Single phase amps to kVA calculation formula
The apparent power S in kilovolt-amps is equal to current I in amps, times the voltage V in volts, divided by 1000:
S(kVA) = I(A) × V(V) / 1000
Three phase amps to kVA calculation formula
Calculation with line to line voltage
The apparent power S in kilovolt-amps is equal to phase current I in amps, times the line to line RMS voltage VL-L in volts, divided by 1000:
S(kVA) = √3 × I(A) × VL-L(V) / 1000
Calculation with line to neutral voltage
The apparent power S in kilovolt-amps is equal to phase current I in amps, times the line to neutral RMS voltage VL-N in volts, divided by 1000:
S(kVA) = 3 × I(A) × VL-N(V) / 1000
Where,
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S = Apparent Power in Volt-Amps
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V = Voltage in Volts
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I = Current in Amperes
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VL-L = Line to Line Voltage in 3-Phase Circuits
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VL-N = Line to Neutral Voltage in 3-Phase Circuits
Example Problem
Find the kVA rating of a single phase transformer if the primary current rating is 120 amperes and RMS voltage is 120V.
Solution:
S = (120V x 125A) ÷ 1000
kVA = S = 15kVA
Three Phase Amps to kVA Calculation
Calculation with Line to Line Voltage
Apparent Power in kVA = (√3 x Voltage in Volts x Current in Amperes) ÷ 1000
S = (√3 x VL-L x I) ÷ 1000
Example:
Calculate the apparent power in kVA if the value of current is 28A and RMS voltage is 208V (line to line) three phase.
Solution:
S = (1.732 x 208V x 28A) ÷ 1000
kVA = S = 10kVA
Calculation with Line to Neutral Voltage
