Most viewed questions in Power Systems / GO Electrical

0 votes

0 answers

41

GATE Electrical 2015 Set 1 | Question: 16
Consider a HVDC link which uses thyristor based line-commutated converters as shown in the figure. For a power flow of $750$ MW from System $1$ to System $2$ ... $V_{1} = −500 \text{ kV} , V_{2} = −485 \text{ kV} $ and $I = −1.5 \text{ kA}$

Consider a HVDC link which uses thyristor based line-commutated converters as shown in the figure. For a power flow of $750$ MW from System $1$ to System $2$, the voltage...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

42

GATE Electrical 2014 Set 2 | Question: 6
Two identical coupled inductors are connected in series. The measured inductances for the two possible series connections are $380$ $μH$ and $240$ $μH$. Their mutual inductance in $μH$ is ________

Two identical coupled inductors are connected in series. The measured inductances for the two possible series connections are $380$ $μH$ and $240$ $μH$. Their mutual in...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

43

GATE Electrical 2015 Set 2 | Question: 17
A $3$-bus power system network consists of 3 transmission lines. The bus admittance matrix of the uncompensated system is $\begin{bmatrix} -j6 &j3 &j4 \\ j3&-j7 &j5 \\ j4& j5 & -j8 \end{bmatrix}$ pu. If the shunt ... $−j7.0$ $−j8.5$ $−j7.5$ $−j9.0$

A $3$-bus power system network consists of 3 transmission lines. The bus admittance matrix of the uncompensated system is$\begin{bmatrix}-j6 &j3 &j4 \\ j3&-j7 &j5 \\ ...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

44

GATE Electrical 2013 | Question: 52
In the following network, the voltage magnitudes at all buses are equal to $1 p.u.$, the voltage phase angles are very small, and the line resistances are negligible. All the line reactances are equal to $j1$ $\Omega.$ The voltage phase angles in rad at buses $2$ and $3$ ... $\theta _2=0,\theta _3=-0.1$ $\theta _2=0.1,\theta _3=0.1$ $\theta _2=0.1,\theta _3=0.2$

In the following network, the voltage magnitudes at all buses are equal to $1 p.u.$, the voltage phase angles are very small, and the line resistances are negligible. All...

piyag476

1.6k points

piyag476 asked Feb 11, 2017

0 votes

0 answers

45

GATE Electrical 2013 | Question: 33
For a power system network with $n$ nodes, $Z_{33}$ of its bus impedance matrix is $j0.5$ per unit. The voltage at node $3$ is $1.3\angle -10^{\circ}$ per unit. If a capacitor having reactance of $-j3.5$ ... $0.325\angle -100^{\circ}$ $0.325\angle 80^{\circ}$ $0.371\angle -100^{\circ}$ $0.433\angle 80^{\circ}$

For a power system network with $n$ nodes, $Z_{33}$ of its bus impedance matrix is $j0.5$ per unit. The voltage at node $3$ is $1.3\angle -10^{\circ}$ per unit. If a cap...

piyag476

1.6k points

piyag476 asked Feb 11, 2017

0 votes

0 answers

46

GATE Electrical 2014 Set 3 | Question: 6
The line $A$ to neutral voltage is $10\angle 15^\circ$ for a balanced three phase star-connected load with phase sequence $ABC$. The voltage of line $B$ with respect to line $C$ is given by $10\sqrt{3}\angle 105^\circ$ $10\angle 105^\circ$ $10\sqrt{3}\angle -75^\circ$ $-10\sqrt{3}\angle 90^\circ$

The line $A$ to neutral voltage is $10\angle 15^\circ$ for a balanced three phase star-connected load with phase sequence $ABC$. The voltage of line $B$ with respect to ...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

47

GATE Electrical 2014 Set 1 | Question: 31
In an unbalanced three phase system, phase current $I_a=1\angle (-90^{\circ})\: \text{pu}$ , negative sequence current $I_{b2}=4\angle (-150^{\circ})\: \text{pu}$, zero sequence current $I_{c0}=3\angle 90^{\circ}\: \text{pu}.$ The magnitude of phase current $I_b$ in $\text{pu}$ is $1.00$ $7.81$ $11.53$ $13.00$

