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Ward Leonard Speed Control System for a DC Motor with Diagram

Updated on April 13, 2010

As a very flexible, reliable means of motor speed control, the Ward Leonard System is unmatched.

The system is made up of a driving motor which runs at almost constant speed and powers a dc generator as shown in the diagram. The generator output is fed to a dc motor. By varying the generator field current, its output voltage will change. The speed of the controlled motor thus can be varied smoothly from zero to full speed. 

Since control is achieved through the generator shunt field current, the control equipment is required only for small current values. A potentiometer or rheostat in the generator field circuit enables he variation of output voltage from zero to the full value and also in either direction. The controlled motor has a constant excitation. Its speed and direction are thus determined by the generator output. 

Depending upon the particular duties of the controlled motor, series windings may be incorporated in the field of the motor and also the generator. This may result in additional switching to reverse the controlled motor depending upon the compounding arrangements.

The driving motor or prime motor for the Ward Leonard System can be a dc motor, an ac motor, a diesel engine, etc. Any form of constant and almost constant speed drive can be used, since its function is only to drive the generator.


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      praveen k d 3 years ago

      nice explain

    • profile image

      I. Comfort 5 years ago

      Very simplified

    • profile image

      I. Comfort 5 years ago

      Very simplified

    • profile image

      Lawrence 6 years ago

      Perfect explanation.

    • profile image

      sateesh 6 years ago

      very simple expalnation

    • profile image

      Brian Hodgson 6 years ago

      Very good explanation thank you

    • profile image

      REY 6 years ago

      thanx,,,,i got wat i was searching for

    • profile image

      tandroid 6 years ago

      I actually understood for once.

    • profile image 7 years ago


    • profile image

      jinnu 8 years ago

      what would be the panel diagram of this (word-leonard) method

    • profile image

      peter GIZO 8 years ago


    • thevoice profile image

      thevoice 8 years ago from carthage ill

      well explained hub thanks


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