Electric power, while on one hand a blessing, can also prove to be very dangerous if not handled properly and with caution. Careful grounding and insulation of wires is hence very important while handling power cords.
If suitable insulation is not provided, the wires can become overheated, damaged and cause electric shocks to anyone handling them. If the insulation is of poor quality, it can easily be damaged by a power overload and cause danger. Insulation of wires and cables not only ensures safety but also has an impact on the electrical aspects of the wire. Insulation jackets prevent dielectric losses; provide resistance against moisture, temperature and harsh environmental conditions.
A wide variety of insulating materials are being used nowadays. The most common ones are PVC (Polyvinyl Chloride), PE (Polyethylene), XLPE, EPR and paper/oil based insulation.
· PVC Insulation:
Out of these, PVC is used the most as an insulating material for the production of power cords. It is a thermoplastic compound. Cost effectiveness, resilience and the ease of its availability are some of the important factors contributing to its popular use. It has excellent electric and insulation properties, covers a wide temperature range and has long durability. It is cheap and readily available in the market. It is a very good choice in preventing fire hazards. It is the most common insulating material of choice for domestic use. It is also widely used in telecommunication cables. It has low production cost and is easy to mold, manage and handle.
PVC also has some disadvantages. It is not health and environment friendly. It is unstable towards heat and high temperatures and has limited thermal capability. Upon combustion, due to its chlorine content, PVC produces HCL and thick, black, toxic smoke. Occurrence of dielectric losses is more prevalent while using PVC insulation.
· PE Insulation:
PE is a thermosetting plastic and belongs to a class of polymers called polyolefin’s. The occurrence of dielectric losses is very less when PE insulation is used. Hence, it has excellent electric properties. It has a low dielectric constant, low dielectric loss and high initial dielectric strength. It has the prominent advantage of low power loss.
However, the chemical structure of PE is such that it cannot withstand water treeing. Furthermore, it has limited thermal resistance. It disintegrates easily at higher temperatures. It is also not suitable for using under moist conditions as it is sensitive to moisture.
· XLPE(Cross linked Polyethylene):
The chemical structure and bonds of XLPE are such that various polyethylene chains are linked together. This cross linkage imparts important insulating and electric properties to XLPE. The cross links provide it with excellent insulating strength. It also has high thermal resistance. It can withstand high temperatures (105 degree Celsius and above).Therefore, it is recommended for use in high temperature applications. Its dielectric losses are low but not as efficient as PVC or PE. It shows a variable range of resistance towards water treeing. It has increased load carrying ability.
· Paper based insulation:
Paper based insulation cables are also in use. Paper based insulation wires are generally used for higher voltage applications. It has been in use for a long period of time and is durable. But it does not have efficient cost effectiveness and is difficult to handle, produce and manage.