Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II ELECTRICAL AND ELECTRONICS ENGINEERING Previous Question Paper (December - 2017 - R15)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
What is meant by active and passive elements? Give one example for each.
Answer
Active elements are components capable of generating or supplying energy to a circuit, such as a voltage or current source. Passive elements are components that consume or store energy, such as resistors, capacitors, or inductors. Examples: A battery is an active element, and a resistor is a passive element.
Define loading effect of an instrument?
Answer
The loading effect occurs when an instrument connected to a circuit alters the circuit's original operating conditions due to its own internal impedance. This leads to inaccurate measurements because the instrument draws current or changes the voltage distribution in the circuit it is intended to measure.
Why the external characteristics of a DC shunt generator is more drooping than that of a separately excited generator?
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What is the significance of back emf in DC motor?
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Full load copper loss in a transformer is 1600W. What will be the loss at half load?
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Why almost all large size Synchronous machines are constructed with rotating field system type?
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Draw the output waveform across the load resistance R, if the input waveform is as shown in Figure 1.
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A transistor is a current-controlled device. Justify the statement.
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What is meant by deflection factor of CRO?
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Give some applications of CRO.
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Part B
What are the essential requirements of measuring instruments?
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Three equal resistors each of R ohms are connected in delta. Derive the value of resistors in the equivalent star.
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Discuss about voltage and current division principles.
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Find the current through each branch shown in Figure 2 by network reduction technique.
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Give the classification of DC generators with their connection diagrams. Write their relevant voltage equations.
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A 500V dc shunt motor running at 700 rpm takes an armature current of 50A. Its effective armature resistance is 0.4Ω. What resistance must be placed in series with the armature to reduce the speed to 600 rpm, the torque remaining constant?
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Derive from the fundamental, emf equation of Dc generator.
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Describe the working of 3 point starter for DC shunt motor with neat diagram. What are the safety devices incorporated in starter?
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Explain in detail about torque -production process of synchronous machine(generating mode).
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A 40 kVA, 6600/250 V single phase transformer has the following parameters: R1 = 8Ω, R2 = 0.02Ω, X1= 15Ω and X2 = 0.05Ω. Find full-load regulation at power factor: i) 0.8 lagging ii) 0.8 leading.
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How do you determine the regulation of an alternator using synchronous impedance method experimentally?
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Deduce the equation for rotor current of a 3-phase induction motor.
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Obtain the expression for the diode current and draw the forward and reverse characteristic.
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Explain how a transistor acts as an amplifier.
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Explain about various current components in a forward biased p-n junction diode.
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What do you understand by the term ‘equivalent circuit’ of a transistor? Draw equivalent circuit of the generalized transistor amplifier.
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Draw the block diagram of a CRO and explain the different components.
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How is the frequency of an ac signal measured with the help of CRO? Explain in detail.
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What are the difference between dual trace and dual beam oscilloscopes?
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