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SCR Commutation MCQs

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

Question 1
Power ElectronicsSCR Commutation

SCR commutation means the process of?

  • ATurning the SCR OFF
  • BTurning the SCR ON by gate current
  • CIncreasing its breakover voltage
  • DMeasuring its gate resistance
Report an error
Correct Answer: A. Turning the SCR OFF
Explanation: Commutation reduces SCR current below the holding level and provides sufficient recovery conditions for the device to regain blocking capability.
Reference: Standard power electronics: scr commutation
Question 2
Power ElectronicsSCR Commutation

In a line-commutated AC rectifier, an SCR can turn OFF naturally when?

  • AIts current falls to zero and reverse voltage is available
  • BIts gate pulse is removed while current remains high
  • CIts gate is made more positive
  • DThe supply frequency becomes zero
Report an error
Correct Answer: A. Its current falls to zero and reverse voltage is available
Explanation: Natural commutation uses the AC source to bring current to zero and reverse-bias the outgoing SCR.
Reference: Standard power electronics: scr commutation
Question 3
Power ElectronicsSCR Commutation

Forced commutation is especially required for a conventional SCR in many?

  • ADC circuits
  • BPurely line-commutated AC circuits only
  • CPassive resistor networks with no source
  • DUncontrolled diode rectifiers
Report an error
Correct Answer: A. DC circuits
Explanation: A DC source has no natural current zero, so auxiliary circuitry is often required to force SCR current below holding current.
Reference: Standard power electronics: scr commutation