Transcript
Prepared by: Braj Bihari B.Tech(IT)
DC MACHINES
DC CONSTRUCTION
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Field System
Armature
Armature Cont..
Armature Windings
Armature winding cont..
Commutator
Commutator and Brushes
Principle of Operation of DC Generator and DC Motor
Principle of Operation
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DC GENERATOR OPERATION
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DC MOTOR
DC MOTOR
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EMF or Armature Voltage Equation
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Torque
Types of DC Motor
Classification of DC Machines
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Speed and Torque Characteristics of a DC Motor
Separately Excited Equations
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Torque- Speed Characteristics
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Selection of DC Motor for Particular Applications
Separately Excited Motors
1. Accurate Speed2. Speed variation is required from very low
value to high value.3. Used in steel rolling mills, paper machines,
diesel-electric propulsion of ships.
Shunt Motors
It is constant speed motor so it used for:
1. Where the speed between no load to full load has to be maintained almost constant.
2. Where it is required to drive the load at various speeds and any one of the speed is required to be maintained almost constant for a relatively long period.
Series Motors
It is variable speed motor:
1. Where high torque is required at the time of starting to accelerate heavy loads quickly.
2. Where the load is subjected to heavy fluctuations and speed is required to be adjusted automatically.
3. Most suitable for electric traction, cranes, elevators, vacuum cleaners, air drives, sewing machines, fans and air compressors.
Compound Motors
1. Where high torque is required at the time of starting and where the load may be thrown off suddenly.
2. Where the load is subjected to heavy fluctuations.
3. Best suited for punching and shearing machines, rolling mills, lifts and mine-hoists.
Applications
Applications
The d.c. machine can operate as either a motor or a generator, at present its use as a generator is limited because of the widespread use of ac power.
Large d.c. motors are used in machine tools, printing presses, fans, pumps, cranes, paper mill, traction, textile
mills and so forth.
Small d.c. machines (fractional horsepower rating) are used primarily as control device-such as tacho-generators
for speed sensing and servomotors for position and tracking.
Paper and Steel Mills
Steel MillsSteel Mills
Mining and Machine Tools
Robots and Petrochemicals
Thanks
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