Using electrical system software for engineering projects
Much has changed since the days of slide rules and bookcases full of engineering references. Here a group of experts share their experiences and opinions about using electrical system and design software to add value to their engineering projects.
- Keith Lane, PE, RCDD/NTS/RTaPM, LC, LEED AP, president/CEO, Lane Coburn and Associates LLC, Bothell, Wash.
- Rick Sparkman, PE, electrical engineer, CH2M HILL, Portland, Ore.
- Syed Peeran, PhD, PE, senior engineer, Camp Dresser and McKee Inc., Cambridge, Mass.
- Brian Rener, PE, LEED AP, senior manager, M+W U.S. Inc., Chicago
Q. Which types of electrical system software programs do you use in your job?
Lane: The types of software our firm uses include CAD, BIM, 3-D, and collision detection software. Specific software packages include:
- Autodesk MEP, Navisworks, and Revit
- Bentley MicroStation
- SKM software for selective coordination and arc flash studies
- Server software packages from Neher-McGrath Calculations, CalcWare AmpCalc, and CYME Power Engineering Software and Solutions
- Electrical Designers’ Reference (EDR) for quick short-circuit and voltage drop calculations
- Visual and Visual Professional for 2-D and 3-D lighting photometric analyses
- Microsoft Project and Primavera SureTrack for project design and construction scheduling.
We have also used Microsoft Excel to develop numerous proprietary programs for various tasks such as analyzing harmonics, reliability studies, panel schedules, load calculations, asymmetric fault current calculations, voltage drop, lighting calculations, motor control center schedules, and conduit fill spreadsheets.
Sparkman: I use several software systems of varying complexity as a part of my regular work tasks. On the technically advanced end of the spectrum, I use ESA’s EasyPower and SKM’s PTW software for load calculations, short-circuit analyses, protective device coordination, and arc flash analyses. Some specific tasks such as duct bank calculations are performed using CalcWare’s AmpCalc or Polywater for cable pulling tension calculations. Our drawings are produced using various versions of AutoCAD depending on specific client needs. Recently, we have used AutoCAD MEP2011 for full 3-D design. The program we use most often is probably Microsoft Excel. I use Excel for a multitude of tasks—from quick voltage-drop calculations to complicated data-tracking with long strings of formulas.
Peeran: In the past, electrical system designers relied on a few rules-of-thumb, hand calculations, tables and graphs provided by equipment manufacturers, and lessons learned during the engineer’s past experiences. Today, sophisticated and reliable software programs are available to assist in every aspect of the system design, such as transformer sizing, cable sizing, demand load studies, voltage-drop and power-factor studies, short-circuit studies to select circuit breakers, device-coordination studies to correctly set protective devices, harmonic analyses to verify compliance with IEEE Std. 519, arc flash studies to verify compliance with NFPA 70E, and motor-starting voltage-dip studies. In addition to the available software, many companies such as Camp Dresser and McKee have developed proprietary programs based on Microsoft Excel for panelboard scheduling, cable and conduit sizing, and cable pulling. Over the past 15 or 20 years, the use of the software has increased and is now accepted as an engineering design aid.
Rener: We use SKM Systems’ Dapper and Captor software programs for short circuit, time-current coordination, and arc flash studies. We also use generator sizing software, AGi32 software from Lighting Analysts for interior and exterior lighting including 3-D photometric calculations, and Autodesk Revit software for building information and 3-D modeling.
Q. What are the typical capabilities or features of the electrical system software programs you use? Of these features, which do you use most frequently?
Lane: For most mission-critical projects we use 3-D Modeling, collision detection, and BIM. Over the last 10-15 years we have run numerous selective device coordination studies as well as arc flash studies. We have also completed numerous Neher-McGrath duct-bank heating calculation analyses for our own mission-critical designs.
