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DC Motor or Direct Current Motor
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Speed Control of DC Motor
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Testing of DC Machine
Swinburne Test of DC Machine
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Ward Leonard Method of Speed Control
Armature Reaction in DC Machine
Commutation in DC Machine or Commutation in DC Generator or Motor
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Ward Leonard Method of Speed Control
Principle of Ward Leonard MethodBasic connection diagram of the Ward Leonard speed control system is shown in the figure below. The speed of motor M1 is to be controlled which is powered by the generator G. The shunt field of the motor M1 is connected across the DC supply lines. Now, generator G is driven by the motor M2. The speed of the motor M2 is constant.
When the output voltage of the generator is fed to the motor M1 then the motor starts to rotate. When the output voltage of the generator varies then the speed of the motor also varies. Now controlling the output voltage of the generator the speed of motor can also be controlled. For this purpose of controlling the output voltage, a field regulator is connected across the generator with the dc supply lines to control the field excitation. The direction of rotation of the motor M1 can be reversed by excitation current of the generator and it can be done with the help of the reversing switch R.S. But the motor-generator set must run in the same direction.
Advantages of Ward Leonard System
- It is a very smooth speed control system over a very wide range (from zero to normal speed of the motor).
- The speed can be controlled in both the direction of rotation of the motor easily.
- The motor can run with a uniform acceleration.
- Speed regulation of DC motor in this ward Leonard system is very good.
- It has inherent regenerative braking property.
Disadvantages of Ward Leonard System
- The system is very costly because two extra machines (motor-generator set) are required.
- Overall efficiency of the system is not sufficient especially if it is lightly loaded.
- Larger size and weight. Requires more floor area.
- Frequent maintenance.
- The drive produces more noise.
Application of Ward Leonard SystemThis Ward Leonard method of speed control system is used where a very wide and very sensitive speed control is of a DC motor in both the direction of rotation is required. This speed control system is mainly used in colliery winders, cranes, electric excavators, mine hoists, elevators, steel rolling mills, paper machines,diesel-locomotives, etc.
Closely Related Articles DC Motor or Direct Current MotorSpeed Regulation of DC MotorSpeed Control of DC MotorWorking or Operating Principle of DC MotorTorque Equation of DC MotorConstruction of DC Motor | Yoke Poles Armature Field Winding Commutator Brushes of DC MotorTesting of DC MachineSwinburne Test of DC MachineLosses in DC MachineArmature Reaction in DC MachineCommutation in DC Machine or Commutation in DC Generator or MotorMethods of Improving CommutationStarting Methods to limit Starting Current and Torque of DC Motor3 Point Starter | Working Principle and Construction of Three Point Starter4 Point Starter | Working Principle and Construction of Four Point StarterMore Related Articles Electrical Motor | Types Classification and History of MotorWorking of Electric MotorTypes of DC Motor Separately Excited Shunt Series Compound DC MotorShunt Wound DC Motor | DC Shunt MotorSeries Wound DC Motor or DC Series MotorCompound Wound DC Motor or DC Compound MotorPermanent Magnet DC Motor or PMDC Motor | Working Principle ConstructionBrushless DC MotorsNew Articles Ring CounterDischarging a CapacitorCharging a CapacitorElectric PotentialParity Generator