Skip to main content

Demand factor and diversity factor of substation

Short answer

An electric load centre is the point at the centroid of loads, distributing power to minimise voltage drop and losses. Demand factor of Block-1 is 200/260 = 0.769; of Block-2 is 160/240 = 0.667. Diversity factor of the substation = (200+160+150+200)/600 = 1.18.

What is electric load centre? In an industry, substation supplies power for four blocks. Block-1 has 6 no. of machines with rating of 70kW, 90kW, 20kW, 50kW, 10kW and 20kW respectively, while maximum demand of block-1 is 200kW. Block-2 has 5 no. of machines of 60kW, 40kW, 40kW, 70kW and 30kW and maximum demand of block-2 is 160kW. Block-3 and 4 has maximum demand of 150kW and 200kW respectively. Determine demand factor of block-1 and 2. If the maximum demand of substation is 600kW, find the diversity factor of the substation.

Electric load centre

An electric load centre is the point from which power is distributed to a group of loads, located at the centre of gravity of those loads (X = ΣPx/ΣP, Y = ΣPy/ΣP). Placing the substation there keeps LV feeders short, reducing voltage drop, losses and cable cost.

Demand factor of Block-1 and Block-2

Demand factor = Maximum demand / Connected load

Block-1 connected load
 = 70 + 90 + 20 + 50 + 10 + 20 = 260 kW
DF(1) = 200 / 260 = 0.769

Block-2 connected load
 = 60 + 40 + 40 + 70 + 30 = 240 kW
DF(2) = 160 / 240 = 0.667

Diversity factor of the substation

Sum of individual maximum demands
 = 200 + 160 + 150 + 200 = 710 kW
Maximum demand of substation = 600 kW

Diversity factor = 710 / 600 = 1.183

Answer: Demand factor of Block-1 = 0.769, of Block-2 = 0.667; diversity factor of the substation = 1.18.

The blocks do not reach their peaks at the same time, so the substation needs to be sized for 600 kW rather than 710 kW.

✓ Answer checked by Claude Opus 5.5 (high effort)

Related questions

All Industrial Power Distribution and Illumination chapter 1 questions →