, transformer impedance values, and KVA sizes must all be visually inspected and recorded. The covers are then reinstalled when we have gathered this information. Equipment de-energization is extremely unusual.
- Information on Loading
After the field survey is completed and the information on the drawings has been checked, the data is imported into our software programme (SKM Power Tools) and the Short Circuit, Coordination, and Arc Flash analysis services are performed.
- Carry out a short-circuit investigation.
After loading the data into SKM Power Tools, the 3 phase and single line ground fault currents are measured and plotted against the protective device’s “activity ratings” to see if it can clear the fault. To clear a “bolted fault,” a protective device’s duty rating determines how much fault current the device can handle. In other words, if the available fault current is less than the device’s duty rating, the device will do exactly what it was designed to do. If the fault currents exceed the duty rating, the device will most likely fail, resulting in an arc flash.
- Specified coordination
A coordination study is then done using the field data and SKM Power Tools. The fault will be cleared by the nearest protective device upstream of the fault in a fully coordinated system, without affecting protective devices further upstream. The impact of a problem on the overall electrical distribution will be limited to the location of the defect.
It is vital to examine the time vs. current characteristics of each device and compare them to the characteristics of any upstream devices in order to ensure that all overcurrent protection devices are coordinated.
If a fault arises, the localised protection device should clear it; otherwise, the fault will propagate back through the system and may trip the building’s main service device, causing the entire facility to lose power.
We can clear up the coordination issues by adjusting the settings of those protection devices that cross over on the time-current curve. At the fault location, the fault clears. Long time delay, short time pickup, short time delay, and instantaneous are some of the common adjustments we make to a protective device.
- Arc Flash Assessment
Our report includes an analysis of the equipment being evaluated in the study in its “as is” state. We offer suggestions to reduce incident energy levels, such as maximising coordination, when appropriate. We can modify for both strong coordination and reduced “incident energy levels” for those protective devices that have the ability to make setting adjustments, as described in section 5 above. A coordinated arc flash is accompanied by arc flash incident energy. When one does not complement the other, we must analyse both in order to maximise the ideal setting(s) for each.
- Evaluation of the System
Completing the Arc Flash study entails the following steps:
- The Arc Flash labels creation and application.
- Electrical personnel training.
Protective Gear for Employees (PPE)
Clothing and equipment that provide full-body protection in the case of an arc flash or electrical shock are known as Personnel Protective Equipment (PPE). The protection is based on the NFPA 70E recommendation of no more than a second-degree burn. A second-degree burn is usually not life-threatening and can be treated.
Labels for Arc Flash
All labels must provide the nominal voltage and arc flash boundary, as well as at least one of the following: available incident energy with matching working distance, minimum arc rating of clothing, or specific level of personal protective equipment. In general, we prefer to offer more information than is required by NFPA 70E on an arc flash label. All of the information described is available, as you can see from our sample label.
Training for Arc Flash
Who should be trained in electrical safety? The final phase in the Arc Flash Analysis is to provide electrical safety training to any employees who may operate with electrical equipment. Hallam-ICS employees are qualified to conduct electrical safety training.