In an unbalanced three phase system, phase current $I_a=1\angle (-90^{\circ})\: \text{pu}$ , negative sequence current $I_{b2}=4\angle (-150^{\circ})\: \text{pu}$, zero s...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

48

GATE Electrical 2015 Set 2 | Question: 20
Find the transformer ratios $a$ and $b$ such that the impedance ($Z_{in}$) is resistive and equals $2.5 \Omega$ when the network is excited with a sine wave voltage of angular frequency of $5000$ rad/s. $a = 0.5, b = 2.0$ $a = 2.0, b = 0.5$ $a = 1.0, b = 1.0$ $a = 4.0, b = 0.5$

Find the transformer ratios $a$ and $b$ such that the impedance ($Z_{in}$) is resistive and equals $2.5 \Omega$ when the network is excited with a sine wave voltage of an...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

49

GATE Electrical 2014 Set 2 | Question: 20
While measuring power of a three-phase balanced load by the two-wattmeter method, the readings are $100$ $W$ and $250$ $W$. The power factor of the load is ______.

While measuring power of a three-phase balanced load by the two-wattmeter method, the readings are $100$ $W$ and $250$ $W$. The power factor of the load is ______.

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

50

GATE Electrical 2016 Set 2 | Question: 54
An energy meter, having meter constant of $1200$ revolutions/kWh, makes $20$ revolutions in $30$ seconds for a constant load. The load, in $kW$, is __________.

An energy meter, having meter constant of $1200$ revolutions/kWh, makes $20$ revolutions in $30$ seconds for a constant load. The load, in $kW$, is __________.

makhdoom ghaya

9.4k points

makhdoom ghaya asked Jan 29, 2017

0 votes

0 answers

51

GATE Electrical 2014 Set 2 | Question: 40
A synchronous generator is connected to an infinite bus with excitation voltage $E_f$ = $1.3$ $pu$. The generator has a synchronous reactance of $1.1$ $pu$ and is delivering real power $(P)$ of $0.6$ $pu$ to the bus. ... Neglect stator resistance. The reactive power $(Q)$ in $pu$ supplied by the generator to the bus under this condition is _________.

A synchronous generator is connected to an infinite bus with excitation voltage $E_f$ = $1.3$ $pu$. The generator has a synchronous reactance of $1.1$ $pu$ and is deliver...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

52

GATE Electrical 2014 Set 3 | Question: 19
An $LPF$ wattmeter of power factor $0.2$ is having three voltage settings $300 V$, $150 V$ and $75 V$, and two current settings $5 A$ and $10 A$. The full scale reading is $150$. If the wattmeter is used with $150 V$ voltage setting and $10 A$ current setting, the multiplying factor of the wattmeter is _________.

An $LPF$ wattmeter of power factor $0.2$ is having three voltage settings $300 V$, $150 V$ and $75 V$, and two current settings $5 A$ and $10 A$. The full scale reading i...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

53

GATE Electrical 2016 Set 2 | Question: 14
A power system has $100$ buses including $10$ generator buses. For the load flow analysis using Newton-Raphson method in polar coordinates, the size of the Jacobian is $189 \times 189$ $100 \times 100$ $90 \times 90$ $180 \times 180$

A power system has $100$ buses including $10$ generator buses. For the load flow analysis using Newton-Raphson method in polar coordinates, the size of the Jacobian is$18...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Jan 29, 2017

0 votes

0 answers

54

GATE Electrical 2014 Set 2 | Question: 43
Three phase $100$ $MVA$ ,$25$ $kV$ generator has solidly grounded neutral. The positive, negative, and the zero sequence reactances of the generator are $0.2$ $pu$, $0.2$ $pu$, and $0.05$ $pu$, respectively, at ... phase to ground fault occurs at the terminal of the unloaded generator, the fault current in amperes immediately after the fault is _________.

