What is Electric Pole?
Electric poles are a general term referring to a variety of poles and towers that are used as the supporting structures for overhead power line conductors. Generally, the electric poles have the following characteristics:
- A high level of mechanical strength, which allows it to bear the weight of conductors as well as other stresses like as wind.
- Lightweight without impacting the material’s ability to withstand mechanical stress.
- In terms of both initial and subsequent costs, the price is quite reasonable.
- Longer life.
- The conductors were designed to be easily accessible for maintenance purposes.
Wooden poles, concrete poles, steel poles, and rail poles are the many types of poles that are used for transporting overhead lines.
Which poles are to be used is determined by the significance of the load, the location and the place, the cost impact of such building, which includes the cost of maintenance, and the consideration of the profit element of the effort. In low voltage lines, usually employ a single pole line for all of the phases, including earth and natural. The electrical system makes use of several types of different poles for its various components.
Types of Electric Pole
Different types of electric pole are
1). Wooden Electric Pole
2). Concrete Electric Pole
3). Steel Tubular Electric Pole
4). Rail Electric Pole
Wooden Electric Pole
A considerable amount of low-tension line (400 volts and 230 volts) and high-tension line (11 kilovolts) was supported by wooden poles. When necessary for the 33 KV line, used wooden poles at certain points. A wooden pole’s cost-effectiveness is substantially lower in comparison to that of any other electric pole, and the expenditure that has been made for its foundation is likewise relatively extremely low in comparison to other foundation costs. The wooden pole will remain in good condition for an extended length of time provided that it is properly maintained and treated.
The ability of the wooden poles to support the weight of the electric cables is used to categorise them into one of three distinct classes.
- The breakdown force required to break is more than 850 kg/cm2.
- The force required to cause a breakdown ranges from 630 to 850 Kg/cm2.
- The force required to cause the material to fail ranges from 450 to 630 kg/cm2.
The component of wood that will be utilised for the electric pole has to be perfect. For this particular use, straight wood is strongly recommended. In the rare circumstance it is necessary, two poles of shorter length may be joined together and used.
Wooden Pole Treatment
The curing of the wood comes first. That is, the wood must be well dried. The mushroom may cause harm to the wood, and termites may cause the most damage to the wood. The wood is harmed as a result of heat and dampness. These sorts of damage are more common in the section of the pole below (or) near the ground level. The wood is chemically treated to prevent it from dampness and termites. Tar combined with Creojet Oil (or) Copper Crom Arsenic is recommended for optimal maintenance. The following therapy is known as the Askew treatment. The poles are maintained within a cylindrical air-sealed tank throughout this operation. Poles are submerged in Copper Crom Arsenic chemical in the tank. For at least one hour, 100 kilogram per square metre pressure is produced within the tank. Because of the high pressure, the chemical enters the pores of the wood. As a result, moisture and termites cannot damage the wood for an extended period of time.
If the wood is not adequately treated for any reason, two coats of Creojet oil should be sprayed to the whole surface of the pole before constructing it. Bituminous Creojet Oil should be applied to the soil as well as up to 50 cm (20 inches) above the soil. If this is not feasible, tar must be placed to the pole’s surface. If none of the treatments are practicable, should at least burn the bottom-outer surface of the pole up to two meters to protect it against termites and dampness.
The top of the pole should be chopped into a pointed cone shape so that water does not accumulate on top. Then, in the top section of the pole, cut the necessary slots to fit the cross arms snugly. The drilled hole diameter ranges from 17 mm to 20 mm. D-shaped iron clamp grooves are not needed for installation; a bored hole at the requisite distance is sufficient. The distance between the top hole with the pole’s top tip should be at least 200 mm (8 inches). Before the treatment, all such holes (or) grooves should be made. Once the pole has been treated, such holes & grooves should be avoided. If produce holes (or) grooves after the treatment, must fill them with creosote oil or bitumen.
Concrete Electric Pole
Types of Concrete Electric Pole
Concrete poles are classified into two types:
1). P.C.C. Poles
2). R.C.C. Poles
1). P.C.C. Poles
Plain Cement Concrete poles (P.C.C. poles) are now employed on a significant scale in 11 KV & 400/230 volt systems; in addition, use PCC poles in the 33KV H.T. Line. This kind of pole is more expensive than the wooden pole but less expensive than a steel pole. This kind of pole has a longer lifespan and requires less maintenance. The strength of the PCC Pole is far superior than that of a wood pole but significantly less than that of a steel pole. The main drawbacks of this pole are heavy and easily broken.
The cement concrete electric pole is constructed of cement concrete. It strengthens the concrete with iron bars (or) rods to boost its strength. During concreting, add a copper strip 25mm 3mm within the pole for earthing purposes, or maintain a hollow channel in pole for inserting the earthing wire. During concreting, retain 20 mm diameter holes on the pole to install various fittings as needed.
