This software was developed jointly by ontario hydro hydro one, mcmaster university and cyme international, under the auspices of the canadian electricity association. Computer assisted teaching of underground power cables. Understanding the nehermcgrath calculation and the. They consider only temperaturelimited, currentcarrying capacity of.
Using electrical system software for engineering projects much has changed since the days of slide rules and bookcases full of engineering references. Produces over 30 standard and customizable reports, all. Today, the greater majority of utilities and cable manufactures have been using the iec287 standard 2 based on the nehermcgrath model. Described methodological procedure needs to be followed in order to obtain good and.
A set of experiments was performed on a direct buried cable to compare with the nehermcgrath method and commercially available software programs. Thermal analysis software all industrial manufacturers videos. Calculation of the cable ampacity considers only power cables since control cables. Rather than using software the relies on nehermcgrath, i use a finite element analysis package and build the models. Electrical engineers will appreciate the updated electrical cad software, which is available in various product options, including e3. The software tracedrawer from ridgeview instruments ab is designed to help scientists evaluate, summarize and present results from multiple realtime interaction experiments. The lightsout data center, also known as a darkened or a dark data center, is a data center that, ideally, has all but eliminated the need for direct access by personnel, except under extraordinary circumstances. The cable capacity ampacity calculation and cable sizing are based on the nec accepted nehermcgrath method and iec 60287 standard for steadystate. The software is an efficient tool for making complex calculation tasks straightforward and easy. Based on nec nehermcgrath approach transient temperature calculation urban load profile normal rating uniformly raising loading of all circuits in duct bank until one reaches a temperature of 90oc emergency rating loading on the circuit is raised while holding the remaining circuits constant and a temperature of oc is reached. Duct bank heating calculations are essential for critical.
Uses the nehermcgrath approach where iec 60287 does not apply considers nonunity load factor. Evaluating software tools for electrical system design. Businesses and schools are reopening again but many restrictions and limitations remain. Get a handson demonstration of the programs use before you put out the money. As a result all ceus based on the 2014 nec and the 2014 nesc courses are no longer valid for state of alaska license renewals. The software examines cable temperatures and ampacity in performing analysis of existing systems. Cableizer is completely webbased because we believe saas is the future. We have found that this program is easy to use, very stable, and meets our high quality standards. It is also critical to hire a professional electrical engineer with expertise in both critical environments topology and on providing nehermcgrath calculations. Here a group of experts share their experiences and opinions about using electrical system and design software to add value to their engineering projects.
The 50 best electrical engineering software tools pannam. In this section we will explain some of the functions from the programs main menu. Too few utilities have stringent specifications or qualityassurance programs for. This allowed an engineer to look up the appropriate cable size based on current rather than calculating the cable size using nehermcgrath calculations 4. Iec 60287 for cable thermal analysis gives analytical expressions for the computation of the geometric factor of threecore cable insulation, whereas the nehermcgrath approach makes a. They consider only temperature limited, current carrying capacity of cables. Pdcs ampacity calculations are based upon the nehermcgrath procedure, modified using iec 60287 for parameters such as sheath losses.
The cymgrd software is a substation grounding grid design and analysis program specially developed to help engineers optimize the design of new grids and reinforce existing grids, of any shape, by virtue of easy to use, builtin danger point evaluation facilities. Iterative techniques based on nehermcgrath and iec60287. At project x, a concreteencased mediumvoltage duct bank is designed to enter the building and snake under some water pipes, and enter the electrical. Lca performed a nehermcgrath heating calculation analysis for a large data center. 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.
The nehermcgrath model has been widely accepted for over 50 years. In the nehermcgrath nm equation, delta td, is a term added to the ambient temperature, ta, to compensate for heat generated in the jacket and insulation for higher voltages. The nehermcgrath approach for cable thermal calculation approach uses a userdefined load factor, whereas the iec 60287 approach assumes a unity load factor. Cableizer is a software package for the design of power cable systems using electrical, mechanical, thermal and environmental calculations. The validation of the results obtained with the cymcap software provides increased confidence when upgrading existing power cable installations and designing new ones, thus maximizing the benefits from the considerable capital investment associated with them. Mgo insulated coaxial instrument cable development for. Understanding the nehermcgrath calculation and the ampacity.
