A Meter has full scale deflection of $$90^\circ$$ at a current of 1A. The response of the meter is square law. Assuming spring control, the current for a deflection at $$45^\circ$$ will be
ISRO Scientist or Engineer Electrical 2014
For the following questions answer them individually
A Single-phase Energy meter is operating on 230 V, 50 Hz supply with a load of 20 A for two hours at UPF. The meter makes 1380 revolutions in that period. The meter constant is
In case of power measurements by two wattmeter method in a balanced 3-phase system with pure inductive load
It is required to measure temperature in the range of $$1300^\circ C$$ to $$1500^\circ C$$. The most suitable thermocouple to be used as transducer would be
Which dc motor will have highest percentage increase in input current for given percentage increase in torque
In a three phase delta transformer, one phase burns up. The transformer will supply
In an auto transformer, power is transferred through
Buchholzrelay is a
In Scott connection, if the ratio of the main transformer is k, then the teaser transformer has transformation ratio of
With core type transformers, the limbs are stepped so as to
In alternator, during hunting when the speed becomes super synchronous, the damper bars develop
It is never advisable to connect a stationary alternator to live bus-bar because it
Under no load condition, the angle between the induced voltage and the supply voltage in synchronous motor is
Synchronous motors are not self starting because
A three phase induction motor running at 1440 rpm on rated supply will run at the following rpm when fuse of one phase gets burnt
Dispersion coefficient $$\sigma$$ is the ratio of
In the circle diagram for a 3-phase induction motor, the diameter of the circle is determined by
While conducting short-circuit test on a transformer the following side is short circuited
Thrust developed by a linear induction motor depends on
The crawling in an induction motor is caused by
The main disadvantagesof using short pitch winding in alternators is that it
Armature reaction in an alternator mainly affects
A universal motor is one which
If the field of a synchronous motor is under excited, the power factor will be
Synchronous capacitor is
Two bulbs, one 250V, 100 W and second 250V, 25 W are connectedin series and 440V AC, 50Hzis applied across the two bulbs. Whichof the following will happen,
A wave form shown as Input is applied across primary of a pulse transformer which has 1 : 1 turns ratio. The output on the secondary side will be as shown in the Figure
The following circuit (shown in Figure) resonates at
The distribution system shown in Figure is to be protected by over current system of protection
For proper fault discrimination directional over current relays will be required at locations
A 50 Hz bar primary CT has a secondary with 500 turns. The secondary supplies 5 A current into a purely resistive burden of 1 Ω. The phase angle between the primary and
secondary current is
The moving coil in a dynamometer wattmeter is connected
For an unbalanced fault with paths for zero sequence currents, at the point of fault
An ideal OPAMP is used to make an inverting amplifier. The two input terminals of the OPAMP are at the same potential because,
What is the “swamping” resistance which is connectedin series with the working coil of a voltmeter to drastically reduce the error in measurement caused due to variation in
temperature is made up of?
If the poles of a system lie on the imaginary axis, the system will be:
Which one of the following is the most likely reason for large overshoot in a control system
Which of the following correctly represents the sequence of operations of isolator circuit breaker and earthing switch while opening a circuit
A comparator circuit is used to
Out of the following methods of heating the one which is independent of supply frequency is
An SCR triggered by current pulse applied to gate-cathode can be turned OFF
In the loaded-frequency control system with tree governor action, the increase in load demand under steady condition is met,
Power transmission lines are transposed to reduce
The current carrying capacity of cables in DC is morethan thatin AC mainly due to
The fact that a conductor carries more current on the surface as compared to core, is known as
In Gauss-Sidel load flow method, the number of iterations may be reduced if the correction in voltage at each bus is multiplied by,
For a fault in a power system, the term critical clearing time is related to,
The rate of rise of re-striking voltage (RRRV)is dependent upon,
One of the main advantages of Swinburne’s test is that it,
A6 pole, 50 Hz, $$3 - \phi$$ induction motor is running at 950 rpm and has rotor Cu loss of 5kW. Its rotor input is .................... kW
In the shaded pole squirrel cage induction motor the flux in the shaded part always
A saturable core reactor is basically a
If a body reflects entire radiation incident on it then it is known as,
The illumination is directly proportional to the cosine of the angle made by the normal to the illuminated surface with the direction of the incident flux. Above statement is associated with
The concentration of minority carriers in an extrinsic semiconductor under equilibrium is
Reactancerelay is normally preferred for protection against
If a combination of HRC fuse and circuit breaker is used, the C.B. operates for
Lightning arrestor should be located
Ferranti effect on long overhead lines is experienced when it is
In a nuclear power station, moderator is used to,
What is the output waveform when $$V_{in}$$ is given square wave?
A pony motoris used for the starting of which of the following motor
A PWMswitching scheme is used with three phaseinverter to
The earth wire should not be thinner than a
The ripple factor of a full-wave rectifier circuit compared to that of a half wave rectifier circuit without filter is
In a highly inductive circuit , a small capacitance is added in series. Then the angle between applied voltage and resultant current will be
The inertia constant of the two machines which are not swinging together are M1 and M2. The equivalent inertia constant of the system is:
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 impressed voltage to obtain twice the rated torque at starting should be
The charge on an electron is known to be $$1.6 \times 10^{-19}$$ coulomb. In a circuit the current flowing is 1 A. How many electrons will be flowing through the circuit in a second?
A thermal protection switch is used to provide protection against:
With V/F ratio keeping constant, if the frequency is decreased below the base value and the voltage is decreased proportionally, is fed to an Induction motor, its starting torque and the peak torque for variable frequency & voltages will be
A function f from the set of natural numbers to integers defined by
$$f(n) = \begin{cases}\frac{n - 1}{2}, & when n is odd\\-\frac{n}{2}, & when n is even\end{cases}$$ is
lf the sum of the roots of the quadratic equation $$ax^2 + bx + c = 0$$ is equal to the sum of the squares of their reciprocals, then $$\frac{a}{c}, \frac{b}{a}$$ and $$\frac{c}{b}$$ are in
If $$\left(\frac{1 + i}{1 - i}\right) = 1$$, then
If a vertex of a triangle is (1, 1) and the mid-points of two sides through this vertex are (-1, 2) and (3, 2), then the centroid of the triangle is
Let $$A = \begin{bmatrix}0 & 0 & -1 \\0 & -1 & 0 \\-1 & 0 & 0 \end{bmatrix}$$. The only correct statement about the matrix A is
If one root of the equation $$x^2 + px + 12 = 0$$ is 4, while the equation $$x^2 + px + q = 0$$ has equal roots, then the value of 'q' is
A person standing on the bank of a river observes that the angle of elevation of the top of a tree on the opposite bank of the river is $$60^\circ$$ and when he retires 40 meter away from the tree the angle of elevation becomes $$30^\circ$$. The breadth of the river is
A particle moves towards east from a point A to a point B at the rate of 4 km/h and then towards north from B to C atthe rate of 5 km/h. If AB = 12 km and BC = 5 km, then its
average speedfor its journey from A to C and resultant average velocity direct from A to C are respectively
If $$\tan \theta = \frac{8}{15}$$ and $$\theta$$ is acute, then $$\cosec \theta$$
A student is to answer 10 out of 13 questions in an examination such that he must chooseat least 4 from thefirst five questions. The numberof choices available to him is
