Finding complex power in AC circuit

In summary, the question is about finding complex power with given current and impedance values. The user tried using i2z method but got a different answer than the one given by a website. They are unsure about what went wrong and are seeking clarification on the concept of finding complex power with given values.
  • #1
Raghav Gupta
1,011
76
In a branch I have to find complex power which is having current 19.41<-37.3 A and impedance 4+j3 Ω
What I used is i2z and I was getting 1489.85 - j1152.74 W.
This is wrong but I don't know how because by this site the answer was different
http://www.rapidtables.com/calc/electric/power-calculator.htm
Can someone tell me what is wrong going on?
 
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  • #2
Is this a homework problem?
 
  • #3
Chandra Prayaga said:
Is this a homework problem?
No the homework problem was something other. When I was doing it in middle this query araised. I just want to ask the concept that when impedance is given and current is given, the complex power should be Vi or i2z, isn't it?
 
  • #4
The voltage is give as ## V = I * Z = I * Re(Z) + I * I am (Z) ##. The second term is 90 degrees out of phase with respect to current. The average power dissipated is then ##I_{RMS}^2 * Re(Z) ##
 

Related to Finding complex power in AC circuit

1. What is complex power in an AC circuit?

Complex power in an AC circuit is the combination of real and reactive power. Real power represents the actual energy being transferred and consumed by the circuit, while reactive power represents the energy stored and released by the circuit due to inductance and capacitance. Together, they form a complex number, where the real part is the real power and the imaginary part is the reactive power.

2. How is complex power calculated in an AC circuit?

Complex power is calculated using the formula S = P + jQ, where S is the complex power, P is the real power, and Q is the reactive power. Real power is calculated as the product of voltage, current, and the cosine of the phase angle between them. Reactive power is calculated as the product of voltage, current, and the sine of the phase angle between them.

3. What is the significance of complex power in an AC circuit?

Complex power is important in AC circuits because it helps us understand the total power being consumed by the circuit, as well as the reactive components that affect voltage and current. It is also used in power factor calculations, which determine the efficiency of an AC circuit.

4. Can complex power be negative in an AC circuit?

Yes, complex power can be negative in an AC circuit. This occurs when the reactive power is greater than the real power, resulting in a negative imaginary component. This can happen when there is a leading power factor, where the current leads the voltage, or when there is a capacitive load in the circuit.

5. How does complex power differ from apparent power in an AC circuit?

Complex power and apparent power are often confused, but they are not the same. Apparent power is the total power being supplied to the circuit, and is calculated as the product of voltage and current. It is represented by the magnitude of the complex power, without taking into account the phase angle. Complex power, on the other hand, takes into account the phase difference between voltage and current, providing a more accurate representation of the power in the circuit.

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