Basic steps that cable ampacity software tools use are discussed below. We have standardized the usage of powertools for windows captor and dapper. Cable ampacity iec neher mcgrath programwill be invoked using this function. 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. We have provided professional engineering services for general contractors, developers, designbuild electrical contractors, electrical consultants, mechanical consultants, mechanical contractors, architects, owners and governmentcity. Since then, considerable research efforts have been expended in modifying the neher mcgrath method and enhancing its modelling capabilities under both steadystate and variable loading conditions 29. When you dont have the software and want to do quick calculations on simple ductbanks, annex b is a good tool. A fresh look at addressing the future electric grid by carson bates. It offers a large set of tools to facilitate comparison, such as alignment. Refinements to the nehermcgrath model 00483997 docshare. Alan zhang senior electric power system specialist xendee. Find out how to determine the optimal cable sizes, physical attributes, and maximum derated ampacity using nehermcgrath method and iec 287 standard. The neher mcgrath calculations is a method for calculating underground cable temperatures and cable ampacity ratings. The program supports a transient thermal analysis option which includes the following.
However, these traditional methods of cable ampacity calculations approximate. Thermal analysis software all industrial manufacturers. This new thermal analysis software features a guidance function to simplify various types. Developed power cable ampacity calculation engine software based on nehermcgrath and iec60287, automated protective device coordination and evaluation algorithm, automated power system design. I understand that neher mcgrath calcs in skm require an add in and that it is very expensive. This gives me more flexibility in defining the problems and handling unususal circumstances. There are several software packages available that will calculate the nehermcgrath equations. The iec international electrotechnical commission and neher mcgrath cable ampacity program is undergoing continuous development to make it as comprehensive and as easy to use as possible. The cymcap software is dedicated to the calculation of ampacity and. The method is used whether the installations are in ambient air. Cable steadystate temperature calculation cable thermal. Despite these differences, all allowable ampacity values found in the code are determined using ieee method 835, which in turn is based on the neher mcgrath method see insert.
Conductor ampacity calculation part eight electrical. The results show the nehermcgrath calculations and cymcap software outputs. I understand that neher mcgrath calcs in skm require an add in and that it is. The program uses the neher mcgrath calculation procedure to determine underground cable temperatures or cable ampacity ratings for virtually any duct bank or direct burial cable configuration. There are several software packages available that will calculate the neher mcgrath equations. Understanding the nehermcgrath calculation and the ampacity of. Refinements to the nehermcgrath model for calculating the. The accuracy of the calculation provides increased confidence in the design, upgrading, and analysis projects. Using electrical system software for engineering projects. It addresses steady state and transient thermal cable rating as per the analytical techniques described by nehermcgrath and the international standards iec.
Therefore, for each case considered, the nehermcgrath model provides a conservative value f o r the cable ampacity and the new method for calculating the ampacity suggests that the current in all of the cables cari be increased beyond the nehermcgrath value without thermally overloading the cables. I use quickfield for 2d and flexpde for 3d modeling. Pdc also uses several internally developed mathcad sheets to perform more complicated calculations that are not easily modeled using standard ampacity software. The available tables, however, are based on installation and material assumptions which may not be readily apparent or even applicable to a given. Electrical engineers use powertools to perform harmonic analysis, transient stability analysis, short circuit analysis, and to determine demand load, voltage drop, arcflash hazard analysis and protective device coordination. Make sure the software is compatible with your computer and operating system. Cable ampacity tables for direct current traction power. Delta td is called the dielectric loss temperature rise and is insignificant for voltages below. There are also computer programs that base their assumptions on different methods but those are separately explained.
Despite these differences, all allowable ampacity values found in the code are determined using ieee method 835, which in turn is based on the nehermcgrath method see insert. Any ideas on a company or a person who may be interested in doing this calculation for me. The method is used whether the installations are in ambient air tables 1, 2, 3 and 4, or underground appendix d. Find out how to determine the optimal cable sizes, physical attributes, and maximum derated ampacity using neher mcgrath method and iec 287 standard. If you can design the ductbank system so that you have three sets of 6 conduits, with each set of 6 conduits in its own concrete, and the three concrete banks separated from each other by, let us say, 5 feet edgetoedge the 5 feet is a guess, not a code requirement, then you can use the tables that apply to the voltage. Iec 60287 for cable thermal analysis gives analytical expressions for the computation of the geometric factor of threecore cable insulation, whereas the neher mcgrath approach makes a.
If you can design the ductbank system so that you have three sets of 6 conduits, with each set of 6 conduits in its own concrete, and the three concrete banks separated from each other by, let us say, 5 feet edgetoedge the 5 feet is a guess, not a code requirement, then you can use the tables that. We have provided professional engineering services for general contractors, developers, designbuild electrical contractors, electrical consultants, mechanical consultants, mechanical contractors, architects, owners and governmentcity agencies. Using the nehermcgrath formula in selection of conductor size at the terminations although conductor ampacities calculated using the nehermcgrath formula may exceed those found in a table of allowable ampacities, such as table 310. To avoid the complex calculations associated with these methods, engineers often refer to published tables to obtain cable ampacities. Nehermcgrath institute professional engineers certify.
