Calculadora de Resistência de Aterramento
Calcule a resistência de aterramento para sistemas elétricos seguros.
Required kVA (with growth)
226 kVA
Required kVA (with growth) vs Total Connected Load
Formula
Transformer Sizing
The transformer must handle the maximum demand load with adequate margin.
Method
Maximum demand = Total connected load x Demand factor
Required kVA = Max demand (kW) / Power factor x (1 + Growth margin)
The demand factor accounts for the fact that not all loads operate simultaneously. The growth margin reserves capacity for future expansion (typically 15-25%).
Exemplo Resolvido
200 kW total connected load, 80% demand factor, 0.85 PF, 20% growth.
- 01Maximum demand = 200 x 0.80 = 160 kW
- 02Required kVA = 160 / 0.85 x 1.20 = 225.9 kVA
- 03Select the next standard size: 250 kVA transformer.
Perguntas Frequentes
What are standard transformer sizes?
Common three-phase ratings: 100, 160, 200, 250, 315, 400, 500, 630, 800, 1000, 1250, 1600, 2000, 2500 kVA. Always select the next size above the calculated requirement.
What is a typical demand factor?
Commercial buildings: 60-80%. Industrial plants: 50-70%. Residential complexes: 40-60%. Hospitals: 70-85%. Higher demand factors apply when loads are more likely to operate simultaneously.
Should I account for starting current of motors?
For the transformer sizing, demand factor typically covers motor starting since not all motors start simultaneously. However, for large individual motors (above 15% of transformer rating), verify the voltage dip during starting is acceptable.
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