What is the concept of connecting only a portion of the motor winding during starting in part-winding starters?
1 Answer
The concept you're referring to is called "part-winding starters." Part-winding starters are a type of motor starter used to reduce the inrush current and voltage drop that occurs during the starting of large electric motors. These starters are commonly used in applications where the motor's starting current could cause issues such as voltage sags, equipment damage, or tripping of protective devices.
The idea behind part-winding starters is to connect only a portion of the motor winding to the power supply during the initial starting phase. Electric motors typically have multiple sets of windings that are designed to be connected in different ways for various operating conditions. Part-winding starters take advantage of this by initially energizing only a subset of these windings.
Here's how it works:
Initial Connection: During the starting process, only a part (usually half) of the motor winding is connected to the power supply. This reduces the overall impedance of the circuit, resulting in a lower inrush current and reduced voltage drop across the motor terminals.
Reduced Current Surge: When the motor is started with only a portion of the windings connected, the current drawn from the power supply is lower than if all windings were connected. This reduced current surge helps prevent voltage sags in the power distribution system and reduces the mechanical and thermal stresses on the motor itself.
Progressive Connection: After a predetermined time or when the motor reaches a certain speed, the remaining windings are connected to the power supply, providing the motor with full power. This is typically done through a switching mechanism within the part-winding starter.
Smooth Transition: By progressively connecting the windings, the motor's starting process is smoother and less abrupt, reducing the mechanical shock to the driven equipment and the motor itself.
Part-winding starters are effective in controlling inrush currents and reducing the strain on electrical systems during motor starting. However, they are typically used in larger motor applications where the design of the motor allows for separate winding connections. It's important to note that not all motors are designed to support part-winding starting arrangements.
Modern motor control technologies have evolved, and there are now alternative methods to achieve similar results, such as using soft starters or variable frequency drives (VFDs). Soft starters and VFDs offer more precise control over motor starting and stopping, as well as additional features like speed control and protection mechanisms.
The idea behind part-winding starters is to connect only a portion of the motor winding to the power supply during the initial starting phase. Electric motors typically have multiple sets of windings that are designed to be connected in different ways for various operating conditions. Part-winding starters take advantage of this by initially energizing only a subset of these windings.
Here's how it works:
Initial Connection: During the starting process, only a part (usually half) of the motor winding is connected to the power supply. This reduces the overall impedance of the circuit, resulting in a lower inrush current and reduced voltage drop across the motor terminals.
Reduced Current Surge: When the motor is started with only a portion of the windings connected, the current drawn from the power supply is lower than if all windings were connected. This reduced current surge helps prevent voltage sags in the power distribution system and reduces the mechanical and thermal stresses on the motor itself.
Progressive Connection: After a predetermined time or when the motor reaches a certain speed, the remaining windings are connected to the power supply, providing the motor with full power. This is typically done through a switching mechanism within the part-winding starter.
Smooth Transition: By progressively connecting the windings, the motor's starting process is smoother and less abrupt, reducing the mechanical shock to the driven equipment and the motor itself.
Part-winding starters are effective in controlling inrush currents and reducing the strain on electrical systems during motor starting. However, they are typically used in larger motor applications where the design of the motor allows for separate winding connections. It's important to note that not all motors are designed to support part-winding starting arrangements.
Modern motor control technologies have evolved, and there are now alternative methods to achieve similar results, such as using soft starters or variable frequency drives (VFDs). Soft starters and VFDs offer more precise control over motor starting and stopping, as well as additional features like speed control and protection mechanisms.