A starter is an essential component required to start a DC motor. The primary function of the starter is to provide an initial boost of electrical energy to the motor's armature, enabling it to overcome the initial inertia and begin rotation. Without a starter, the motor would not start and could potentially damage the electrical circuit.
To understand why a starter is necessary, it is essential to understand the working principle of a DC motor. A DC motor operates on the principle of Fleming's Left-hand rule, which states that when a conductor carrying current is placed in a magnetic field, it experiences a force perpendicular to both the direction of current and magnetic field. This force causes the conductor to rotate, which, in turn, drives the motor's shaft.
However, to start the motor, an initial torque must be applied to overcome the motor's static friction and start the rotational motion. This initial torque is generated by an external force, such as a starter, which provides the required electrical energy to the motor's armature. The starter, typically a DC series motor, is connected in series with the motor's armature, and its magnetic field is used to provide the initial torque.
When the starter is energized, the magnetic field generated by the starter interacts with the magnetic field of the motor's armature. This interaction generates a torque that causes the armature to rotate. As the armature begins to rotate, the magnetic field generated by the armature increases, which, in turn, increases the torque provided by the starter. Once the motor reaches its rated speed, the starter is switched off, and the motor continues to run under its own power.
The need for a starter is particularly crucial in high-power applications, such as industrial machinery, where the starting current drawn by the motor can be several times higher than the motor's rated current. This high starting current can cause significant damage to the motor and electrical circuit if not controlled properly. The starter serves as a current limiter, limiting the initial current drawn by the motor to a safe level.
In addition to providing an initial boost of electrical energy, the starter also serves other essential functions, such as protection against overloading and under-voltage. The starter contains protection devices, such as overload relays and under-voltage relays, which protect the motor from damage due to overloading or low voltage.
In conclusion, a starter is an essential component required to start a DC motor. It provides an initial boost of electrical energy to the motor's armature, enabling it to overcome the initial inertia and begin rotation. The starter also serves as a current limiter, protecting the motor and electrical circuit from damage due to high starting currents. In high-power applications, the need for a starter is particularly crucial as it prevents damage to the motor and electrical circuit and ensures reliable operation of the system.