LT-less distribution

Rural networks inherited by NPCL and subsequently expanded to widen the scope of supply was in line with European practices characterized by long low tension (LT) network fed from an 11/0.4 kV transformer. Even for supplying to widely dispersed load blocks of agricultural pumps, similar LT network arrangement was adopted resulting in an unsatisfactory situation stemming from factors like:

  • Rampant pilferage from accessible low voltage lines causing revenue losses.
    Field survey suggested that on an average, there existed 2 cases of unauthorized abstraction of energy for every 3 authorized agricultural connections.
  • High technical losses attributable to high LT current on the network.
  • Calculations based on field data indicated that for a group of load consisting of 3 authorized and 2 unauthorized pump connections, the technical loss accounted for 8.17% of the total energy intake for 3 authorized connections.
  • High peak power loss of network due to unauthorized load
    For a given situation of 3 authorized and 2 unauthorized pumps, the peak power loss was found 40 % of the total authorized power requirement.
  • Unsatisfactory voltage profile at consumer installations.
    The minimum voltage at the customer premises was recorded as 370 volts against the rated voltage of 430 Volts
  • Unreliable supply consequent upon overloading of LT lines
    LT faults per annum per 100-circuit km of lines supplying agricultural pumps were as high as 1500.

Against this backdrop, high voltage distribution system (HVDS) was conceived in NPCL as a means to curb the menace of pilferage of energy, reduce peak power loss, improve voltage profile and enhance reliability of supply arrangement.