LBFK series low-voltage compound switch refers to connecting SCR and magnetic latching relay in a parallel way, adopting internal single chip for controlling, making SCR undertakes zero-passing switching at the moment of switching i.e. switching on when the voltage passes zero and switching off when the current passes zero; the conducting time of SCR is very short (doesn’t generate heat), and then, the magnetic latching relay will be connected for running. Therefore, it has advantage of SCR switch that there is no inrush current in case of passing zero, and the advantage that there is no power loss when the AC contractor is running. In this case, defects including heating during the running of SCR and spark in case of contactor switching are avoided. It is a kind of relatively ideal switch. Especially because that there is no inrush current or spark when the magnetic latching relay is on or off, the service life of its electrical apparatus is longer than the design service life, and its mechanical service life reaches millions of times, which may guarantee long-term running.