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Armlab

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Armlab

  1. 1. PRESENTED BY:  MUQADSA IFTIKHAR (09ABELT0290)  ZUNAIB ALI (09ABELT0296) INTERNAL GUIDE  ENGR. SANIA SAEED
  2. 2. ABSTRACT • The purpose of a motor speed control is to take a signal representing the demanded speed and drive the motor at that speed.
  3. 3. INTRODUCTION  The speed of dc motor is directly proportional to the supply voltage, if we reduce the supply voltage from 12V to 6V, the motor will run at half the speed.  SCR “phase-angle controlled” drive -By changing the firing angle, variable DC output voltage can be obtained.  Here we are using microcontroller applications. For this we are using TAP changing and by using this we are setting the speed of motor.
  4. 4. MAIN COMPONENTS 1. 220 V , 50Hz AC Supply 2. Tap changing Step Down Transformer 3. DC motor 4. Thyristor (SCR) 5. NPN Transistor 6. 5V DC Supply
  5. 5. A tap changer is a device fitted to power transformers for regulation of the output voltage to required levels. This is normally achieved by changing the ratios of the transformers on the system by altering the number of turns in one winding of the appropriate transformer/s. Tap changers offer variable control to keep the supply voltage within the limits. The 2 ½% step can be used on transformers with automatic tap changing equipment.
  6. 6. Voltage regulation is normally achieved by changing the ratios of the transformers on the system by altering the number of turns in one winding of the appropriate transformer/s. Tap changers offer variable control to keep the supply voltage within these limits. Tap changers can be on load or off load. On load tap changers generally consist of a diverter switch and a selector switch operating as a unit to effect transfer current from one voltage tap to the next. Tap changers can be adjusted to fit the application needs.
  7. 7.  To supply a desired voltage to the load.  To counter the voltage drops due to loads.  To counter the input supply voltage changes on load.  Additionally required to perform the task of regulation of active and reactive power flows.
  8. 8.  Some form of impedance is present to prevent short circuiting of the tapped section.  A duplicate circuit is provided so that the load current can be carried by one circuit whilst switching is being carried out on the other.
  9. 9. Tap point is placed  In star connected winding, near the star point.  In delta connected winding, at the center of the winding.  In autotransformer, between the series and common windings
  10. 10. No-Load Tap Changer (NLTC or DETC) On Load Tap Changer (OLTC  Mechanical tap changers  Thyristor-assisted tap changers  Solid state (thyristor) tap changers
  11. 11. DC MOTOR  The DC motor is electric motor that runs on direct current electrically.  DC motor works based on the LORENTZ FORCE.  In DC motor voltage is proportional to speed ADVANTAGES  Low initial cost  High reliability  Simple control of motor speed
  12. 12.  Reduction of power losses  Voltage profile enhancement  Voltage stability  Less heat produce
  13. 13. Applications  ROBOTIC CONTROLS.  SWING MACHINES.  ELECTRONIC BIKES.  WINDING MACHINES.  DC OPERATED DRILL MACHINES.  MOBILE AIR CONDITION FANS.  TOYS.  ELCTRONIC DOOR CONTROLLERS.  ELECTRONIC CHAIRS (beauty parlor etc.)
  14. 14. CONCLUSION  We have achieved the required speed and thyristor is a very good device for obtaining the variable DC there by controlling the motor speed.  This circuit is just a basic circuit for understanding DC motor speed control. In case of HWR we got zero voltage in negative half cycle that’s why has power efficiency.
  15. 15. Any query

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