Question 1

A 50Hzgenerating unit hasH-constant of 2MJ/MVA. The machine is initially operating in steady state at synchronous speed, and producing 1puof real power. The initial value of the rotor angle is 5, when a bolted three phase to ground short circuit fault occurs at the terminal of the generator. Assuming the input mechanical power to remain at 1pu, the value of in degrees, 0.02 second after the fault is

Question 2

A sustained three-phase fault occurs in the power system shown in the figure. The current and voltage phasors during the fault (on a common reference), after the natural transients have died down, are also shown. Where is the fault located?

Question 3

The circuit shown in the figure has two sources connected in series. The instantaneous voltage of theACsource (involt) is given byv(t) = 12 sint.If the circuit is in steady-state, then the rms value of the current (inAmpere) flowing in the circuit is

Question 4

In a linear two-port network, when 10Vis applied to Port 1, a current of 4Aflows through Port 2 when it is short-circuited. When 5Vis applied to Port 1, a current of 1.25Aflows through a 1resistance connected across Port 2. When 3Vis applied to Port 1, then current (inAmpere) through a 2resistance connected across Port 2 is

Question 5

In the given circuit, the parameterkis positive, and the power dissipated in the 2resistor is 12.5W. The value ofkis

Question 6

A separately excitedDCmotor runs at 1000rpmon no load when its armature terminals are connected to a 200VDCsource and the rated voltage is applied to the field winding. The armature resistance of this motor is 1. The no-load armature current is negligible. With the motor developing its full load torque, the armature voltage is set so that the rotor speed is 500rpm. When the load torque is reduced to 50% of the full load value under the same armature voltage conditions, the speed rises to 520rpm. Neglecting the rotational losses, the full load armature current (inAmpere) is?

Question 7

ADCmotor has the following specifications: 10 hp, 37.5A, 230V;flux/pole= 0.01Wb,number of poles = 4, number of conductors = 666, number of parallel paths = 2. Armature resistance = 0.267. The armature reaction is negligible and rotational losses are 600W. The motor operates from a 230VDCsupply. If the motor runs at 1000rpm, the output torque produced in (inNm) is?

Question 9

A 200/400V, 50Hz, two-winding transformer is rated at 20kVA. Its windings are connected as an auto-transformer of rating 200/600V. A resistive load of 12is connected to the high voltage (600V) side of the auto-transformer. The value of equivalent load resistance (inOhm) as seen from low voltage side is?

Question 10

Two single-phase transformersT1andT2each rated at 500kVAare operated in parallel. Percentage impedances ofT1andT2are (1+j6) and (0.8+j4.8), respectively. To share a load of 1000kVAat 0.8 lagging power factor, the contribution ofT2(inkVA) is?

Question 11

In the signal flow diagram given in the figure,u1u1andu2u2are possible inputs whereasy1y1andy2y2are possible outputs. When would theSISOsystem derived from this diagram be controllable and observable?

Question 12

The transfer function of a second order real system with a perfectly flat magnitude response of unity has a pole at(2j3)(2j3).List all the poles and zeroes?

Question 13

Find the transfer functionY(s)X(s)YsXsof the system given below?

Question 14

The open loop poles of a third order unity feedback system are at 0,-1,-2. Let the frequency corresponding to the point where the root locus of the system transits to unstable region beK. Now suppose we introduce a zero in the open loop transfer function at -3, while keeping all the earlier open loop poles intact. Which one of the following isTRUEabout the point where the root locus of the modified system transits to unstable region?

Question 15

Consider a functionf(x) = 1-|x|xon -1x1. The value ofxat which the function attains a maximum, and the maximum value of the function are:r