Practical power cable ampacity analysis ced engineering. This example illustrates that most electrical duct bank installations will typically not require any derating based on the heating calculations. Hello all, i will be using software etap for underground duct ampacity calculations. Ampacity and other design considerations for medium.
The accuracy of the software provides increased confidence when upgrading power cable installations and designing new ones. The above figures can be divided to groups as follows. Nehermcgrath calculations are important, especially if the design sizing will ever be fully loaded. Although local authorities may require these calculations. Learn how to save design time using the raceway rulebook to autolayout cables within duct banks. I will be requesting information for cables from the cable manufacture, want to. Conduit duct bank calculations construction monkey. Creating underground duct banks and inair installations. In article conductor ampacity calculation part eight, i listed the rules, tables and figures that construct the second method for conductors ampacity calculations by using nehermcgrath formula under engineering supervision, as provided in 310.
Calculates the duct bank size based on the quantity of conduits, the size and type of conduit. The multiple duct banks and backfills addon module mdb is designed to determine the steadystate ampacity of cables installed in several neighboring duct. In this example, i use a 4,000amp duct bank with a design load of 3,000 amps and increase the load factor to approximately 85%. Cable sizing and its effect on thermal and ampacity values. The calculator lets you know the amount of dirt to remove, the amount of dirt to return, the amount of concrete for a duct bank, and the amount of left over dirt. Mar 01, 2008 this example illustrates that most electrical duct bank installations will typically not require any derating based on the heating calculations. Engineering data for copper and aluminum conductor electrical. Home download center electrical software underground cable ampacity calculator you may find the allowable ampacity for underground cable configurations by taking the time to look up the tables and diagrams of the canadian electrical code. A underground duct bank cable ampacity and thermal calculation study will. In a duct bank, data and electrical cables are laid out within pvc conduits that are bundled together. A manufacturer list on their website that 750kcmil, 1c, rhw2, is rated in a duct for 535a based on 1 ckt. Cable ampacity software cable sizing software cable.
Cable thermal analysis software cable thermal capacity. Underground duct bank ampacity calculation electric power. Cable sizing, duct bank, ampacity, underground power distribution. The duct bank optimizer addon module allows the user to determine the optimal placement of several circuits within a duct bank. Performing electrical cable heating calculations can be a cumbersome task, but theyre essential to accurately determining the allowable ampacity of an underground electrical duct bank installation. The results, based on a single ampacity calculation, are shown below. They consider only temperaturelimited, currentcarrying capacity of cables.
I can find references in the 2002 nec for cables rated 2,000 volts and up fig. Duct bank heating calculations are essential for critical environments data centers electrical heating calculations may need to be performed when large amounts electrical duct banks with significant amounts of conduits and conductors are routed below grade in the earth. Duct bank optimizer module the duct bank optimizer addon module allows the user to determine the optimal placement of several circuits within a duct bank. This paper presents an efficient algorithm to find optimal underground cable configuration with maximum ampacity in a concrete duct bank. Power cable ampacity software eatons mission is to improve the quality of life and the environment through the use of power management technologies and services. For duct banks, specify the number of rows, columns, ambient temperature, and soil thermals resistivity, etap as a cable ampacity calculation software, computes the derated ampacity based on the hottest location not exceeding the maximum operating temperature. Cable ampacity power system software and arc flash hazard. The challenges posed by the complexity of estimating and of estimating the local increase in ambient temperature obtained by colocating many cables in a duct bank create a market niche in the electric power industry for software dedicated to ampacity estimation. The very first step that needs to be taken when designing an underground cable system is to define which circuits needs to be routed through the duct bank. Newton originally written in 1996 revised february 16, 20. Appendix b in the nec assumes the same wire size in each conduit and each wire has the same amp loading.
The synergi electric module cable ampacity lets you determine how soil condition and duct bank configuration affect cable ampacity. The four sides of all duct banks have 3 inches of concrete cover over the outside ducts, and 2 inches of concrete between ducts. Cable ampacity tables for direct current traction power systems. More specifically, the module can recommend various circuit configurations within a duct bank so that. We provide sustainable solutions that help our customers effectively manage electrical, hydraulic and mechanical power more safely, more efficiently and more reliably. This program is especially beneficial for our clients who are designing duct banks that deviate from the nec duct bank tables.
Duct bank dimensions the tops of all duct banks are 30 inches below grade. Cable ampacity tables for direct current traction power. So if the choice is to utilize the values in tables table 310. A underground duct bank cable ampacity and thermal calculation study will determine if your duct bank design will support the loads and not cause conductor over heating. As with voltage drop, underground duct bank calculations are not a code requirement. Note the derate of the conductor current carrying capability from 272 to 196 amps. The cymcap software is dedicated to performing ampacity and temperature rise calculations. Underground cable ampacity electrical engineering portal.
