N2 Electrical Trade Theory|The Easy Way! 29 2.4.2 Waterproof insulating materials


Water and moisture are two of the biggest enemies of electricity. Some insulators such as PVC, rubber and glass are naturally waterproof but many good insulators are porous and have to be sealed.


Ceramic insulators are glazed to make them waterproof and to make it more difficult for dirt and water to settle on. When the insulators are exposed to rain, the glazing makes it easy for the rain to clean them.


Varnishes and resins are oſten used to waterproof porous insulating materials such as cotton, paper and asbestos.


Exercise 2.3 1. What is the main function of an insulating material?


2. What does silicone based insulation look like and what are its major functional characteristics?


3. Mention three heat resistant insulating materials with which you are familiar and give an example of where each one can be used.


4. Give two functions of the glazing on a porcelain insulator. 5. What is the function of a drip skirt on a glazed porcelain insulator?


6. What is the main difference in appearance between a low voltage and a high voltage glazed porcelain insulator?


2.5 Reticulation network


Power stations are oſten situated at considerable distances from the consumers. In order to transmit electrical energy economically over long distances, it is necessary to do so at high voltages and by means of overhead conductors.


2.5.1 High voltage transmission


An increase in voltage permits a reduction of current and the less the current, the smaller the cross-sectional area of the conductor required.


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