Arc Flash Analysis
Protection coordination, short circuit analysis and arc flash analysis are the major studies performed regularly to ensure the system is properly protected and workers are safe. We have performed and reviewed the studies by other consultants for our clients. We have experience with all major power system study software such as ETAP, SKM, CDEGS (grounding), and EasyPower and have programmed GE Multilin, Schweitzer, Siemens, and Schneider protection relays for all applications.
We have represented clients/owners to review the studies completed by other consultants. Some of the concerns listed below we encounter during the review of the short circuit, protection coordination and arc flash studies:
Data Collection :
Data collection can be a lengthy process depending on the size of the facility and will require the client's significant involvement. This can increase the project cost and impact the project schedule. We noticed that important data is not collected and assumptions are made. On the other side, some of the collected data has very little or no impact on the studies but takes a lot of resources to collect it. A discussion with the client before start collecting the data can be very helpful.
Modelling :
Similar to data collection, modelling the system can also be a lengthy process. Depending on the type of study, the modelling can be adjusted to reduce the project cost. As an example of arc flash study, small motors and other static loads are not required to be modelled. A discussion with the client can improve the cost and schedule.
Performing the :
Study
Properly setting up software options is very important for the study. The electrode configuration for all the equipment is an important parameter which can affect the arc flash results. The client's operation team is not consulted to evaluate different operation scenarios and define the buses where incident energy should be calculated. We have noticed that incident energy is calculated on a large number of buses where energized work is not performed. On the other hand, some of the buses are missed where energized work is performed.
Recommendation :
The recommendations are not clearly stated in the report and some of the recommendations can not be implemented without significant cost and loner outage. We have helped clients when recommendations were made to replace the equipment where the short circuit current was higher than the equipment rating. The study had not considered the current limiting fuses and equipment series rating. After further discussion with the engineering company, the recommendations were removed.
Study Report :
A good report is one of the main deliverables at the end of the project. A report template should be discussed with the client before it is prepared. We have seen thousands of page reports with a lot of unnecessary information. The software output reports are directly added to the report without evaluating if the client needs this information or not. On the other hand, important information is not included in the report.
Deliverable :
Software model with libraries is not always provided to the client. The model is required to update the studies in future. Some of the main deliverables are
1) A final authenticated pdf report.
2) A word copy of report
3) Software files including customized libraries
4) Protection relay programming files to upload to the relays
5) All the connected data