Match the following measuring equipment with their specific application:

(A) Kelvin double bridge                               (P) Capacitance

(B) Wind bridge                                              (Q) Self-inductance

(C) Schering bridge                                       (R) Frequency

(D) Maxwell’s bridge                                     (S) Low resistance

In a poly-phase squirrel-cage induction motor, increased starting torque can be obtained by

When a fixed amount of power is to be transmitted, the efficiency of transmission increases when

A fault occurring at the terminals at the terminals of an unloaded synchronous generator operating at its rated voltage has resulted in the following values of current and voltage

The fault that has occurred is _________________.

A generator is supplying 1 per unit power to an infinite bus through the system shown in figure. Following fault at F, circuit breakers  and  open simultaneously. The  relationships in per unit are given by

Pre-fault condition:

During fault condition:

When  remain closed:

After  open:

Calculate the critical angel  before which breakers

 and  must open so that synchronism is not lost.

A sample power system network is shown in figure. The reactance’s marked are in p.u. The p.u value of  of the Bus Admittance Matrix  is:

In a 4 bus system the circuit breakers and the various zones of protection are shown in figure. If the circuit breakers E, F and G trip, the location of the fault is on ___________

The operating state that distinguishes a silicon controlled rectifier (SCR) from a diode is

Figure shows the circuit schematic of a chopper driven, separately excited d.c. motor. The single-pole double-throw switch operates with a switching period  is 0.2. The motor may be assumed lossless, with an armature inductance of 10 mH. The motor draws an average current of 20A at a constant back emf of 80V, under steady state.

(a) Sketch and label the voltage waveform  of the chopper for one switching period

(b) Sketch and label the motor current  for one switching period.

(c) Evaluate the peak-to-peak current ripple of the motor.

Two identical watt-meters are connected to measure power in a 3-phase 3-wire balanced load. What is the load power factor if

(a)

(b) Either  is zero ____________

The three stage Johnson ring counter shown in figure is clock at a constant frequency of  from the starting stage of . The frequency of outputs  will be

The ratio and phase angle errors in a well designed current transformer (CT) are kept within specified limits by using

Figure shows an electric voltage regulator. The zener diode may be assumed to require a minimum current of 25 mA for satisfactory operations. The value of R required for satisfactory voltage regulation of the circuit is

Figure below shows a common emitter amplifier. The quiescent collector voltage of the circuit is approximately

With ideal operational amplifiers, the circuit in figure simulates the output equation

The signal flow graph of figure has ____________ forward paths/and ____________ feedback loops.

A first order system and its response to a unit step input are shown in figure. The system parameters are

a= _______________

K= _______________

A unity feedback system has an open-loop transfer function of the form         

Which of the loci shown in figure can be valid root-loci for the system?

Which of the following is the transfer function of a system having the Nyquist plot in figure?

The terminal voltage and currents of a two-port network are indicated on the figure. If the two-port is reciprocal, then

Complete the truth table for the combinational circuit shown in figure.

The relative current directions through the Primary (P) and Secondary (S) of a single phase transformer connected to a resistive load on the secondary side, are indicated in the various cross-sectional views given in figure. Which of these are correct representations

Damper winding is provided in a poly-phase synchronous motor in order to

The resolution of an 8-bit A/D converter is ________________%

The V-I characteristic as seen from the terminal pair (A,B) of the network of figure (a) is shown figure (b), if a variable resistance  is connected across the terminal pair (A,B), the maximum power that can be supplied to  would be

Two coils having equal resistance but different inductances are connected in series.

The time-constant of the series combination is:  

In the figure shown,  are ideal ammeters. If  read 5 and 13A respectively, reading of  will be

Level compounded D.C generator is used for which of the following applications?

In figure shown, assume the Zener diode and the operational amplifier to be ideal.        

( gain  )

Figure shows a bridge for measuring the resistance and inductance of a choke.

If the resistors  can have a variation of  and C a variation of  from their nominal values, estimate the percentage error in the evaluation of R and L.

Precautions are essential for ensuring that the secondary of a CT is not open circuited when the primary circuit carries a current because

A one port active network has an input admittance Y, the magnitude of which is shown in figure as a function of frequency. The circuit is resistive or capacitive in different frequency ranges.

