For the circuit given in FIGURE 1 the power factor is 0.72 lagging and the power
ID: 1329416 • Letter: F
Question
For the circuit given in FIGURE 1 the power factor is 0.72 lagging and the power dissipated is 375 W. Determine the: apparent power reactive power the magnitude of the current flowing in the circuit the value of the impedance Z and state whether circuit is inductive or capacitive. A 50 kW load operates from a 60 Hz 10 kV rms line with a power factor of 60% lagging. Determine the capacitance that must be placed in parallel with the load to achieve a 90% lagging power factor. A series RLC circuit is connected to a 5 V supply, the frequency of the supply is adjusted to give a maximum current of 11.9 mA at 2.5 kHz. The Q factor is 70. Determine the component values of the circuit.Explanation / Answer
here,
considering
Pf = power factor
I = current
RP = Reactive power
AP = Apparent power
pf = cos x
cosx = pf
cosX = 0.72
x = 43.94 degrees
as
Magnitude of Current Power = Voltage * Current * Power factor
375 = 120 (I) (0.72)
I = 4.34 A
Reactive power = Voltage * I *sin 43.94
RP = 120 * 4.34 * sin43.945
RP = 19.41 VAR
AP = sqrt(Power^2 + RF^2)
AP = sqrt(120^2 + 19.41^2)
AP = 121.55 VA
as,
R = r*cos(theta) = r*PF
X = r*sin(theta)
j = sqrt(-1)
tan(theta) = X/R
impedance = Z = R + j*X
X = R*tan(theta)
X = r*PF*tan(theta)
X =10*0.72*tan(43.94)
X = 6.938
If it's lagging then it's an inductive load. This is typical with larger transformers & motors.