What could possibly prevent the mishap that would happen if the live overhead catenary - contact system comes in contact system comes into contact with earth or train roof ?? This was asked by a fellow passenger of mine whilst my recent train journey. The simplest, yet convoluted answer is "Protective Relaying". 

A relay is the most important component in any protection system. During a fault or any abnormal conditions, one or more of the electrical quantities such as current, voltage, phase a...
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