Transformer Sizing Calculator
Determine the exact transformer kVA required for your load based on Phase, Voltage, and Amperage. Crucial for commercial and industrial generator setups.
Convert Horsepower (HP) to Watts (W) easily. Useful for sizing generators and understanding power requirements.
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Power Input
Minimum Transformer Size
83.1
kVA
kVA = (480 × 100 × 1.732) / 1000
It is highly recommended to size the transformer at least 20-30% larger than the calculated minimum.
Understanding Transformer Sizing
Properly sizing a transformer is crucial to prevent overheating, voltage dips, and equipment failure, especially when connecting generators to facilities or specific machinery.
Formulas:
-
Single Phase:
kVA = (Volts × Amps) / 1000
-
Three Phase:
kVA = (Volts × Amps × √3) / 1000
Where √3 is approximately 1.732.
Important Considerations:
- Growth Factor: Always include a 20% to 30% margin for future expansion and continuous load capability.
- Motor Loads: If the load includes large motors, you may need to size the transformer based on the Locked Rotor Amps (LRA) instead of running amps to accommodate startup spikes.
- Standard Sizes: Transformers are manufactured in standard kVA sizes (e.g., 15, 30, 45, 75, 112.5, 150, 300 kVA). Always round up your calculation to the next standard size.
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