The octal equivalent of the HEX number AB.CD is

The value of   where C is the contour  is

Let a signal be applied to a stable linear lime-invariant system. Let the corresponding steady state output be represented as. Then which of the following statements is true?

The frequency spectrum of a signal is shown in the figure. If this signal is ideally sampled at intervals of 1ms. Then the frequency spectrum of the sampled signal will be

A voltage source inverter is used to control the speed of a three-phase, 50 Hz, squirrel cage induction motor. Its slip for rated torque is 4%. The flux is maintained at rated value. If the stator resistance and rotational losses are neglected, then the frequency of the impressed voltage to obtain the rated torque at starting should be

Consider the discrete-time system shown in the figure where the impulse response of G(z) is g(0) = 0, g(1) = g(2) = 1, g(3) = g(4) = ……. = 0

This system is stable for range of values of K

The matrix A given below is the node incidence matrix of a network. The columns correspond to branches of the network while the rows correspond to nodes.  Let denote the vector of branch voltages while that of branch currents. The vector denotes the vector of node voltages relative to a common ground.

Which of the following statements is true?

The differential equation is discretized using Euler's numerical integration method with a time step ΔT > 0.  What is the maximum permissible value of ΔT to ensure stability of the solution of the corresponding discrete time equation?

A loaded dice has following probability distribution of occurrences

If three identical dice as the above are thrown, the probability of occurrence of values

1, 5 and 6 on the three dice is

,  are Z-transforms of two signals x[n], y[n] respectively.  A linear time invariant system has the impulse response h[n] defined by these two signals as , where * denotes discrete time convolution. Then the output of the system for the input  

The system is to be compensated such that its gain-crossover frequency becomes same as its uncompensated phase-crossover frequency and provides a 45° phase margin. To achieve this, one may use         

A signal is processed by a causal filter with transfer function G(s). For a distortion free output signal waveform, G(s) must

If u(t), r(t) denote the unit step and unit ramp functions respectively and u(t)*r(t) their convolution. Then the function u(t+1)*r(t−2) is given by

The incremental cost curves in Rs/MWhr for two generators supplying a common load of 700 MW are shown in the figures. The maximum and minimum generation limits are also indicated. The optimum generation schedule is:                 

Divergence of the vector field

is

 is a low-pass digital filter with a phase characteristics same as that of the above question if

A bridge circuit is shown in the figure below. Which one of the sequences given below is most suitable for balancing the bridge?

The integral equals

A signal x(t) is given by         

Which among the following gives the fundamental Fourier term of x(t)?

IC 555 in the adjacent figure is configured as an Astable multi-vibrator. It is enabled to oscillate at t=0 by applying a high input to pin 4. The pin description is: 1 and 8 − supply: 2-trigger; 4-reset; 6-threshold; 7-discharge. The waveform appearing across the capacitor starting from t=0, as observed on a storage CRO is

A three-phase, three-stack, variable reluctance step motor has 20 poles on each rotor and stator stack. The step angle of this step motor is

A, B, C and D are input bits, and Y is the output bit in the XOR gate circuit of the figure below. Which of the following statements about the sum S of A. B, C, D and Y is correct?

The probes of a non-isolated, two-channel oscilloscope are clipped to points A. B and C in the circuit of the adjacent figure Vin is a square wave of a suitable low frequency. The display on Ch1 and Ch2 are as shown on the right.  Then the “Signal” and “Ground” probes S1, G1 and S2, G2 of Ch1 and Ch2 respectively are connected to points

"Six MOSFETs connected in a bridge configuration (having no other power device) MUST be operated as a Voltage Source Inverter (VSI)'". This statement is

The system shown in figure below,

Can be reduced to the form

With        

A single-phase voltage source inverter is controlled in a single pulse-width modulated mode with a pulse width of 150° in each half cycle. Total harmonic distortion is defined as , where  is the RMS value of the fundamental component of the output voltage. The THD of output AC voltage waveform is

The system shown in the figure is         

The figure below shows a three phase self-commutated voltage source converter connected to a power system. The converter's dc bus capacitor is marked as C in the figure. The circuit is initially operating in steady state with δ = 0 and the capacitor dc voltage is equal to . You may neglect all losses and harmonics. What action should be taken to increase the capacitor dc voltage slowly to a new steady slate value?

