Transmission and Distribution Line

If this is what you are referring, I believe all three wires are the same phase.

Rixter, did you take these photos recently? :)

I scarfed them off the internet recently.

These phase separators are what I used to see when I worked on designing the support towers (tubular ones, not lattice). They were used to separate the conductors of one phase. The other conductors of that circuit were a considerable distance apart, like 15 or 20 feet (high tension lines.) Remember that I designed the towers, not the electrical part. I think the separators were used for 2 purposes. One, to increase the area of the conductor without making it huge and hollow; I think this reduced line losses due to corona and whatever else happens. Two, to provide some vibration damping so line galloping does not happen. You have probably seen line galloping on small cables (telephone & power) close to the ground. There can be one or several nodes between poles. This happens due to something called "vortex shedding" at very low wind speeds which causes alternating small forces on the conductor. If this vortex shedding happens to match the natural frequency of the conductor, galloping can happen. Those things you see on the lines that look a bit like dumbbells are vibration dampers.

These are commonly used to physically separate and support multiple conductors (all of the same phase) from each other.

The reasons include preventing conductors of the same phase in close proximity from clashing with each other (for example due to wind) and reducing the line inductance (I believe).

I believe they may also be used for the same purposes on multi-phase circuits using insulated overhead conductors rather than bare conductors, the conductor insulation providing the protection against short circuits in wet weather.

Was this what you were after?

Actual question should have been this: "why do we use bundle conductors instead of using single conductor of larger size for high voltage transmission?"

Not really, because the OP is not speaking of transmission lines, bundled or not, but insulated *distribution* lines where each conductor is a separate phase. Note both the voltages mentioned initially - 33/11 kV - and, in a later post, the insulation colors. Transmission lines operate at hundreds of kV and are not insulated.

It is done to maintain clearance between phases also but at distribution voltage level only. Insulating separators which are not affected by rain are used. This is more relevant in old distribution lines (with increased sag due to ageing and repeated load cycling) I guess.

Spacer damper device provides the necessary spacing of subconductors from each other while allowing the subconductors to vibrate without causing damage to the subconductors. The spacer damper device includes a series of clamps spaced along a hoop formed of rigid material by a series of springs about the hoop which are between the clamps.

In preferred embodiments, a pair of aluminum clamps are used to fix the relationship between the subconductors along the rigid hoop, and to provide attachment to the subconductors while allowing articulation in the case of bending vibration. The most dangerous case of fatigue is the bending of the subconductor against the clamp. Other spacer-dampers do not allow freedom of bending. The present invention allows freedom of bending so that zero bending stress occurs during any subconductor vibration. The articulation in the present invention is resisted by a rubber washer which is positioned along the rigid hoop and sandwiched between the clamp and the flat steel washer. Each steel washer is adjacent to a spring. This causes the rubber washer to resist bending motion by shearing in the rubber. In the event that the rubber fails over a long time, the pressure provided by the springs will continue to push the steel washer against the clamp, thus resisting bending of the subconductor by dry friction (coulomb type damping).

The above described damping action will occur in any number of subconductors from two to four to six or more. The only difference between spacer-damper parameters is the number of subconductors and the diameter of the hoop.

Individual design of the product may be achieved by varying the diameter of the hoop, the diameter of the round rod that forms the hoop, the size of the clamps that attach to the subconductor, the number of clamps, the spacing of the clamps, the composition of the material (common grade steel etc. ), and the design of the clamp itself.

The OP stated the line voltage as being 33/11 kV - distribution rather than transmission voltages. Where you see these used with distribution lines, they are not vibration dampers but rigid, triangular, insulated spacers between insulated phases. Typically they are closely spaced with anywhere from several to a dozen between adjacent poles, depending on pole spacing. They are often ribbed in the manner of high-voltage insulators.

Yes You are right, it must be rigid, and that you see is result of bad installation

...amd they won't be wood. Wood absorbs moisture, which forms a conductive path, and an extraneous conductive path is exactly what is not needed in power distribution systems.

Let me be precise, I'm a Nigerian and i reside in Nigeria till now. In Nigeria almost all the distribution lines' phases ( Red, Yellow,Blue and Neutral) of 33/11kv Are spaced with wooden stick. So, How come these wires are not shot circuited (bridge together) when it is raining and there is supply of voltage on the line.

If they are insulated lines, then there is not much danger of shorting together due to rain.

May We see photos please? Let's see What kind of damper?

If the wires are actually colored, as you indicate, then they are self-insulated. I've never seen colored distribution wires, but I've never been to Nigeria...

Wood can be impregnated with wax, so it does not absorb water, and is then a pretty good insulator, even when wet.

Rain water is very close to being pure and therefore is pretty much non-conductive.

Only the contaminants present on the surfaces are conductive which usually are removed very quickly by the rain water.

Wood was the insulator of choice long before the electrical field started using other manmade materials and it is still being used sucessfully.

The "sticks" are actually for preventing "line slap" (conductor contact) during high wind conditions which if not prevented would/will cause significant conductor damage and/or line trip (de-energization).

Wood spacers are a problem still. Although rain tends to wash away surface contaminants, as soon the rain hits they mix with the rain forming a conductive film. Where the phase insulation is damaged or weak you can have flashover which carbonises the wood, making it conductive. The arc persists until either a breaker blows upstream or the spacer burns through. The arc can continue even after the spacer has burnt through, thank to metal ions in the arc channel from vaporised conductor material.

Wood spacers are a bad idea but better than nothing at all, except in coastal areas where constant exposure to salt spray can impregnate the wood making it permanently conductive.

I was looking to see if anyone would state this fact. Rain water although as you state is pretty much none conductive. In Fact PURE water is a di electric. None conductive. Also Wood wet or not is not a good conductor even if covered in salt water that does conduct. There can be some conduction due to contamination. This happens sometimes after a long dry spell then rain hits and you get some jump. But what ever is causing the semi short will be vaporized guite quickly and not a problem anymore. Hope that Helps. And glad you posted this. Most folks are not aware that pure water does not conduct. But be careful with this statement. Why. Some folks THINK that distilled water is pure. It can be but normally is not. Many compound or VOCs will distill right along with the water. I use Reverse samosas to get almost pure water and Carbon Blocks to get rid of Most VOCs. Jim Davison PS I with would get this list earlier. Buy the time I get it it already has a lot of answers. Jim

so what do you think about snow ?

The purpose of the "sticks" is NOT to insulate between phases, but to prevent slapping and vibration of the wires in the wind. I would be willing to bet that the length of the stick is too long to allow much, if any flash over, even in the rain. Not that I know for sure, but that is my best guess.

My logic for this is as follows. If there was, say a half meter of air, how could that insulate less than a stick of the same length. So therefore, the stick is not there to prevent arcing or to provide insulation. It must be there for some other reason. Maintain separation, or prevent vibration, or to prevent slapping in heavy winds.