Study of technical parameters of magnetic starters and switches installed in workshop networks

Abstract

The study of technical parameters of low-voltage switching devices of Russian production – magnetic starters PML and switches RE19 has been carried out. The problem of evaluating energy efficiency of operation of magnetic starters and switches installed in in-plant power supply systems has been presented. The main destabilizing factors significantly affecting the technical characteristics of switching devices with voltage up to 1 kV have been given. Reliability of functioning of the investigated devices, first of all, depends on the degree of wear of switching contacts. The dependences of the heating temperature of the contact areas of switching devices on the loading coefficient have been studied. It has been revealed that with the increase of loading of devices in the range from 1,0 to 2,0Inom the temperature of contacts and contact areas is within the permissible limits in accordance with the requirements of GOST 403-73. The main factors influencing the resistance of contact connections – current flowing through the contacts, their dimensions and heating temperature – have been shown. According to the results of theoretical and experimental studies approximating functions of dependences of resistance of contacts and contact connections of switching devices on rated current have been developed and errors of the calculated method of contact resistance estimation have been determined. The developed dependencies can be used to determine the equivalent resistance of networks of in-plant power supply when estimating the level of power losses, which will increase the reliability of the results obtained.