Alternative Resource-saving Differential Electric Motor Protection

The author presents the principle of operation of alternative resource-saving differential protection for high-voltage electric motors, made with adjustable selection of settings, without the use of measuring current transformers (CT) and current relays with ferromagnetic cores, which have significant weight and dimensional parameters and high cost. The result is the creation of resource-saving protection for the protection of electric motors, made on inductive coils and reed switches. Protections with their application can be used as an alternative to the traditional protections of electric motors made on electromechanical, semiconductor and microprocessor bases and at the same time by their characteristics are not inferior to them. The scientific novelty is that this protection has the effect of resource saving of used materials, thus allowing to realize significant savings of copper and steel, and represents a new approach in realization of differential protection for electric motors. All structural elements of the presented protection are made of heat-resistant, durable and lightweight plastic, type «PLA», printed on a 3D printer. The resource-saving of these protections is in the use of inductance coils and reed switches, which are, both in terms of their cost and weight and dimensional parameters, an order of magnitude cheaper and smaller in size and weight than the above-mentioned measuring CTs. The use of the presented protection increases the reliability of relay protection, both the cell itself, where it is installed, and the electrical installation, which is an electric motor connected to it. The proposed differential protection is made in the form of a structure with the installation of its elements inside the cell of complete (closed) switchgear voltage 6-35kV and in the electric motor