Resistance of Field Regulator in DC Shunt Motor

Field regulator is an important component in a DC shunt motor which is responsible for controlling the field current. The resistance of the field regulator determines the amount of current flowing through the field winding, thereby influencing the motor's speed and torque characteristics.

The resistance of the field regulator is typically specified in ohms and is denoted by the symbol 'Rf'. It is important to choose the appropriate resistance value for the field regulator to ensure optimal motor performance.

The resistance of the field regulator is determined based on various factors such as motor design, voltage rating, and desired operating characteristics. In the case of a DC shunt motor, the resistance of the field regulator is typically in the range of 100 ohms.

Explanation:

1. DC Shunt Motor:
- A DC shunt motor is a type of DC motor where the field winding is connected in parallel (shunt) with the armature winding.
- It is widely used in various applications due to its simple construction, good speed regulation, and ability to provide high starting torque.

2. Field Regulator:
- The field regulator is a device that controls the field current in a DC shunt motor.
- It consists of a variable resistance connected in series with the field winding.
- By adjusting the resistance, the field current can be varied, thereby controlling the motor's speed and torque characteristics.

3. Importance of Field Regulator Resistance:
- The resistance of the field regulator determines the amount of current flowing through the field winding.
- A higher resistance value reduces the field current, resulting in a slower motor speed.
- Conversely, a lower resistance value increases the field current, leading to a higher motor speed.

4. Order of Resistance:
- The given question states that the resistance of the field regulator in a DC shunt motor is of the order of 100 ohms.
- The term "order" refers to the magnitude of the resistance value.
- In this case, the resistance value is approximately 100 ohms, which is the correct answer (option 'A').

In conclusion, the resistance of the field regulator in a DC shunt motor is typically in the range of 100 ohms. This resistance value plays a crucial role in controlling the field current and, subsequently, the speed and torque characteristics of the motor.