LOADING

Questions

  • Low frequency supply is obtained by 


  • Which type of load is offered by cranes and hoists? 


  • The electric drive posses the following drawback : 


  • Match the items in List I with those of List II and select your answers using the codes given in the lists :

    List I     List II

     (Type of duty)            (Applications)

     (A) Continuous duty   1. Machine tools

     (B) Short time duty    2. Sirens

     (C) Continuous duty   3. Blowers

    with intermittent

    periodic loading

     (D) Continuous duty   4. Conveyors

    with starting and braking


  • A pole-changing squirrel cage induction motor employed in derricks has four, eight and twenty four pole. The lowest speed is used in : 


  • Which motor has widest variety of methods for speed control? 

  • In suburban services as compared with urban service : 


  • In electric traction, the coefficient of adhesion is represented by


  • In the speed-time curve of a train, speed in and time in are_________plotted. 


  • A locomotive exerts a tractive effort of 35,300 N in hauling a train at 48 km/h on the level track. If the motor is to haul the same train on a gradient of 1 in 50 and the tractive effort required is 55,180N determine the power delivered by the locomotive if it is driven by (i) dc series motors (ii) induction motors,


  • For the transmission of power, a direct drive is only preferred when :


  • Which of the following is NOT an AC drive? 


  • The motor used in electric traction is 


  • Which of the following methods is NOT used for DC drive? 


  • The approximate continuous rating of a motor for a load of 100 HP for 20 minutes at 3/4th  load for next 10 minutes and a no load for next 20 minutes is : 


  • Which traction system employs the metadyn control method? 


  • What is the frequency of a single phase traction system? 


  • Which of the below is an example of short time, intermittent loads?  


  • The load characteristics of rolling mill : 


  • Which among the following is mechanical braking? 


  • Which of the following motors one will choose to drive the rotary compressor? 


  • Specific energy consumption is maximum in_________ service. 


  • In India diesel locomotives are manufactured at 


  • Operating voltage for d.c. traction is 


  • The most preferred motor used in water pumping is : 


  • In AC locomotives, squirrel cage induction motors are used, the method of speed control is :


  • The motor enclosure used in wood-working industry is 


  • An electric train taking of constant current of 600A moves on a section of line between two substation 8 km apart maintained at 575V and 590V respectively. The track resistance is 0.04 Ohm per km both go and return. The point of minimum potential along the track is at a distance from 575V substation is 


  • The most economical method of electric braking is : 


  • A motor has to be selected for following load cycle. Load uniformly rising from zero to 100 hp in 10 minutes after which it is constant at 100 hp for the next 10 minutes, followed by no load period of 30 minutes. Suitable size of continuous rated motor is : 


  • Which of the following is the cause of passive load?


  • Light duty cranes are used in which of the following? 


  • The main drawback of electric drive is that 


  • Which type of frame is preferred for motors in moist surroundings? 


  • The basic elements of an electric drive are 


  • The speed time curve for urban service has no 


  • What kind of operation(s) is/are performed in winch and crane applications?


  • An electric motor may give noise due to 


  • The least expensive drive is 


  • Which of the following three-phase AC systems is used in electric traction? 


  • Which of the following is preferred for automatic drives? 


  • What is the advantage of electric braking? 


  • An electric train employing a d.c. series motor is running at a fixed speed. When a sudden drop in voltage of supply takes place, then this results in_________. 


  • A rotary converter generally 


  • A low frequency supply is given to the singlet phase AC system for track electrification because


  • Long distance railways operate on 


  • The most preferred motor used in traction is :


  • Heavy duty cranes are used in


  • The characteristics of drive for crane hoisting is 


  • Motor used for elevators is generally 


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