DC Compound Motor

DC Compound MotorPresentation TopicGroup MemberSahib ullah BEE F14 207 Zain Aslam BEE F14 270M Faisal Khan BEE F14 291

LayoutIntroductionCircuit DiagramWorkingSpeed Control MethodologyApplicationsLimitationsReferencesQ/A

IntroductionElectrical Motor: it is machine which convert Electrical energy into Mechanical energy

AC Motor: Motor that run on alternating current (AC)

DC Motor: Motor that run on Direct current (DC)

DC Compound Motor Dc compound motor is the combination of series motor and shunt motorIt has a series field winding that is connected in series with the armature and shunt field winding that is in parallel with the armatureThe combination of series and shunt winding Allow motor to have a torque characteristics of the series motor And the regulated speed characteristics of shunt motor

Circuit Diagram

Types Of DC Compound MotorThe compound wound DC motor can further be subdivided into 2 major types on the basis of its field winding connection with respect to the armature winding and they are:

Long Shunt Compound Wound DC Motor

Short Shunt Compound Wound DC Motor

Long Shunt Compound Wound DC Motor

Short Shunt Compound Wound DC Motor

Sub classificationDepending on the polarity of the connection of shunt field winding, series field winding, and armature:

Cumulative Compound Motor

Differential Compound Motor

Cumulative Compounding of DC Motor

Differential Compounding of DC Motor

Working Of Cumulative Compound MotorMost common DC motor:Provides high starting torque and good speed regulation at high speedCan start even with large load and then operate smoothly when the load varies slightlyRecall that:Shunt motor can provide smooth operation at full speed, but can't start with large load attachedSeries motor can start with heavy load, but it speed cant be controlled

Working Of Differential Compound MotorConnection in slightly different mannerTwo magnetic field oppose each other in this caseThe motor will tend to over speed when the load is reduced just like series motorSpeed also drop more then the cumulative compound motor when the load increases at full RPM

Speed Controlled MethodologyTerminal voltage of the armature V. External resistance in armature circuit R.Flux per pole . The first two cases involve change that affects armature circuit and the third one involves change in magnetic field Therefore speed control of DC motor is classified asArmature control methodField control method

Applications Cumulative Compound MotorThese motor have high starting torqueThey can be operated even at no loads as they run at a moderately high speed at no loadHence cumulative compound motor are used for following applicationsElevators 6. Business MachineRolling mills 7. Machine toolsPunches 8. Agitators Shears 9. Mixersplaners 10. Presses

Applications Differential Compound MotorThe speed of these motor increases with the increases in the load which lead to an unstable operation

Therefore we cant use this motor for any practical applications

SummaryThe dc compound motor is used where a compromise is needed between the series and the shunt motor. The compound motor has better speed characteristic than the series motor and better torque characteristics than the shunt motor. The motor can be connected so that the shunt field and the series fields are in the same direction. This is the cumulative connection.

LimitationsThe speed of a DC compound motor can be easily controlled. It is enough if we change just the voltage supplied to it.

The differential type is not use in any event.

Protected from any physical damage at starting.

Comparison B/w Shunt, Series and CompoundShunt Motors: Constant speed motor (speed regulation is very good). Adjustable speed, medium starting torque. Applications: centrifugal pump, machine tools, blowers fans, reciprocating pumps, etc.

Series Motors: Variable speed motor which changes speed drastically from one load condition to another. It has a high starting torque.Applications: hoists, electric trains, conveyors, elevators, electric cars.

Compound motors: Variable speed motors. It has a high starting torque and the no-load speed is controllable unlike in series motors.Applications: Rolling mills, sudden temporary loads, heavy machine tools, punches, e t c

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ReferencesGoogleWikipediaSlideshare.netElectric machines fundamental by champion