FS7755

Rev. 1.1

12/22

I(t)

I(t)

V(t)

V(t)

Instantaneous

Power Signal

Instantaneous

Power Signal

Instantaneous

Real Power Signal

Instantaneous

Real Power Signal

0V

0V

V× I

2

V×I

2

Fig6 DC Component of Instantaneous Power Signal

Conveys Real Power Information (PF ≦ 1)

3

Non-sinusoidal Voltage and Current

The real power calculation method also holds true for non-sinusoidal current and voltage waveforms. All

voltage and current waveforms in practical applications will have some harmonic content. Using the

Fourier Transform, instantaneous voltage and current waveforms can be expressed in terms of their

harmonic content.

∑

∞

≠

×

0

2

h

(1)

Where:

v(t) is the instantaneous voltage

and

∑

∞

≠

×

0

I

2

h

(2)

Where:

i(t) is the instantaneous current

and

Using Equations (1) and (2), the real power P can be expressed in terms of its fundamental real power

Where:

(3)