--- title: "T/F: urban design, transformer location first" subject: "Transmission and Distribution System Design" chapter: 7 key: "semester_8/transmission_and_distribution_system_design:tf-urban-transformer-location-first" source: https://www.bctengineer.com/q/semester_8/transmission_and_distribution_system_design/tf-urban-transformer-location-first site: BCT Engineering --- # T/F: urban design, transformer location first Transmission and Distribution System Design · Chapter 7: Distribution System Design - Asked in: 2074 Bhadra, 1+3 marks - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_8/transmission_and_distribution_system_design/tf-urban-transformer-location-first - Whole chapter: https://www.bctengineer.com/md/semester_8/transmission_and_distribution_system_design/chapter-7 ## Question 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. ## 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. ## Answer **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 design | Reason | |---|---| | Conductor chosen first | Standardised sizes, high load everywhere | | Then service area/length | Set by voltage drop limit | | Then transformer size and location | Number 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.) ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. The statement is: A. True B. False; start from conductor and transformer rating C. True for rural only D. False because location is never needed Answer: B. In urban design the conductor and permitted drop come first. (Key point: Truth value) 2. Correct urban sequence: A. Locate transformer, then conductor B. Load density, conductor, max LT length, transformer size, then place at load centre C. Transformer, load, conductor D. Place anywhere Answer: B. Conductor fixes the service area which fixes size and positions. (Key point: Order) 3. What controls transformer placement in urban areas? A. Village locations B. How far the chosen conductor carries power within the voltage-drop limit C. Land only D. Colour Answer: B. Load is everywhere, so the drop limit controls. (Key point: What controls) 4. In rural areas load centre is fixed first because: A. Loads are clustered in villages B. Loads are uniform C. Conductors vary D. Transformers are free Answer: A. Loads appear as clusters. 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