Automatic control systems for electric power metering cabinet heating

Abstract

The study concerns the analysis of heating methods of a thermal cabinet: electric power metering cabinet with equipment and additional mounted automatic control system (ACS) based on multi-electrode composite electric heaters or a 12k carbon heating cable. Schematic diagrams and specifications of the automatic control system for the heating methods under consideration are discussed. To obtain graphs of the temperature dependences in the places of installation of thermal resistances on the cooling time of the heating cabinet in the thermal-vacuum chamber for various automatic heating systems, the installation locations of thermal resistances were determined: inside the heating cabinet - in the area of the thermostat that controls the heating; in the upper part of the heating cabinet - at the level of the electricity meter and on the upper electric heater on the right; in the lower part of the heating cabinet - on the lower electric heater on the right and the lower electric heater on the left; in the thermal-vacuum chamber - above the thermal cabinet. The performance of the thermal cabinet equipment at subzero temperatures was studied. The use of the TBV-2000 ILKA thermal-vacuum chamber made it possible to perform a set of thermophysical tests of various heating ACS at subzero ambient temperatures. The results obtained make it possible to establish stable operation of the proposed heating ACS when using MCE electric heaters down to minus 60°C; when using 12k carbon cable - up to minus 45°C. The selection of a rational automatic control system for heating was carried out. Thermal imaging diagnostics of the used MCE electric heaters showed the uniformity of thermal fields and the efficiency of local surface-distributed electrical heating which made it possible to determine the rational zones for the location of the MCE in the thermal cabinet.