Ward-Leonard control is a voltage control method used in electrical systems to control the speed of DC motors. It was developed by Harry Ward Leonard in the early 20th century and is widely used in various industrial applications.

Explanation:

Voltage Control Method:
Ward-Leonard control is a voltage control method because it uses a variable voltage source to control the speed of the motor. In this method, a DC generator (also known as a motor generator set) is used to control the speed of the main DC motor.

Field Control Method:
While field control is a method used in some DC motor control techniques, Ward-Leonard control is not specifically a field control method. Field control involves varying the strength of the magnetic field in the motor to control its speed or torque. In Ward-Leonard control, the field current of the motor remains constant while the armature voltage is varied to control the speed.

Armature Resistance Control Method:
Armature resistance control is another method used in some DC motor control techniques, but it is not applicable to Ward-Leonard control. Armature resistance control involves varying the resistance in the armature circuit to control the motor speed. In Ward-Leonard control, the armature resistance remains constant while the voltage applied to the armature is varied.

Field Diverter Method:
Field diverter control is another method used in some DC motor control techniques, but it is not specifically related to Ward-Leonard control. Field diverter control involves diverting a portion of the field current away from the motor to control its speed. In Ward-Leonard control, the field current remains constant.

In conclusion, Ward-Leonard control is a voltage control method used to control the speed of DC motors. It is not specifically a field control, armature resistance control, or field diverter control method.