How to Choose Overhead Insulated Cable?

Four principles for choosing overhead cables

In the selection of overhead cable, overhead cable, in general, should pay attention to the models, and specifications (conductor cross-section) of choice.

View Details

Overhead cable type selection

Selection of overhead cable, consider the use, laying conditions, and safety, for example,

Depending on the application, the choice of power cables, overhead insulated cables, control cables;

Depending on the laying conditions, the choice of general plastic insulated cables, steel armored cable, steel wire armored cable, cable, and other anti-corrosion;

According to security requirements, you can choose retardant cables, fire-retardant cables, flame retardant cables, and fire-resistant cables.

Overhead cable size selection

Determine the use of overhead cable specifications (conductor cross-section), the general should consider heat, voltage loss, economic current density, mechanical strength, etc. selection criteria. According to experience, in low-voltage power lines because the load current is large, it is generally to press the heating conditions are selected cross-section, and then check the voltage loss and mechanical strength; low voltage lighting lines because of their high-level requirements, press the allowable voltage loss condition Select profile, then checking fever conditions and mechanical strength; high-voltage lines, then press the economic current density select section, and then checking their condition and allow the voltage loss fever; and high voltage overhead lines, but also checking its mechanical strength. If the user does not have experience, you should consult the relevant specialized units or persons.

Explanation:

1. The same specification aluminum wire carrying capacity of approximately 0.7 times the copper core, the choice of aluminum wire large a size comparable copper wire, XLPE insulation can choose a file size small, the fire-resistant overhead cable should choose the larger size.

2. this table is calculated based on a three-phase capacity 380V, Cosφ = 0.85 as the base, if the single-phase 220V, Cosφ = 0.85, capacity should × 1/3.

3. When the ambient temperature is high or the methods used for surface, with its safe current carrying capacity will drop, and you should choose a larger size; when the starter motor is used frequently, should be used 2 ~ 3 specifications.

4. This form of PVC insulated wire laid by a single overhead calculated, if it is wearing a tube or a plurality of laying, should be used 2 ~ 3 specifications.

5 The above data is for reference only, the final design and determine the cable type and size should refer to the relevant professional information or electrician manual.

Overhead cable transport and storage

1. Prohibited transportation of dropped cable or equipped with cable reels from a height, especially at lower temperatures (typically about 5 ℃ and below), throw, throw cable will likely result in insulation, and sheath cracking.

2. Possible, avoid storing in an open way to the exposed cables, the cable tray does not allow flat.

3. Lifting packages, the prohibited several dishes at the same time lifting. In vehicles, ships, and other means of transport, the cable tray uses appropriate methods to be fixed, to prevent collision or falls, and to prevent mechanical damage to cables to each other.

4. Cable is strictly prohibited from contact with acids, bases, and mineral oils, to be stored with corrosive substances isolated. There shall be no storage warehouse destroyed cable insulation and corrosion of metals harmful gases.

5. Cable during custody should be periodically rolling (summer 3 months, other seasons can be extended as appropriate). When you scroll, the store-down rim rolls upward, to avoid the bottom surface of damp rot. When storing should always pay attention to the cable head intact.

You will get efficient and thoughtful service from Qinfong.

6. Cable shelf-life period is limited to the factory, usually not more than a year and a half, no longer than two years.

Installation and construction of the overhead cable

Design and construction of wire and cable laying installation shall be the relevant provisions of GB -94 "Electrical Engineering cable design specifications", etc., and to adopt the necessary cable accessories (terminals and joints). Power Supply System in the quality, safety, and reliability is not only the quality of the wire cable itself but also with the construction quality cable accessories and related lines.

Through statistical analysis of line fault, due to construction, installation and connection and other factors caused the failure is often much greater than the probability of failure caused by faulty wire cable body. Therefore, to correctly use overhead cable and related accessories, in addition to specifications for design and construction, we must also pay attention to the following aspects of the problem:

1. Cable laying installation by a qualified professional unit or professionals does not comply with the relevant norms of construction and installation requirements, it may cause the cable system can not to function properly.