In the neher mcgrath nm equation, delta td, is a term added to the ambient temperature, ta, to compensate for heat generated in the jacket and insulation for higher voltages. Use of computer programs for calculation of underground cable ampacity software programs usually use neher mcgrath method for the calculation of the cable ampacity. This new thermal analysis software features a guidance function to simplify various types of measurements. Although these programs may not provide identical results, the. 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. Practical power cable ampacity analysis ced engineering. Since then, considerable research efforts have been expended in modifying the nehermcgrath method and enhancing its modelling capabilities under both steadystate and variable loading conditions 29. Pdf refinements to the nehermcgrath model for calculating. The thermal analysis developed by netzsch uses a software that has a series of integrated programs. Fyi effective 5918 the state of alaska has officially adopted the 2017 nec and the 2017 nesc as of 5918. The emphasis will be on important but infrequently used commands. This method employs a lot of simplifications and has its limitations. Learn how to save design time using the raceway rulebook to autolayout cables within duct banks.
Mcgrath,the calculation of the temperature rise and load capability of cable systems, aiee transactions, part iii, volume 76, pp 752772, october, 1957. Considering the number of calculations needed to determine ampacity using the nehermcgrath method, it is obvious why engineers would. Dec 06, 20 the program uses the neher mcgrath calculation procedure to determine underground cable temperatures or cable ampacity ratings for virtually any duct bank or direct burial cable configuration. In electrical engineering, nehermcgrath is a method of estimating the steady state. Alternative approach to the one presented in the nec is the use of equations for determining cable current carrying rating. Lca performed a neher mcgrath heating calculation analysis for a large data center.
Duct bank ampacity calculation lets talk about the 18 duct system. Therefore, for each case considered, the neher mcgrath model provides a conservative value f o r the cable ampacity and the new method for calculating the ampacity suggests that the current in all of the cables cari be increased beyond the neher mcgrath value without thermally overloading the cables. Sep 22, 2011 using electrical system software for engineering projects much has changed since the days of slide rules and bookcases full of engineering references. Because of the lack of need for staff to enter the data center, it can be operated without lighting. It is cost effective, accessible anywhere, easily customisable, has improved interoperability, offers easier installation and. There are instances where the application of the ampacity tables including the. Any conceivable underground duct bank configuration can be input into the software. Any electrical continuing education classes taken on or after may 9, 2018 must be based on the 2017 nec or the 2017 nesc. Software programs usually use nehermcgrath method for calculation of the cable ampacity. Powertools for windows ptw is created and sold by skm systems analysis, inc. The iec international electrotechnical commission and nehermcgrath cable ampacity program is undergoing continuous development to make it as comprehensive and as easy to use as possible. The neher mcgrath equation was discovered by two cable engineers in 1957. There are various computer programs available for calculating cable ampacities. Alan zhang senior electric power system specialist.
Nehermcgrath, ambient temperature and environmental condition ampacity derating. Conductor ampacity calculation part eight electrical knowhow. Practical power cable ampacity analysis pdh online. The program is standalone, independent from paladin designbase environment. Uses the nehermcgrath approach where iec 60287does not apply considers nonunity load factor. Developed power cable ampacity calculation engine software based on neher mcgrath and iec60287, automated protective device coordination and evaluation algorithm, automated power system design. If you are using windows 7 64 bits you can use windows virtual machine. The neher mcgrath approach for cable thermal calculation approach uses a userdefined load factor, whereas the iec 60287 approach assumes a unity load factor. Acceptable cable rating programs are epri ace, epri utw, cyme cymcap and usamp. The nehermcgrath equation was discovered by two cable engineers in 1957. It addresses steadystate and transient thermal cable rating as per the analytical techniques described by neher mcgrath and the international standards iec 287 and iec 853. Iterative techniques based on neher mcgrath and iec60287.
Additionally, various wire sizes can be used within the duct bank configurations. A data center american english, or data centre british english, is a building, dedicated space within a building, or a group of buildings used to house computer systems and associated components, such as telecommunications and storage systems since it operations are crucial for business continuity, it generally includes redundant or backup components and. The nehermcgrath calculations is a method for calculating underground cable. Cable ratings shall be determined using an industry accepted modeling program. But would like to be able to be more scientific about it. Cable thermal analysis software cable thermal capacity. Cable ampacity tables for direct current traction power systems. Additional analysis capabilities will be made available as they are developed. Please feel free to email us with your particular project requirements and we can help you find the software package that best suits your needs. Etap allows users to run the following calculations.
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