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.
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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.
