Performing an Arc Flash Study can be expensive in terms of both money and time. It requires maintenance staff, supervision, and onsite engineers’ involvement which pulls them away from working on other high priorities for your organization. Further, upper management may not understand the compliance or safety value that a well performed arc flash study brings to the organization.
This article was written to stress the importance of the data collection process not only because it is the foundation of your analysis but because the data being collected can be collected in a way that is useful to the rest of your organization. The benefits of the data collection process should be leveraged to help you justify the effort.
What kind of data needs to be collected for an Arc flash study?
Arc Flash study relies on having information on system sources, impedances, protection, and configuration. There is a lot of data that needs to be collected for each of these categories which includes the following basic information:
· Available Short Circuit Currents
· X/R ratio
· Transformer sizes, voltage, and impedance
· Cables size, and length
· Electrode Configuration
· Breaker Size, Model
· Trip Unit, Settings
· Relays Model, and Settings
The process of collecting the information above requires opening panels and documenting the following: equipment nameplates, cable sizes and lengths, breaker settings, and relay settings.
Preparation is essential when preparing for data collection. This preparation starts by making sure the following are complete prior: Single Lines are up-to-date, unique equipment tags for each piece of equipment have been assigned on the single line (the tags should match field nameplates). The data collection should prepare blank datasheets for each piece of equipment prepopulated with header and equipment tag data.
Your single line drawing should be at least 80% correct by the time you get to the field. This will allow you to focus on gathering data instead of spending time updating your Single Line drawing. If you are trying to verify your single line and gather data, it will be extremely difficult to do a good job at either.
The unique equipment tag will eventually be put on your arc flash label, so it is important that the tag identifier be unique and consistent across drawings, arc flash labels, and field tags. In my experience organizations struggle at naming equipment but in my opinion proper tagging one of the most important things that can be done to improve operations and personnel safety. Workers rely on equipment to be properly tagged for lock out tagout and startup and shut down of equipment. If you have multiple names for equipment spend the time to update your equipment labeling to protect your coworkers.
Once your equipment tags are assigned, create blank data sheets for each piece of equipment.
You are now ready to collect data in a meaningful way.
Site Electric Services uses a tablet to collect data. We embed nameplate photos, settings, and ratings directly into the datasheet for use later by facilities and maintenance staff. The benefit of using a datasheet to organize the data is that the photos taken do not need to be relabeled or identified once back at the office. Identifying photos later is time consuming, can lead to mistakes, and is sometimes not even possible. The datasheet information is saved in a fillable PDF form for future use.
The data collection is an unavoidable cost associated with performing an Arc Flash Study. Leveraging the data collected into something that benefits overall safety, reliability, as well as provides a useful tool for your staff to utilize when performing maintenance and during remodels and retrofits as a design basis.
The benefit of using the datasheet method is that it provides detailed photographs and settings for equipment and circuit breakers. This can be used by engineers and field staff to help them make decisions and help them avoid unnecessary trips to the field to collect data on a piece of equipment.