Magnetic Saturation Reactor In The Application Of The Asynchronous Motor Based On PLC

Motor will cause great starting-current in the process of directed starting, the idamage not be ignored by grid.To help solve the problem, use soft starter to realize the controlling of the current usually. There are kinds of soft starting, like star/triangle, autotransformer, reactor, thyristor and magnetic controlling etc. The popular style in low voltage is thyristor soft start, because it is small,compacted-structure, good-starting repeatability.However in high-middle voltage the thyristor soft start need multiply parallel connected thyristors,but standard of the thyristor is strict.Magnetic controlling soft start have not these problems, and it is high reliability, good adaptability to environment, good stability, small volume and free maintenance.This paper research on magnetic controlling soft start.The low voltage dragged motor in this paper is pump,its parameter is37KW,50HZ,working voltage is380V.Researching low voltage for the reason is due to cost.And the motor has the same control method and the strategies in low voltage and in high voltage,the difference is level and capacity of the insulation of the magnetic saturation.This article elaborate the PLC tehnology in asynchronous motor soft starter used in automatic control and its superiority,with specific proceed.In tandem in squirrel-cage motor stator loop in magnetic saturation reactor,electronic devices.PID regulation to form a set of starting system.Siemens S7-200PLC as control system, general principle is that when starting the motor due to the series of adjustable reactance, starting current is little.Starting process applying the PLC control system adjustable reactance,starting current is little.Starting process applying the PLC control system adjustas the adjustable reactance control voltage, so that the reactance decreases to zero, the motor run from the starting stable state to the normal operation state and bypass the adjustable reactance after that quit running, motor starting process will is finish.This paper contents including:designing PLC control circuit, selecting hardware module; Selecting the suitable magnetic saturation reactor, setting parameters and calculation; The analysis and simulation with saturable reactor of single-phase magnetic properties, designing and simulating the system of magnetic controlling soft start.