1. Full pressure direct start

When both the grid capacity and load allow for full voltage direct start, full voltage direct start can be considered.

The advantages are convenient operation and control, simple maintenance, and relatively economical. Mainly used for starting low-power motors, from the perspective of energy conservation, this method is not suitable for motors larger than 11kW.

2. Self coupling pressure reduction startup

The use of multi tap voltage reduction of autotransformers can not only meet the needs of starting different loads, but also obtain greater starting torque. It is a commonly used voltage reduction starting method for starting larger capacity motors.

Its * * advantage is that it has a large starting torque, and when its winding tap is at 80%, the starting torque can reach 64% of the direct starting torque. And the starting torque can be adjusted through tapping. It is still widely used today.

3. Y – Δ Start

For squirrel cage asynchronous motors with triangular stator windings in normal operation, if the stator windings are connected in a star shape during startup and then in a triangle shape after startup, the starting current can be reduced and its impact on the power grid can be alleviated. This start-up method is called star delta decompression start-up, or simply star delta start-up (Y – Δ start-up).
When using star delta starting, the starting current is only 1/3 of what it was when starting directly using the delta connection. If the starting current during direct startup is calculated as 6-7 Ie, then during star delta startup, the starting current is only 2-2.3 times. This means that when using star delta starting, the starting torque is also reduced to one-third of the original direct starting torque when using the delta connection.
Suitable for situations where there is no load or light load startup. And compared to any other pressure reducing starter, its structure is the simplest and its price is also * * *. In addition, the star delta starting method has another advantage, which is that when the load is light, the motor can operate in a star connection. At this point, the rated torque can be matched with the load, which can improve the efficiency of the motor and thus save power consumption.

4. Soft starter

This utilizes the phase-shifting voltage regulation principle of thyristors to achieve voltage regulation starting of electric motors, mainly used for starting control of electric motors, with good starting effect but high cost. Due to the use of thyristor components, there is significant harmonic interference during thyristor operation, which has a certain impact on the power grid.

In addition, fluctuations in the power grid can also affect the conductivity of thyristor components, especially when there are multiple thyristor devices in the same power grid. Therefore, the failure rate of thyristor components is relatively high, and due to the involvement of power electronics technology, there are also high requirements for maintenance technicians.

5. Inverter

The frequency converter is the most technologically advanced, comprehensive, and effective motor control device in the field of modern motor control. It adjusts the speed and torque of the motor by changing the frequency of the power grid. Due to the involvement of power electronics technology and microcomputer technology, the cost is high and the requirements for maintenance technicians are also high. Therefore, it is mainly used in fields that require speed regulation and high speed control requirements.