Consider a single-phase load with an applied voltage v ( t ) = 150 cos ( ω t + 10 ° ) volts and load current i ( t ) = 5 cos ( ω t + 50 ° ) A . (a) Determine the power triangle. (b) Find the power factor and specify whether it is lagging or leading. (c) Calculate the reactive power supplied by capacitors in parallel with the load that correct the power factor to 0.9 lagging.
Consider a single-phase load with an applied voltage v ( t ) = 150 cos ( ω t + 10 ° ) volts and load current i ( t ) = 5 cos ( ω t + 50 ° ) A . (a) Determine the power triangle. (b) Find the power factor and specify whether it is lagging or leading. (c) Calculate the reactive power supplied by capacitors in parallel with the load that correct the power factor to 0.9 lagging.
Solution Summary: The author illustrates the power triangle drawn as shown in Figure 1. Value of applied voltage is v(t)=150mathr
Consider a single-phase load with an applied voltage
v
(
t
)
=
150
cos
(
ω
t
+
10
°
)
volts
and load current
i
(
t
)
=
5
cos
(
ω
t
+
50
°
)
A
. (a) Determine the power triangle. (b) Find the power factor and specify whether it is lagging or leading. (c) Calculate the reactive power supplied by capacitors in parallel with the load that correct the power factor to 0.9 lagging.
Calculate the value of capacitance in the following figure that must be connected in parallel with the load to correct the source power factor to 0.94 lagging. The frequency f = 60 Hz
8. The total power supplied to a balance delta load is found in the same way as for a
balance wye load.
True
False
Either
Neither
12. A load of 20 + j35 ohms is connected across a 220 V, 60 Hz supply. Find the
reactive power of the load in var.
595
2420
1042
1382
13. A type of DC source where the characteristic output voltage has perfect
unidirectional waveform and is based on electrochemical principle.
Generator
Inverter
Converter
Battery
14. Calculate the Rf of a circuit whose impedance is 20+j35 and current of 2A.
0.86
0.91
0.50
0.71
15. What capacitor shall be installed in parallel with a circuit to achieve a unity power
factor if the reactive power of a circuit is 200VARS and the voltage is 100V.
80.45 microfarad
53.05 microfarad
It's already in unity
62.45 microfarad
When a resistor is connected across the terminals of an ac generator (117 V) that has a fixed frequency, there is a current of 0.332 A in
the resistor. When an inductor is connected across the terminals of the same generator, there is a current of 0.365 A in the inductor.
When both the resistor and the inductor are connected in series between the terminals of this generator, what is (a) the impedance of
the series combination and (b) the phase angle between the current and the voltage of the generator? Note: The ac current and voltage
are rms values and power is an average value unless indicated otherwise.
(a) Number
(b) Number
Buda
i
Vrms
R
Irms.R
Circuit 1
Units
Units
Vrms.
Irms, L
Circuit 2
>
L
Vrms
R
www
Circuit 3
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