Explanation:

The speed control of a DC shunt motor in both directions can be achieved using the Ward Leonard method. This method is widely used in industrial applications where precise and smooth speed control is required. The Ward Leonard method involves the use of a separate motor-generator set, which acts as a variable frequency and variable voltage source for the DC shunt motor.

Ward Leonard Method:
The Ward Leonard method consists of the following components and their working:

1. Motor Generator Set:
- The motor-generator set consists of a motor (called the prime mover) and a generator.
- The prime mover is an AC motor, typically an induction motor, which is connected to the AC power supply.
- The generator is a DC generator, which is mechanically coupled to the prime mover.

2. Motor Field Control:
- The field winding of the DC shunt motor is connected to a variable resistor called the field rheostat.
- By adjusting the resistance of the field rheostat, the field current and hence the magnetic field strength can be controlled.
- This allows for the control of the speed of the motor.

3. Motor Armature Control:
- The armature voltage of the DC shunt motor is controlled by the generator in the motor-generator set.
- The generator output voltage can be varied by adjusting the field current of the generator.
- By varying the generator field current, the armature voltage of the DC shunt motor can be controlled.

4. Speed Control:
- By adjusting the field rheostat and the generator field current, the speed of the DC shunt motor can be varied in both directions.
- Increase in field current of the generator increases the armature voltage, which in turn increases the speed of the motor.
- Decrease in field current of the generator decreases the armature voltage, resulting in a decrease in the speed of the motor.

Advantages of Ward Leonard Method:
- Precise and smooth speed control in both directions.
- Ability to control the motor speed over a wide range.
- Good dynamic response and stability.
- Ability to provide regenerative braking.

Conclusion:
The Ward Leonard method is a reliable and efficient method for speed control of a DC shunt motor in both directions. It provides precise speed control and is widely used in applications where accurate speed control is required, such as cranes, elevators, and rolling mills.