Under balanced operating conditions, consider the three-phase complex power delivered by the three-phase source to the three-phase load. Match the following expressions, those on the left to those on the right. (i) Realpower, P 3 ϕ (a) ( 3 V LL I L ) VA (ii) Reactive power, Q 3 ϕ (b) ( 3 V LL I L sin ϕ ) var (iii) Total apparent power, S 3 ϕ (c) ( 3 V LL I L cos ϕ ) W (iv) Complex power, S 3 ϕ (d) P 3 ϕ + j Q 3 ϕ Note that V LL is the rms line-to-line voltage, I L is the rms line current, and ϕ is the power-factor angle.
Under balanced operating conditions, consider the three-phase complex power delivered by the three-phase source to the three-phase load. Match the following expressions, those on the left to those on the right. (i) Realpower, P 3 ϕ (a) ( 3 V LL I L ) VA (ii) Reactive power, Q 3 ϕ (b) ( 3 V LL I L sin ϕ ) var (iii) Total apparent power, S 3 ϕ (c) ( 3 V LL I L cos ϕ ) W (iv) Complex power, S 3 ϕ (d) P 3 ϕ + j Q 3 ϕ Note that V LL is the rms line-to-line voltage, I L is the rms line current, and ϕ is the power-factor angle.
Solution Summary: The author explains the correct option for the type of power. The rmsline voltage supply by the generator is V_LL, and the angle difference between voltage and current.
Under balanced operating conditions, consider the three-phase complex power delivered by the three-phase source to the three-phase load. Match the following expressions, those on the left to those on the right.
(i) Realpower,
P
3
ϕ
(a)
(
3
V
LL
I
L
)
VA
(ii) Reactive power,
Q
3
ϕ
(b)
(
3
V
LL
I
L
sin
ϕ
)
var
(iii) Total apparent power,
S
3
ϕ
(c)
(
3
V
LL
I
L
cos
ϕ
)
W
(iv) Complex power,
S
3
ϕ
(d)
P
3
ϕ
+
j
Q
3
ϕ
Note that
V
LL
is the rms line-to-line voltage,
I
L
is the rms line current, and
ϕ
is the power-factor angle.
Which of the following descriptions IS NOT correct for loads in power
systems?
A. The purely resistive load absorbs the real power from the power grid
B. The purely inductive load absorbs the positive reactive power from the power grid
C. The purely capacitive load absorbs the positive reactive power from the power grid.
D. The average value of the instantaneous power through loads is equal to its real power.
In an ac circuit, power factor correction or improvement is achieved by
A. Connecting a resistor in parallel with the inductive load
B. Connecting an inductor in parallel with the inductive load
C. Connecting a capacitor in parallel with the inductive load
A balanced delta-load can be converted to an cquivalent balanced wye-
load by dividing the delta-load impedance by
A. square root of 3
В.3
C. 1/3
A 60 Hz sinusoidal voltage v = 141sinwt is applied to a series RL circuit. The values of the resistance and the inductance are 3 ohms and 0.016 henry respectively. a) Compute the rms value of the current and its phase angle with respect to the voltage.b) write the expression of the instantaneous current.
A single phase AC chopper supplies a pure inductive load of 0.02H from 220V, 50HZ
AC supply. The triggering angle of the thyristors is 100°. (Assume the circuit is ideal.)
a. Sketch the circuit
b. Develop the load current expression and find the decay angle of the load current
c. Sketch the load voltage and load current waveforms
d. Calculate the RMS value of load voltage
e. Calculate the RMS value of load current
f. If the triggering angle of the thyristors is chosen as 60°. Explain the operation of the
circuit.
Chapter 2 Solutions
Power System Analysis and Design (MindTap Course List)
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