Answers
Answers
Let's assume that we have 4/0 ACSR, the spans are 200 ft, and the conductor as shown is 2ft above the position it should be, and that both conductors were sagged the same, and the cross-arms are relatively level and poles are relatively straight, and there is no ice.
1) At what temperature will the conductor return to a normal position?
2) What is the existing tension at 120?F?
3) What would the tension have to be at 120?F to avoid uplift down to zero degrees and what would the tension be at zero degrees?
For extra credit:
Approximately how many pounds of pull is being exerted on the unbroken insulator at 35?F?
I'll post the answers later if no one wants to venture a guess (unless I forget).
Seeing no takers, here is what I came up with:
First, it was tough to find 2ft of uplift with a reasonable span length and temperature ranges so I looked at the picture closer. It looks closer to 1.5 ft and the wire looks closer to 1/0 ACSR. I based this on the width and height of the exposed pin as compared to the wire. The pin is probably about 5/8" wide and about 6" tall (above the cross-arm).
Also, with an ambient of 35?F, the current in the wire could add another 15 degrees or so, depending on the loading, sun, wind, etc., but for simplicity sake, I'm picking a conductor temp of 35?F in the picture.
With that, we have the following for the conductor final state:
1) At what temperature will the conductor return to a normal position: With 2.94 ft of sag at 35? and tension of 988 lb, we have 4.43 ft of sag at 81?F and a tension of 656 lb at the "normal" position
2) What is the existing tension at 120?F: 576 lb with a sag of 5.05 ft.
3) What would the tension have to be at 120?F to avoid uplift down to zero degrees and what would the tension be at zero degrees: 375 lb and 7.76 ft of sag at 120?. 656 lb and 4.43 ft of sag at 0?.
Extra credit: 14.7 lb
