Wednesday, 8 July 2020

Questions on Marine electrical technology function 5 meo class IV orals (PART-1)

Marine electrical technology

 (FUNCTION 5)

  • What is a magnetic contactor? Where is it used?
  • What happens in soft starter?
  • What is a relay? How is it different from a magnetic contactor?
  • Difference between ACB and OCB?
  • Can you draw a DOL starter circuit?
  • What's non essential load ?
  • What is the meaning of overload?
  • What is HRC fuse?
  • What is meaning of short circuit?
  • What is transformer rating and why is it required ?
  • How is protection provided for OL and SC?What do u mean by eddy currents
  • What r d reasons for eddy currents to form and where do they form?
  • What is the function of a fuse?What is power factor?
  • What is a commutator and its used?
  • What is the normal setting of overload relays?
  • How does a thermal overload relay work?
  • What is single phasing?
  • How can single phasing happen?
  • What is the harm caused by single phasing?
  • What protection is provided against single phasing?
  • Why is it necessary that incoming alternator frequency is more than bus bar?
  • What is dark lamp and bright lamp method for synchronizing? How is the connection made?
  • Apart from renewing bearings is there any reason for opening up motors for maintenance?
  • Why is reverse power protection required?
  • Why is this reverse power used instead of reverse current in alternators?
  • What is the meaning of excitation in an alternator?
  • Is the field current in an alternator AC or DC ?
  • Is the field rotating or stationary?
  • How is field current supplied?
  • What is a brush less alternator?
  • How is the excitation achieved in brushless alternator?
  • What is the meaning of residual magnetism?
  • Why is an air compressor started unloaded?
  • How is the speed of a 3-phase induction motor varied?
  • How is the direction of rotation varied?
  • How does this cause a rotation to change?
  • How is the speed of a DC motor varied?
  • How is the direction varied?
  • What is a diode?
  • What is a zener diode?
  • What is a thyristor? What is an SCR?
  • How does an inverter work?
  • How does a tube light work?
  • What is the function of the starter in a tube light?
  • What is the function of the choke?
  • Where is a slip ring used and where is a commutator used?
  • What is capacitance?
  • Does current flow though a capacitor?
  • What is the unit for capacitance ?
  •  What is a neutral?
  • What is the difference between neutral and earth?
  • What is a synchronous condenser?
  • Where and why is synchronous condenser used?
  • If a motor is wound star and you want to change to delta what should you do?
  • If the AVR, is defective, when additional loads come on will the generator be able to take it?
  • How do you test, reverse power trip, high current trip, preferential trip?
  • What is residual magnetism? Where is it important?
  • Sometimes, when you change the running direction of a E/R blower (from supply to exhaust) it trips. Why?
  • What is the function of the friction clutch mechanism used in purifiers?
  • What is the regular maintenance done on batteries?
  • What safety precautions need to be taken during maintenance on batteries?
  • Why is special lighting used in battery rooms? 
  • What is the voltage available from each cell in a lead acid battery?
  • What is the full battery voltage ?
  • How is this voltage achieved?
  • What is the meaning of a normally open contact?
  • How does a Salinometer function?
  • How does the air compressor start and stop automatically?
  • How is the cold room temperature maintained?
  • What is a self-monitoring alarm circuit?
  • Out at sea, if there is a black out during your watch, what action will you take?
  • After a black out the emergency generator comes on; On restoring the main supply we are closing the circuit breaker of the main generator with out bothering about synchronizing. How is this possible?
  • How does the emergency generator start automatically?
  •  If all your air bottles are at low pressure and there is a blackout how do you start the generators?
  •  What is a shaft generator?
  • Even though the main engine runs at varying speeds, how does the alternator maintain constant frequency?
  • Is the alternator connected star or delta
  • Why is 440 V used for motors and 110/220 V used for lighting?

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