FIELD: power engineering. SUBSTANCE: during accidents involving decrease in power system frequency and voltage, auxiliary-power pieces of equipment of some power units are changed over to stand-by auxiliary-power transformers. auxiliary-service loads of power units and power transmission lines running from power units selected for disconnection are continuously monitored by means of logic power adder and when power of chosen load is within permissible minimal and maximal values, enabling signal is passed from power system to disconnect chosen power units. EFFECT: improved reliability. 2 cl, 1 dwg