If the loop gain K of a negative feedback system having a loop transfer function is to be adjusted to induce a sustained oscillation then        

The state equation for the current , shown in the network shown below in terms of the voltage , and the independent source V, is given by

is an n-tuple nonzero vector.  The n × n matrix

Let x and y be two vectors in a 3 dimensional space and <x, y> denote their dot product. Then the determinant

Which one of the following statements regarding the INT (interrupt) and the BRQ (bus request) pins in a CPU is true?

Consider a synchronous generator connected to an infinite bus by two identical parallel transmission lines. The transient reactance x' of the generator is 0.1pu and the mechanical power input to it is constant at 1.0pu. Due to some previous disturbance, the rotor angle (δ) is undergoing an un-damped oscillation, with the maximum value of  equal to . One of the parallel lines trips due to relay mal-operation at an instant when · as shown in the figure. The maximum value of the per unit line reactance, x, such that the system does not lose synchronism subsequent to this tripping is

The linear operation L(x) is defined by the cross product , where  and  are three dimensional vectors. The 3×3 matrix M of this operation satisfies

Then the Eigen values of M are

The associated figure shows the two types of rotate right instructions R1, R2 available in a microprocessor where Reg is a 8-bit register and C is the carry bit. The rotate left instructions L1 and L2 are similar except that C now links the most significant bit of Reg instead of the least significant one.

Suppose Reg contains the 2's complement number 11010110. If this number is divided by 2 the answer should be

The common emitter forward current gain of the transistor shown is .

The transistor is operating in

Cayley-Hamilton Theorem states that a square matrix satisfies its own characteristic equation.

Consider a matrix

A satisfies the relation        

The associated figure shows the two types of rotate right instructions R1, R2 available in a microprocessor where Reg is a 8-bit register and C is the carry bit. The rotate left instructions L1 and L2 are similar except that C now links the most significant bit of Reg instead of the least significant one.

Such a division can be correctly performed by the following set of operations

A 3 V dc supply with an internal resistance of 2Ω supplies a passive non-linear resistance characterized by the relation. The power dissipated in the non linear resistance is

Cayley-Hamilton Theorem states that a square matrix satisfies its own characteristic equation.

Consider a matrix

 equals

The three-terminal linear voltage regulator is connected to a  load resistor as shown in the figure. If  is 10 V, what is the power dissipated in the transistor?

A solid sphere made of insulating material has a radius R and has a total charge Q distributed uniformly in its volume. What is the magnitude of the electric field intensity, E, at a distance r (0<r<R) inside the sphere?

An inductor designed with 400 turns coil wound on an iron core of  cross sectional area and with a cut of an air gap length of 1mm. The coil is connected to a 230 V, 50 Hz AC supply.  Neglect coil resistance, core loss, iron reluctance and leakage inductance

The current in the inductor is

In the circuit shown in figure switch \(SW_1\), is initially CLOSED and \(SW_2\) is OPEN. The inductor L carries a current of 10A and the capacitor is charged to 10 V with polarities as indicated. \(SW_2\), is initially CLOSED at  and \(SW_1\), is OPENED at t=0. The current through C and the voltage across L at  is

The input signal  shown in the figure is a 1 kHz square wave voltage that alternates between +7V and −7V with a 50% duty cycle. Both transistors have the same current gain, which is large. The circuit delivers power to the load resistor . What is the efficiency of this circuit for the given input?  Choose the closest answer.

