Two wattmeters used to measure power of a 3-phase balanced load reads W_{1}, and W_{2}. The reactive Dower drawn bv the load is

- a)W
_{1}+ W_{2} - b)W
_{1 }- W_{2} - c)√3(W
_{1}+ W_{2}) - d)√3(W
_{1}- W_{2})

Correct answer is option 'D'. Can you explain this answer?

AMAN MEHROTRA answered • 9 hours ago

We know that:

(W_{1}-W_{2}) = V_{L}I_{L}sin φ = Q_{1 }- φ

so, Q_{3} - φ = √W_{1} - W_{2})

(W

so, Q

Arunpaul Paul asked • 14 minutes ago

The impulse response of an initially relaxed linear system is e^{-3t} u(t). To produce a response of te^{-3t} u(t), the input must be equal to

- a)3
^{e-t}u(t) - b)
- c)e-3
^{t }u(t) - d)e
^{-t}u(t)

Correct answer is option 'C'. Can you explain this answer?

ANIMESH SAHU answered • 9 hours ago

We know that, impulse response = =

Transfer fuction.

For given system,

Now, c(t) = t e^{-3t}

∴

So, R{s) = C(s) x (s + 3)

or, r(t) = Required input = e^{-3t} u(t)

Transfer fuction.

For given system,

Now, c(t) = t e

∴

So, R{s) = C(s) x (s + 3)

or, r(t) = Required input = e

Anil Swami asked • 20 minutes ago

Consider the following statements: In root-locus plot, the breakaway points

1. Ned not always be on real axis alone

2. Must lie on the root loci

4. Must lie between 0 and – 1

Which of these statements are correct ?

1. Ned not always be on real axis alone

2. Must lie on the root loci

4. Must lie between 0 and – 1

Which of these statements are correct ?

- a)1, 2 and 3
- b)1 and 3
- c)2 and 3
- d)None of the above

Correct answer is option 'B'. Can you explain this answer?

A linear time invariant system, initially at rest when subjected to a unit step input gave response c(t) = te^{-t}(t __>__ 0). The transfer function of the system is

- a)
- b)
- c)
- d)

Correct answer is option 'A'. Can you explain this answer?

NAMAN UPADHYAY answered • 9 hours ago

Given, c(t) = te^{-t}

∴

Now, r(t) = u(t) (unit step input)

∴

So,

∴

Now, r(t) = u(t) (unit step input)

∴

So,

The input to the 3-phase, 50 Hz circuit shown in figure below is 100 V. For a phase sequence of ABC, the wattmeters would read

- a)W
_{1}= 866 W and W_{2}= 866 W - b)W
_{1}= 577.35 W and W_{2}= 1154.70 W - c)W
_{1}= 1154.72 W and W_{2 }= 577.36 W - d)W
_{1}= 1732 W and W_{2}= 0 W

Correct answer is option 'B'. Can you explain this answer?

DIVANSHU GUPTA answered • 9 hours ago

Wattmeter readings are:

W_{1} = V_{L}I_{L} cos (30 + φ)

and W_{2} = \/_{L}I_{L} cos (30 - φ)

Here,

and φ = 30°

∴

Now,

and

W

and W

Here,

and φ = 30°

∴

Now,

and

Saurav Kumar asked • 44 minutes ago

In connection with arc the extinction in circuit breaker, resistance switching is employed where in a resistance is placed in parallel with the poles of the circuit breaker as shown in the figure. This process introduces damping in the LC circuit. For critical damping, the value of 'R' should be equal to

- a)
- b)
- c)
- d)

Correct answer is option 'C'. Can you explain this answer?

The Laplace transform of unity function is

- a)1
- b)zero
- c)s
- d)1/s

Correct answer is option 'D'. Can you explain this answer?

NAVEEN TYAGI answered • 9 hours ago

The laplace transform of unity function i.e.

Consider the function F(s) = where F(s) is the Laplace transform of f(t) is equal to

- a)5
- b)2.5
- c)infinity
- d)zero

Correct answer is option 'B'. Can you explain this answer?

