How to Find Out the Current Taken By Long Tranmission Over Head Lines

Helo everyone,

I am working for the Indian Railway and is presently looking after the 25 kV over head electrification of tracks. I am currently handling the electrification of a new track for a length of about 150 kms. as per the existing practice the verticvcal supportis i.e. traction masts are erected and the cantilever pipes for hodling the catenary wire and contact wire are also fixed. The copper caternary consisting of 107 Sq.mm cadmium copper is first strung and then the 65 Sq.mm copper contact wire is also strung. The stringing is usually done in day time and is generally done for say 2 to 3 kms per day. In order to avoid theft of copper caternary and contact wires during night time, the strung copper catenary wires and contact wires are usually energised with 2200 volts supply. The 2200 volts supply is derived from a 5 kvA 230 volts / 2200 volts single phase step up transformer. The name plate of the transformer reads the primary no load current of about 20 Amps. While the LV side of the trafnsformer is protected with a 6 amps single pole MCB backed by a 63 Amps rewireable fuse unit the HV side is protected by a HT drop out fuse rated 1.0 amps. The idea is that any effort to steal the copper wires are likely to reult an earth fault and therby the 6 Amps MCB should trip. Upon tripping of this 6 Amps MCB a circuit will sense the absence of supply on the load side of this 6 amps MCB and will initiate a hooter. At one of the station it is observed that the raw supply to the 6 amsp MCB is taken from a distribution board which is having a 16 amps MCB as feeder control. While testing the working of the system by intentionally connecting the charged wire to earth it is observed that both the 6 amps and 16 amsp MCB are tripping. Thus the hooter supply also fails and the purpose gets defeated. Can any one guide me how do I calculate the value of charging current for every kilometer of wires run or so and also how to calculate the fault current based on the length of the wire and thridly what should I do to avoid tripping of 16 A MCB and ensure that only the 6 amps MCB trips. Can any one also plz tell me whether i can include / attach drawings / photos to make my questions more clear in this forum and if so how do i do it.