An inductor designed with 400 turns coil wound on an iron core of  cross sectional area and with a cut of an air gap length of 1mm. The coil is connected to a 230 V, 50 Hz AC supply.  Neglect coil resistance, core loss, iron reluctance and leakage inductance

The average force on the core to reduce the air gap will be

If  and  then for , the Nyquist plot for becomes asymptotic to the line

Consider the protection system shown in the figure below. The circuit breakers, numbered from 1 to 7 are of identical type. A single line 10 ground fault with zero fault impedance occurs at the midpoint of the line (at point F), but circuit breaker 4 fails to operate ("stuck breaker"). If the relays are coordinated correctly, a valid sequence of circuit breaker operations is

The circuit in the figure is a current commutated dc-dc chopper where. is the main SCR and is the auxiliary SCR. The load current is constant at 10A. is ON.  is triggered at t = 0. is turned OFF between

A 1:1 Pulse Transformer (PT) is used to trigger the SCR in the adjacent figure. The SCR is rated at 1.5 kV,250A with 250mA, 150mA, and 150mA, 100mA. The SCR is connected to an inductive load, where L = 150mH in series with a small resistance and the supply voltage is 200V dc. The forward drops of all transistors/diodes and gate-cathode junction during ON state are 1.0 V

The resistance R should be

A 1:1 Pulse Transformer (PT) is used to trigger the SCR in the adjacent figure. The SCR is rated at 1.5 kV,250A with 250mA, 150mA, and 150mA, 100mA. The SCR is connected to an inductive load, where L = 150mH in series with a small resistance and the supply voltage is 200V dc. The forward drops of all transistors/diodes and gate-cathode junction during ON state are 1.0 V

The minimum approximate volt-second rating of the pulse transformer suitable for triggering the SCR should be: (volt-second rating is the maximum of product of the voltage and the width of the pulse that may be applied)

Consider the feedback control system shown below which is subjected to a unit step input. The system is stable and has the following parameters and         

The steady state value of z is

Consider the R-L-C circuit shown in figure.

For a step-input, the overshoot in the output will be

Consider the R-L-C circuit shown in figure.

If the above step response is to be observed on a non-storage CRO, then it would be best to have the , as a

A three phase balanced star connected voltage source with frequency to rad/s is connected to a star connected balanced load which is purely inductive. The instantaneous line currents and phase to neutral voltages are denoted by  and respectively, and their RMS values are denoted by V and I.         

If,

then the magnitude of R is

A single-phase fully controlled thyristor bridge ac-dc converter is operating at a firing angle of 25° and an overlap angle of 10° with constant dc output current of 20 A. The fundamental power factor (displacement factor) al input ac mains is

A three-phase, fully-controlled thyristor bridge converter is used as line commutated inverter to feed 50 kW power at 420 V dc to a three-phase, 415V (line), 50 Hz ac mains. Consider dc link current to be constant. The RMS Current of the thyristor is

Suppose we define a sequence transformation between "a-b-c" and "p-n-o" variables as follows:

where  and k is a constant. Now, if it is given that:

 then,

A single phase full-wave half-controlled bridge convener feeds an inductive load. The two SCRs in the converter are connected to a common DC bus. The converter has to have a freewheeling diode

A three-phase, 440 V, 50 Hz ac mains fed thyristor bridge is feeding a 440 V dc, 15 kW, 1500 rpm separately excited dc motor with a ripple free continuous current in the dc link under all operating conditions. Neglecting the losses, the power factor of the ac mains at half the rated speed, is

A single-phase, 230V, 50 Hz ac mains fed step down transformer (4:1) is supplying power to a half-wave uncontrolled ac-dc converter used for charging a battery (12 V dc) with the series current limiting resistor being 19.04 Ω. The charging current is

The R-L-C series circuit shown is supplied from a variable frequency voltage source. The admittance-locus of the R-L-C network at terminals AB for increasing frequency ω is

In the circuit of adjacent figure the diode connects the ac source to a pure inductance L.

