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Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
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When Q is positive the current _______________ the voltage
lags
leads
inphase
out of phase
lags
In an AC circuit, the reactive power Q is defined as positive when the load is inductive in nature. For an inductive load, the current waveform lags behind the voltage waveform by an angle ╧Х.
In an AC circuit, the reactive power Q is defined as positive when the load is inductive in nature. For an inductive load, the current waveform lags behind the voltage waveform by an angle ╧Х.
Q=VIsin(╧Х) тАФ Definition of reactive power
P+jQ=VIтИЧ=VIej╧Х тАФ Complex power representation
The magnetic field in an inductor requires time to build up and collapse, which opposes the instantaneous change in current. This delay causes the current peak to occur after the voltage peak. Mathematically, for a purely inductive load, the phase difference is 90┬░ (or ╧А/2 radians), resulting in a lagging power factor.
Positive Q indicates inductive characteristics (Lagging Power Factor).
Negative Q indicates capacitive characteristics (Leading Power Factor).
Current lags voltage by ╧Х in inductive circuits where Q>0.
Inductive components are essential for transformers and motors.
Easier to analyze phase relationships in power system networks.
Lagging power factor reduces overall system voltage stability.
Requires reactive power compensation (capacitors) to improve efficiency.
Induction motors
Transmission lines with significant series reactance
In power systems, shunt capacitors are used to compensate for positive Q by injecting negative reactive power.
Option B is the opposite case, representing a capacitive circuit (Q<0).
A is correct тАФ When Q is positive, the load is inductive, which forces the current to lag behind the voltage.
Remember the mnemonic 'ELI the ICE man': In an Inductor (L), E (Voltage) leads I (Current); in a Capacitor (C), I leads E.