An isolated communications apparatus applied to a transformer. The transformer includes N first rectifier units and a second rectifier unit, and the isolated communications apparatus includes N first control units, a second control unit, and a signal convergence unit. The first control units are connected to the first rectifier units in a one-to-one correspondence. Each first control unit is connected to the signal convergence unit, and the signal convergence unit and the second control unit are connected through an optical fiber. The signal convergence unit is configured to: receive first data packets from the N first control units, send the first data packets to the second control unit, receive at least one second data packet from the second control unit, determine a first control unit corresponding to each second data packet, and send each second data packet to a corresponding first control unit.