Transmission line hookup

CNET editor Dong Ngo explains home power line networking and answers frequently asked questions about the technology. This post is part of an ongoing series. For the other parts, check out the related stories section below. Power line networking basically turns a building's existing electrical wiring -- the wires that carry electricity to different outlets in the house -- into network cables, meaning they also carry data signals for a computer network.

And this means virtually all households, in the U. S at least, are "wired for" power line networking. It doesn't replace a regular network, so you'll still need a router, but it's a good way to extend your existing network into new places. Home power line networking is far less popular than Wi-Fi, or even running network cables, however, mostly because consumers are not aware of its existence and benefits.

I'm going to change that.

Power line networking is used in many ways, including in large projects such as smart grids and power line broadband service, which uses power line connectivity to provide an Internet signal, just like a DSL service that uses an existing telephone line for the same purpose. However, in this post I'll only talk about home power line networking, where the technology is used to connect either Ethernet-ready wired devices, or Wi-Fi wireless devices.

This is the most popular use of power line networking and generally is based on power line adapters. Each of these adapters has at least one network port. You need two adapters to create the first power line connection -- this is why most adapters are available in a kit of two. The first adapter is connected to a router or a switch of an existing wired LAN local-area network , via its network port. The second adapter is connected to an Ethernet-ready device such as a computer or a printer. Now just plug both adapters into their wall sockets and you will add the Ethernet-ready device to the network.

There's nothing else connecting the two adapters other than the electrical wiring in between the two wall sockets being used. After the first connection is created, you need another adapter for each additional network device usually. Some power line adapters have more than one network port so they can support multiple Ethernet-ready devices at the far end of a power line connection. This is similar to connecting wired devices, but in this case the second adapter has a built-in access point to create a Wi-Fi network of its own.

The LAN is extended from the first adapter to the second one, which then broadcasts a Wi-Fi signal so that wireless devices, such as laptops, tablets, and smartphones, can be part of the network. Some networking devices, such as routers or switches, also have power line connectivity built in. This type of combo device makes sense because they need to be plugged into the wall to operate anyway.

Power line networking is being developed by the HomePlug Powerline Alliance and there are two main standards that you should know: It's now becoming obsolete. HomePlug AV , introduced in , has an initial cap speed of Mbps, which is fast enough to carry multimedia content, hence the AV designation for Audio and Video.

Single-wire transmission line

This standard also supports bit AES encryption for security. In testing, the actual sustained speed of these adapters is somewhere from 20Mbps to 60Mbps. Whereas previously Powerline was an independent standard, this brought it under the same umbrella as the other networking standards and protocols. This specification guarantees interoperability between adapters from different vendors, and on top of that the cap speed is now increased to Mbps.

In real-world testing, Powerline AV indeed offers significantly higher sustained speed than Powerline AV, giving speeds ranging from 90Mbps to Mbps. There's also a new standard called HomePlug AV 2 that promises real Gigabit Ethernet network speed via a power line connection.

Power line standards

The biggest advantage of power line networking is convenience, especially when compared with a regular wired network. Instead of having to run network cables, you just plug the adapters into the wall sockets. You can build a home power line network off your original network in a matter of minutes. When compared with a Wi-Fi signal, the second advantage of a power line connection is you can extend a network to the far end of a house or a basement easily, which a Wi-Fi signal might have a hard time reaching, especially in homes with thick walls.

On top of that, a power line connection is very similar to a regular wired connection in terms of latency, meaning you can access the Internet with almost no lag at all. Thirdly, compared with Wi-Fi extenders, a power line connection is so much better since you can easily add another Wi-Fi network in the far end of a house independently from the existing Wi-Fi network. The worker might work alongside the lines, from a platform that is suspended from them, or may sit or stand directly on the line itself. It is imperative that the worker maintain appropriate and adequate limits of approach to any part at a different potential.

The first procedures for barehand working were developed in by Harold L. Rorden, a high-voltage engineer for American Electric Power. As the lineman approaches the wire, an arc will form between them as the worker is charged. This arc can be debilitating, and the worker must immediately bond himself electrically to the line to prevent further arcing.

transmission line supports

Once on the line, the worker is safe from shock as both the lineman and the wire are at the same electric potential , and no current passes through his body. This is the same principle that allows birds to safely alight on power lines. When the work is completed, the process is reversed to remove the worker safely from the wire. Barehand working provides the lineman with greater dexterity than the hot stick method, and may be the preferred option if conditions permit it.

This is a set of overalls made from or woven throughout with conducting fibers. The suit is in effect a wearable Faraday cage , which equalizes the potential over the body, and ensures there is no through-tissue current.

Single-wire transmission line - Wikipedia

A lineman wearing a Faraday suit can work on live, high-power lines by being transported to the lines in a helicopter. The worker can perform maintenance sitting on an outrigger platform attached to the helicopter while the aircraft hovers next to the line. When approaching the line a long wand is touched to the line to equalize the potential of the aircraft to that of the line, then a breakaway bonding wire connected to the helicopter's frame is attached to the line during work.

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Alternatively the worker can transfer to the wires from the helicopter and crawl down the wires, then be picked up by the helicopter after the work is completed. Calculation of minimum approach distances take account of switching surges and other transients. Transmission systems are often fitted with coordinated protection devices called autoreclosers , which are circuit breakers that automatically attempt to remake a circuit after a fault. In the event that a fault did occur it would be most undesirable for the autorecloser to re-energise the circuit because the limits of approach would be greatly reduced and the workers' position could be compromised.

Hence, auto-reclosing equipment is rendered inoperative while live working takes place. Additional protection against unplanned overvoltage events such as switching surges can be provided by means of a surge diverter known as portable protective air gap. An electric arc is extremely bright, including in the ultraviolet , and can cause arc eye , a painful and potentially blinding condition. Workers may be provided with appropriately tinted goggles that protect their vision in the event of a flash, and provide defence against debris ejected by an arc.

Government regulations may regulate conditions for live working conditions. From Wikipedia, the free encyclopedia. Safety and Health for Engineers. Regulations Standards - 29 CFR. Occupational Safety and Health Administration. Retrieved 3 December Retrieved 8 December Proceedings of the 8th International Conference on Live Maintenance. Performance of Protective Clothing. Archived from the original on 19 April Retrieved 11 April Retrieved from " https: Electric power Electrical safety.

Common applications

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