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Short note: Factor of maximum utilization Ku

Short answer

Factor of maximum utilization (ku) = actual maximum power used / rated power (ku ≤ 1). Accounts for equipment not running at full rating (e.g., motors at 0.75, lighting/heating at 1). Applied per load before simultaneity factor ks. Example: 10 kVA motor with ku=0.75 counted as 7.5 kVA for board demand calculation.

Write a short note on factor of maximum utilization (Ku).

The factor of maximum utilization (ku) is the ratio of the maximum power actually taken by a load in normal operation to its rated (installed) power:

ku = Actual maximum power used / Rated power   (ku ≤ 1)

It is used in industrial load estimation (IEC method) because equipment rarely runs at full rating. For example, a motor is chosen with a margin and usually runs at about 75% of its rating.

Typical values:

  • Motors in industry: ku ≈ 0.75
  • Incandescent lighting and heating: ku = 1
  • Socket outlets: depends on what is plugged in

Example: a 10 kVA motor with ku = 0.75 is counted as 7.5 kVA when the demand of its distribution board is worked out. ku is applied to each individual load, before the factor of simultaneity ks is applied to groups.

✓ Answer checked by Claude Opus 5.5 (high effort)

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