Hot questions in Power Systems / GO Electrical

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41

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

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makhdoom ghaya asked Feb 11, 2017

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42

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

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43

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

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44

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

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makhdoom ghaya asked Feb 11, 2017

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45

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

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makhdoom ghaya asked Feb 11, 2017

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46

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

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piyag476 asked Feb 11, 2017

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47

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

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makhdoom ghaya asked Feb 11, 2017

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48

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

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piyag476 asked Feb 11, 2017

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49

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

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makhdoom ghaya asked Feb 11, 2017

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50

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

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makhdoom ghaya asked Feb 11, 2017

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51

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

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makhdoom ghaya asked Feb 11, 2017

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52

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

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makhdoom ghaya asked Feb 11, 2017

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53

GATE Electrical 2016 Set 2 | Question: 53
Two identical unloaded generators are connected in parallel as shown in the figure. Both the generators are having positive, negative and zero sequence impedances of $j0.4$ p.u., $j0.3$ p.u. and $j0.15$ p.u., respectively. If the pre-fault ... a line-to-ground $(L-G)$ fault at the terminals of the generators, the fault current, in p.u., is ___________.

Two identical unloaded generators are connected in parallel as shown in the figure. Both the generators are having positive, negative and zero sequence impedances of $j0....

makhdoom ghaya

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makhdoom ghaya asked Jan 29, 2017

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54

GATE Electrical 2016 Set 2 | Question: 36
In the balanced $3$-phase, $50$ Hz, circuit shown below, the value of inductance $(L)$ is $10$ mH. The value of the capacitance $(C)$ for which all the line currents are zero, in millifarads, is ___________.

In the balanced $3$-phase, $50$ Hz, circuit shown below, the value of inductance $(L)$ is $10$ mH. The value of the capacitance $(C)$ for which all the line currents are ...

makhdoom ghaya

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makhdoom ghaya asked Jan 29, 2017

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55

GATE Electrical 2016 Set 1 | Question: 21
Consider a system consisting of a synchronous generator working at a lagging power factor, a synchronous motor working at an overexcited condition and a directly grid-connected induction generator. Consider capacitive $VAr$ to be a ... source and induction generator and synchronous generator are sinks of reactive power. All are sources of reactive power.

Consider a system consisting of a synchronous generator working at a lagging power factor, a synchronous motor working at an overexcited condition and a directly grid-con...

makhdoom ghaya

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makhdoom ghaya asked Jan 29, 2017

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56

GATE Electrical 2016 Set 2 | Question: 38
The single line diagram of a balanced power system is shown in the figure. The voltage magnitude at the generator internal bus is constant and $1.0$ p.u. The p.u. reactances of different components in the system are ... transferred during the pre-fault condition to the maximum real power that can be transferred under the faulted condition is _________.

The single line diagram of a balanced power system is shown in the figure. The voltage magnitude at the generator internal bus is constant and $1.0$ p.u. The p.u. reactan...

makhdoom ghaya

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makhdoom ghaya asked Jan 29, 2017

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57

GATE Electrical 2016 Set 2 | Question: 13
A power system with two generators is shown in the figure below. The system (generators, buses and transmission lines) is protected by six overcurrent relays $R_{1}$ to $R_{6}$ ... are $R_{1}, R_{2}$ $R_{2}, R_{6}$ $R_{2}, R_{5}$ $R_{1}, R_{6}$

A power system with two generators is shown in the figure below. The system (generators, buses and transmission lines) is protected by six overcurrent relays $R_{1}$ to $...

makhdoom ghaya

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makhdoom ghaya asked Jan 29, 2017

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58

GATE Electrical 2016 Set 2 | Question: 41
The power consumption of an industry is $500$ kVA, at $0.8$ p.f. lagging. A synchronous motor is added to raise the power factor of the industry to unity. If the power intake of the motor is $100$ kW, the p.f. of the motor is ___________.

The power consumption of an industry is $500$ kVA, at $0.8$ p.f. lagging. A synchronous motor is added to raise the power factor of the industry to unity. If the power in...

makhdoom ghaya

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makhdoom ghaya asked Jan 29, 2017

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59

GATE Electrical 2016 Set 2 | Question: 51
Three single-phase transformers are connected to form a delta-star three-phase transformer of $110$ kV/ $11$ kV. The transformer supplies at $11$ kV a load of $8$ MW at $0.8$ p.f. lagging to a nearby plant. Neglect the transformer losses. The ratio of phase currents in delta side to star side is $1 : 10\sqrt{3}$ $10\sqrt{3} : 1$ $1 : 10$ $\sqrt{3} : 10$

Three single-phase transformers are connected to form a delta-star three-phase transformer of $110$ kV/ $11$ kV. The transformer supplies at $11$ kV a load of $8$ MW at $...

makhdoom ghaya

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makhdoom ghaya asked Jan 29, 2017

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60

GATE Electrical 2016 Set 1 | Question: 20
The magnitude of three-phase fault currents at buses $A$ and $B$ of a power system are $10$ pu and $8$ pu, respectively. Neglect all resistances in the system and consider the pre-fault system to be unloaded. The pre-fault voltage at all buses in the ... $0.8$ pu. The voltage magnitude at bus $A$ during a three-phase fault at bus $B$, in pu, is __________.

The magnitude of three-phase fault currents at buses $A$ and $B$ of a power system are $10$ pu and $8$ pu, respectively. Neglect all resistances in the system and conside...

makhdoom ghaya

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makhdoom ghaya asked Jan 29, 2017