Introduction to power cables and cable accessories

Power generation, power network transmission of electric energy needs through overhead lines or cable lines to achieve. A cable that transmits and distributes electrical energy, called a power cable. There are many kinds of power cables, which are divided into:

1. Oil paper insulation: integrated package type, shielding type of viscous impregnated paper insulation and non-drip impregnated paper insulation, freestyle oil-filled cable, steel tube pneumatic cable, etc.;

2. Plastic cable: PVC insulated cable, polyethylene insulated cable, cross-linked polyethylene insulated cable;

3. Rubber insulation: natural rubber insulated cable, ethylene propylene rubber insulated cable, etc.

The characteristics of oiled paper insulated cable and crosslinked polyethylene insulated cable

Oiled paper insulated cable: 

1. Adhesive impregnated paper insulated power cable: This product was developed earlier, with stable manufacturing quality, long manufacturing and operation experience, and long working life; The disadvantage is that the oil is easy to drip, should not be used for high drop laying, allow the work field strength is low, should not be used for high voltage;

2. Non-drip impregnated paper insulated power cable: the cable impregnated agent does not drip at the working temperature, suitable for high drop laying, longer working life than the adhesive impregnated cable, has higher insulation stability, but the cost is higher than the adhesive impregnated paper insulated cable; At present, the production and laying of oiled paper insulated cables are very few, generally only in the repair and maintenance of old lines.

Cross-linked polyethylene cable:

Have excellent electrical properties, high dielectric strength, insulation intensity big, small dielectric constant and dielectric loss tangent, has high heat resistance and aging resistance, allowed working temperature is high, large carrying capacity, suitable for high and vertical installation, is a kind of current popular cable, at present most of the route laying using this type of cable, applied voltage grade is higher and higher.

Cable accessories refers to all kinds of cable lines and intermediate connections and terminal connections, it and the cable together constitute the transmission network; Cable accessories are mainly based on the characteristics of cable structure, not only to meet and restore the performance of the cable, but also to ensure the extension of cable length and terminal connection.

According to its use is generally divided into terminal connection and middle connection, terminal connection is divided into indoor terminal and outdoor terminal, in general, outdoor terminal refers to the outdoor cable joint, indoor terminal refers to the connection of cables and electrical appliances; Intermediate connections are divided into two types: straight type and transition type. Two cables with the same type of insulation structure connected to each other are called straight type, and two cables with different types of insulation structure connected to each other are called transition type. There are many kinds of cable accessories, which are generally common as follows. Each type has its own characteristics and limitations, and any technology can not replace each other.

1. Wrapping type: cable accessories made of rubber strip (self-adhesive) wrapped on site are called wrapping type cable accessories, which are easy to loosen, have poor weather resistance and short life;

2. Watering type: with thermosetting resin as the main material field watering, the selected materials are epoxy resin, polyurethane, acrylic resin, the fatal defect of the accessory is easy to produce bubbles during curing;

3. Molded type: it is mainly used for the production of the middle cable connection, which is moulded and warmed on site and integrated with the cable. The production process of this accessory is complex and takes a long time, and it is not suitable for the terminal connector.

4. Cold type: with silicone rubber, epdm, chlorohydrin rubber elastomer in the factory processing pre expansion and add plastic support bar and forming, when installation, drew support to rebound, the tube body with rubber inherent shrinkage "elastic effect" on the cable and cable accessories, known as the "cold", the most suitable for the attachment can't use fire situation of construction, such as mining, etc.;

5. Heat shrinkable: different components with "memory effect" are made of rubber and plastic alloy, and the accessories are made of heating and shrinking on the cable. The accessories have the characteristics of light weight, simple and convenient construction, reliable operation, etc.

6. Prefabricated type: different components are molded by silicone rubber injection vulcanization at one time, and only the accessories made by inserting cables into the interface contact are retained in the field construction, so as to reduce the unmeasured factors such as the construction process environment to the lowest strength. The disadvantage is that each product is only applicable to one specification, and the installation is difficult; Prefabricated accessories The installation material below the cable trident and shield port is still heat shrinkable or cold shrinkable, which is a combination of prefabricated and heat shrinkable/cold shrinkable.