CHEMICAL REACTION ENGINEERING QUIZ

The applications of selenium rectifiers are usually limited to potential of

100 V

30 V

20 V

10 V

TRUE ANSWER : ?
YOUR ANSWER : ?

The internal efficiency of a mercury arc rectifier depends on

voltage and current

r.m.s. value of current

current only

voltage only

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The cathdde voltage drop, in a mercury arc rectifier, is due to

expenditure of energy in overcoming the electrostatic field

expenditure of energy in ionization

expenditure of energy in liberating electrons from the mercury

surface resistance

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Selenium rectifier can be operated at temperatures as high as

25°C

40°C

60°C

75°C

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A rotary converter operates at a

high power factor

None of the listed here

zero power factor

low power factor

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In a mercury arc rectifier positive ions are attracted towards

anode

mercury pool

cathode

shell bottom

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The potential drop in the arc, in a mercury arc rectifier, varies

0.05 V to 0.2 V per cm length of the arc

0.5 V to 1.5 V per cm length of the arc

none of the listed here

2 V to 3.5 V per cm length of the arc

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Normally, which of the following is used, when a large-scale conversion from AC. to D.C. power is required?

Rotary converter

Mercury arc rectifier

Motor converter

Motor-generator set

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

phase

polarity

magnitude

All of the listed here

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In a rotary converter I2R losses as compared to a D.C. generator of the same size will be

Remain same

More

None of the listed here

Less

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