PlacementPrepElectrical power is transmitted at high voltage mainly to:
Solution
For the same power, higher voltage means lower current and lower I²R loss.
Answer: (A) Reduce line losses
Technical · Electrical and Electronics (EEE)
Power Systems MCQs for placement tests
20 technical questions of moderate difficulty, as asked in campus placement and company tests. Each has a short explanation.
The standard power frequency in India is:
Solution
India uses 50 Hz.
Answer: (A) 50 Hz
Which type of power plant is usually used for base load?
Solution
Base-load plants run continuously at low running cost.
Answer: (A) Nuclear or coal thermal plant
The Ferranti effect is:
Solution
Line capacitance causes the voltage to rise on long, lightly loaded lines.
Answer: (A) The receiving-end voltage rising above the sending-end voltage at light load
Corona loss in overhead lines increases with:
Solution
Corona occurs when the air around conductors ionises.
Answer: (B) Higher voltage and humid weather
Bundled conductors are used in EHV lines to:
Solution
They increase the effective conductor radius.
Answer: (D) Reduce corona and line reactance
A circuit breaker differs from a fuse in that it:
Solution
A fuse must be replaced after it blows.
Answer: (A) Can be reset and reused
Which relay is used for protecting a transformer against internal faults?
Solution
It detects gas from internal faults in oil-filled transformers.
Answer: (B) Buchholz relay
Power factor is defined as:
Solution
PF = P/S = cos φ.
Answer: (A) The ratio of real power to apparent power
A load draws 10 kW at 0.8 power factor. Its apparent power is:
Solution
S = P/pf = 10/0.8 = 12.5 kVA.
Answer: (B) 12.5 kVA
Power factor can be improved by connecting:
Solution
Capacitors supply the reactive power that inductive loads draw.
Answer: (C) Capacitors in parallel with the load
The most common type of fault in power systems is:
Solution
Single line-to-ground faults make up most faults.
Answer: (C) Single line-to-ground fault
Which fault is the most severe, though least frequent?
Solution
It gives the highest fault current.
Answer: (D) Three-phase symmetrical fault
The per-unit system is used to:
Solution
Quantities are expressed as fractions of base values.
Answer: (B) Simplify calculations across different voltage levels
Load factor is defined as:
Solution
A high load factor means the plant is used steadily.
Answer: (D) Average load divided by maximum demand
Lightning arresters protect equipment from:
Solution
They divert surge current to earth.
Answer: (D) Voltage surges
HVDC transmission is preferred over HVAC for:
Solution
HVDC has no reactive power or charging-current problems over long distances.
Answer: (C) Very long distances and undersea cables
The unit of electrical energy used for billing is:
Solution
1 unit = 1 kWh.
Answer: (B) kWh
Suspension insulators are used for lines above about:
Solution
Pin insulators become uneconomical above about 33 kV.
Answer: (C) 33 kV
Sag in overhead lines is provided to:
Solution
A tightly stretched conductor would break under temperature and wind loads.
Answer: (A) Avoid excessive tension in the conductor
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