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T/F: radial operation of distribution in Nepal

Short answer

TRUE. NEA operates both primary (33/11 kV) and secondary (400/230 V) distribution radially, even though some urban 11 kV feeders have open-loop ties that are normally open. This radial operation minimizes cost, simplifies protection, and supports rural electrification, though at the expense of reliability and tail-end voltage.

With reference to a distribution system design, state whether the following statement is True or False with justification: In Nepal, the primary and secondary distribution systems operate in radial.

TRUE.

In Nepal (NEA's distribution under the INPS), both levels are operated radially:

  • Primary distribution (33 kV and 11 kV): feeders leave the grid or distribution substation and branch out to the 11/0.4 kV transformers along one path. Some urban 11 kV feeders in Kathmandu Valley and other cities have tie switches or ring main units forming loops. These are kept normally open (open loop) and the feeders are still operated radially. The tie is closed only to transfer load during faults or maintenance.
  • Secondary distribution (400/230 V): each distribution transformer feeds its own LT lines radially to the consumers. There is no interconnection between transformers.

Reasons for radial operation:

  1. It has the lowest cost for Nepal's low and scattered load density and long hilly feeders.
  2. Protection is simple (drop-out fuses, OC/EF relays, reclosers) and operation is easy.
  3. It is easy to extend for rural electrification.

Its main drawbacks are lower reliability, poor tail-end voltage and higher losses. NEA reduces these through sectionalizing, open-loop ties in cities and more substations.

✓ Answer checked by Claude Opus 5.5 (high effort)

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