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Load centre, connected load, 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.

What is electric load center? Explain with example of following terminology (i) connected load (ii) maximum demand.

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:

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.

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:

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.

✓ Answer checked by Claude Opus 5.5 (high effort)

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