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T/F: urban design, transformer location first

Short answer

False. In urban areas with uniform load density, the LT conductor is selected first; the maximum feeder length set by voltage drop determines the service area. Transformer size and location then follow, placed at load centres.

State and justify whether the following statement is true or false: For design of urban distribution line first select the transformer location and then size of the conductor.

FALSE.

Justification

In urban areas the load density is high and the load is spread almost uniformly along streets. The design does not start from a fixed transformer location; it starts from the LT conductor and transformer rating, and the transformer locations follow from them.

Usual urban design steps:

  1. Estimate the load density (kW/km or kVA/km²) of the area from consumer surveys and load forecast.
  2. Select a standard LT conductor size (for example ACSR Rabbit/Weasel or ABC cable used by NEA), considering current capacity, economy and uniformity of stores.
  3. With this conductor and the permitted LT voltage drop (about 5–8 %) and loss limit, find the maximum length of LT feeder that one transformer can supply.
  4. From that service area and the load density, choose the standard transformer size (e.g. 100, 200, 300 kVA).
  5. Finally place the transformers at the load centres of the service areas, so that each serves an area of the computed size.
Urban designReason
Conductor chosen firstStandardised sizes, high load everywhere
Then service area/lengthSet by voltage drop limit
Then transformer size and locationNumber of transformers = total load / area per transformer

Because the load is everywhere, a transformer can be placed in many points; the controlling constraint is how far the selected conductor can carry power within the voltage-drop limit. So the order in the statement (location first, then conductor) is reversed.

(By contrast, in rural areas the loads are clustered in villages, so the load centre is fixed first by the village location.)

✓ Answer checked by Claude Opus 5.5 (high effort)

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