Transformer kVA Calculator
SI
Imp
Imperial
Inputs
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Phase
Single-phase uses V x I / 1000. Three-phase uses sqrt(3) x line-to-line voltage x line current / 1000.
Three phase
Single phase
Input basis
Calculate from volts and amps, or from real power and power factor.
Volts + amps
kW + power factor
Load voltage
(V)
Line-to-line voltage for three-phase loads, or winding/load voltage for single-phase.
V
Load current
(I)
Line current in amperes.
A
Real power
(P)
Real load power in kW.
kW
Power factor
(PF)
Used to convert kW to kVA and to estimate real kW when amps are entered.
Sizing margin
(M)
Extra capacity before rounding to the next listed standard size.
%
Results
Default result
Edit inputs
Recommended standard size
(S_std)
75
kVA
Pass
next listed three-phase size
Also computed
Design kVA with margin
(S_design)
62.35
kVA
Load kVA
(S_load)
49.88
kVA
Standard-size full-load current
(I_fl)
90.21
A
Load current
(I_load)
60
A
Standard-size utilization
(U)
Pass
66.51
%
Spare capacity vs load
(S_spare)
25.12
kVA
Real power at PF
(P)
44.89
kW
Show 1 more results
Method notes
2 notes
Three-phase kVA uses sqrt(3) x line-to-line volts x line current / 1000.
This is a transformer apparent-power screen. Final selection still needs continuous-load rules, inrush, motor starting, harmonic heating, impedance, enclosure, temperature rise, primary/secondary protection and local code review.
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