Verified Mathematical Model & Formulation
Single Phase: kVA = (Volts × Amps) / 1,000 Three Phase: kVA = (Volts × Amps × 1.732) / 1,000 Recommended kVA = Calculated kVA × 1.25 (Safety/Growth Margin)
Determines the apparent power capacity in kilovolt-amperes (kVA) to accommodate the continuous primary/secondary load with a recommended 25% safety buffer for inrush and future load growth.
Configurable Parameters & Standard Units
- Phase (1 = Single Phase, 3 = Three Phase): (Default: 3 count)
- Secondary Voltage (V): (Default: 208 v)
- Full Load Current (A): (Default: 100 a)
- Growth & Safety Margin (%): (Default: 25 percent)
Standard Worked Example & Practical Verification
Scenario: Powering a 208V 3-phase building subpanel with 120A total connected load.
Calculated Solution
54.0 kVA Required (Select Standard 75 kVA Unit)
Practical Takeaway: A 45 kVA transformer would operate dangerously near 96% of maximum thermal limit.
Frequently Asked Questions
What are standard commercial transformer kVA sizes?
Standard 3-phase commercial transformer sizes include 15, 30, 45, 75, 112.5, 150, 225, 300, 500, 750, and 1,000 kVA.