- 2073 Bhadra · 2 marks
Short note: Factor of simultaneity Ks
Short answer
Factor of simultaneity (ks) = group maximum demand / sum of individual maximum demands (ks ≤ 1). Accounts for non-coincident peaks; reciprocal of diversity factor. Applied at each distribution level after ku. Typical values: 2-3 circuits 0.9, 4-5 0.8, 6-9 0.7, ≥10 0.6; lighting 1, sockets 0.1-0.2. Example: 5 motors each 7.5 kVA, ks=0.8 gives board demand 30 kVA.
Write a short note on factor of simultaneity (Ks).
The factor of simultaneity (ks), also called the coincidence factor, accounts for the fact that all loads of a group do not run at the same time. It is the ratio of the maximum demand of a group of loads to the sum of their individual maximum demands:
ks = Max demand of group / Σ(individual MDs)
(ks ≤ 1)
It is the reciprocal of the diversity factor. ks is applied at each level of distribution (sub-board, main board, transformer) after ku has been applied to each load.
Typical values (IEC 61439 for distribution boards):
| Number of circuits | ks |
|---|---|
| 2 – 3 | 0.9 |
| 4 – 5 | 0.8 |
| 6 – 9 | 0.7 |
| 10 or more | 0.6 |
By function: lighting 1, heating and air conditioning 1, socket outlets 0.1–0.2.
Example: a board feeds 5 motors each with a demand of 7.5 kVA. With ks = 0.8, the board demand is 5 × 7.5 × 0.8 = 30 kVA instead of 37.5 kVA.
✓ Answer checked by Claude Opus 5.5 (high effort)
Related questions
- Selecting distribution transformer size using Ku and Ks · Industrial Power Distribution and Illumination, chapter 4 · asked 3×
- Transformer size for given industry (figure) · Industrial Power Distribution and Illumination, chapter 4 · asked 2×
- Bending stress and safety factor of a spur pinion · Machine Design I, chapter 9
All Industrial Power Distribution and Illumination chapter 1 questions →