Voltage drop calculations for engineers beginners eep. The nehermcgrath equation was discovered by two cable engineers in 1957. Work as a software engineer creating mobile applications for route accounting which integrated with parallel server accounting package. Rather than using software the relies on nehermcgrath, i use a finite element analysis package and build the models. In electrical engineering, nehermcgrath is a method of estimating the steadystate. For circuits with other parameters, the nehermcgrath acresistance calculation method is used. By estimating the temperature of the cables, the safe longterm currentcarrying capacity of the cables can be calculated. Although conductor ampacities calculated using the nehermcgrath formula may exceed those found in a table of allowable ampacities, such as table 310. For distinctive duct bank configurations, an electrical system design engineer must utilize the neher mcgrath calculation method. Control engineering embedded intelligence increases. Here a group of experts share their experiences and opinions about using electrical system and design software to add value to their engineering projects. Its a mostly straight forward set of calculations and tables that are well documented in the nec. We highly suggest that all results and calculation be made under the guidance of and licence professional engineer that specializes in this type of work. Find and hire freelancers for arc flash study guru.
Refinements to the nehermcgrath model for calculating the ampacity of underground cables sally m. Nehermcgrath are specialized and complicated calculations. While an engineer is required to oversee the computations. In electrical engineering, nehermcgrath is a method of estimating the steady state.
It addresses steadystate and transient thermal cable rating as per the analytical techniques described by nehermcgrath and the international standards iec 287 and iec 853. Powertools for windows ptw is created and sold by skm systems analysis, inc. Engineers are often called upon to calculate ampacity and temperature rise of. Lead engineer continental electrical construction company. High medium and low voltage power engineering software. This would cause the sensors output to turn off and then back on which must be handled by software or the sensor needs to be readjusted. Pllp 2011 lca performed a nehermcgrath heating calculation analysis for a large data center to determine if the electrical distribution system was designed properly.
Engineers have calculated cable ampacity from the time cables were first. Nmin0005 large software corporation, redmond washington. Contact us to learn more about multiday training session now available to all current cyme software users. In this instance, an engineer iii would comfortable and capable supervise a design group of 710 people, with one or several engineers. We stay connected to our clients with a company ftp site and with video conferencing and live meetings. The cymcap software is dedicated to the calculation of ampacity and temperature rise. This software was developed jointly by ontario hydro hydro one, mcmaster university and cyme international, under the auspices of the canadian electricity association. Calculations are in accordance with the industry accepted neher mcgrath calculation procedures. Keith lane has a significant amount of experience in the design and troubleshooting of critical facilities. A proper application of the neher mcgrath formula requires an extremely experienced electrical engineer who has made these calculations a major part of his or her professional specialty.
Software programs usually use nehermcgrath method for calculation of the cable ampacity. Electrical engineer resume engineering resource group, inc. This calculator also provides wire size correction factors for temperature, number of conductors in a raceway, and voltage drop for long wire runs. In its abbreviated form, the neher mcgrath formula appears straightforward. Conductor ampacity calculation part eight electrical. Engineers familiar with ohms law know that electrical current flowing through. Etap electrical power system analysis software power.
Pdcs ampacity calculations are based upon the nehermcgrath procedure, modified using iec 60287 for parameters such as sheath losses. Refinements to the nehermcgrath model 00483997 docshare. The 50 best electrical engineering software tools pannam. Fluency in the current version of cad software employed by the. Master advanced software, including skm agi 32 and scymecad. Mcgrawhills national electrical code 2011 handbook, 27th edition article 310. The calculated voltage drop values are approximate. Solar pv power plant underground cable sizing case study. Etap electrical engineering software offers the best and most comprehensive suite of integrated power system enterprise solution.
Neher and mcgrath are the surnames of two electricians who wrote a famous article about how to calculate the capacity of current ampacity of cables. Cable thermal analysis helps engineers design cable systems to operate to their maximum potential. Underground cables need a proper burial nehermcgrath. The project engineer utilizes his or her creativity, foresight, and mature engineering judgment to anticipate and solve engineering problems, determine program objectives and requirements, and develop standards and guides. Power engineering, also called power systems engineering, is a subfield of electrical engineering that deals with the generation, transmission and distribution of electric power as well as the electrical devices connected to such systems including generators, motors and transformers. We have found that this program is easy to use, very stable, and meets our high quality standards. In electrical engineering, neher mcgrath is a method of estimating the steadystate temperature of electrical power cables for some commonly encountered configurations. Cable sizing cable thermal analysis part 3 youtube. Consulting specifying engineer evaluating software.
Here is a brief description on this issue from the user guide of the electrical productivity pack from cad technology center that i helped to create. Used dapper, captor, edsa neher mcgrath ampacity software for technical evaluation. Mcgrath were two electrical engineers who wrote a paper in 1957 about how to. Hundreds, if not thousands, of tools, mobile apps, and software products exist in the marketplace, all targeted to electrical engineering professionals. The cable was selected based on a maximum operating temperature 75. A set of experiments was performed on a direct buried cable to compare with the nehermcgrath method and commercially available software programs. Lca performed a nehermcgrath heating calculation analysis for a large data center. The nehermcgrath calculations is a method for calculating underground cable temperatures and cable ampacity ratings.