ANOOP KUMAR answered • 9 hours ago

Using final value theorem

A three-phase 220 V supply is applied to a balanced A-connected three phase load. The phase current being I_{ab} =. 10∠-30°A as shown in the given figure, The total power received by the Δ-load is

- a)2250 W
- b)6232 W
- c)5715 W
- d)-2200 W

Correct answer is option 'C'. Can you explain this answer?

AVANEENDRA JODHA answered • 9 hours ago

I_{ab} = 10∠-30°A

So, 1_{bc }= 10∠-150°A

and I_{ca} = 10∠-270° A

Phase current,

I_{a} = I_{ab }- I ca = ( 10 ∠- 30° - 10∠-270°) A

= 10[cos 30° - jsin 30° - cos 270° + jsin 270°]

= 10[0.866- j0 .5 - 0 - j1]

= 8.66-j15 = 17.32 ∠-60° A

∴ I_{a} = 17.32 ∠-60°A

∴ Total power received

= √3 V_{L}I_{L} cos φ_{L}

= 3V_{P}I_{P} cos φ_{ph}

= 3 x 220 x 10 x cos 30°

= 5715W

So, 1

and I

Phase current,

I

= 10[cos 30° - jsin 30° - cos 270° + jsin 270°]

= 10[0.866- j0 .5 - 0 - j1]

= 8.66-j15 = 17.32 ∠-60° A

∴ I

∴ Total power received

= √3 V

= 3V

= 3 x 220 x 10 x cos 30°

= 5715W

Kishan Pathak asked • 1 hour ago

As compared to full wave rectifier using two diodes, the four diode bridge rectifier has the dominant advantage of

- a)higher current carrying capacity
- b)lower peak inverse voltage requirement
- c)lower ripple factor
- d)higher efficiency

Correct answer is option 'B'. Can you explain this answer?

Which of the following is not true regarding an open loop control system?

- a)Highly affected by non-linearities.
- b)Open loop systems are inaccurate.
- c)These are not reliable.
- d)The effect of parameter variation and internal noise is less.

Correct answer is option 'D'. Can you explain this answer?

ANURAG ANNAPURNA answered • 9 hours ago

The effect of parameter variation and internal noise is more in an open loop system.

Indrajit Mal asked • 2 hours ago

A pure capacitance connected across 50Hz, 230V supply consumes 0.04W. This consumption is attributed to

- a)ohmic loss due to ohmic resistance of plates
- b)loss of energy in dielectrics
- c)capacitive reactance in ohms
- d)both (a) & (b)

Correct answer is option 'D'. Can you explain this answer?

The unit impulse response of a control system is given by c(t) = -te^{-t} + e^{-t}. Its transfer function is

- a)
- b)
- c)
- d)

Correct answer is option 'D'. Can you explain this answer?

HARSH RAJ answered • 9 hours ago

Given, c(t) = -te^{-t} + e^{-t} (impulse response)

We know that,

(Impuise response} = Transfer function (H(s))

∴

We know that,

(Impuise response} = Transfer function (H(s))

∴

Galloping in transmission line conductors arises generally due to

- a)Asymmetrical layers of ice formation
- b)Vortex phenomenon in light winds
- c)Heavy weight of the line conductor configuretions
- d)Adoption of horizontal conductor configuretions

Correct answer is option 'A'. Can you explain this answer?

SHAHIL AGRAWAL answered • 9 hours ago

Jeya Kumar asked • 3 hours ago

A 2-terminal network consist of one of the RLC elements. The element is connected to an ac supply. The current through the element is IA when an inductor is inserted in series between the source and element 2IA the current through the element becomes. What is this element ?

- a)A resistor
- b)An inductor
- c)A capacitor
- d)Cannot be a single element

Correct answer is option 'C'. Can you explain this answer?

Manoj Pawar asked • 5 hours ago

In the optimum generator scheduling different power plants, the minimum fuel cost is obtained when

- a)only the incremental fuel cost of each plant is the same
- b)the penalty factor of each plant is the same
- c)the ratio of the incremental fuel cost to the penalty factor of each plant is the same.
- d)the incremental fuel cost of each plant multiplied by its penalty factor is the same

Correct answer is option 'D'. Can you explain this answer?

