If in a Y-connected ac generator, each phase voltage has a magnitude of 90 VRMS, what is the magnitude of each line voltage?

A three-phase cylindrical rotor synchronous generator has a synchronous reactance Xs and a negligible armature resistance. The magnitude of per phase terminal voltage is VA and the magnitude of per phase induced emf is EA. Considering the following two statements, P and Q, P: For any three-phase balanced leading load connected across the terminals of this synchronous generator, VA is always more than EA Q: For any three-phase balanced lagging load connected across the terminals of this synchronous generator, VA is always less than EA Which of the following options is correct?

A

P is false and Q is true

B

P is true and Q is false

C

P is false and Q is false

D

P is true and Q is true

Transient stability of the generator is dependent on (a) generator reactance; lower reactance decreases peak power and increases initial rotor angle. (b) how heavily the generator is loaded. (c) generator inertia; higher the inertia, slower the rate of the change of angle. (d) generator output during fault Which of the above is incorrect?

A

a

B

b

C

c

D

None of the above

A 50 Hz synchronous generator is initially connected to a long lossless transmission line which is open circuited at the receiving end. With the field voltage held constant, the generator is disconnected from the transmission line. Which of the following may be said about the steady state terminal voltage and field current of the generator?

A

The magnitude of terminal voltage decreases, and the field current does not change.

B

The magnitude of terminal voltage increases, and the field current does not change.

C

The magnitude of terminal voltage increases, and the field current increases.

D

The magnitude of terminal voltage does not change and the field current decreases.

Which of the following statements is/are correct with respect to a Scott-connected transformer? I. It can do 3-phase to 2-phase conversion II. It can do 2-phase to 3-phase conversion III. It can do 2-phase to 4-phase conversion IV. It can do 3-phase to 4-phase conversion

A

Statements IV and II

B

Statement II only

C

Statements III and IV

D

Statements I and II

The network formed by resistors and capacitors for modifying the rate of change of gain and the phase shift is called a compensating network. Which of the following statements are not correct ? (A) The main purpose of a compensating network is to modify the performance of op-amp ciruit over the desired frequency range (B) There are two types of op-amps : internally compensated and externally compensated (C) 741 C is an externally compensated op-amp while 709 C is internally compensated op-amp (D) The phase lag and phase lead are most commonly used compensating networks in op-amps (E) Phase lag contributes a positive phase angle and phase lead a negative phase angle Choose the most appropriate answer from the options given below :

A

(B) and (C) only

B

(B) and (E) only

C

(C) and (D) only

D

(C) and (E) only

In a turbopump system using a gas generator cycle, the flame temperature in the separate gas generator where a small portion of overall propellant is burned is _________ compared to the main gas generator and its mixture ratio is _________ compared to that of the main gas generator.

A

same, lower

B

lower, different

C

lower, higher

D

higher, different

Consider the following statements regarding parallel connection of 3-phase transformers: 1. The secondaries of all transformers must have the same phase sequence. 2. The phase displacement between primary and secondary line voltages must be the same for all transformers which are to be operated in parallel. 3. The primaries of all transformers must have the same magnitude of line voltage. Which of the above statements are correct?

A

1, 2 and 3

B

1 and 3 only

C

1 and 2 only

D

2 and 3 only

Assertion: The process of testing the frequency response of amplifier and filter can be done by sweep frequency generator that automatically varies its frequency over a pre-determined range. Reason: The sweep frequency generator should have a ramp generator which applies a linear ramp voltage the input of a voltage tuned oscillator (VTO).

A

Both A and R is true and R is the correct explanation of A

B

Both A and R is true and R is not the correct explanation of A

C

A is true but R is false

D

A is false but R is true

A three-phase ∆-connected generator is driving a balanced load such that each phase current is 12 A in magnitude. When I_θa = 12 ∠30° A, what are the polar expressions for the other phase currents?

A

I_θb = 12 ∠150° A, I_θc = 12 ∠-90° A

B

I_θb = 12 ∠120° A, I_θc = 12 ∠30° A

C

I_θb = 12 ∠30° A, I_θc = 12 ∠120° A

D

I_θb = 12∠ 90° A, I_θc = 12 ∠90° A

Two generators A and B have 6 poles each. Generator A has wave wound armature while generator B has lap wound armature. The ratio of the induced e.m.f. is generator A and B will be

A

2 : 3

B

3 : 1

C

3 : 2

D

1 : 3

If in a Y-connected ac generator, each phase voltage has a magnitude of 90 VRMS, what is the magnitude of each line voltage?

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