Describe and sketch Ward Leonard System

In this system, motor speed can be control from zero to full in either direction and also able to give the motor a robust torque characteristic. This system is used in ship steering gear and windlass of deck machinery.

 

From main A.C supply a A.C motor is running which is connected through a coupling to a D.C generator. D.C generator has a rotor. Now from main A.C supply a transformer is used to lower the voltage and rectified it to d.c. Then it passes to the d.c field winding through potentiometer. Potentiometer is a variable control resistor, which will give the magnetic field strength to D.C generator and maintain the polarity of the pole in required direction. If polarity altered, then working motor will run in opposite direction. Potentiometer ensures the strength and direction of the motor.