Sparkman: Most programs have more features than I ever actually use. The technically advanced programs such as PTW require multiple classes and training to be able to use them to their full potential. The features that I use are one-line diagram creation, load-flow modeling, and short-circuit calculations—for systems as well as for single-point spot checks. Conversely, I use AmpCalc to its fullest potential to perform heat calculations on multiple groups of conduits and have actually maxed out the system size available on one particularly large project with approximately 400 underground 480-V conduits. Microsoft Excel is general-purpose spreadsheet software that is not specific to power applications, and yet it is invaluable in day-to-day engineering. The features I use in Excel range from daily routines such as meeting notes to data tracking and data visualization. I also use Excel’s formulas to manipulate large amounts of data, usually loading criteria by physical location for the client’s facility.
Peeran: The most commonly used modules of the electrical system design software are the load flow, short circuit, protective device evaluation and coordination, and lighting design. In addition to these, a large number of designs require arc flash analyses, harmonic analyses, and motor-starting studies. OSHA now requires that electrical equipment be affixed with proper warning labels to alert the operating personnel of the degree of exposure to arc flash hazards. These labels are generated by the software’s arc flash analysis module. Because VFDs, fluorescent lighting, computer rooms, electronic instrumentation, and other nonlinear loads now constitute increasing proportions of the total load in industrial systems, harmonic analysis is necessary. In water and wastewater treatment plants, induction motors of several thousand horsepower drive the pumps. In such systems, it is required to run motor-starting studies to ensure that limitations imposed by the utility are not exceeded.
Rener: As a design firm, the features we use most often are short-circuit and lighting calculations. Time-current coordination and arc-flash calculations are typically provided as part of construction submittals, based on the specific equipment that will be purchased.
Q. Of the electrical system software programs you use, what features or capabilities would you like to see added?
Lane: Software developers need to continually strive to make the programs more intuitive and user friendly. They also need to maintain their databases to ensure that all products can be analyzed.
Sparkman: It would be beneficial to have more options for exporting proprietary output files into commonly used formats. For example, I would like more control exporting coordination study values or panel schedules to something other than a data dump with comma-separated values. This would allow other designers and engineers access to the useful data without having to have intimate knowledge of how the software works.
Peeran: In attempts to include more features and more modules, some software developers lose sight of an important attribute: user-friendliness. The data input and output reports are complicated and needlessly lengthy. They can be comprehended only by those who are trained in the software. This is an area in which the software companies can develop. The outputs should be formatted better, should be easy to read, and intelligible.
Renewable energy sources such as photovoltaic (PV) arrays and wind farms are getting greater attention now. Here is another area in which software companies can expand. Although many stand-alone programs are available for designing PV and wind farm systems, there is a need to integrate these programs into other programs such as load flow and short-circuit studies.
Rener: We have been using the latest BIM software. Unfortunately, software for electrical and mechanical engineers has lagged the versions developed for architecture. Also, advancements in BIM and other 3-D software suites require significantly faster computer workstations and IT networks.
Q. How have these electrical system software programs helped you in performing your job?
Lane: Certainly, we are more productive. More importantly, these programs allow us to engineer more projects, cost-effective projects, and safer projects.
Sparkman: The electrical software programs that I use help significantly. They provide a level of accuracy that can be matched by hand calculations, but not with the same consistency or in the same timeframe. They allow quick documentable calculations, which come in handy when on a busy project. I have multiple Excel files from several projects with long descriptive filenames and dates that stemmed from quick calculations that grew into full project documents. They also allow easy expansion from a small system one-line diagram into a much larger system. There are also certain clients who require specific software to be used, so having a resume including knowledge of multiple systems increases the ability to pick up new clients and new projects.
Peeran: While designing a modern distribution system, several operating scenarios must be examined to ensure that the system performs satisfactorily in the normal, emergency, and other operational modes. The software is invaluable for looking at various what-if situations. Otherwise, one does not really feel comfortable about the design. A detailed study is required in each situation. The studies become very useful design aids.
