Electric current in amps (A) to apparent power in volt-amps (VA).
You can calculate volt-amps from amps and volts, but you can't convert amps to volt-amps since volt-amps and amps units do not measure the same quantity.
The apparent power S in volt-amps (VA) is equal to current I in amps (A), times the RMS voltage V in volts (V):
S(VA) = I(A) × V(V)
So volt-amps are equal to amps times volts:
volt-amps = amps × volts
or
VA = A ⋅ V
What is the apparent power in VA when the current is 12A and the voltage supply is 120V?
Solution:
S = 12A × 120V = 1440VA
What is the apparent power in VA when the current is 12A and the voltage supply is 190V?
Solution:
S = 12A × 190V = 2280VA
What is the apparent power in VA when the current is 12A and the voltage supply is 220V?
Solution:
S = 12A × 220V = 2640VA
So The apparent power S in volt-amps (VA) is equal to square root of 3 times current I in amps (A), times the line to line RMS voltage VL-L in volts (V):
S(VA) = √3 × I(A) × VL-L(V)
So volt-amps are equal to square root of 3 times amps times volts:
kilovolt-amps = √3 × amps × volts
or
kVA = √3 × A ⋅ V
What is the apparent power in VA when the current is 12A and the voltage supply is 120V?
Solution:
S = √3 × 12A × 120V = 2494VA
What is the apparent power in VA when the current is 12A and the voltage supply is 190V?
Solution:
S = √3 × 12A × 190V = 3949VA
What is the apparent power in VA when the current is 12A and the voltage supply is 220V?
Solution:
S = √3 × 12A × 220V = 4572VA
An ampere is the unit of electric current, which is the number of electrons flowing through a circuit. An ampere is a current generated by a force of 1 V acting through a resistance of 1 ohm (Ω).
It's important to note that calculations vary between single and three phase power, so you need to know which one you have.
Single Phase Equation.
VA = Volts X Amps
kVA = Volts x Amps / 1000
Three Phase Equation. For three-phase, you multiply the square root of 3 (√3) or 1.732 by the line-to-line voltage by the amps.
VA = √3 x Volts x Amps
kVA = √3 x Volts x Amps / 1000
Example
single phase. What is the VA of a 120VAC single phase load that draws 12 amps?
volts = 120
amps = 12
KVA = Volts X Amps = 120 X 12 = 2400VA
three phase. What is the KVA of a 480VAC three phase load that draws 86 amperes?
Voltage Line to Line = 480
amps = 86
kVA = √3 x Volts x Amps / 1000 = 1.732 x 480 x 86/1000 = 71.5 kVA
VA = VRMS x IRMS (4)
You can calculate the apparent power in volt-amperes for an AC circuit by multiplying the measured RMS voltage by the measured RMS current.
10 amperes
For example, a transformer with a 100 VA rating can handle 100 volts at one ampere (amp) of current. The kVA unit represents kilovolt-ampere or 1,000 volt-ampere. A transformer with a 1.0 kVA rating is the same as a transformer with a 1,000 VA rating and can handle 100 volts at 10 amps of current.
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