Maximum Demand Calculation 3 Phase May 2026

(if loads are independent, DF ~1.2) But here, conveyor and HVAC may run together → use 1.1. Adjusted MD_kW = ( 55.31 / 1.1 = 50.28 , kW)

Abstract Maximum Demand (MD) is the highest average power drawn by an electrical installation over a specified interval (typically 15–30 minutes). Accurate MD calculation is essential for sizing cables, transformers, switchgear, and for determining utility tariff structures. In three‑phase systems, MD must account for phase imbalances, power factor, load diversity, and peak coincidence. This paper presents a systematic approach to MD calculation, from basic formulas to advanced software‑based techniques, supported by real‑world examples. 1. Introduction Electrical installations rarely operate at full load continuously. The maximum demand represents the peak load that the system must sustain without overloading. Utilities use MD to design supply infrastructure and to charge large consumers (demand charges, often in $/kVA or $/kW). Underestimating MD leads to frequent overload trips; overestimating leads to oversized, capital‑intensive equipment. maximum demand calculation 3 phase

Weighted PF = Total kW / Total kVA without diversity? Compute: (if loads are independent, DF ~1

Load Name | kW | PF | kVA | Demand Factor | Coincident kW | Coincident kVA ----------|----|----|-----|---------------|---------------|--------------- ... | | | | | | Total coincident kW = _______ Weighted PF = _______ MD_kVA = Total coincident kW / PF = _______ Add margin (____ %) = _______ Selected MD = ______ kVA In three‑phase systems, MD must account for phase

MD_kVA = 50.28 / 0.808 = 62.23 kVA

If welder connected to L1‑L2, and conveyor on L2‑L3, the peak phase might be L2. For final design, balance loads.

kVA per load (without diversity): Lighting: 10/0.9 = 11.11 Sockets: 15/0.8 = 18.75 Conveyor: 23.91/0.85 = 28.13 Welder: 30 kVA (given) ×0.3 duty = 9 kVA HVAC: 18/0.8 = 22.5 Sum kVA = 11.11+18.75+28.13+9+22.5 = 89.49 kVA Sum kW = 10+15+23.91+5.4+18 = 72.31 kW (note: welder active 5.4, not 30) Weighted PF = 72.31/89.49 = 0.808