Original title: a quick method to calculate the sag of conductor! (Conscience Edition) Part1 Apprentice On a certain day in a certain month in a certain year, Anyway, when I was an apprentice, Go to the construction site with the old comrades of the unit. The owner asked us to estimate the conductor sag of a certain gear. The old Comrade took out his calculator. After pressing a few times, He said the answer confidently. I was shocked at that time! In my perception, Isn't calculating the sag of a conductor supposed to be like this? Expand the full text Such a complicated formula, Shouldn't we use software to calculate? How can you figure it out with a calculator? After the meeting, I consulted the old comrades. The old Comrade just said to me lightly: "Multiply the span squared by 7" Me: That's it? Old Comrade: This is it! I know that asking too many questions will expose my ignorance. So I didn't ask. In the dead of night, I opened the book secretly. I hope I can find the answer from the book. Part2 Sag Curve Template Finally, On page 216 of Overhead Transmission Line Design, I seem to have found the answer! Draw the key points! In the past, when there were no computers and no Dao Heng, The sagging curve of the plane section is drawn by hand. For ease of drawing, The designer defines the K value of the sag template, Use this value to make a sag template! Universal sag template And the value of K is: Combined with the maximum sag calculation formula: At the same time, the height difference of the hanging point is ignored (cosβ = 1). In other words: The calculation of the original sag is really: The square of the span multiplied by a value! Getting closer to the truth! Part3 Plan section Why is K equal to 7? Why not equal to 3,
Titanium 6Al4V wire , equal to 10, equal to 20? This is a problem! Wait! This K seems to have been seen somewhere. Right! Plane section!!! Bottom line: Original The K value can be output in the plane section diagram output by Dao Heng, However, his K value is slightly different from that in the textbook. But (in fact, Dao Heng has an option to choose): Namely: Next, let's test whether our reasoning is correct: As shown in the figure above, the span is 336m and K = 7.8891 Thus: f (sag) = 336 × 336 × 7.8891 × 10-5 =8.9 ！！！ The result is consistent with that of the plane section drawing! In short, let's divide the sag calculation formula into two parts, one is the K value of the sag template, and the other is the square of the span. Sag is calculated by multiplying the value of K by the square of the span. The K value can be queried in the plane section view. Part4 Regularity If the K value is often inquired through the plane section, First, it is possible that the project has not yet produced a plane section in the early stage. Second, it is inconvenient to carry inquiries with you. In fact, the value of K has a general range and law. If it is only a rough estimate, It's perfectly adequate. According to the query summary of the editor, The following rules are obtained: 1) The K value is independent of the power level. 2) The value of K has little to do with the type of conductor. 3) The icing affects the K value, and the larger the icing is, the larger the K value is. 4) The safety factor affects the K value, and the greater the safety factor, the greater the K value. In particular,
nickel titanium wire, the K value of the steel pipe pole line is very large. Sum up 1) General line K = 7 ~ 9 General line refers to: Conventional conductor, no icing, normal setting out (safety factor 2.5 ~ 3.0) 2) Iced line K ≈ 12 3) Steel pipe pole line K ≈ about 20 Source: Power Transmission Interesting Forum Return to Sohu to see more Responsible Editor:.
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