A 130-MVA, 13 .2-kV three-phase generator, which has a positive-sequence reactance of 1.5 per unit on the generator base, is connected to a 135-MVA, 13 .2 Δ /115 Y-kV step-up transformer with a series impedance of (0.005+10.1) per unit on its own base. (a) Calculate the per-unit generator reactance on the transformer base. (b) The load at the transformer terminals is 15 MW at unity power factor and at 115 kV Choosing the transformer high-side voltage as the reference phasor, draw a phasor diagram for this condition. (C) For the condition of part (b), find the transformer low-side voltage and the generator internal voltage behind its reactance. Also compute the generator output power and power factor.
A 130-MVA, 13 .2-kV three-phase generator, which has a positive-sequence reactance of 1.5 per unit on the generator base, is connected to a 135-MVA, 13 .2 Δ /115 Y-kV step-up transformer with a series impedance of (0.005+10.1) per unit on its own base. (a) Calculate the per-unit generator reactance on the transformer base. (b) The load at the transformer terminals is 15 MW at unity power factor and at 115 kV Choosing the transformer high-side voltage as the reference phasor, draw a phasor diagram for this condition. (C) For the condition of part (b), find the transformer low-side voltage and the generator internal voltage behind its reactance. Also compute the generator output power and power factor.
A
130-MVA,
13
.2-kV
three-phase generator, which has a positive-sequence reactance of 1.5 per unit on the generator base, is connected to a
135-MVA,
13
.2
Δ
/115
Y-kV
step-up transformer with a series impedance of (0.005+10.1) per unit on its own base. (a) Calculate the per-unit generator reactance on the transformer base. (b) The load at the transformer terminals is 15 MW at unity power factor and at 115 kV Choosing the transformer high-side voltage as the reference phasor, draw a phasor diagram for this condition. (C) For the condition of part (b), find the transformer low-side voltage and the generator internal voltage behind its reactance. Also compute the generator output power and power factor.
Light-emitting diodes (LEDs) are diodes made with III-V compound semiconductor materials such as aluminum gallium arsenide (AlGaAs), aluminum indium gallium phosphide (AlInGaP) or indium gallium nitride (InGaN), instead of silicon. The LEDs emit light when the device is operated under forward bias. LEDs of different colors have different turn-on voltages VD(on). For example:
VD(on) :
Red: ~ 1.6 V
Yellow: ~ 1.7 V
Green: ~ 1.8 V
Blue: ~ 2.8 V
White: ~ 3.8 V
(a) Model these five LEDs with a simplified piecewise linear model
(b) A rule of thumb is that it takes about 1 mA of current to “light” an LED while ~ 10 mA is needed for it to appear bright. Use the piecewise linear model for the LEDs, for the over-voltage indicator circuit to the right, find the values of Vin which will cause D1 or D2 to light (i.e. when ID1 or ID2 exceeds 1 mA).
Consider a fixed and updated instrumentation amplifier (where two resistors are lumped into one
resistor), analyze the circuit if a common voltage source (VICM) is connected to two inputs.
A₁
R₂
+
R₁
R₂,
RA
www
www
R₁
R₁
www
A3
X
R₁
R₂
www
www
R₁₂
+
Vo
RA
A2
V2 O-
+
R₂
12
R₁
Show that the input impedance of a lossy transmission line of length L connected to a load
impedance of Z is given by
Z₁Cosh(yL) + ZoSinh(yL)
Zin = Zo ZoCosh(YL) + Z₁Sihh(YL)
ex
Where Cosh(x) =
and Sinh(x) =
are the hyperbolic cosine and sine, respectively.
2
2
Chapter 3 Solutions
MindTap Engineering, 1 term (6 months) Printed Access Card for Glover/Overbye/Sarma's Power System Analysis and Design, 6th
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