Protection System in Case of Conductor Failure

"both end sources"??? What does that mean?

So tell me, who's life is more important, the person under the transmission line that should not have been there but was probably trying to steal copper wire or dismantle the tower braces for the steel scrap, or the thousands of people hooked up to medical equipment that will die if the power to an entire city is cut off to save him, or the fires that will rage because the pumps are shut down, or the accidents that will happen when all the traffic lights go out?

But to answer your question, systems already exist that can do that, however everything we do has consequences... HV transmission protection is complex because it is often a "greatest good" scenario.

The weight and inertia of the falling conductor can readily kill some one that is why at construction sites it is mandatory to wear a safety Helmet - Do you have a hard hat on your head?

At the engineering platform methods sech as conductor re-inforcement, Sag and Tension calculations are done to ensure that the conductor does not break even under heavy storms and ice loading conditions.

Intertripping of CB's are regularly applied using microwave, pilot wires, PLCC, fiber optic etc. but the limitation is that the sensing and protection devices have inherent requirement of operation time so as to fulfil a command therefore practically the operation cannot be instantaneous, further system reliability is a prime consideration.

GA from me, mountk2.

It should be noted that the protection systems used for transmission lines usually trip them within 0.5 second or less, and often in just a few cycles after detecting that a fault has occurred on the line.

Sensitive ground fault protection is fairly common to disconnect a distribution power line that has fallen down due to a tree fall, car-VS-pole accident, intentional damage, etc.

Also look up "ground fault neutraliser" (less common, but still quite effective apparently)