In an AC (alternating current) circuit, power in a pure inductive circuit is an important concept. Let's break down the key points related to power in a pure inductive circuit:
Inductive Reactance (XL): In a pure inductive circuit, the main component affecting the current flow is the inductor. The inductor introduces a property called inductive reactance (XL), which is the opposition offered by the inductor to the flow of alternating current. Inductive reactance is directly proportional to the frequency (f) of the AC signal and the inductance (L) of the coil. Mathematically, XL = 2πfL.
Voltage and Current Relationship: In an ideal inductor, the voltage and current are out of phase by 90 degrees in a pure inductive circuit. This means that the current lags behind the voltage by a quarter of a cycle. The current waveform reaches its peak after the voltage waveform.
Power Factor (PF): In a pure inductive circuit, the power factor is defined as the cosine of the phase angle between the voltage and the current. In this case, the power factor is zero, as the phase difference between voltage and current is 90 degrees. Mathematically, PF = cos(θ), where θ is the phase angle.
Real Power (Active Power): In a pure inductive circuit, the real power (P) is zero. This means that no net energy is transferred from the source to the circuit, and the inductor doesn't dissipate power in the form of heat. The energy is alternately stored in the magnetic field of the inductor during one half-cycle and returned to the circuit during the other half-cycle.
Reactive Power: In a pure inductive circuit, the entire power is reactive power (Q). Reactive power is the power that flows back and forth between the source and the inductor, without being dissipated as useful work. It is necessary to establish and maintain the magnetic field in the inductor.
Apparent Power: The apparent power (S) in a pure inductive circuit is equal to the reactive power, as there is no real power being consumed. Mathematically, S = Q.
In summary, in a pure inductive circuit, the power factor is zero, meaning that no real power is consumed or dissipated. All the power is reactive, and it alternates between the source and the inductor. This makes pure inductive circuits useful in applications where reactive power compensation or control is required, such as power factor correction systems.