Why do we need a starter to start a DC motor ?
Starter is used to limit the starting inrush current to prevent motor winding from daamage
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A DC motor requires a starter for various crucial reasons:
1). To control the initial inrush current: When a DC motor is started, there is no back electromotive force (EMF) as the rotor is stationary. This absence of back EMF results in a high initial current, known as inrush current, which can be damaging to the motor’s components and power supply due to excessive voltage drops.
2). To protect the motor: The high inrush current can lead to overheating, potentially damaging the motor’s insulation and shortening its lifespan. A starter helps in gradually increasing the current, safeguarding the motor from thermal stress.
3). To ensure smooth acceleration: A starter enables the motor to smoothly increase its speed, preventing mechanical stress on both the motor and the connected load. This controlled acceleration contributes to a longer lifespan for the equipment.
4). To maintain system stability: In a complex system with multiple motors and electrical devices, starting a DC motor without a starter can cause instability in the power supply, resulting in voltage sags and affecting other equipment.
5). To comply with safety standards: Many safety regulations mandate the use of starters to limit inrush current and protect the motor and electrical system from damage.
Various types of starters are available for DC motors , such as
- Resistor starters,
- Autotransformer starters, and
- Electronic starters,
each serving the purpose of controlling the motor’s initial current and ensuring its safe operation.
There are various types of starting methods for DC motors, which include:
1). Resistor Starters
Incorporate resistors in the armature circuit to restrict the initial current flow.
These resistors are progressively bypassed as the motor accelerates.
2). Autotransformer Starters
Employ an autotransformer to decrease the initial voltage supplied to the motor, thus limiting the initial current.
3). Electronic Starters
Make use of power electronics to regulate the voltage and current delivered to the motor, enabling precise management of the starting sequence.
The utilization of a starter guarantees that the DC motor commences operation safely, functions effectively, and has an extended operational lifespan.
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