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Controlled Rectifiers MCQs

Practice Controlled Rectifiers MCQs with four options, answers and explanations for focused Electronics & Telecommunication Engineering revision.

Question 1
Power ElectronicsControlled Rectifiers

In phase-controlled rectifiers, firing angle alpha is measured from?

  • AThe reference point where the device would naturally become forward-biased in the supply cycle
  • BThe instant of maximum load current only
  • CThe end of every negative half-cycle only
  • DThe gate-current peak regardless of supply waveform
Report an error
Correct Answer: A. The reference point where the device would naturally become forward-biased in the supply cycle
Explanation: The firing delay angle alpha specifies how long triggering is delayed from the natural forward-bias reference in each applicable cycle.
Reference: Standard power electronics: controlled rectifiers
Question 2
Power ElectronicsControlled Rectifiers

For a single-phase half-wave controlled rectifier with a purely resistive load, increasing firing angle from 0 toward 180 degrees generally causes the average output voltage to?

  • ADecrease
  • BIncrease
  • CRemain constant
  • DBecome independent of the supply
Report an error
Correct Answer: A. Decrease
Explanation: Delaying SCR turn-on shortens the conduction interval, reducing the average output voltage for a resistive load.
Reference: Standard power electronics: controlled rectifiers
Question 3
Power ElectronicsControlled Rectifiers

In a controlled rectifier, delaying the firing angle generally provides control over the?

  • AAverage output voltage
  • BSupply frequency
  • CNumber of semiconductor layers
  • DPhysical transformer turns ratio
Report an error
Correct Answer: A. Average output voltage
Explanation: Phase control changes the portion and polarity-weighted interval of the AC waveform applied to the load, thereby controlling average output voltage.
Reference: Standard power electronics: controlled rectifiers