Considering the number of calculations needed to determine ampacity using the nehermcgrath method, it is obvious why engineers would. Electrical design engineer preparation of design criteria, one line diagrams, specification for electrical equipment, scope of work document for installation subcontracts for chemical plant expansion. These parameters were used by the design engineer in the nehermcgrath method to specify conductor size and such installation details as cable spacing and depth. Edsa neher mcgrath ampacity software for technical evaluation. Conduct or oversee distribution analysis including voltage drop, voltage droop, and underground heat effect nehermcgrath calculations. Arc flash forum view topic arc flash study qualifications. This gives me more flexibility in defining the problems and handling unususal circumstances.
It is the engineers responsibility to determine if a load factor less than 1. Thomas electrical engineer, pe 62 chamberlain street. View tomas martins profile on linkedin, the worlds largest professional community. Change how wire is autosized or allow override for engineering judgement revit, in some cases, cannot properly calculate voltage drop due to how it automatically assigns wire size. But, its not always easy for busy electrical engineers to find the time to search the top 50 tools for an. Lane coburn and associates has a significant amount of expertise and experience in the design and troubleshooting of underground installations including ampacity calculations using the nehermcgrath equations. Using electrical system software for engineering projects much has changed since the days of slide rules and bookcases full of engineering references. Real power engineers is an electrical, power and controls systems engineering firm committed to developing technical business and consulting services by means of assessment, design development and commissioning of electrical power systems. The nehermcgrath method is the electrical industry standard for calculating cable ampacity, most often employed via lookup in tables of precomputed results for common configurations. My goal is to place as many 12g wires in a conduit as possible while maintainin. Nehermcgrath calculations provide an alternative method for computing derating of conductors in conduit.
Now, at the forefront of preconstruction innovation and technological improvements. It is incumbent on the engineer to determine the purpose of the conductors in ug ductbanks, and perform appropriate ampacity calculations that find the most economical design that results in safe operation. Skm analysis neher mcgrath model auto cad mep microsoft suite our benefits include. He holds a bsce degree from the university of maryland and a fundamentals in engineering certificate. The nehermcgrath calculations are very complex and involve many calculations and equations and can be exceedingly time consuming. Project and field tested accuracy for added confidence. Using electrical system software for engineering projects.
Cyme power engineering software power consultants limited. Neher mcgrath are specialized and complicated calculations. The nehermcgrath method has been widely accepted as an accurate and relatively simple way to calculate the ampacity of underground cables. At times, particularly buried cables, resorting to nehermcgrath software is necessary but most of the time the nec procedure suffices, and it is a regulatory requirement in most jurisdictions, and a recognized standard in all of the others in the. Cable thermal analysis software cable thermal capacity.
We also have extensive experience with 3d modeling, 3d animation, autodesk building systems, revit and bentley bim for bim building information modeling and other software including skm power tools. I use quickfield for 2d and flexpde for 3d modeling. Mcgrath,the calculation of the temperature rise and load capability of cable systems, aiee transactions, part iii, volume 76, pp 752772, october, 1957. Pdc also uses several internally developed mathcad sheets to perform more complicated calculations that are not easily modeled using standard ampacity software. I tried to purchase a software program, so i can do it myself, but have had no luck or response from them on how to purchase the software. The results show the nehermcgrath calculations and cymcap software outputs. Nehermcgrath institute professional engineers certify. W123 with oes3 technology can detect the multicolored object without the sensors output turning off and on or having to readjust the sensor when products change color. This allowed an engineer to look up the appropriate cable size based on current rather than calculating the cable size using nehermcgrath calculations 4. Nmin0008 internet corporation, moses lake washington. Electric association of chicago serving the chicagoland. Applying steadystate cable temperature calculations for.
Verified with software and manufacturer calculated and published results. We have standardized the usage of powertools for windows captor and dapper. The lead engineer provides a variety of designs, diagrams and drawings, and conducts ocp, heat. Refinements to the nehermcgrath model for calculating the. Over 100 years ago, harry witz created a small business that has responded to changing times with an entrepreneurial spirit. They consider only temperaturelimited, currentcarrying capacity of. Nmin0006 financial corporation, east coast, in progress nmin0007 internet corporation, arizona, data center. The calculation is based on the nec accepted nehermcgrath approach, which employs a thermal circuit model to represent heat flow situations.
The neher mcgrath calculations is a method for calculating underground cable temperatures and cable ampacity ratings. Electrical engineer resume engineering resource group. The program uses the nehermcgrath calculation procedure to determine underground cable temperatures or cable ampacity ratings for virtually any duct bank or direct burial cable configuration. Ampcalc is suitable for cable installations utilized in industrial, commercial and utility electrical power distribution systems. Our handson training sessions provide users with the skills and knowledge required to perform different power engineering analyses using the software. Electrical design engineer preparation of design criteria, one line diagrams, specification for electrical equipment, scope of work. Cable ampacity calculations nei electric power engineering, inc. The advanced wire ampacity calculator will calculate the maximum ampacity for a wire based on wire gauge, preferred or available wire insulation, conductor type and installation specifications.
215 1214 66 551 625 1605 1561 316 17 130 799 655 646 809 1040 1366 798 1036 664 995 763 1498 518 586 1290 88 1246 1521 750 859 1113 81 1095 603 1104 180 1174 809 971 518 409 282 1306 523 1034 503