Rener: On the client side, visualization in 3-D is a great communication tool. We are now working with our partners and clients to extend into virtual reality systems where one can simulate moving around inside the models.
From the construction side, the 3-D software is reducing coordination and interference issues. For example, being able to clearly see an electrical duct bank as it crosses an exterior foundation wall has been a great improvement to the accuracy of our designs.
Q. In your opinion, how has electrical system software changed over the last five years? In the past 10 years?
Lane: These programs are becoming more user-friendly and intuitive, but there still is room for improvement.
Sparkman: The primary change to electrical system software over the past five years has been to make it easier for engineers to use. There have been some advances in technical abilities such as arc flash calculations, but the primary functions have always been there. The integration of a simple graphical user interface along with intuitive controls to manage high-level calculations is vital to making the software easier to use. The past 10 years have undoubtedly shown more change, but as a young engineer with six years of experience using engineering software, I will have to wait a while to answer that one.
Peeran: In the last 10 years, the software vendors have included more modules in the packages they offer. They have also increased the capability of each module. From the initial 300 bus system, programs are now available to model 2,000 or more buses, cables, and other equipment. More types of electrical equipment can now be modeled such as on-load tap changing transformers, harmonic filters, reactors, VFDs, UPSs, and overhead transmission lines.
In the last five years, we have seen much expansion in program libraries of equipment characteristics. The libraries form an essential part of the software. A more comprehensive library makes the software more useful.
Rener: Certainly there has been a transition from numerical input to graphical input on the calculation software over my career. Inputting electrical system data into calculation programs is now like drawing in CAD systems. Before, it was more like working in spreadsheets.
Q. Describe a recent project in which you have used electrical system software, and its challenges and successes.
Lane: We are continually providing 3-D modeling of large underground duct banks for mission-critical projects in conjunction with Neher-McGrath heating calculations. It is a very interactive process with the switchgear vendors, the electrical contractors, and our studies. One study really cannot be done without the other. It is a back-and-forth process of not only determining the most cost-effective routing of the underground conductors, but also ensuring that under all failure scenarios, the conductors will not overheat.
We see many engineers providing plans that rely on the electrical contractor to provide both the 3-D modeling and the duct bank heating calculations. In our opinion, this level of detail should be provided with the engineer-stamped drawings. We have been asked to provide our services on projects that were not designed properly—not using the appropriate coordination and engineering software.
Sparkman: My most recent project was working on a fast-paced semiconductor fabrication facility. I used several software packages starting with AmpCalc and Polywater to design the underground conduit package. While the pulling tension calculations proved to be relatively simple, the heating was another matter. It took many iterations of AmpCalc scenarios and design questions with the structural team to come up with a design that could accommodate the level of power under the concrete slab that we needed. While the underground design was in progress, the high level one-line diagram was being finalized using EasyPower.
This has been a long, ongoing process, starting with the initial skeleton structure and then down to the details of specific breaker and relay details for the coordination study. Dealing with the sheer volume of distribution equipment along with the pace of design and construction was made easier with the use of electrical system software. The use of Excel and a database to track an AutoCAD drawing to a specific panel is critical to effectively support pulling in the construction schedule and meeting the client’s needs.
Peeran: A large hospital complex in New England decided to install gas-turbine driven cogenerators to augment the utility power and make it more reliable. A detailed study was required to determine how best to integrate the cogenerators into the vast distribution system of the complex. At least six what-if situations had to be modeled and studied. The challenge was to model several situations to study the stability of the generators in parallel with the utility upon the loss of one or more utility lines feeding the complex. In many buildings of the complex, transformers are bussed on the low voltage side and are protected by network protectors. The analysis was required to determine whether any network protector would trip under emergency conditions due to reverse power flow.
Rener: We recently upgraded to the latest BIM software. The hardware requirements forced us to purchase new high-end computers. Also, the BIM files were not compatible with previous versions, which made sharing the files with others more challenging.