Wednesday, January 6, 2016

Advantages of Maintenance Free Chemical Earthing System over Conventional Earthing System

Conventional Earthing: The conventional copper pit type earthing has a very erratic behavior and the ohmic values of earth resistance vary drastically on the following seasonal factor:
1. The humidity factors in all the seasons vary because ambient temperature of ground varies. The thumb rule for calculating humidity at a 20°c ambient temperature and 1° variation in either side (+/-) will vary the humidity level in the ground by 16%. You can now understand why the ohmic values remain erratic during the life of the system.
2. There is a general accepted fact and practice that pit type earthing is watered through an additional pipe running through the depth of pit in summer season obviously because of dry climate and low humidity.
3. Contrary to the belief that winter is a wet climate and has a higher humidity level it is a myth and humidity is very low in winter because the ambient temperature is in the vicinity of 4 to 6°c and as per the formula given in the paragraph one the humidity is reduce by 16% of every degree of temperature. The humidity is reduced by 16x (20-6) =224%. This is an open secret and it can be verified in the newspaper report under the heading “Today’s Weather”.
4. The coal used in the earthing pit burns and turns into ash under high level of fault currents and on the top of it the quality of coke is used is very poor(Generally in Powder form).
5. The salt used becomes water itself and looses its hygroscopic properties. Conclusion: The life of pit type of earthing is not more than 3 years irrespective of maintenance.

Chemical Pipe earthing: In the above type of earthing the following important factors are taking into the consideration:
1. The hollow pipe used in the chemical pipe earthing is fitted with a G.I. strip of “appropriate size” and CCM (Crystalline conducive mixture) is compressed into the pipe and pipe is sealed at both the end.
2. CCM is a semi metal and the hollow pipe filled with CCM behave like a solid pipe and therefore the current carrying capacity increases substantially.
3. The CCM has a high melting temperature of 2500°c and unlike coal it will not burn into ashes under high temperatures of 1500°c under high fault currents occurring due to phase to phase or phase to earth fault.
4. The humidity factor (The moisture level) is maintained by Aluminium Silicate surrounding the electrode in a slurry form. The Aluminium Silicate has a property of absorbing water 13 times its weight and doesn’t dissolve in the water. It remains moist and soft throughout the life. A minimum rain fall of 2.5 cm in a year makes the Aluminium Silicate moist and humid for next one year and therefore the cycle keeps on repeating year of year. Therefore, because of quality of Aluminium Silicate no additional watering is done whether in summer, winter or rainy season i.e. under any climatic condition.

Conclusion:- The life of chemical earthing as per the reports from USA and other countries is more than 15 years with no failure records. e) In India the technology is only few years old and the failure record is almost negligible. The earthing system properly installed under the guidance of manufacturers can safely assure years and years of working life. It does not NEED any maintenance unlike Conventional plate earthing.