One of the contactor mutual switching circuits for dual power supplies

Mutual switching of dual power supplies means that the load is powered by two power supplies, and the two power supplies work at the same time and bear the electrical load respectively. When
one of the power supplies fails, the tie switch automatically closes, and all loads are powered by the non-power outage circuit.
The circuit is shown in Figure 14-131. Under normal circumstances, power supply No. 1 supplies power to the load of section A bus, and power supply No. 2 supplies power to
the load of section B bus. Note: The auxiliary contacts
    of circuit breakers QFi and QF2 must act one At time before the main contacts (mechanical adjustment is available), otherwise two different power supplies will merge in an instant, causing a short circuit.