In modern 2024-25 EV charging systems, what is the typical efficiency target for on-board DC-DC converters?

The correct answer is B: 90-95%. Modern automotive DC-DC converters target 90-95% efficiency using advanced topologies, SiC MOSFETs, and optimized gate drives to minimize losses in 12V auxiliary systems.

A 8-pole, 3-phase induction motor is required to run at approximately 720 RPM at 50 Hz. The approximate slip required is:

The correct answer is A: 0.04 or 4%. Ns = 120f/P = (120 × 50)/8 = 750 RPM. For Nr = 720 RPM, s = (750 - 720)/750 = 30/750 = 0.04 or 4%.

In compensator design, if both transient and steady-state improvements are needed, which approach is preferred?

The correct answer is C: Lead-lag compensator. Lead-lag compensator combines lead (improves transient) and lag (improves steady-state) characteristics for overall system improvement.

In a circuit, the star-delta transformation is used to:

The correct answer is D: Both A and B. Star-delta transformation converts between two three-terminal network configurations, simplifying circuit analysis by eliminating nodes that cannot be solved directly.

For the state-space system: ẋ = Ax + Bu, y = Cx + Du. The controllability matrix rank must equal n for the system to be completely state controllable. What is n?

The correct answer is A: Number of states. For complete state controllability, rank of [B AB A²B ... Aⁿ⁻¹B] must equal n, the order/number of states of the system.

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Electrical Engg (EEE)
Power Systems

Electrical machines, power systems, circuits

51 Q 7 Topics Take Mock Test

Difficulty: All Easy Medium Hard 51–51 of 51

Topics in Electrical Engg (EEE)

All Circuit Analysis 100 Electrical Machines 100 Power Systems 100 Control Systems 100 Power Electronics 100 Electrical Measurements 40 Digital Electronics 100

Q.51 Medium Power Systems

In load flow analysis, which bus is used to represent the reference point for voltage angle?

A Load bus (PQ bus)

B Generator bus (PV bus)

C Slack bus (Reference bus)

D Transformer bus

Correct Answer: C. Slack bus (Reference bus)

EXPLANATION

The slack bus serves as the reference point with fixed voltage magnitude and phase angle (typically 0°) in load flow studies.

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Electrical Engg (EEE) Power Systems

Electrical Engg (EEE)
Power Systems