Three phase $100$ $MVA$ ,$25$ $kV$ generator has solidly grounded neutral. The positive, negative, and the zero sequence reactances of the generator are $0.2$ $pu$, $0.2$...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

55

GATE Electrical 2014 Set 1 | Question: 45
The Bode magnitude plot of the transfer function $G(s)=\dfrac{K(1+0.5s)(1+as)}{s(1+\frac{s}{8})(1+bs)(1+\frac{s}{36})}$ is shown below: Note that $-6dB/octave = -20 dB/decade.$ The value of $\dfrac{a}{bK}$ is ________.

The Bode magnitude plot of the transfer function $G(s)=\dfrac{K(1+0.5s)(1+as)}{s(1+\frac{s}{8})(1+bs)(1+\frac{s}{36})}$ is shown below:Note that $-6dB/octave = -20 dB/dec...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

56

GATE Electrical 2014 Set 1 | Question: 40
A distribution feeder of $1\:km$ length having resistance, but negligible reactance, is fed from both the ends by $400V$, $50\:Hz$ balanced sources. Both voltage sources $S_1$ and $S_2$ are in phase. The feeder supplies concentrated loads of unity power factor as shown in the figure. ... $25\:A$ $50\:A$ and $50\:A$ $25\:A$ and $75\:A$ $0\:A$ and $100\:A$

A distribution feeder of $1\:km$ length having resistance, but negligible reactance, is fed from both the ends by $400V$, $50\:Hz$ balanced sources. Both voltage sources ...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

57

GATE Electrical 2015 Set 1 | Question: 54
Find the transfer function $\dfrac{Y(s)}{X(s)}$ of the system given below $\dfrac{G_{1}}{1-HG_{1}} + \dfrac{G_{2}}{1-HG_{2}} \\$ $\dfrac{G_{1}}{1+HG_{1}} + \dfrac{G_{2}}{1+HG_{2}} \\$ $\dfrac{G_{1}+G_{2}}{1+H (G_{1}+G_{2})} \\$ $\dfrac{G_{1}+G_{2}}{1-H (G_{1}+G_{2})}$

Find the transfer function $\dfrac{Y(s)}{X(s)}$ of the system given below$\dfrac{G_{1}}{1-HG_{1}} + \dfrac{G_{2}}{1-HG_{2}} \\$$\dfrac{G_{1}}{1+HG_{1}} + \dfrac{G_{2}}{1+...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

58

GATE Electrical 2014 Set 2 | Question: 41
There are two generators in a power system. No-load frequencies of the generators are $51.5$ $Hz$ and $51$ $Hz$, respectively, and both are having droop constant of $1$ $Hz$/$MW$. Total load in the system is ... are operating under their respective droop characteristics, the frequency of the power system in $Hz$ in the steady state is ___________.

There are two generators in a power system. No-load frequencies of the generators are $51.5$ $Hz$ and $51$ $Hz$, respectively, and both are having droop constant of $1$ $...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

59

GATE Electrical 2016 Set 1 | Question: 41
A $30 MVA$, $3$-phase, $50 Hz$, $13.8 kV$, star-connected synchronous generator has positive, negative and zero sequence reactances, $15\%$, $15\%$ and $5\%$ respectively. A reactance $(X_{n})$ is connected between the neutral of the ... The value of $X_{n}$ (in p.u.) that will limit the positive sequence generator current to $4270 \: A$ is ________.

A $30 MVA$, $3$-phase, $50 Hz$, $13.8 kV$, star-connected synchronous generator has positive, negative and zero sequence reactances, $15\%$, $15\%$ and $5\%$ respectively...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Jan 29, 2017

0 votes

0 answers

60

GATE Electrical 2014 Set 3 | Question: 42
The complex power consumed by a constant-voltage load is given by $(P_1+jQ_1)$, where, $1 \: kW \leq P_1 \leq 1.5 \text{ kW}$ and $0.5 \: \text{kVAR} \leq Q_1 \leq 1 \text{ kVAR}$. A compensating shunt ... is the net reactive power consumed by the capacitor-load combination. The reactive power (in $\text{kVAR}$) supplied by the capacitor is _________.

