Electrical Engineering questions for GATE, PSU recruitment and SSC JE draw from network theory, electrical machines, power systems, control systems, measurements and instrumentation, analog and digital electronics, and electromagnetic fields. Numerical answers include the formula used and the unit at each stage, which is where marks are commonly lost even when the approach is correct.
What is the typical slip value for a squirrel-cage induction motor operating at full load?
Answer: B
Full load slip for squirrel-cage motors typically ranges from 3-5% for good efficiency
Q.82Easy
A transformer has primary turns = 1000, secondary turns = 100. If primary current is 2 A, what is the secondary current (neglecting losses)?
Answer: C
Using transformer equation: Np/Ns = Is/Ip; 1001000 = Is/2; Is = 20 A
Q.83Easy
The rotating magnetic field in a 3-phase induction motor rotates at:
Answer: A
The rotating magnetic field produced by the 3-phase stator winding rotates at synchronous speed (Ns = 120f/P), independent of load or rotor speed.
Q.84Easy
In an autotransformer, if primary turns = 100 and secondary turns = 400, the voltage transformation ratio is:
Answer: B
In an autotransformer, the turns ratio is N2/N1 = 100400 = 14, so voltage transformation ratio is Vs/Vp = 1:4 for a step-up autotransformer.
Q.85Easy
A 3-phase induction motor has 4 poles and operates from a 50 Hz supply. The synchronous speed is:
Answer: A
Synchronous speed Ns = 120f/P = (120 × 50)/4 = 1500 rpm for a 4-pole motor at 50 Hz.
Q.86Easy
In a transformer, the no-load current lags the applied voltage by approximately:
Answer: C
At no-load, the transformer draws mainly reactive (magnetizing) current, which lags the applied voltage by approximately 90°, giving a power factor of about 0.1-0.2.
Q.87Easy
A shaded pole induction motor uses ________ for starting torque generation.
Answer: B
Shaded pole motors use a copper ring or shaded pole around part of the pole face to create a phase shift in the magnetic field, producing starting torque without additional components.
Q.88Easy
What is the primary function of a circuit breaker in a power system?
Answer: A
Circuit breakers detect abnormal currents and automatically disconnect faulty sections to prevent equipment damage and cascading failures.
Q.89Easy
Which of the following is NOT a renewable energy source integrated into the Indian grid?
Answer: C
As of 2024-25, tidal energy has not been commercially integrated into the Indian grid on a significant scale, unlike solar, wind, and biomass.
Q.90Easy
What is the standard frequency of the Indian power grid?
Answer: A
India follows the 50 Hz standard frequency for AC power systems, as per IEC standards.
Q.91Easy
In a power system, the angle between voltage and current phasors is known as:
Answer: B
The phase angle (φ) between voltage and current phasors determines the power factor of the system.
Q.92Easy
In India's 2024-25 grid, which state has the highest installed renewable energy capacity?
Answer: A
Gujarat leads in combined renewable capacity including solar parks and wind farms as per latest 2024-25 CEA reports.
Q.93Easy
In a 400 kV transmission line in India's western grid, if the series reactance is 0.35 Ω/km and the line length is 250 km, what is the total series reactance of the transmission line?
Answer: A
Total series reactance = 0.35 Ω/km × 250 km = 87.5 Ω. This is a fundamental calculation for transmission line parameters commonly tested in GATE and ESE.
Q.94Easy
What is the primary function of a feedback control system?
Answer: A
Feedback control systems work by comparing the desired output with actual output and reducing the error between them through corrective action.
Q.95Easy
The transfer function of a system is defined as the ratio of:
Answer: B
Transfer function G(s) = Y(s)/U(s) is the ratio of Laplace transforms of output to input assuming zero initial conditions.
Q.96Easy
Which of the following represents a first-order system?
Answer: B
A first-order system has only s¹ as the highest power in the denominator. G(s) = K/(τs + 1) is the standard first-order form.
Q.97Easy
The characteristic equation of a system is s² + 4s + 3 = 0. The system is:
Answer: C
Roots are s = -1 and s = -3 (both negative). All poles are in the left half-plane, making the system stable.
Q.98Easy
In a bode plot, the magnitude is plotted on a scale of:
Answer: B
Bode plots use dB (20log₁₀|G(jω)|) for magnitude on a logarithmic scale and phase in degrees on a semi-log plot.
Q.99Easy
For a system G(s) = 1/(s(s+2)), the number of poles at origin is:
Answer: B
The system has one pole at s=0, making it Type 1. The denominator has s¹ factor representing one integration.
Q.100Easy
The settling time of a control system is defined as the time taken to:
Answer: C
Settling time is the time required for the transient to decay and response to remain within 2% (or 5%) of the steady-state value.
