Protection of Electrical Instruments
 Minimum Protection for EHV Lines  :     Overcurrent & Earth Fault Relay.  Distance Protection Relay.       Minimum Protection for Transformer :     Overcurrent & Earth Fault Relay at Primary  & Secondary Side.  Restricted Earth fault .  Differential protection.  Gas pressure Relay, WT, OT Relay.  Over Voltage protection .       Minimum Protection for HV Feeders :      Overcurrent & Earth Fault Relay.  Translay relay.        Minimum Safety Working Clearance of 2.6 mts  to be     maintained in between bare conductors & live parts in 11kV lines .       Different Transmission line Voltages & there Distances.       Transmission line voltages   Transmission line Distances    11 KV (10- 30 km )  33 KV ( 30 - 50 Km)  66 KV ( 50 - 100 Km)  132 KV ( 100 - 200 Km)  220KV ( 200 - 300 Km)  400 KV ( 200 - 300 Km)