Working Principle and Application of Motor Starter

The motor starter is a special electronic device whose main function is to control the current before starting the motor within an acceptable range to ensure the normal operation of the equipment. This article will briefly introduce the working principle, classification and application fields of motor starters.

1. Working principle of motor starter

The main function of the motor starter is to control the current when the motor starts to prevent equipment damage caused by excessive current required when the motor starts and sudden impact on the power grid. Simply put, a motor starter is a "switch" used to start a high-power motor. It can adjust the current during the starting process to reduce the pressure of the motor on the power grid.

The working principle of motor starters is divided into two types: direct start and indirect start. The direct starting method refers to the method of driving the load through the starting ability of the motor itself, while the indirect starting method means that before starting the motor, the starting current is limited to a certain range through the charging circuit, thyristor device, etc., thereby realizing the motor starting. The way. When using a motor starter, factors such as control accuracy, current stability, and starting time also need to be considered.

2. Classification of motor starters

According to the different models and current control methods of motor starters, the classification of motor starters can be divided into the following categories:

(1) Direct starter

Direct starter, also known as motor direct start controller, is the most basic type of motor starter. The direct starter uses a Seldinger brake or a direct start button to use the torque and energy of the motor itself to bring the load to the set speed. The direct starter is suitable for use when the motor power is small and speed regulation is rarely needed.

(2) Auto starter

The autostarter reduces the starting current of the motor by 10% to 50% in the first few seconds to reduce grid pressure and equipment damage. The auto-coupling starter reduces the no-load voltage of the rated voltage power supply through voltage-regulating auto-coupling to reduce the current when the motor starts.

(3) Pressure reduction starter

A voltage reducing starter uses a voltage reducer to regulate the voltage at which the motor starts. The decompression starter can achieve "soft start", especially for constant torque loads with large load inertia or large starting current. Because it has the advantages of gradual acceleration and smooth current rise, using the decompression starter can reduce the impact on the motor and control. System damage.

(4) Thyristor starter

The thyristor device starter uses electronic devices to control and adjust the current when the motor is started. Its main advantage is that the thyristor device adjustment reduces the impact of sudden increases in current and large motor disturbances on the power system, and protects the motor and power supply. system.

3. Application fields of motor starters

Motor starters are widely used in the starting, control and protection of various large-scale electromechanical equipment. Specific application areas mainly cover the following aspects:

(1) Metallurgical industry: Motor starters are widely used in the start-up control and protection of metallurgical equipment such as high-power casting machines, high-precision rolling mills, high-efficiency dryers, high-power electric arc furnaces, and heavy-duty coal washers.

(2) Mining industry: In mining, mineral processing, ore collection and other mine production, motor starters also play an important role. Coal mining machinery, coal preparation equipment, ore processing equipment, etc. all need to use motor starters.

(3) Transportation industry: Electric motor starters are also widely used in the transportation field, such as railway locomotives, electric transmission vehicles, subway trains, etc.

The emergence of motor starters provides a great guarantee for the normal operation of electromechanical equipment. Different motor starters play different roles in different fields, so choosing a suitable motor starter is of great significance to the protection of equipment and systems.

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