Ice

[ptonsparky]

I wondered I much weight was on the local power lines due to icing in Jan. Published in a recent POCO magazine they calculated, using one 15" piece of ice 4" in diameter that fell from a power line in this area, that each 300 foot span was loaded with an extra 1480 pounds of ice. The lines are engineered for 1/2" of ice at 185 lbs.

 

[ramdiesel3500]

Lets see, 4" diameter ice 300' long. Well 2*2*3.14/144*300= 26 cubic feet of ice at about 56 lbs per cubic foot weighs about 1465 lbs. Thats vertical weight. How about tension on the wire. When you figure the vector angles, those wires had several tons of tension force on them. Probably snapped most of them in two or broke down the poles. So how long was the power outage??

 

[aja21]

Lets see, 4" diameter ice 300' long. Well 2*2*3.14/144*300= 26 cubic feet of ice at about 56 lbs per cubic foot weighs about 1465 lbs. Thats vertical weight. How about tension on the wire. When you figure the vector angles, those wires had several tons of tension force on them. Probably snapped most of them in two or broke down the poles. So how long was the power outage??

I'm in the same area as ptonsparky and the outages varied, some were nearly a month in the romote areas. I work for one of the POCO's and one of the other POCO's lost 90 miles (thats not a typo i said 90) it the 115kv two pole structures, still down, setting new ones with helicopters now. They also lost at least 40 miles of 345kv big steel structures, also still down. Theyr'e talkin at least June before its back. We are generating our peakers on an increased schedule because these lines won't allow them to get full generation out of thier biggest coal plant.

 

[Mike03a3]

Lets see, 4" diameter ice 300' long. Well 2*2*3.14/144*300= 26 cubic feet of ice at about 56 lbs per cubic foot weighs about 1465 lbs. Thats vertical weight. How about tension on the wire. When you figure the vector angles, those wires had several tons of tension force on them. Probably snapped most of them in two or broke down the poles. So how long was the power outage??

If the wire is in the middle of that cylinder of ice, you need to subtract the volume of the wire to get the volume of ice.

How much does 300' of wire weigh?

 

[don_resqcapt19]

Why can't we load the trasmission lines enough so the I^2R heating keeps the ice from forming? I understand that under heavy loads the temperature of a trasmission line is above 50?C. I also have heard that there were some experments with controled short circuits to "snap" the wires to break the ice off. http://www.ewh.ieee.org/reg/7/canrev/canrev37/landry_eng.pdf

Don