Дослідження особливостей умов роботи електричних апаратів в аграрному виробництві

Abstract

Silver and composite materials based on it are used for making contacts of switching electric devices as the only material that can provide low and stable transient resistance and high resistance to electric arc erosion. The growth of the value of precious materials, the exhaustion of traditional resources, leads to a search for ways of their more rational use and economy. Ukraine has no silver reserves. The main strategic directions of reducing the cost of using silver are the effective measures of its use at the stages of manufacturing the apparatus, the design of electrical control systems and the proper operation of switching devices. Currently, the industry manufactures magnetic starters with different classes of wear resistance from 0.3 to 4 million cycles and automatic switches with a wear resistance of 20-100 thousand cycles [3]. Most scientific developments are aimed at increasing the electrical resistance and arch strength of contact materials. The work on the development of composite materials with low silver content is actively underway [2]. To date, little research has been done Crystal or composite materials based on silver are used for making contacts of switching electric devices. Sometimes Since the reduction in the weight of the contacts is directly proportional to the number of switches, each electrical apparatus is characterized by a limiting number of switches, or electrical wear and tear. In switching devices, the mass of contacts is different and is within the range of several milliograms in low-current relays to dozens of grams in high-current devices. In most cases, the life of electrical wear is completely ineffective, which leads to economic losses. The theoretical distribution is calculated in the software environment of applications of the package "MathCad". The theoretical distribution of the number of devices depending on the number of commutations is depicted in Fig. 1 Devices with frequent switches include machines that work in the automated systems, where they are controlled directly from the automatic control system. Most technological machines use electromagnetic actuators, as well as automatic switches, which are controlled directly by operators. These devices are characterized by a rather low switching frequency, which, as a rule, does not exceed 10 turns per day. Taking into account the specifics of agricultural production, it should be noted that a significant part of the equipment operates seasonally, which also does not require high wear and tear. Taking into account such a real frequency of switching on devices with low switching, it is necessary to connect devices with wear to 50 thousand for the estimated 10 years of operation. If we consider the percentage segment of such devices, then they constitute an overwhelming majority. Conclusions 1. It is advisable to increase the range of switching devices differing in the class of electric resistance in the direction of its reasonable reduction. 2. When designing control circuits for technological equipment, duplication of switching groups should be avoided.