to connect the generator to the mains when its voltage exceeds the mains voltage;
disconnecting the generator from the mains when its voltage drops below the mains voltage (at a certain value of reverse current);
preventing the generator from being connected to the mains with incorrect polarity;
non-automatic (manual) switching on of the generator into the mains;
signalling of generator switching on to the mains;
signalling of feeder breakage between the plus terminal of the generator and the apparatus.
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