PDA

View Full Version : Calculation of conductor strength



230kv
10-23-2006, 02:01 PM
If some body help me to know Calculation of conductor strength, for example:-
If we need replace deadened insulators for 230kv and the conductor is drake 795mcm,the span almost 300m,what is the breaking load for chain hoist & other tools like slings.. we should use?? :confused:
Did there is any calculation formula for that? please help…
Thanks for every body.

mscheuerer
10-23-2006, 07:21 PM
If some body help me to know Calculation of conductor strength, for example:-
If we need replace deadened insulators for 230kv and the conductor is drake 795mcm,the span almost 300m,what is the breaking load for chain hoist & other tools like slings.. we should use?? :confused:
Did there is any calculation formula for that? please help…
Thanks for every body.

230kv, it starts with the conductor;

Since you didn't say whether or not your stranding was steel or alum cable (ACSR?) the specs pretty much dictate the following;

DRAKE 795 MCM
Section: (in2)
AL = 0.625
Total = 0.725

Stranding Design:
AL = 26
Steel = 7

Stranding: (in.)
AL = 0.175
Steel = 0.136

Diameter (in.)
Cable = 1.108
Steel = 0.408

Total Weight (lb/1000ft)
1,094.1

Rated Strength (breaking lbs)
31,656

Max Resistance @ 20 Deg. C (Ohms @ 1000ft)
0.0215

Convert your 300m run from your total weight@lbs divided by your breaking load. Be sure your insulators are capable of supporting as well; unless you plan on using another anchoring device (strongly recommended) when pulling accross your span. Your hoists/slings/hoists etc... should be rated based on those figures. Always go higher.

LINETRASH
10-23-2006, 09:09 PM
Mscheuerer,

You made my head itch with all them fancy numbers..

Guess I'm used to florida (at least in distribution)..jack it till 'ya cant get anymore, and get two for loss.

All kidding aside, I admire a real guru of the game, hip to conductor strength.

Ride on brother!

mscheuerer
10-23-2006, 09:32 PM
Mscheuerer,

You made my head itch with all them fancy numbers..

Guess I'm used to florida (at least in distribution)..jack it till 'ya cant get anymore, and get two for loss.

All kidding aside, I admire a real guru of the game, hip to conductor strength.

Ride on brother!


Thanks LT!, we could have easily said to just hook up your trusty come'a'long strap; cinch it up real tight and pull until you can't pull no more.... but he wanted a calculation...

Be Safe!

loodvig
10-24-2006, 02:14 PM
Oh man, I remember those days. Ya jack it up untill you can't get anymore and the foreman tells ya 'take two more cliks for what ya gonna loose'.

eskimo
11-19-2006, 10:21 AM
If some body help me to know Calculation of conductor strength, for example:-
If we need replace deadened insulators for 230kv and the conductor is drake 795mcm,the span almost 300m,what is the breaking load for chain hoist & other tools like slings.. we should use?? :confused:
Did there is any calculation formula for that? please help…
Thanks for every body.

Your question was for what your riggin' should be for the tension your dealing with. When in doubt rig BIG. Drake is always strung tight, T.I.T. Tight.
You'll need your sag to find the tension. mscheuerer gave you the wire weight. Okay I am limited by this forum to write the formula that you need so here it is in long hand.
Span squared mulitplied by the weight per foot of the conductor this will be divided by 8 mulitplied by the feet in sag.
You said almost 300m, so we'll call it 300 yards which is almost 300m and we'll use 15 feet for your sag just for an example.
We'll have to keep it american here with feet and inches.
So you'll have 900 feet squared times 1.094 ,which is 900X900X1.094 divided by 8X15, so you end up with 886,140 divided by 120 which in turn gives you 7384.5 lbs of tension. More then your 3 ton hoist will want so break out the 6 ton and a chicago that will fit 1.108 and a sling and shackle that will handle the weight. The weight of the wire per foot was given earlier as per thousand, 1094lbs per thousand to convert you carry your decimal three places to the left to get per foot, which is 1.094
Always write out your formula on paper so you can check your work. You might fat finger the buttons on your calculator, this way you can check your values

(span x span)x weight per foot/8 x sag in feet. the 8 will never change and the span to work in the formula will always be in feet.

Get a range finder and a calulator and rig big.
We're working with bluebird and a 9 ton hoist replacing midspans.
Be safe

Eskimo