The pole’s cross-section is always larger at the bottom than at the top. The PCC pole’s cross section is rectangular rather than square.
Concrete poles are classified into 11 classes based on their lateral load capability and height.
| Pole classification | Height (Mtr) | Footing Deftness Excavation (Mtr) | Maximum Lateral Load (Kg2) |
| 1 | 16.5 m to 17 m | 2.40 | 3000 Kg2 |
| 2 | 16.5 m to 17 m | 2.40 | 2300 Kg2 |
| 3 | 16.5 m to 17 m | 2.40 | 1800 Kg2 |
| 4 | 16.5 m to 17 m | 2.40 | 1400 Kg2 |
| 5 | 14.5 m to 16 m | 2.30 | 1100 Kg2 |
| 6 | 11.5 m to 12 m | 2.00 | 1000 Kg2 |
| 7 | 11.5 m to 12 m | 2.00 | 800 Kg2 |
| 8 | 11.5 m to 12 m | 2.00 | 700 Kg2 |
| 9 | 9.5 m to 11 m | 1.80 | 450 Kg2 |
| 10 | 8 m to 9 m | 1.50 | 300 Kg2 |
| 11 | 6 m to 7.5 m | 1.20 | 200 Kg2 |
The excavation of footings depends on the condition of the soil and varies by location.
2). R.C.C. Poles
In recent times, the reinforced concrete poles (R.C.C. Poles) have become an extremely popular choice for use as line supports. When compared to steel poles, they offer a stronger mechanical strength, a longer life, and the ability to support larger spans. In addition to this, they provide a pleasant view, are low maintenance, and effectively insulate the space they surround.
The perforations in the poles make it easier to climb the poles, & at the same time, they cut down on the load that the line supports have to carry. The high expense of transporting these kinds of electric poles is the primary challenge associated with their use because of the heavyweight of the poles themselves. Therefore, in order to save the high expense of shipping, such poles are often constructed at the location where they will be used.
Steel Tubular Electric Pole
Steel tubular poles have a substantially higher load bearing capability than wooden poles and concrete poles. These poles will last longer if adequate maintenance is performed. However, because to the high cost, the usage of this pole is steadily reducing. These poles are utilised in low & medium current 400/230 volt systems. These poles are also used in 11 KV H.T. lines. In certain circumstances, like as a 33 KV system, employ these poles.
Types of Steel Tubular Electric Pole
Tubular poles are classified into two types:
1). Swaged Pole
2). Stepped Pole
1). Swaged Pole
Swaged Tubular Poles are made using high-grade raw materials such as MS steel and sheets throughout the manufacturing process. The reason that this pole is swaged as opposed to simply linked gives it an advantage in terms of its strength and stability. Because of the adaptability of steel, these poles may be used for a broad variety of applications in the commercial, residential, and municipal sectors. Architects, engineers, and design experts can employ them.
Installation times may be kept to a minimum because to the product’s durability and strength, in addition to its lightweight and maintenance-free structure, which helps keep expenses for shipping down.
Swaged poles are constructed using tubes of exceptional quality that are either welded or seamless and are cut to appropriate lengths before being swaged and linked together. The term “swaged poles” refers to a variety of lighting fixtures, such as single- and double-hanging light poles, as well as traffic light poles and street light poles.
The ERW welded tubes are cut to the appropriate lengths and then swaged and connected together to create swaged poles.
2). Stepped Pole
The production of Stepped Poles makes use of an unique hot-swaged joint technique. The application of heat to pipes of greater diameter in order to fuse them together with pipes of smaller diameter results in very strong pipe junctions.Â
The joints are completely impermeable, and the whole pole is able to keep its strength over its full length. Because there is no requirement for welding, the joints will not become less secure over the course of their lifetime.
Rail Electric Pole
As rail poles have the highest possible strength, they also have the highest possible cost. The weight is likewise greater, and as a result of this weight component, the cost of transportation, loading, and unloading is also more.
This pole is not used for the line that operates at 400/230 volts. Rail poles are used for both the 11 KV & 33 KV systems. The rail poles that are used in overhead lines typically come in four different sizes.
- 30 kg/m
- 37 kg/m
- 45kg/m
- 52 kg/m
11 KV systems typically use rail poles that weigh 45kg/m, and in 33 KV systems, use rail poles that weigh either 45kg/m or 52 kg/m. The length of the various sizes of rail poles ranges from 9 m to 13 m in length.
At least one coat of red oxide is applied to each rail pole before it is used for rail transportation.
The longevity of the pole may be improved by applying a tar layer to the lower portion from the ground up to a certain height above it.
The rail pole’s ability to support loads in a vertical direction is greater than its capacity to support loads in a horizontal direction.
