--- title: "Load centre, connected load, maximum demand" subject: "Industrial Power Distribution and Illumination" chapter: 1 key: "semester_6/industrial_power_distribution_and_illumination:load-centre-connected-load-md" source: https://www.bctengineer.com/q/semester_6/industrial_power_distribution_and_illumination/load-centre-connected-load-md site: BCT Engineering --- # Load centre, connected load, maximum demand Industrial Power Distribution and Illumination · Chapter 1: Introduction - Asked in: 2073 Bhadra, 4 marks - Video: [मैक्सिमम डिमांड क्या होता है || What is MD (Maximum demand) hindi | How work M.D. power electrical](https://www.youtube.com/watch?v=oHBP-M48cX4) — Electrical Dost - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/industrial_power_distribution_and_illumination/load-centre-connected-load-md - Whole chapter: https://www.bctengineer.com/md/semester_6/industrial_power_distribution_and_illumination/chapter-1 ## Question What is electric load center? Explain with example of following terminology (i) connected load (ii) maximum demand. ## Short answer Load centre is the distribution point at the load centre of gravity (ΣPᵢxᵢ/ΣPᵢ) minimizing voltage drop and cable cost. Connected load is sum of nameplate ratings (e.g., 4×10kW motors + 20×40W lamps + 2×2kW heaters = 44.8 kW). Maximum demand is highest actual draw (e.g., 30 kW), always ≤ connected load; demand factor = 30/44.8 = 0.67. ## Answer #### Electric load centre An electric load centre is the point from which power is distributed to a group of loads, placed at or near the "centre of gravity" of those loads so that low-voltage feeders are as short as possible. Its position is found from: ```text X = Σ(Pᵢ·xᵢ)/ΣPᵢ , Y = Σ(Pᵢ·yᵢ)/ΣPᵢ ``` The substation or main distribution board placed there reduces voltage drop, losses and cable cost and makes the system more reliable. #### (i) Connected load Connected load is the **sum of the nameplate (rated) ratings** of all equipment connected to the supply system of a consumer, in kW or kVA. **Example:** a workshop has 4 motors of 10 kW, 20 lamps of 40 W and 2 heaters of 2 kW. ```text Connected load = 4×10 + 20×0.04 + 2×2 = 40 + 0.8 + 4 = 44.8 kW ``` #### (ii) Maximum demand Maximum demand is the **greatest load actually drawn** by the consumer at any time during a period, usually measured as the highest 15- or 30-minute average. Because all equipment never runs at full load together, maximum demand is less than connected load. **Example:** in the workshop above, the highest load recorded by the MD meter in a month is 30 kW (3 motors near full load plus lights and one heater). So: ```text Maximum demand = 30 kW Demand factor = 30 / 44.8 = 0.67 ``` Maximum demand decides the transformer, cable and switchgear size and the demand charge on the bill. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Why is the substation placed at the load centre? A. To lengthen the HV line B. To increase fault current C. To raise the voltage drop D. Short LV feeders reduce voltage drop, losses and cable cost Answer: D. Placing it at the centre of gravity of loads keeps LV runs short. (Key point: Load centre) 2. What is connected load? A. The greatest load drawn in a month B. Average load over a day C. The sum of nameplate ratings of all connected equipment D. Load of the largest motor only Answer: C. Connected load is the total rated capacity, not the actual draw. (Key point: Connected load) 3. What is the connected load of 4 motors of 10 kW, 20 lamps of 40 W and 2 heaters of 2 kW? A. 30 kW B. 44.8 kW C. 44.0 kW D. 48.8 kW Answer: B. 40 + 0.8 + 4 = 44.8 kW. (Key point: Connected load example) 4. In the example the MD meter reads 30 kW. What is the demand factor? A. 0.67 B. 1.49 C. 0.75 D. 0.30 Answer: A. 30/44.8 = 0.67; MD is below connected load because not everything runs at full load together. 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