In phase-shift control method the control is carried out by varying the of grid voltage

Related Mcqs:

1. In a phase-shift control method, the phase shift between anode and grid voltages can be achieved by means of______________?

   A. shunt motor
   B. synchronous motor
   C. induction regulator
   D. synchronous generator

2. In mercury arc rectifiers having grid, the arc can be struck between anode and cathode only when the grid attains a certain potential, this potential being known as______________?

   A. maximum grid voltage
   B. critical grid voltage
   C. any of the above
   D. none of the above

3. In a grid control of mercury arc rectifiers when the grid is made positive relative to cathode, then it the electrons on their may to anode.

   A. accelerates
   B. decelerates
   C. any of the above
   D. none of the above

4. Which of the following rectifiers are primarily used for charging of low voltage batteries from AC supply ?

   A. Mechanical rectifiers
   B. Copper oxide rectifiers
   C. Selenium rectifiers
   D. Electrolytic rectifiers
   E. Mercury arc rectifiers

5. Ageing of a selenium rectifier may change the output voltage by__________?

   A. 5 to 10 per cent
   B. 15 to 20 per cent
   C. 25 to 30 per cent
   D. none of the above

6. The voltage drop between the anode and cathode, of a mercury arc rectifier comprises of the following_____________?

   A. anode drop and cathode drop
   B. anode drop and arc drop
   C. cathode drop and arc drop
   D. anode drop, cathode drop and arc drop

7. The voltage drop at anode, in a mercury arc rectifier is due to_____________?

   A. self restoring property of mercury
   B. high ionization potential
   C. energy spent in overcoming the electrostatic field
   D. high temperature inside the rectifier

8. In a mercury pool rectifier, the voltage drop across its electrodes___________?

   A. is directly proportional to load
   B. is inversely proportional to load
   C. varies exponentially with the load current
   D. is almost independent of load current

9. The cathdde voltage drop, in a mercury arc rectifier, is due to_____________?

   A. expenditure of energy in ionization
   B. surface resistance
   C. expenditure of energy in overcoming the electrostatic field
   D. expenditure of energy in liberating electrons from the mercury

10. With a motor converter it is possible to obtain D.C. voltage only upto__________?

    A. 200-100 V
    B. 600—800 V
    C. 1000—1200 V
    D. 1700—2000 V