Complete the following table:

Figure shows a common emitter amplifier

(a) Simplify the circuit by applying Thevenin’s theorem to the biasing network  at the base of the transistor

(b) Assuming  to be a short for the frequency range considered. Draw the small signal a.c. model of the circuit obtained in (a) by using the simple model for the transistor shown in figure.

(c) Evaluate the small signal gain of the amplifier.

The switch S in figure is closed at t=0. If  and  respectively, voltages across the capacitors in steady state will be :

A 500 MVA, 11 KV synchronous generator has 0.2 p.u. synchronous reactance. The p.u. synchronous reactance on the base values of 100 MVA and 22 KV is:

(a) Find the transfer function

 for the network shown in figure.

(b) What is the order of the system?

(c) Now if the inductance value is changed to 2H, what will be the order of the modified network?

A unity feedback system has the forward loop transfer function

(c) Without calculating the real-axis breakaway

 points. Sketch the form of root loci for the system

The system having the Bode magnitude plot shown in figure has the transfer function

The hysteresis and eddy current losses of a single phase transformer working on 200V, 50 Hz supply are  respectively. The percentage decrease in these, when operated on a 160V, 40 Hz supply are :

A prime mover drives a 6 pole, 3-phase induction frequency converter. The converter is connected to 60 Hz, 3-phase supply on the primary. If the prime mover speed is 3000 rpm, the frequencies of the possible outputs from the converter are

Ring main distribution system is preferred to a radial system, because

A 100 MVA generator with 10% reactance and a 200 MVA generator with 8% reactance (reactances on their own bases) are connected as shown in figure. The fault level on bus 1 is to be restricted to 1500 MVA. Calculate, on 100 MVA base.          

(i) The reactance of bus bar reactor X

(ii) Fault level of bus 2

(iii) MVA rating of circuit breaker C

A separately excited d.c. motor has to be run at 125% of rated speed when delivering 50% torque. The excitation will be _______________.

A 50 MVA, 132/66 kV, , three phase power transformer is protected by percentage differential relays. If the current transformers (CTs) located on the delta and wye sides of the power transformer are 300/5A and 1200/5A respectively.        

Match the functions of the following protective elements in SCR applications:

The current passing through a 10 Ohm resistor of figure (a) has the waveform in figure (b). The reading of the PMMC voltmeter connected across the resistor

A toroidal iron ring has a uniform cross-sectional area of 50, and a mean magnetic path length of 100mm. the ring has an air-gap of 1mm, the ring is excited with a dc current of 1 A through a coil of 100 turns wound uniformly along its length. The iron may be assumed to be perfect magnetic material. The effect of fringing at the gap may be assumed to increase the effective area of magnetic flux at the gap by 10%.

Evaluate
(a) The exciting mmf of the coil
(b) The effective reluctance of magnetic circuit
(c) The inductance of the coil
(d) The energy stored in the magnetic field under the above excitation.

Match the windings of a large D.C series motor and their functions:

The mica layer  in a parallel plate capacitor with an effective area of 120 has a damaged section equivalent to a hole of 0.5 mm diameter. Which of the following would be significantly affected by the damage?

In figure calculate

(a) The power delivered by each source

(b) The power dissipated in each resistor

A 5 kW, 400 V, 50 Hz, 4 pole, delta connected three-phase induction motor is supplied by a cable of negligible inductance. On starting the motor using a star-delta starter, it is found that the starting torque is the same on star as well as delta connection, due to the voltage drop in the feeder resistance. The equivalent circuit parameters of the motor are as follows:

Determine the feeder resistance.

A 10 kVA, 380V, 4-pole, 50 Hz, star-connected cyclindrical rotor alternator has a stator resistance and synchronous reactance of 1 ohm and 15 ohms respectively. It supplies a load of 8 kW at rated voltage and 0.8 power factor lagging.

An underdamped second-order system having a transfer function of the form has a frequency response plot shown in the figure. Then the system gain K is _______________ and the damping factor is approximately ___________________.

A 10 kW, 6 pole, D.C generator develops an EMF of 200V at 1500 rpm. The armature has a lap connected winding. The average flux density over a pole pitch is 0.9 Tesla. The length and diameter of the armature are 0.25m and 0.2m respectively. Calculate

(a) The flux per pole

(b) The total number of active conductors in the armature

(c) The torque developed by the machine when the armature supplies a current of 50A.

Two transmission lines are connected in cascade, whose ABCD parameters are         

Respectively. Find the resultant ABCD parameters.