Can you imagine an electrical system or better to say an electrical power supply system or an electrical machine that is not insulated from outer environment and is open to you ?
The answer is off course No.
The basic reason behind this insulation is safety of the operator or a common man. The insulation protect the direct contact between the current carrying conductor called live conductor or live wire and you.
If you touch the live wire, no matter by knowingly or unknowingly, you will definitely go through a shock proportional to the voltage in the wire. Machines are to reduce human work load not human life, so in any electrical system safely is first and insulation do this job efficiently. There are thousand of insulating material available but a good insulating material should have following properties :
- High Resistance : A good insulation material must have high resistance so that leakage current through the material should be minimum. This reduces the chances of electrical shock.
- High Break over/Breakdown VOLTAGE : A good insulating material should have high breakdown voltage so that it may not get broken or destroyed during high voltage pulse across it.
- Proper Heat Dissipation : The insulation of an insulator decreases with the increase in temperature so if the temperature of an insulator increases due to excessive heat produced, its resistance will be decreased and it will not serve its purpose.
- Small effect of Environment: A good insulator must have as minimum effect of external environment factors as possible. It should not loose its resistance due to water drops or other environmental factors.
Some of good insulating materials used in Electrical Industry are :
- Perma Wood
- Fiber Glass
- Insulating Oil or Transformer Oil
- Gases like SF6