Shunt Motor Starters

Shunt motor starters are used to control the starting and stopping of shunt motors. These starters provide a means to control the flow of current to the motor windings, ensuring a smooth and controlled startup process. There are several types of shunt motor starters that can be used, including the 3-point and 4-point starter, the 5-point starter, and the 5-point and 3-point starter.

3-Point Starter
A 3-point starter is a type of shunt motor starter that is commonly used to control the starting and stopping of shunt motors. It consists of three main components: the main contacts, the field contacts, and the armature contacts. The main contacts are used to connect the motor to the power supply, while the field contacts are used to control the flow of current to the motor field winding. The armature contacts are used to control the flow of current to the motor armature winding.

4-Point Starter
A 4-point starter is another type of shunt motor starter that can be used. It is similar to the 3-point starter, but it also includes an additional set of contacts called the overcurrent release contacts. These contacts are used to protect the motor from excessive current during startup. If the current exceeds a certain threshold, the overcurrent release contacts will open, cutting off the power supply to the motor.

5-Point Starter
A 5-point starter is a more advanced type of shunt motor starter that includes additional features for better control and protection. In addition to the main contacts, field contacts, and armature contacts found in the 3-point and 4-point starters, it also includes an additional set of contacts called the no-volt release contacts and the reverse current release contacts. The no-volt release contacts are used to prevent the motor from accidentally restarting after a power failure, while the reverse current release contacts are used to protect the motor from reverse current flow.

The Correct Answer
According to the given options, the correct answer is option 'A', which states that the shunt motor starters that can be used are the 3-point and 4-point starter. This means that both the 3-point and 4-point starters are suitable for controlling the starting and stopping of shunt motors. However, it is important to note that other types of starters, such as the 5-point starter, can also be used depending on the specific requirements of the motor and the application.