2. Manpower when laying cable, unified command, and control rhythm, every 1.5 to 3 meters cable with one shoulder, side discharge side pull, slowly cast.

3. Mechanical cast cable, generally use a dedicated cable laying machine tools equipped with the necessary traction, traction size appropriate to control uniform, in order to avoid damaging the cable.

4. Cast cable before, to check whether the cable appearance and head are intact, note the direction of rotation of the cable reel when cast, do not crush or scratch the cable sheath, not to low temperature in winter when the best way to school straight cable, in order to avoid insulation, sheath cracking.

5. When laying the cable's bend radius is greater than a predetermined value. Before cable laying installation, the insulation resistance between the rear with V megger cable conductors are normal, and according to the cable model specifications, different length and ambient temperature on the measurement results be properly corrected, the small size (less real 10m㎡ core conductor) cable should measure whether the conductor of.

6. Such as burying cables, paying attention to soil conditions, laying cables under the general building not less than 0.3 meters deep, soft, or the surrounding environment has become more complex, such as arable land, construction sites or roads, there should be some buried depth (0.7 to 1 meter) to prevent accidental damage to buried cables, if necessary erect signs.

There are many kinds of wires and cables, each of which has different models, specifications and structures. Aerial insulated cable is barely used in households, but is widely used outdoors. Aerial insulated cable is extremely important, which is related to the electricity consumption of every household. Aerial cable is needed when electricity is delivered from power stations to families. So what is exactly the aerial insulated cable? What are the properties of the aerial insulated cable as well?

Knowing about the aerial insulated cable

Aerial cable is a kind of special cable manufactured by the production techniques similar to that of cross-linked cable. It is a new electricity transmission mode between aerial conductors and underground cables. Aerial cables are widely used in outdoor electricity transmission. Aerial insulated cables are generally high-voltage lines. Thus for the conditions that they are underground or close to buildings in distance, aerial insulated cables must be selected.

The aerial insulated cable series of products are composed of the tightly pressed copper and the aluminum (aluminum alloy) conductor, the inner shielding layer, the weather-resistant insulating materials and outer shielding layer. They not only have the power cable's power transmission characteristics, but also have strong mechanical properties of the aerial insulated cable. Compared with one electric wire, the aerial insulated cable has the advantages of small laying distance, high safety and reliability, and excellent weathering resistance.

Main technical characteristics of the aerial insulated cable

Weather resistance. The high-voltage aerial insulated cable, besides meeting high electrical performance requirements, also requires good weather resistance to work safely under long-term sunlight irradiation and it is beneficial to typhoon prevention. After the adoption of aerial insulated cable conductors, the short circuit will not be caused when the conductors collide instantly, which reduces the malfunctions and greatly improves the typhoon resistance of the lines.

About the Insulation level. The aerial insulated cable is obviously superior to general cross-linked cables when used. The aerial cable is shared by the main insulation and air medium. Therefore, comprehensively, the insulation performance of aerial cable is high comparably.

Terrific insulation performance. Because of the extra layer of insulation, the insulation performance is superior to that of bare conductors. The aerial insulated cable can also have the reduction on the distance between lines, on the insulation requirements for the supportive parts of lines, and increase the number of circuits on the same pole.

Excellent corrosion resistance. Because there is an insulating layer on the outer layer, the degree of oxidation corrosion is less than that of bare conductor, and the corrosion resistance is stronger, which can prolong the service life of the lines.

Prevention against external damages. The aerial insulated cable is less affected by external factors such as trees and dust, and short circuit and grounding accidents are reduced as well.

Easy erection and maintenance. It can be erected on any kind of pole and tower, or along the wall. Under special circumstances, it can also walk through trees and be directly fixed on the trunk with metal fittings. It can be erected in a single circuit, or multiple circuits can be erected on the same pole.