The diode conducts for

In the figure given below all phasors are with reference to the potential at point "O". The locus of voltage phasor   as R is varied from zero to infinity is shown by

The circuit shown in the figure is

The switch S in the circuit of the figure is initially closed. It is opened at time t = 0.  You may neglect the Zener diode forward voltage drops. What is the behavior of  for t > 0?

The dc motor, which can provide zero speed regulation at full load without any controller, is

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

A 100 kVA, 415V (line), star-connected synchronous machine generates rated open circuit voltage of 415 V at a field current of 15 A. The short circuit armature current at a field current of 10A is equal to the rated armature current. The per unit saturated synchronous reactance is         

An isolated 50 Hz synchronous generator is rated at 15 MW which is also the maximum continuous power limit of its prime mover. It is equipped with a speed governor with 5% droop. Initially, the generator is feeding three loads of 4 MW each at 50 Hz. One of these loads is programmed to trip permanently if the frequency falls below 48 Hz. If an additional load of 3.5 MW is connected then the frequency will settle down to

In a transformer zero voltage regulation at full load is

A single-phase 50kVA, 250V/500V two winding transformer has an efficiency of 95% at full load, unity power factor. If it is reconfigured as a 500V/750V autotransformer, its efficiency at its new rated load at unity power factor will be

The electromagnetic torque  of a drive, and its connected load torque are as shown below. Out of the operating points A, B, C and D, the stable ones are

A three-phase squirrel cage induction motor has a starting torque of 150% and a maximum torque of 300% with respect to rated torque at rated voltage and rated frequency. Neglect the stator resistance and rotational losses. The value of slip for maximum torque

In the figure, transformer , has two secondary, all three windings having the same number of tums and with polarities as indicated. One secondary is shorted by a 10 Ω resistor R, and the other by a 15 µF capacitor.  The switch SW is opened (t = 0) when the capacitor is charged to 5V with the left plate as positive. At t=0+ the voltage and current are

A three phase squirrel cage induction motor has a starting current of seven times the full load current and full load slip of 5%.

If an autotransformer is used for reduced voltage starting to provide 1.5 per unit starting torque, the autotransformer ratio (%) should be

A three phase squirrel cage induction motor has a starting current of seven times the full load current and full load slip of 5%.

If a star-delta starter is used to start this induction motor, the per unit starting torque will be

A three phase squirrel cage induction motor has a starting current of seven times the full load current and full load slip of 5%.

If a starting torque of 0.5 per unit is required then the per unit starting current should be

Consider the transformer connections in a part of a power system shown in the figure. The nature of transformer connections and phase shifts are indicated for all but one transformer. Which of the following connections, and the corresponding phase shift , should be used for the transformer between A and B?

Two regional systems, each having several synchronous generators and loads are interconnected by an ac line and a HVDC link as shown in the figure. Which of the following statements is true in the steady state:

Consider a bundled conductor of an overhead line, consisting of three identical sub-conductors placed at the corners of an equilateral triangle as shown in the figure. If we neglect the charges on the other phase conductors and ground, and assume that spacing between sub-conductors is much larger than their radius, the maximum electric field intensity is experienced at        

The total reactance and total susceptance of a lossless overhead EHV line, operating at 50 Hz. are given by 0.045pu and 1.2pu respectively. If the velocity of wave propagation is , then the approximate length of the line is

Consider the two power systems shown in figure A below, which are initially not interconnected, and are operating in steady state at the same frequency. Separate load flow solutions are computed individually for the two systems, corresponding to this scenario. The bus voltage phasors so obtained are indicated on figure A. These two isolated systems are now interconnected by a short transmission line as shown in figure B, and it is found that.

The bus voltage phase angular difference between generator bus X and generator bus Y after the interconnection is

A 230 V (Phase). 50 Hz, three-phase, 4-wire system has a phase sequence ABC. A unity power-factor load of 4 kW is connected between phase A and neutral N. It is desired to achieve zero neutral current through the use of a pure inductor and a pure capacitor in the other two phases. The value of inductor and capacitor is