Top of duct bank top of conduit bottom of duct bank bottom of conduit. With those modules, the user can evaluate the magnetic flux density at any point on or above the ground of an underground cable installation, determine the positive and zero sequence impedances and admittances for all the cables present in an. A 6way duct bank with 2 rows and 3 colum ns of ducts is listed as a 2 x 3 duct bank. Ampcalc for windows is a computer program from calcware which calculates power cable ampacity ratings andor cable operating temperatures for user defined cable installations. As of the 2011 version, the national electrical code nec publishes ampacity tables in article 310. For a better background read the article where did table 310. Engineering data for copper and aluminum conductor. Calculation of the cable ampacity considers only power cables since control cables transmit very little current that has negligible effect to the overall temperature rise. The earth and dirt rho are again set at the standard 90.
Pdf configuration optimization of cables in ductbank. Engineers are often called upon to calculate ampacity and temperature rise of. Models duct banks, pipe cables, extruded cables, directly buried cables, casings, or mixtures thereof. Basic steps that cable ampacity software tools use are discussed below.
Ampacities are calculated for single or multiple underground systems including. A prime example would be a data center application. Comparison of finite element analysis to iec60287 for. Cable ampacity software cable sizing software cable derating.
Find out how to determine the optimal cable sizes, physical attributes, and maximum derated ampacity using nehermcgrath method and iec 287 standard. Resources used include detailed cable parameters, maps paper and digital, asbuilt drawings, operations and maintenance records. Conductor ampacity calculation part ten electrical knowhow. Cymcap cable ampacity software power cable ampacity rating simgrid markets cymcap software and provides technical support as well as trainings. U, v, and y constants for pvc conduits in cable ampacity. For an existing system, the cable thermal analysis software examines cable. The ieee 399 standard applies to underground cables. Etaps cable ampacity software is used for calculating cable ampacity based on nec, ieee, icea, iec, and bs standards for underground duct banks, cable trays cable ampacity software cable ampacity analysis cable ampacity software ieee standard. Overview of rules implemented in powertools, including nec and recommended industry standard practices.
Cable ampacity power system software and arc flash. Usamp prime software models all types of underground power cables pipetype, extruded, and solid paper. Underground duct bank ampacity calculation budhiman electrical op 18 jul 18 19. The cymcap software is dedicated to the calculation of ampacity and temperature. For the same service and feeder duct bank sections modeled for cable pulling at project x, the burial depths of these conductors are continually adjusted due to structural and other utility coordination. Understanding the nehermcgrath calculation and the. I was wondering what all information for cable is required to use nehermcgrath equation. Computes steadystate and transient ampacities and temperatures for multiple cables with equal or unequal loading. To verify this hypothesis we performed a series of ampacity calculations with two methods. Improper heating calculations can lead to an undersized duct bank, which can be a costly mistake to fix if its even possible. Cable ampacity software additional modules allows performing several analyses of interest for cables installations other than thermal analysis. Cyme power engineering software and solutions power.
Ampacity and other design considerations for medium voltage cables used in renewable energy applications earle c. Underground duct bank ampacity calculation blackjackjacques marineocean 18 jul 18 19. U, v, and y constants for pvc conduits in cable ampacity question. For the constants u,v and y, pvc conduit in concrete is not an option.
Cable sizing and its effect on thermal and ampacity values in. Described methodological procedure needs to be followed in order to obtain good and accurate results. Understanding the nehermcgrath calculation and the ampacity of conductors by gerald c. Maximum depth to the top of electrical duct banks shall be 750 mm 30 in. Use of and creating library models for physical cables and ducts. Underground duct bank ampacity calculation electric. Etap cable ampacity calculation software cable ampacity. The accuracy of the software provides increased confidence when upgrading power cable installations and designing new. With those modules, the user can evaluate the magnetic flux density at any point on or above the ground of an underground cable installation, determine the positive and zero sequence impedances and admittances for all the cables. The accuracy of the calculation provides increased confidence in the design, upgrading, and analysis projects.
Ampacity and other design considerations for medium voltage. Understanding the nehermcgrath calculation and the ampacity. The cymcap software is dedicated to the calculation of ampacity and temperature rise calculations for power cable installations. Duct banks are groups of conduits designed to protect and consolidate cabling to and from buildings. Cable sizing and its effect on thermal and ampacity values in underground power distribution over the past decade, underground power distribution has become increasingly popular due to its reliability, safety, aesthetic characteristics, as well as the ever increasing focus on the environmental impacts of the various stages of. In portion of duct near heat source temperature deration must be applied, but it may be applied to 90. Do i need to derate the conductor ampacities because theyre buried together in a ductbank. Practical power cable ampacity analysis velimir lackovic, mscee, p. Cyme power engineering software and solutions power cable. Aug 11, 2010 learn about cable ampacity features in etap 7. We use etaps stateoftheart cable thermal software module and accurately determine the ampacity and thermal limitations of different underground raceways and duct banks. The software examines cable temperature and ampacity in performing analysis of existing systems.
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