The complex power consumed by a constant-voltage load is given by $(P_1+jQ_1)$, where, $1 \: kW \leq P_1 \leq 1.5 \text{ kW}$ and $0.5 \: \text{kVAR} \leq Q_1 \leq 1 \te...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

61

GATE Electrical 2015 Set 1 | Question: 51
Two single-phase transformers $T_{1}$ and $T_{2}$ each rated at $500$ kVA are operated in parallel. Percentage impedances of $T_{1}$ and $T_{2}$ are $(1 + j6)$ and $(0.8 + j4.8)$, respectively. To share a load of $1000$ kVA at $0.8$ lagging power factor, the contribution of $T_{2}$ (in kVA) is _______.

Two single-phase transformers $T_{1}$ and $T_{2}$ each rated at $500$ kVA are operated in parallel. Percentage impedances of $T_{1}$ and $T_{2}$ are $(1 + j6)$ and $(0.8 ...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

62

GATE Electrical 2016 Set 1 | Question: 42
If the star side of the star-delta transformer shown in the figure is excited by a negative sequence voltage, then $V_{AB}$ leads $V_{ab}$ by $60^\circ$ $V_{AB}$ lags $V_{ab}$ by $60^\circ$ $V_{AB}$ leads $V_{ab}$ by $30^\circ$ $V_{AB}$ lags $V_{ab}$ by $30^\circ$

If the star side of the star-delta transformer shown in the figure is excited by a negative sequence voltage, then$V_{AB}$ leads $V_{ab}$ by $60^\circ$$V_{AB}$ lags $V_{a...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Jan 29, 2017

0 votes

0 answers

63

GATE Electrical 2016 Set 1 | Question: 40
A three-phase cable is supplying $800 kW$ and $600 kVAr$ to an inductive load. It is intended to supply an additional resistive load of $100 kW$ through the same cable without increasing the heat dissipation in the cable, by providing a three- ... voltage is $3.3 kV$, $50 Hz$, the capacitance per phase of the bank, expressed in microfarads, is ________.

A three-phase cable is supplying $800 kW$ and $600 kVAr$ to an inductive load. It is intended to supply an additional resistive load of $100 kW$ through the same cable wi...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Jan 29, 2017

0 votes

0 answers

64

GATE Electrical 2014 Set 2 | Question: 47
Suppose that resistors $R_1$ and $R_2$ are connected in parallel to give an equivalent resistor $R$. If resistors $R_1$ and $R_2$ have tolerance of $1 \%$ each, the equivalent resistor $R$ for resistors $R_1=300\: \Omega$ and $R_2 = 200 \: \Omega$ will have tolerance of $0.5 \%$ $1 \%$ $1.2 \%$ $2 \%$

Suppose that resistors $R_1$ and $R_2$ are connected in parallel to give an equivalent resistor $R$. If resistors $R_1$ and $R_2$ have tolerance of $1 \%$ each, the equiv...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

65

GATE Electrical 2013 | Question: 45
A $4$ – pole induction motor, supplied by a slightly unbalanced three-phase $50 Hz$ source, is rotating at $1400\:rpm$. The electrical frequency in $Hz$ of the induced negative sequence current in the rotor is $100$ $98$ $52$ $48$

A $4$ – pole induction motor, supplied by a slightly unbalanced three-phase $50 Hz$ source, is rotating at $1400\:rpm$. The electrical frequency in $Hz$ of the induced ...

piyag476

1.6k points

piyag476 asked Feb 11, 2017

0 votes

0 answers

66

GATE Electrical 2015 Set 1 | Question: 43
A $50 \text{ Hz}$ generating unit has H-constant of $2 \text{ MJ/MVA}$. The machine is initially operating in steady state at synchronous speed, and producing $1 \:pu$ of real power. The initial value of the rotor angle $\delta$ ... power to remain at $1 \: pu$, the value of $\delta$ in degrees, $0.02$ second after the fault is _________.