Manoj Sharma asked • 5 hours ago

In a thyrite lightning arrester the resistance

- a)varies linearly with applied voltage
- b)increases with the applied voltage
- c)Decreases linearly with the applied voltage
- d)is high at low current and low at high current

Correct answer is option 'D'. Can you explain this answer?

Mohsin Khan asked • 6 hours ago

While using air-blast circuit beaker, current chopping is a phenomenon often observed when

- a)A long overhead line is switched off
- b)A bank of capacitors is switched off
- c)A transformer on no-load is switched off
- d)A heavy load is switched off

Correct answer is option 'C'. Can you explain this answer?

Aman Sajwan asked • 7 hours ago

In a 3 phase full converter, the firing angle is less than 60º. The instantaneous output voltage

- a)will have positive part only
- b)will have both positive and negative parts
- c)may have both positive and negative parts
- d)will have negative part if load is inductive

Correct answer is option 'A'. Can you explain this answer?

Pinkesh Patel asked • 7 hours ago

The output of a continuous-time linear time-invariant system is denoted by T{x(t)} where x(t) is the input signal A signal z(t) is called eigen-signal of the system T, when T{z(t)} = yz(t), where γ is a complex number, in general and is called an eigenvalue of T. Suppose the impulse response of the system T is real and even. Which of the following statements is TRUE?

- a)cos(t) is an eigen-signal but sin(t) is not
- b)cos(t) and sin(t) are both eigen-signals but with different eigenvalues
- c)sin(t) is an eigen-signal but cos(t) is not
- d)cos(t) and sin(t) are both eigen-signals with identical eigenvalues

Correct answer is option 'D'. Can you explain this answer?

Renjiv Mohanan asked • 8 hours ago

In extrinsic semiconductor, conductivity varies with respect to temperature.

- a)For low temperature, it decreases then increases
- b)It decreases as temperature increases
- c)It increases as temperature increases
- d)For low temperature it increases then increases

Correct answer is option 'B'. Can you explain this answer?

Potu Madhavi asked • 11 hours ago

For the same voltage drop, increasing the voltage of a distributor n-times.

- a)reduces the x-section of the conductor by n times
- b)increases the x-section of the conductor by n times
- c)reduces the x-section of the conductor by n
^{2}times - d)increases the x-section of the conductor by n
^{2 }times.

Correct answer is option 'A'. Can you explain this answer?

Shital Devake asked • 13 hours ago

Galloping in transmission line conductors arises generally due to

- a)Asymmetrical layers of ice formation
- b)Vortex phenomenon in light winds
- c)Heavy weight of the line conductors
- d)Adoption of horizontal conductor configurations

Correct answer is option 'A'. Can you explain this answer?

Taranhaar Kumar asked • 13 hours ago

Voltage remaining constant, if the frequency is increased then

- a)eddy current losses will decrease
- b)hysteresis loss will decrease
- c)eddy current losses will remain unchanged
- d)hysteresis losses will remain unchanged

Correct answer is option 'C'. Can you explain this answer?

Md Suhail Khan asked • 13 hours ago

Which property of delta function indicates the equality between the area under the product of function with shifted impulse and the value of function located at unit impulse instant ?

- a)Replication
- b)Sampling
- c)Scaling
- d)Product

Correct answer is option 'B'. Can you explain this answer?

Suraj Kumar asked • 13 hours ago

Which of the following device can be used as a phase advancer ?

- a)3-f induction motor squirrel cage type
- b)3-f induction motor slip ring type
- c)synchronous motor working at leading power factor
- d)synchronous motor working at lagging power factor

Correct answer is option 'C'. Can you explain this answer?

Sunil Manjani asked • 15 hours ago

The Hartley-Shannon theorem sets a limit on the

- a)highest frequency that may be sent over a given channel
- b)maximum capacity of channel with a given noise level
- c)maximum number of coding levels in a channel with a given noise level
- d)maximum number of quantizing levels in a channel with a given noise level

Correct answer is option 'B'. Can you explain this answer?

