Questions

Multiple-choice questions you can practise one by one. Open a question, tap an answer and see at once whether it is right. For a random set, try Quick practice.

941 questions

• Where are electrons found in an atom?

  Electrical Engineering Materials › Unit 1: Introduction to Materials · Easy

• Which element is widely used in semiconductor devices?

  Electrical Engineering Materials › Unit 1: Introduction to Materials · Easy

• Which subatomic particle has a negative charge?

  Electrical Engineering Materials › Unit 1: Introduction to Materials · Easy

• A chopper drive requires low output ripple at a given load and inductance. Which design change can often help, subject to switching-loss limits?

  Industrial Electronics & Control of Drives › Unit 3: Inverters, Choppers, Dual Converters and Cyclo-Convertors · Hard

• A single-phase fully controlled bridge feeds an inductive DC load. The current is continuous and the firing angle is increased from a small value toward 90 degrees. What happens t…

  Industrial Electronics & Control of Drives › Unit 2: Controlled Rectifiers · Hard

• A gate trigger pulse arrives while an SCR is reverse-biased. What is the expected result for a conventional SCR?

  Industrial Electronics & Control of Drives › Unit 1: Introduction to Thyristors · Hard

• A designer chooses a heat sink for an SCR. Which set of factors is most relevant?

  Industrial Electronics & Control of Drives › Unit 1: Introduction to Thyristors · Hard

• In a three-phase bridge converter, commutation overlap increases because source inductance is significant. What is the likely effect on average DC output voltage?

  Industrial Electronics & Control of Drives › Unit 2: Controlled Rectifiers · Hard

• A controlled rectifier's input power factor deteriorates as firing delay increases. What is the main explanation?

  Industrial Electronics & Control of Drives › Unit 2: Controlled Rectifiers · Hard

• A converter must provide variable-frequency AC from a DC source for an AC motor. Which topology is most directly suitable?

  Industrial Electronics & Control of Drives › Unit 3: Inverters, Choppers, Dual Converters and Cyclo-Convertors · Hard

• A cycloconverter's output waveform contains significant low-order harmonics. Which design concern is most directly affected?

  Industrial Electronics & Control of Drives › Unit 3: Inverters, Choppers, Dual Converters and Cyclo-Convertors · Hard

• A cycloconverter supplies a low-frequency motor load from a three-phase source. Why is output frequency usually limited to a fraction of input frequency in conventional line-commu…

  Industrial Electronics & Control of Drives › Unit 3: Inverters, Choppers, Dual Converters and Cyclo-Convertors · Hard

• For a dual converter, why must the firing controls of the two bridges be coordinated?

  Industrial Electronics & Control of Drives › Unit 3: Inverters, Choppers, Dual Converters and Cyclo-Convertors · Hard

• A dual converter is operated in circulating-current mode. What component or arrangement is commonly used to limit circulating current?

  Industrial Electronics & Control of Drives › Unit 3: Inverters, Choppers, Dual Converters and Cyclo-Convertors · Hard

• Compared with a square-wave inverter, PWM control can improve output waveform quality by:

  Industrial Electronics & Control of Drives › Unit 3: Inverters, Choppers, Dual Converters and Cyclo-Convertors · Hard

• In a series resonant inverter, the resonant circuit is important mainly because it:

  Industrial Electronics & Control of Drives › Unit 3: Inverters, Choppers, Dual Converters and Cyclo-Convertors · Hard

• A voltage-source inverter leg must avoid turning on both complementary switches simultaneously. Why?

  Industrial Electronics & Control of Drives › Unit 3: Inverters, Choppers, Dual Converters and Cyclo-Convertors · Hard

• In a voltage-source inverter, why is a DC-link capacitor commonly used?

  Industrial Electronics & Control of Drives › Unit 3: Inverters, Choppers, Dual Converters and Cyclo-Convertors · Hard

• A DC motor drive needs regenerative braking so energy can flow from the motor back to the source. Which chopper operating capability is required?

  Industrial Electronics & Control of Drives › Unit 4: Thyristor Control of Electric Drives · Hard

• A chopper switch operates at a fixed frequency. The on-time is increased while the total period remains constant. Which parameter increases?

  Industrial Electronics & Control of Drives › Unit 3: Inverters, Choppers, Dual Converters and Cyclo-Convertors · Hard