Abstract
In the article the author presents resource-saving current protections for consideration. Until now, one of the unsolved problems of modern electric power industry is the construction of relay protection of electrical installations without the use of measuring current transformers (CT). This issue has been repeatedly raised at international conferences on large power systems (CIGRE). The fact is that such current transformers are metal-intensive, bulky and have expensive insulation. This paper is directly related to the solution of this issue and presents protections that are alternatives to conventional protections. At present, as it is known, microprocessor-based relay protection devices are widely implemented in production, the reliability of which is not higher than that of electromechanical or semiconductor-based devices. The issue of resource saving in the electric power industry has been repeatedly raised, remaining relevant for relay protection without the use of expensive and having significant weight and dynamic parameters measuring metal-intensive current transformers (CTs). The development of resource-saving shortcircuit relay protection devices without the use of metal-intensive measuring current transformers (CTs) with metal cores was started in the 60s of the last century, which remain relevant to this day.