What does sagging telephone wires mean?
What does sagging telephone wires mean?
The lines are often heavily loaded because of increased power consumption, and the conductors, which are generally made of copper or aluminum, expand when heated. That expansion increases the slack between transmission line structures, causing them to sag.
Do telephone wires sag in summer?
The telephone wires will sag in summer due to expansions. While putting up the wires between the pole care is taken care in winter they are kept light so that they may not sag too much.
Why are the telephone wires hang loosely?
Telephone wires are kept slightly loose when they are laid because heat. Therefore, without a slack they could become too tight and break in winters or pull loose from their anchors in summers . This is the reason why wires are kept slightly loose when they are laid.
Why do telephone wires sag down during summer days?
Since metals expand with a rise in temperature, therefore telephone wires sag in summers. The wires are intentionally left a bit loose otherwise in winters they would contract and break. Thermal expansion is the tendency of materials to expand when exposed to heat.
How is sagging calculated?
w is the weight per unit length of the conductor. So, having calculated the value of x1 and x2, we can easily find out the value of sag S1 and sag S2. The above formula is used to calculate sag when the conductor is in still air and ambient temperature is normal. Hence the weight of the conductor is its own weight.
How much weight can telephone wires hold?
The legal weight limits will vary by jurisdiction but, for example, in the southern states of the USA, they range from 80,000 to 88,000 pounds (36,300 to 39,900 kg) — about 40 short tons (35.7 long tons; 36.3 t).
What is phone wire?
Most telephone wire are one or more twisted pairs of copper wire. The most common type is the 4-strand (2 twisted pair). This consists of red and green wires, which makes a pair, and yellow and black wires, which makes the other pair. The RJ-14 uses four wires and it’s used to handle two lines, or 2-line phones.
Why are the telephone cables taut in winter and slacken in summer?
Thermal Properties of Matter. Why do the telephone wires get slackened in summer and get tightened in winter? In summers due to excessive heat, the temperature of the wire increases and wires expand. In winter, the temperature of wires decrease and wires contract.
Why do electrical overhead wires hang loosely instead of being stretched tightly?
Why Power Transmission Cables & Lines are Loose on Electric Poles & Transmission Towers? During transmission of electricity, heat is being dissipated. So, the cables are loose so that even if contraction should occur, there won’t be much tension which would lead to the damage of the cables.
Why are transmission lines not straight?
Why aren’t power lines straight? Wires strung between two transmission towers seem to sag towards the ground. If they were straight, the towers would probably collapse! The lines curve downward so that less force is needed to hold them in place.
What is SAG derive the formula for SAG?
Why do telephone wires have a SAG shape?
This gives the sag shape that is seen with many Telephone wires. The sag is also needed to help with expansion and contraction that happens during the Summer and Winter seasons. Without the sag the Telephone wire can snap during the Winter.
Why do telephone lines sag in the summer?
If you string them tightly in warm weather, when it turns cooler they will contract, increasing the tension in the wire to possibly ‘uncomfortable’ levels, or increasing strain on other parts of the infrastructure. Originally Answered: Why is it advisable to allow telephone lines to sag when stringing them between poles in summer?
What to use for straight wire with no sag?
If you want a straight wire with no sag as on an electrical railroad, you can use a catenary system. This uses a “messenger wire” to support the weight of the contact wire. It has a significant amount of sag to avoid excessive tension.
Is there a way to reduce the SAG in a power line?
Yes, you can reduce the sag by increasing the tension, but you’ll never get the cable horizontal. You can mathematically derive the sag in a cable, an exercise that gets you the famous catenary cable shape. You often find this in advanced mechanics courses.
This gives the sag shape that is seen with many Telephone wires. The sag is also needed to help with expansion and contraction that happens during the Summer and Winter seasons. Without the sag the Telephone wire can snap during the Winter.
If you string them tightly in warm weather, when it turns cooler they will contract, increasing the tension in the wire to possibly ‘uncomfortable’ levels, or increasing strain on other parts of the infrastructure. Originally Answered: Why is it advisable to allow telephone lines to sag when stringing them between poles in summer?
If you want a straight wire with no sag as on an electrical railroad, you can use a catenary system. This uses a “messenger wire” to support the weight of the contact wire. It has a significant amount of sag to avoid excessive tension.
Yes, you can reduce the sag by increasing the tension, but you’ll never get the cable horizontal. You can mathematically derive the sag in a cable, an exercise that gets you the famous catenary cable shape. You often find this in advanced mechanics courses.