Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
Normally, the reactive power has _____________ average value
High
Low
zero
negative
zero
Reactive power represents the power that oscillates between the source and the load but does not perform useful work. Over a complete cycle, the energy stored in the magnetic or electric fields of inductors and capacitors is returned to the circuit, resulting in a net average value of zero.
Reactive power represents the power that oscillates between the source and the load but does not perform useful work. Over a complete cycle, the energy stored in the magnetic or electric fields of inductors and capacitors is returned to the circuit, resulting in a net average value of zero.
Q=VIsin(╧Х) тАФ Instantaneous reactive power
QavgтАЛ=T1тАЛтИл0TтАЛQ(t)dt=0 тАФ Average value definition
In an AC circuit, reactive power Q is defined as the product of VrmsтАЛ, IrmsтАЛ, and sin(╧Х), where ╧Х is the phase angle. Because the instantaneous power p(t)=v(t)i(t) contains a term proportional to sin(2╧Йt), the integral over one full period T=f1тАЛ is zero. Thus, inductors and capacitors store and release energy, creating a net zero work contribution over time.
Reactive power is measured in Volt-Ampere Reactive (VAR).
It is required to maintain the magnetic field in inductive loads (motors, transformers).
It does not perform real work, which is why it is often called 'wattless' power.
Excessive reactive power increases transmission line losses (I┬▓с┤┐).
Necessary for the operation of electromagnetic devices.
Allows for voltage regulation in power systems via SVCs or STATCOMs.
Reduces the effective capacity of power lines and transformers.
Causes unnecessary voltage drops across the system impedance.
Grid voltage stability enhancement.
Induction motor and transformer excitation.
The reactive power oscillates at twice the frequency of the system voltage.
Option D is wrong because while reactive power can be positive or negative (leading or lagging), its average value over a cycle is mathematically zero.
C is correct тАФ Reactive power is purely oscillatory, meaning energy is stored and released periodically, resulting in an average value of zero over one full cycle.
Always remember that 'Reactive' refers to the property of energy oscillation; if it had a non-zero average, it would be 'Real' or 'Active' power.