IEC , Electric cables – Calculation of the current rating – Part 2: Thermal resistance – Section 1: Calculation of thermal resistance. IEC Electric cables – Calculation of the current rating – Part 1: Current rating equations (% load factor) and calculation of losses – Section 1: General . IEC Standard (). [4] Electric Cables – Calculation of the current rating – Part 2: Thermal resistance – Section 2A: A method for calculating.

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IEC calculations for three single-core cables in trefoil in 9 way 3 x 3 duct bank Hello again, is it possible to provide some links for examples that utilizes the approach we have here.

For details, please refer to the first note in this serieswhich lists the other related notes. The standard gives the following equations for the calculation of the cable current rating for all alternating current voltages and direct current up to 5 kV:. IEC calculations for three single-core cables in trefoil in 287–2-1 way 3 x 3 duct bank It is correct: Comments are closed for this post: Thank you for helping keep Eng-Tips Forums free from inappropriate posts. The varying electric field causes IEC calculations for three single-core cables in trefoil 287-21- 9 way 3 x 3 duct bank but we are considering in this case three single-core cables inside one duct, the other duct are not touching for sure.

By joining you are opting in to receive e-mail. IEC calculations for three single-core cables in trefoil in 9 way 3 x 3 duct bank The three single-core cables current is supposed to be the same in all three.

To let a positive comment, I find your website very helpful. Digital Transformation may be defined in a number of different ways by analysts or enterprise software vendors. Thermal resistance — Section 1: Sections on operating conditions — Section 1: Steven has over twenty five years experience working on some of the largest construction projects.

IECitself does have the correct equation. Some or all of this heat is dissipated through the cable insulation, bedding, serving and into the surrounding medium. Defense manufacturing is all about project manufacturing and project accounting. It looks logical, otherwise we would have been a squared resistance in the denominator. IEC calculations for three single-core cables in trefoil in 9 way 3 x 3 duct bank Very good calculation, Adam!

The standard aims to consolidate AC and traction voltages within the industry and defines the following bands: For cables which have varying or cyclic loads, the current rating could possibly be increased. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework. If you iev some expert knowledge or experience, why not consider sharing this with our community.

Change in temperature across a material is equal to the heat input multiplied by the thermal resistance of the material. Are you an Engineering professional? Before you continue reading this note, if you have not done so already we would suggest first reading our IEC introduction note:. Contribute to myElectrcial Have iev opinion or something to say, want to ask or answer questions, share your knowledge then use our site to do 2872–1.

IEC Publication Click here to view the notes indexed by tag. My view is that you should used the equations to select the cable based on your anticipated current rating. The more you exceed the greater the effect. Just another thing I’ve just noticed still easy to figure out because of unexpected results in the section “Buried cables where drying-out of the soil is to be avoided”, AC part, in the numerator, it should be a subtraction instead of an addition.

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It can probably be appreciated by now, that in typical real life situations, this can be quite a complicated calculation. It a good demonstration of innovative You then select an approppropriate protective device to isolated the cable should you exceed this value. The aim of this paper is to present a parametric study to determine the major factors that influence the calculations of current rating for both air and underground cables. I appreciate any advice! In the previous note we looked at the approach taken by the standard to the sizing of cables and illustrated this with an example.

When significant, it becomes a factor to be considered in the sizing of cables. The calculation of each element needs some explanation and these have been split across several notes with each note dealing with one topic. If you have a load current which is genuinely varying, you could use IEC “Calculation of the cyclic and emergency current rating of cables. I’ve modified the drying out equations slightly.

Close this window and log in. You may put in each duct 1, 2, 3 or 4 single core cables.

A method for calculating reduction factors for groups of cables in free air, protected from solar radiation. It’s easy to join and it’s free. Red Flag This Post Please let us know here why 287-21 post is inappropriate.

## IEC 60287 Current Capacity of Cables – Rated Current

The three single-core cables current is supposed to be the same in all three. However, i would like first to get your opinion that the standard is not very clear especially when it comes to single-core cables and thats why many interpertations could be possible. Feedback is one way I can improve the articles.

Have an opinion or something to say, want to ask or answer questions, share your knowledge then use our site to do it. While software is a great asset, many times This note looks at how to obtain the necessary loss factors for use within Hello, i agree with you that the cables inside the duct are in free air since IEC considers that when calculating T’4 by considering the temprature of the medium filling the duct.