The present disclosure relates to a system for refrigeration, heating or air-conditioning technology, particularly a refrigeration system, including a working medium circuit, which has a compressor, a condenser, an expansion valve, and an evaporator connected successively in the flow direction. The polyester filament has a moisture absorption capability of between about 10 and 30 percent by volume. The control circuitry includes a focus compensation device for compensating focus errors caused by wobbles of the optical disc generated during rotations of the optical disc; and a high frequency compensator for compensating focus errors caused by wobbles of the optical disc generated during rotations of the optical disc at a frequency higher than a predetermined frequency. The second powder has a particle size of between 0. The discharging circuit discharges the smoothing capacitor.