Which number system is most commonly used in digital electronics for representing data?

The correct answer is C: Binary. Binary (base-2) is fundamental to digital electronics as it uses 0 and 1 matching ON/OFF states

A network is said to be bilateral if:

The correct answer is B: Its response is same regardless of direction of current flow. Bilateral networks are linear networks where reciprocal relationships hold. Networks with ideal diodes are unilateral (non-bilateral).

The efficiency of a transformer is maximum when:

The correct answer is A: Core loss = Copper loss. Transformer efficiency is maximum when core loss (Pi) equals copper loss (Pcu), i.e., Pi = Pcu.

A priority encoder with 8 inputs has the highest priority assigned to the MSB. If inputs I7=1, I5=1, I3=1, and all others are 0, what is the output?

The correct answer is A: 111 (binary 7). In a priority encoder with MSB having highest priority, when I7=1 (highest priority input), the output represents position 7, which is 111 in 3-bit binary. Lower priority inputs I5 and I3 are ignored.

What is the relationship between power factor and reactive power in a 3-phase system?

The correct answer is A: Q = P × tan(φ). Reactive power Q = P × tan(φ), where φ is the phase angle between voltage and current. This fundamental relationship determines VAR compensation requirements.

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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 1–10 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.1 Medium Power Systems

In a three-phase power system with balanced conditions, the zero-sequence current flows through:

A The neutral conductor and ground path

B Only phase conductors

C Only the power transformer primary

D Generator neutral exclusively

Correct Answer: A. The neutral conductor and ground path

EXPLANATION

Zero-sequence currents (equal in all three phases and same direction) require a return path through neutral or ground.

Test

Q.2 Medium Power Systems

Which of the following is a measure of power quality as per Indian Standards (IS 16001:2017)?

A Voltage harmonics THD and flicker

B Only frequency variation

C Only voltage magnitude variation

D Active power consumption rate

Correct Answer: A. Voltage harmonics THD and flicker

EXPLANATION

IS 16001:2017 defines power quality parameters including THD (Total Harmonic Distortion) and voltage flicker limits.

Test

Q.3 Medium Power Systems

In load flow analysis, which bus type is used to specify active power and voltage magnitude?

A PV (Generator) bus

B PQ (Load) bus

C Slack bus

D Floating bus

Correct Answer: A. PV (Generator) bus

EXPLANATION

PV buses represent generators where active power injection and voltage magnitude are specified; reactive power is calculated.

Test

Q.4 Medium Power Systems

Power system harmonics in Indian grids are primarily caused by:

A Non-linear loads such as power electronic converters and rectifiers

B Only transformer magnetizing current

C Synchronous motor starting

D Transmission line corona discharge exclusively

Correct Answer: A. Non-linear loads such as power electronic converters and rectifiers

EXPLANATION

Modern non-linear loads like switch-mode power supplies, VFDs, and renewable energy inverters are major sources of harmonics in contemporary Indian grids.

Test

Q.5 Medium Power Systems

What is the primary cause of voltage instability in a power system?

A Excessive reactive power demand exceeding supply capacity

B High active power only

C Low frequency operation

D Transformer saturation alone

Correct Answer: A. Excessive reactive power demand exceeding supply capacity

EXPLANATION

Voltage instability occurs when reactive power demand cannot be met, causing voltage collapse, particularly at weak points in the grid.

Test

Q.6 Medium Power Systems

The reactive power generated by an over-excited synchronous generator is:

A Negative (absorbed from the system)

B Positive (supplied to the system)

C Zero

D Depends on load current only

Correct Answer: B. Positive (supplied to the system)

EXPLANATION

Over-excitation increases the magnetic field, causing the generator to supply lagging reactive power to support system voltage.

Test

Q.7 Medium Power Systems

A synchronous motor operating at no-load consumes:

A Only active power

B Only reactive power

C Both active and reactive power equally

D Zero power

Correct Answer: B. Only reactive power

EXPLANATION

At no-load, a synchronous motor supplies only magnetizing current (reactive power) to maintain the magnetic field.

Test

Q.8 Medium Power Systems

Which protective relay is used for phase-to-phase fault detection in transmission lines?

A Instantaneous overcurrent relay

B Differential relay

C Under-frequency relay

D Directional overcurrent relay

Correct Answer: B. Differential relay

EXPLANATION

Differential relays compare currents at both ends of a line and trip if there is a mismatch indicating an internal fault.

Test

Q.9 Medium Power Systems

The per-unit (p.u.) system in power systems is used primarily to:

A Convert all quantities to a common base for easier comparison and calculation

B Measure only reactive power

C Determine transformer losses

D Calculate mechanical power only

Correct Answer: A. Convert all quantities to a common base for easier comparison and calculation

EXPLANATION

Per-unit system normalizes all quantities relative to chosen base values, simplifying analysis and comparison across different voltage levels and equipment ratings.

Test

Q.10 Medium Power Systems

The stability of a power system depends on which of the following factors?

A Only the generator capacity

B Inertia constant, damping torque, and synchronizing torque

C Only transmission line impedance

D Only load demand

Correct Answer: B. Inertia constant, damping torque, and synchronizing torque

EXPLANATION

Power system stability is determined by the rotor dynamics characterized by inertia (M), damping (D), and synchronizing coefficient (Ks).

Test

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