Irshad Shaikh asked • 16 hours ago

The action of JFET in its equivalent circuit can best be represented as a

- a)current controlled current source
- b)current controlled voltage source
- c)voltage controlled voltage source
- d)voltage controlled current source

Correct answer is option 'D'. Can you explain this answer?

Hemalatha S asked • 16 hours ago

The use of electronic instruments is becoming more extensive because they have

- a)the capability to respond to signals from remote places
- b)afast response and compatibility with digital computers
- c)both (a) and (b)
- d)a high sensitivity but less reliability

Correct answer is option 'C'. Can you explain this answer?

Pinkesh Patel asked • 16 hours ago

In the feedback network shown below, if the feedback factor k is increased, then the

- a)input impedance increases and other output impedance decreases
- b)input impedance increases and output impedance also increases.
- c)input impedance decreases and output impedance also decreases.
- d)input impedance decreases and output impedance increases.

Correct answer is option 'A'. Can you explain this answer?

Pinkesh Patel asked • 16 hours ago

The Voltage Source Inverter (VSI) shown in the figure below is switched to provide a 50Hz, square wave ac output voltage v_{o} across an RL load. Reference polarity of v_{o} and reference direction of the output current i_{o} are indicated in the figure. It is given that R = 3 ohms, L = 9.55mH.

Appropriate transition i.e., Zero Voltage Switching (ZVS) / Zero Current Switching (ZCS) of the IGBTs during turn-on / turn-off is

- a)ZVS during turn off
- b)ZVS during turn-on
- c)ZCS during turn off
- d)ZCS during turn-on

Correct answer is option 'D'. Can you explain this answer?

Amit Parashar asked • 18 hours ago

A 50 Hz, 11 kV, 3 phase alternator with earthed neutral having a reactance of 3 ohms per phase and is connected to a bus bar through a circuit breaker, if the distributed capacitance upto CB between the phase and neutral is 0.01 μ F.

What is the peak re striking voltage?

- a)18.36 kV
- b)17.96 kV
- c)15.96 kV
- d)12.65 kV

Correct answer is option 'B'. Can you explain this answer?

Pinkesh Patel asked • 19 hours ago

In the circuit shown below, Q_{1 }has negligible collector-to-emitter saturation voltage and the diode drops negligible voltage across it under forward bias. If V_{cc }is +5V, X and Y are digital signals with 0V as logic 0 and V_{oc} as logic 1, then the Boolean expression for Z is

- a)XY
- b)
- c)
- d)

Correct answer is option 'B'. Can you explain this answer?

Digvijay Kumar asked • 19 hours ago

The load currents in short-circuit calculation are neglected because

1. short-circuit currents are much larger than load currents.

2. short-circuit currents are greatly out of phase with load currents.

Which of these statement(s) is/are correct ?

1. short-circuit currents are much larger than load currents.

2. short-circuit currents are greatly out of phase with load currents.

Which of these statement(s) is/are correct ?

- a)neither 1 nor 2
- b)2 alone
- c)1 alone
- d)1 and 2

Correct answer is option 'C'. Can you explain this answer?

Pinkesh Patel asked • 19 hours ago

Statement for Linked Answer Questions: 64 & 65

The Voltage Source Inverter (VSI) shown in the figure below is switched to provide a 50Hz, square wave ac output voltage v_{o} across an RL load. Reference polarity of v_{o} and reference direction of the output current i_{o} are indicated in the figure. It is given that R = 3 ohms, L = 9.55mH.

In the interval when v_{o} < 0 and i_{o} > 0 the pair of devices which conducts the load current is

- a)Q
_{1}, Q_{2} - b)Q
_{3}, Q_{4} - c)D
_{1}, D_{2} - d)D
_{1}, D_{2}

Correct answer is option 'D'. Can you explain this answer?

Vikash Kumar asked • 20 hours ago

A squirrel cage induction motor having a rated slip of 2% on full load has a starting torque of 50% of full load torque. The starting current is

- a)two times the full load current
- b)four times the full load current
- c)five times the full load current
- d)equal to the full load current

Correct answer is option 'C'. Can you explain this answer?

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