One of the main tools in the electricity industry is the conduction of this energy by wires and cables. Do not system. In this article, we will deal with the cables used in the above distribution and transmission substations.
The cables used in high voltage substations are divided into three categories in terms of application and voltage level: medium voltage cables, low voltage cables and control cables of protection systems.
In choosing cables, it is important to know the characteristics such as insulation materials, material and number of conductors, cross section of conductors, sheath material and armor.
It is important to choose the right cable and install it. Selection without observing the principles and standards will cause excessive losses in the cable or loss of the cable itself. Therefore, by recognizing the principles and standards defined for cables, we try to maximize the efficiency of this system:
Low voltage cables:
Includes a variety of copper and aluminum cables insulated with various polymers that are in the voltage range of 600 to 1000 volts. These cables are used to transmit electricity in various applications from lighting to transmitting driving force to electric motors and..
There is a very wide range of low voltage cables designed specifically for the operating environments in which they are used. Product range includes cables fire proof (IEC 331: For use in sensitive environments where firefighting is very important),Flame resistant (IEC 332: For areas where there is a risk of fire and fire extinguishing is not required but the cable should not be ignited), lead sheath (providing a general protection against the intrusion of hydrocarbons, corrosive gases and water) and reinforced cables ( Provides mechanical protection), low smoke, halogen free, resistant to hydrocarbons and petroleum products.
Medium voltage cables:
Cables with XLPE insulation and copper or aluminum conductors that are in the voltage level of 1 to 36 kV and are widely used in urban and industrial areas. Our medium voltage cables according to IEC standard or alternative BS and VDE are produced.
High voltage wires and cables:
High voltage and high voltage cables are made with copper or aluminum conductor and XLPE insulation and voltage level above 36 kV.
Insulation XLPE is injected into the conductor using a computer-controlled CCV line. The injected XLPE insulation must have a perfectly uniform crystal structure and be free of any impurities or pores. Essential quality control is also applied to key points of the CCV line.
XLPE insulation is physically and chemically very prone to forming chains with water molecules. If water or water vapor is present in the insulation layer, it will cause these chains to form and the rate to drop Electrical insulation resistance be.
Construction wires and cables:
Construction wires and cables are responsible for distributing electricity in the building. These types of wires and cables have different structures. These structures include flexible cables whose conductors must be flexible. The insulation used in them is PVC 70 ºC or PVC 90 ºC or Rubber. This type of cable can be produced in the form of plain copper or tin-plated shield.
Heat Resistant cables are another category of this group that in addition to being flexible conductors, their insulation must be Silicon Rubber. This type of insulation will have a heat tolerance of 180 ° C and Glass Fiber Braid coating is used to further increase their thermal tolerance and also protect the insulation against mechanical damage.
Instrumentation cables in control systems for sending / receiving digital and analog signals to / from equipment and sensors (sensor These cables are basically in the voltage range of 24-110 volts and / or rated current of 4-20 mA. Instrument cables must be protected against electrical interference.
Fire-resistant cables must be able to withstand fire, fire with water and / or fire with mechanical shocks. Cables used in public places and emergency systems such as fire alarm circuits and emergency lighting systems. As a matter of urgency, they should not endanger human health and cabling with the release of acid gases. These cables should be fire suppressant and low in smoke. In other words, these cables should not continue to burn as the source of the fire disappears, or transfer the fire to other locations, or create smoke that prevents emergency lights or exits from being seen.
To protect the cables from environmental factors and mechanical shocks, they are covered with one or more layers (sheaths) of material (copper, lead, steel), plastic paper, especially PVC. Cables are divided into different types according to their outer layers.
Types of cable connections
* End connection
connection * Three-way
connection * Y
-connection * Four-way connection
Joint and its types
To connect the cables in long distances as well as in the branches and end of lines, other devices are used such as joints and overhead cables that are able to protect the connection point from moisture, mechanical pressures and electrical factors.
Joints and overhead cables are often made of cast iron, steel or insulating material (PVC), which are marked with a special mark.