Investigation of induction motor operation from the soft starter in reverse mode with reduced speed

Abstract

Ease of maintenance and high reliability of asynchronous electric drives actively popularize their using in manufacturing. At the same time, such drive has its drawbacks: high currents and significant torque during direct starting from contactor control systems. This problem can be solved using the so-called "service functions" of soft starters. This work at developing these functions and issuing recommendations for their use is aimed. The purpose of the investigation is to determine the possibility of using the "service functions" of soft starters for emergency and service modes of agricultural plants. The investigation of the operation of an induction motor with a soft starter using the provisions of the theory of electrical circuits of sinusoidal and non-sinusoidal currents and using computer analysis was carried out. Investigation on the mechanism of straw shredders using a soft starter was carried out. Performance increasing of such a mechanism is possible using the "reverse" function with a reduced speed, implemented, for example, in SSW900 soft starters. To configure the soft starter, the WEG programming Suite software was used, which, in addition to the function of writing parameters, also contains the function of reading parameters and visualizing them as trends. As a result of the investigation, it was found that the intelligent control of thyristors in soft starters allows to expand their functionality, namely, to reverse the induction motor without using an additional contactor. The implementation of the reverse speed function with appropriate restrictions in soft starters allows reducing the cost of the used electrical equipment for straw shredders. Too much JOG relative voltage to the soft starter can cause large fluctuations in motor speed and must be carefully adjusted.