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Substation capacity and diversity factor from load pattern

Short answer

Combined loads per 4-hour interval: max total = 73 kVA (second 12-16 interval). Substation capacity = 73 kVA (practically 100 kVA standard). Individual max demands: A=22, B=34, C=40 kVA; sum=96 kVA. Diversity factor = 96/73 = 1.315. Substation sized for simultaneous peak, not sum of individual peaks.

The load pattern of ABC complex is:

Time(0:00-4:00)(4:00-8:00)(8:00-12:00)(12:00-16:00)(12:00-16:00)(16:00-20:00)(20:00-24:00)
Load of Block-A in KVA51318916228
Load of Block-B in KVA719223417146
Load of Block-C in KVA312162440354

Calculate: i) Capacity of substation required. ii) Diversity factor. (The fifth column is printed as (12:00-16:00) a second time in the paper.)

The fifth column repeats "(12:00–16:00)"; it is taken as a separate 4-hour interval as printed, giving 7 intervals of data.

Step 1: Combined load in each interval

IntervalABCTotal (kVA)
0–457315
4–813191244
8–1218221656
12–169342467
12–16 (2nd)16174073
16–2022143571
20–2486418

Step 2: Capacity of substation

The substation must supply the highest combined (simultaneous) load:

Max demand of complex = 73 kVA

Answer (i): Required substation capacity = 73 kVA (in practice the next standard transformer, 100 kVA, would be installed).

Step 3: Diversity factor

Individual maximum demands:

Block A max = 22 kVA
Block B max = 34 kVA
Block C max = 40 kVA
Sum         = 96 kVA

Diversity factor
 = Σ individual MDs / Max demand of system
 = 96 / 73
 = 1.315

Answer (ii): Diversity factor = 1.32.

Because the blocks reach their peaks at different times, the substation needs only 73 kVA instead of 96 kVA.

✓ Answer checked by Claude Opus 5.5 (high effort)

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