How can the connection between two circuit breakers be closed and not closed at the same time?
A method of mechanical interlocking. Low voltage circuit breakers are generally available with interlock accessories (connected by steel cables in the middle), and high voltage generally adopts program locks.
Another method is electrical interlocking, that is, the normally closed contact of another circuit breaker is connected in the circuit of circuit breaker so that the circuit breaker cannot be closed. The drawback of this method is that it cannot prevent manual closing.
Safety lock equipment is a kind of planned safety protection equipment to prevent the accidental opening. Many industrial safety accidents can be avoided by adopting appropriate safety/lock equipment.