List of top Electrical Engineering Questions

_____ is a voltage restrained directional relay.
The input of a 98% efficiency, 2000 rpm separately excited dc motor is 5 kW. The torque output is
If \( R_1, R_2, R_3, R_4, R_5 \) are resistances of each of five sections of starter of d.c. shunt motor, then these resistances are
The speed of a d.c. series motor at an armature current of 10 A is 800 rpm. If load torque is proportional to square of speed, then at 5 A the speed will be
Choose a wrong choice on d.c. machine regarding compoles or compensating winding
Swinburne’s test measures the following on a 200 V, 15 kW dc shunt motor:
Input current = 7 A; Field current = 2 A. Estimate field copper loss and iron \& frictional losses. Assume \( R_a = 0.04 \Omega \)
Dummy coils are used in wave wound d.c. machines to reduce
On two sides of a 3-\(\phi\) star / delta transformer the
A 3-\(\phi\), 400 V, 50 Hz, 4 pole induction motor has rotor resistance and standstill reactance of 0.08 Ω and 0.4 Ω respectively. What is its approximate speed at maximum torque?
The external rotor resistance of a 3-\(\phi\) induction motor is increased more than the resistance required to get maximum starting torque. Then maximum torque occurs in \underline{\hspace{2cm} of Torque (y-axis) – Speed (x-axis) characteristic plot.
A 11kV/3.3kV, 100 MVA, 3-phase transformer has equivalent impedance seen from LV side of (1.2 + j4.8) Ω. The per unit impedance of the transformer is
The current and power factor of a 3–\(\phi\) induction motor at no-load are respectively
A 1-\(\phi\), 230 V, 50 Hz transformer is operated at 230 V, 60 Hz. Then its
If R and X are equivalent resistance and equivalent reactance of a transformer respectively, then at maximum voltage regulation, the power factor is
Indicate a correct choice on currents during open circuit (OC) and short circuit (SC) tests of transformer
The slip-speed of a 3-\(\phi\), cage, 50 Hz, induction motor is 20 rpm at no-load. If slip-speed is doubled due to load, then the electrical equivalent of mechanical load will
Two identical coaxial circular coils carry the same current 1 amp but in opposite directions. The magnitude of the magnetic field \( B \) at a point on the axis midway between the coils is
Magnetic dipole moment is ______ of the loop, its direction is normal to the loop
\( \nabla \cdot \vec{B} = 0 \), shows that
The reciprocal of reluctance is
The magnetization \( M \), in amperes per meter is
Choose the correct statement of Reciprocity theorem in single source network:
If BW is bandwidth, \( \omega_r \) is resonant frequency and Q is quality factor of a resonant circuit, then Selectivity is defined as:
The response of a 1-$\phi$ R-L series circuit is \( i(t) = Ae^{-\frac{R}{L}t} + I_m \sin(\omega t - \theta) \). Then the supply voltage should be:
Point charges \( Q_1 = 1\text{nC} \) and \( Q_2 = 2\text{nC} \) are at a distance apart. Which of the following statement is \textbf{incorrect?