Energy saving principle and application of soft starter
There are two shortcomings in direct starting of AC induction motor. Firstly, its starting current can be as high as 5-7 times of the rated current, which requires a large margin of power grid,
Moreover, the service life of electrical control equipment is reduced and the maintenance cost is increased; Secondly, the starting torque can reach twice of the normal torque, which will have an impact on the load,
Increase wear and maintenance of transmission parts. Based on the above reasons, the AC induction motor step-down starting equipment is produced. The traditional starting method of depressurization is Y / △ v
There are two kinds of start-up and auto transformer step-down start-up, each of which has its own disadvantages. When the motor is started with Y / △ starting equipment, there will be a very high voltage at the moment of switching
The mechanical vibration is very harmful to the motor rotor, shaft connector, intermediate gear and load;
The step-down starting equipment of autotransformer is bulky and costly, and it is difficult to control the motor torque matching the load.
Due to the shortcomings of traditional step-down starting equipment, electronic digital soft starting device appears.
The advanced software design method and the latest hardware technology are applied, and the thyristor phase shifting technology is adopted to reduce the voltage applied to the motor
By setting appropriate control parameters, the torque and current of the motor can be well matched with the load requirements.
At the same time, through the cooperation of software and hardware, it can provide all-round protection for the soft starter itself, motor and load. Generally speaking, the power of motor is low
The choice is always greater than the maximum load requirements, the result is that the motor rarely runs under rated power, often in the light load or variable load situation, and the energy is seriously wasted.
During the operation of soft start, the rated output voltage is maintained to ensure that the motor and load enter a stable state after acceleration; After a short period of time,
It will automatically enter the stage of power saving operation. Its unique power-saving control software automatically tracks the load changes, through the continuous integration of current and power factor
Calculation, real-time adjustment, update trigger angle, control output voltage, reduce excitation current, improve power factor, realize power saving.
In addition, its advanced soft stop function can eliminate the water hammer effect of pump load.