A $50 \text{ Hz}$ generating unit has H-constant of $2 \text{ MJ/MVA}$. The machine is initially operating in steady state at synchronous speed, and producing $1 \:pu$ of...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

67

GATE Electrical 2016 Set 2 | Question: 44
A single-phase, $2$ kVA, $100/200$ V transformer is reconnected as an auto-transformer such that its $kVA$ rating is maximum. The new rating, in $kVA$, is ______.

A single-phase, $2$ kVA, $100/200$ V transformer is reconnected as an auto-transformer such that its $kVA$ rating is maximum. The new rating, in $kVA$, is ______.

makhdoom ghaya

9.4k points

makhdoom ghaya asked Jan 29, 2017

0 votes

0 answers

68

GATE Electrical 2013 | Question: 47
When the $\text{Newton-Raphson}$ method is applied to solve the equation $f(x)=x^3+2x-1=0$ ,the solution at the end of the first iteration with the initial guess value as $x_0$ =$1.2$ is $-0.82$ $0.49$ $0.705$ $1.69$

When the $\text{Newton-Raphson}$ method is applied to solve the equation $f(x)=x^3+2x-1=0$ ,the solution at the end of the first iteration with the initial guess value a...

piyag476

1.6k points

piyag476 asked Feb 11, 2017

0 votes

0 answers

69

GATE Electrical 2016 Set 1 | Question: 49
A single-phase, $22 kVA, 2200 V/ 220 V, 50 Hz$, distribution transformer is to be connected as an auto-transformer to get an output voltage of $2420 V$. Its maximum $kVA$ rating as an autotransformer is $22$ $24.2$ $242$ $2420$

A single-phase, $22 kVA, 2200 V/ 220 V, 50 Hz$, distribution transformer is to be connected as an auto-transformer to get an output voltage of $2420 V$. Its maximum $kVA$...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Jan 29, 2017

0 votes

0 answers

70

GATE Electrical 2015 Set 1 | Question: 12
A steady current $I$ is flowing in the $-x$ direction through each of two infinitely long wires at $y = \pm \dfrac{L}{2}$ as shown in the figure. The permeability of the medium is $\mu_{0}$. The $\overrightarrow{B}$-field at $(0,L,0)$ ... $+\dfrac{4\mu _{0}I}{3\Pi L} \hat{Z} \\$ $0 \\$ $-\dfrac{3\mu _{0}I}{4\Pi L} \hat{Z}$

A steady current $I$ is flowing in the $-x$ direction through each of two infinitely long wires at $y = \pm \dfrac{L}{2}$ as shown in the figure. The permeability of the ...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

71

GATE Electrical 2016 Set 1 | Question: 19
In a $100$ bus power system, there are $10$ generators. In a particular iteration of Newton Raphson load flow technique (in polar coordinates), two of the $PV$ buses are converted to $PQ$ type. In this iteration, The ... decreases by two. The number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes decreases by two.

In a $100$ bus power system, there are $10$ generators. In a particular iteration of Newton Raphson load flow technique (in polar coordinates), two of the $PV$ buses are ...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Jan 29, 2017

0 votes

0 answers

72

GATE Electrical 2014 Set 2 | Question: 15
A three phase star-connected load is drawing power at a voltage of $0.9$ $pu$ and $0.8$ power factor lagging. The three phase base power and base current are $100$ $MVA$ and $437.384$ $A$ respectively. The line-to-line load voltage in $kV$ is ________.

A three phase star-connected load is drawing power at a voltage of $0.9$ $pu$ and $0.8$ power factor lagging. The three phase base power and base current are $100$ $MVA$ ...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017

0 votes

0 answers

73

GATE Electrical 2014 Set 2 | Question: 12
A single phase, $50$ $kVA$, $1000V$/$100V$ two winding transformer is connected as an autotransformer as shown in the figure. The $kVA$ rating of the autotransformer is _____________.

A single phase, $50$ $kVA$, $1000V$/$100V$ two winding transformer is connected as an autotransformer as shown in the figure.The $kVA$ rating of the autotransformer is __...

makhdoom ghaya

9.4k points

makhdoom ghaya asked Feb 11, 2017