Online MCQ EE-Circuit Breakers Part Four

Circuit Breakers Part Four (Fill In The Blank)

  1. A sudden short-circuit in an ac system causes a rise in __________ in the short-circuited phase.
  2. The voltage appearing across the circuit breaker pole after final current zero is called __________ voltage.
  3. Thermal ionization of gases occurs at temperature around __________ C.
  4. The electron emission from contact surface caused by incidence of light energy is called __________.
  5. De ionization can take place by the processes of recombination or attachment as well as by process of __________ and __________.
    Answerdiffusion, drift
  6. The behavior of arc in high vacuum is affected by contact material and __________.
    Answerconditions of the contact surface
  7. Sphere gaps are used for measurement of __________.
    Answerhigh voltages
  8. Current breakers are generally overhauled every __________ years.
  9. In circuit breakers, arc is extinguished either by __________ the arc __________ the arc or __________ the arc.
  10. Deterioration of dielectric oil is governed by __________ color.
  11. The characteristics of a fuse is governed by material and __________ of the fuse element.
  12. A fuse should generally have a normal rating 25 to 50 percent above the normal full load current to lake care of __________.
    Answerswitching surges
  13. Skin effect is absent in case of __________ current
  14. Insulators operate under __________ conditions.
  15. Melting point of aluminium is __________.
    Answer657 C
  16. Density of aluminium is nearly __________ of the density of copper.
  17. Melting point of copper is __________ 0C.
  18. Pantograph isolator is preferred for circuits above __________ kV.
  19. __________ current is the rms value of the current which a breaker must carry for a stated time.
    Answershort time
  20. The insulation requirements of switchgear are determined by __________ voltage.
  21. In horn gaps the arc is produced at the __________ during high voltage surge.
  22. Secondary type lightning arresters are used for the protection of __________ transformers.
  23. The
    non-linear resistor in lightning arrester offers __________ resistance
    to the flow of discharge currents and __________ resistance to power
    frequency voltage.
  24. The most severe cause of switching over-voltages is __________.
    Answerclosing of charged line
  25. __________ type lightening arresters are designed to discharge the switching over-voltage as well as lightning over-voltages.
    Answermagnetically blow out type
  26. Traveling
    wave gets reflected from short circuited line with reflected current
    wave of __________ polarity and voltage wave of the __________ polarity.
    Answersame, opposite
  27. Peterson coil is the reactance used in __________ earthing.
  28. The phenomena of arcing grounds is commonly experienced with __________ systems.
  29. In solid grounding system, the neutral is connected to ground without any __________ between neutral and ground.
    Answerintentional impedance
  30. The grounding is generally at the __________ end.
  31. Insulation co-ordination of EHV and UHV line is based on __________.
    Answerswitch over voltages
  32. In delta connected load, the line current return path. Hence line currents __________ zero sequence component.
    Answerdo not have
  33. The negative sequence network has only negative sequence __________.
  34. The
    smallest value of actuating quantity at which protection starts
    operating in relation with the minimum value of fault current in the
    protected zone, is known as __________ of the protective scheme.
  35. Trip circuit is normally a part of __________.
    Answercircuit breakers
  36. The
    time elapsed between the instant of occurrence of fault and instant of
    final arc extinction in circuit breaker is known as __________.
    Answerfault clearing time
  37. The time interval between occurrence of fault and closure of relay contacts is known as __________.
    Answerrelay time
  38. The lime interval between closure of trip circuit and final arc interruption is known as __________.
    Answerbreaker time
  39. Acting ground is also known as __________ fault.
  40. Phase fault is __________ fault.
    Answerline to line
  41. A relay which responds to increase in current is known as __________.
    Answerover current relay
  42. Power line carrier is a __________ signal sent through the power line conductors.
    Answerhigh frequency
  43. Static relays __________ moving parts.
    Answerdo not
  44. An electro-magnetic relay will operate when operating force is __________ restraining force.
    Answergreater than
  45. An electro-magnetic relay will operate when operating force is __________ restraining force.
    Answergreater than
  46. __________ is suitable for outdoor UHV and HV traction system.
    AnswerAir blast circuit breaker
  47. The drop off value to pick-up value of a relay is also known as __________.
    Answerholding ratio
  48. The holding ratio of a relay is usually __________.
    Answerless than 1
  49. A bimetal strip consists of two metal strips having different __________.
    Answercoefficient of thermal expansion
  50. A directional relay senses __________.
online mcq EE-Single Phase Motors Part three
Online MCQ EE-Circuit Breakers Part Three

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