DC motors require a starter for various reasons, primarily to control the initial current surge and ensure proper starting conditions. Here's why a starter is necessary for starting DC motors:
High Starting Current: When a DC motor starts, it draws a high current due to the initial inertia and the back EMF (electromotive force) not yet being developed. This high current can lead to excessive wear and tear on the motor's components, such as the armature and brushes, potentially causing damage and reducing the motor's lifespan.
Voltage Drop: The high starting current can lead to a voltage drop in the power supply system. This voltage drop might affect other devices connected to the same power source and cause operational issues.
Mechanical Stress: Rapid acceleration caused by the high starting current can subject the motor and the mechanical load it is driving to sudden stress and shock, which might lead to mechanical failures or misalignment.
Overheating: The excessive current drawn during start-up can lead to overheating of the motor windings and other components. Overheating can lead to insulation breakdown and further damage to the motor.
Controlled Acceleration: A starter allows for controlled acceleration of the motor by gradually increasing the voltage and current, preventing sudden jerks or shocks to the mechanical system it drives. This controlled acceleration is important, especially in applications where precise speed control is required.
Reduced Wear and Tear: By limiting the initial current surge, a starter helps reduce wear and tear on the motor's brushes, commutator, and other internal components, thus extending the motor's operational life.
To address these issues and ensure a smooth and controlled starting process, a starter is used. A starter typically employs various methods to limit the starting current, such as using resistors, autotransformers, or electronic control circuits. As the motor gains speed and back EMF builds up, the starter gradually reduces its resistance or impedance, allowing the motor to draw more current and achieve its desired operating speed.
In summary, a starter is essential for starting DC motors to prevent damage, reduce wear and tear, control acceleration, and ensure proper operation of both the motor and the connected equipment.