Explain the surge protection of electric locomotive from i) Direct lightening stroke ii) Switching surges

Explain the surge protection of electric locomotive from i) Direct lightening stroke ii) Switching surges
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1 Answer

Answer :

i)Protection of Electric Locomotive From Direct Lightening Stroke: 

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1. The direct lightning strokes may strike on the overhead conductor on the roof of the locomotive. 2. To protect the locomotive from lightning strokes lightning arrester 1 (LA1) is provided it is generally a Rod gap type having the gap length of 210mm. 3. The lightning arrester provides a low resistance path for high voltages and high resistance path for normal power frequency working voltages. The lightning stroke is thus diverted towards earth via lightning arrester. 4. The transformer is critical and costly equipment hence lightning arrester 2 (LA2) is provided along with LA1.The gap of LA2 is 70mm so that its operation time is less.


ii)Protection of Electric Locomotive From Switching Surges:  

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1. The strategy adopted for protection against switching surges is to connect the R-C networks as shown in the above figure. 2. Sometimes the surges of transmission system could find their way to the traction and auxiliary circuits through capacitive coupling at the bushings. 3. These surges get absorbs by the R-C networks which reduce the steepness of the wave front and also help to absorb the energy in the resistance.

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