GATE EE 2008 | Synchronous Machines Question 29 | Electrical Machines

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GATE EE 2008

MCQ (Single Correct Answer)

-0.3

In a stepper motor, the detent torque means

minimum of the static torque with phase winding excited.

maximum of the static torque with phase winding excited.

minimum of the static torque with phase winding unexcited

maximum of the static torque with the phase winding unexcited

GATE EE 2007

MCQ (Single Correct Answer)

-0.3

A three phase synchronous motor connected to ac mains is running at full load and unity power factor. If its shaft load is reduced by half, with field current held constant, its new power factor will be

unity

leading

lagging

dependent on machine parameters

GATE EE 2006

MCQ (Single Correct Answer)

-0.3

A synchronous generator is feeding a zero power factor (lagging) load at rated current the armature reaction is

magnetizing

demagnetizing

cross magnetizing

Ineffective

GATE EE 2005

MCQ (Single Correct Answer)

-0.3

In relation to the synchronous machines, which one of the following statements is false?

In salient pole machines, the direct-axis synchronous reactance is greater than the quadrature-axis synchronous reactance

The damper bars help the synchronous motor self-start

Short circuit ratio is the ratio of the field current required to produce the rated voltage on open circuit to the rated armature current

The V-curve of a synchronous motor represents the variation in the armature current with field excitation, at a given output power

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GATE EE Subjects

Electric Circuits

Network Elements Network Theorems Three Phase Circuits Transient Response Sinusoidal Steady State Analysis Graph Theory Two Port Networks

Electromagnetic Fields

Time Varying Fields Electrostatics Magnetostatics

Signals and Systems

Linear Time Invariant Systems Continuous and Discrete Time Signals Continuous Time Signal Fourier Transform Continuous Time Periodic Signal Fourier Series Discrete Time Signal Z Transformation Miscellaneous Continuous Time Signal Laplace Transform Sampling Theorem

Electrical Machines

Induction Machines D.C Machines Synchronous Machines Transformers

Engineering Mathematics

Linear Algebra Differential Equations Calculus Probability and Statistics Numerical Methods Vector Calculus Transform Theory Complex Variable

General Aptitude

Verbal Ability Logical Reasoning Numerical Ability

Power System Analysis

Parameters and Performance of Transmission Lines Power Generation Cost Power System Stability Symmetrical Components and Symmetrical and Unsymmetrical Faults Circuit Breaker Switch Gear and Protection Per Unit System Load Flow Studies High Voltage Dc Transmission Generating Power Station

Electrical and Electronics Measurement

Error Analysis and Measurement Basic of Indicating Instruments Potentiometer and Instrument Transformers Measurement of Resistance and A.C Bridges Measurement of Energy and Power Digital Voltmeters Questions Cathode Ray Oscilloscope

Analog Electronics

Diode Circuits and Applications Bjt and Mosfet Biasing Small Signal Modeling Feedback Amplifiers and Oscillator Circuits Operational Amplifier Frequency Response 555 Timer

Control Systems

Block Diagram and Signal Flow Graph Polar Nyquist and Bode Plot State Variable Analysis Basics of Control System Routh Hurwitz Stability Time Response Analysis Root Locus Techniques Controller and Compensator

Power Electronics

Choppers and Commutation Techniques Ac Voltage Controllers Single and Three Phase Rectifier Power Semiconductor Devices Inverters

Digital Electronics

Boolean Algebra Logic Gates Combinational Circuits Minimization Logic Families and Memories Sequential Circuits Analog to Digital and Digital to Analog Converter Microprocessor