--- title: "Reducing power loss in distribution systems" subject: "Transmission and Distribution System Design" chapter: 7 key: "semester_8/transmission_and_distribution_system_design:power-loss-reduction-distribution" source: https://www.bctengineer.com/q/semester_8/transmission_and_distribution_system_design/power-loss-reduction-distribution site: BCT Engineering --- # Reducing power loss in distribution systems Transmission and Distribution System Design · Chapter 7: Distribution System Design - Asked in: 2071 Magh, 6 marks; 2067 Mangsir (old course), 8 marks (asked 2 times) - Video: [Lesson 6: How to Reduce Power Loss in a Power System](https://www.youtube.com/watch?v=oGCWT1nwcwA) — JP Smart Solutions Ltd - 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/power-loss-reduction-distribution - Whole chapter: https://www.bctengineer.com/md/semester_8/transmission_and_distribution_system_design/chapter-7 ## Question Briefly discuss the various options available with their limitations for power loss reduction on an already existing distribution network. ## Short answer Shunt capacitors reduce I²R loss but risk overcompensation and harmonics. Reconductoring and raising voltage are effective but costly. Phase balancing, new substations near load, and loss-efficient transformers help. Non-technical loss reduction (ABC, smart meters) yields large gains but faces social resistance. Capacitors and balancing are cheapest first steps. ## Answer Losses in an existing distribution network are **technical** ($I^2R$ in lines and transformers, core loss) and **non-technical** (theft, metering and billing errors). The main options, with their limitations, are: | Option | How it reduces loss | Limitations | |---|---|---| | **Shunt capacitors** at feeders/consumers | Supply kVAR locally, reducing current and $I^2R$ loss; improve voltage | Over-compensation at light load raises voltage; switching needed; harmonic resonance; cost | | **Reconductoring** (larger conductor) | Lower $R$ reduces loss in proportion | High cost; poles may need strengthening; outage during work | | **Raising voltage level** (e.g. 11 kV to 33 kV, more HT and less LT) | Loss ∝ $1/V^2$ | Expensive; transformers, insulators and switchgear must be changed | | **Feeder/network reconfiguration** | Open/close tie switches to balance feeders and shorten paths | Needs switches and loops; benefit limited in radial rural networks | | **New substation or transformer near load centre** | Shortens LT feeders (loss ∝ length) | Land, cost, HT extension needed | | **Phase load balancing** | Removes neutral current and overloaded-phase losses | Loads change with time; needs repeated monitoring | | **Replacing old/oversized transformers** with right-sized, low-loss (CRGO, amorphous) units | Cuts no-load and copper loss | Capital cost; amorphous units are costly and bulky | | **Load management / improving load factor** (ToD tariff) | Lower peak, lower $I^2R$ (loss ∝ peak²) | Depends on consumer response | | **Improving joints and connections, maintenance** | Removes hot-spot losses | Needs continuous effort | | **Reducing non-technical loss**: ABC conductor, proper meters, smart/prepaid meters, inspection | Stops theft and billing loss | Cost; social and political resistance | **Notes on choice:** - Capacitor placement and load balancing are the cheapest and are usually done first. - Reconductoring and voltage upgrading give large savings but need a cost–benefit study (energy saved × tariff vs capital cost). - In Nepal, where non-technical loss has been large, ABC, meter replacement and anti-theft drives (the NEA loss reduction campaign) have given the largest gains. Every option should be justified by comparing the present worth of the energy saved with its investment. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. How do shunt capacitors reduce losses, and what is a limitation? A. Supply kVAR locally, cutting current; over-compensation at light load raises voltage B. Raise resistance of lines; limited by cost C. Increase kW demand; limited by metering D. Reduce frequency; limited by harmonics only Answer: A. Local kVAR reduces current and I^2R loss; over-compensation at light load raises voltage. (Key point: Capacitors) 2. Why does raising the voltage level reduce losses, and what limits it? A. Loss is proportional to V, limited by land B. Loss is proportional to 1/V^2, but equipment must be changed so it is expensive C. Loss is independent of V, limited by tariff D. Loss is proportional to V^2, limited by theft Answer: B. Loss varies as 1/V^2, but transformers, insulators and switchgear must be replaced. (Key point: Voltage upgrade) 3. Which measures target non-technical loss? A. Shunt capacitors and reconductoring B. ABC conductor, proper/smart meters and inspection C. Tie-switch reconfiguration D. Phase balancing Answer: B. Theft and billing losses are tackled by ABC, meters and inspections. (Key point: Non-technical loss) 4. Which measures are usually done first because they are cheapest? A. Voltage upgrading B. Reconductoring C. Capacitor placement and load balancing D. New substations Answer: C. They are low cost and give quick savings. (Key point: First steps) ## Related in Transmission and Distribution System Design - [Capacitor size for maximum loss reduction](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Acapacitor-size-11kv-network) — Transmission and Distribution System Design, chapter 7, asked 5× - [Capacitor size for maximum loss reduction (variant)](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Acapacitor-size-11kv-network-b) — Transmission and Distribution System Design, chapter 7, asked 5× - [LT feeder options: loss and voltage drop, 50 kW](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Alt-feeder-two-options-50kw) — Transmission and Distribution System Design, chapter 7, asked 3× - [Peak loss and voltage drop for LT feeder options](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Alt-feeder-configuration-options) — Transmission and Distribution System Design, chapter 7, asked 2× - [Radial, loop and network distribution merits](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Aradial-loop-network-merits) — Transmission and Distribution System Design, chapter 5 - [Underground vs overhead distribution systems](https://www.bctengineer.com/question.md?key=semester_8%2Ftransmission_and_distribution_system_design%3Aunderground-vs-overhead-distribution) — Transmission and Distribution System Design, chapter 5, asked 4× ## Related in other subjects - [Flow distribution in five-pipe network](https://www.bctengineer.com/question.md?key=semester_4%2Fhydraulics%3Anetwork-five-pipes-flow-distribution) — Hydraulics, chapter 3 - [Line power loss, 138.5∠8° kV and 132 kV](https://www.bctengineer.com/question.md?key=semester_4%2Fpower_system_analysis_i%3Apower-loss-138-5kv-132kv) — Power System Analysis I, chapter 6 - [Nodal analysis currents and power loss](https://www.bctengineer.com/question.md?key=semester_1%2Fbasic_electrical_engineering%3Anodal-analysis-currents-power-loss-1a) — Basic Electrical Engineering, chapter 2 - [Replace existing machine now; AEC and ESL](https://www.bctengineer.com/question.md?key=semester_6%2Fengineering_economics%3Areplace-existing-machine-cash-flow-aec) — Engineering Economics, chapter 5