Loop switching method, device and system

The invention discloses a loop switching method, a device and a system; according to the loop switching method, a first loop and a second loop are connected between first equipment and second equipment; a direct current contactor is serially connected onto the first loop; a controllable switching tube is parallelly connected onto the direct current contactor; when the first loop is connected, the direct current contactor is also connected, the controllable switching tube is disconnected and the second loop is disconnected; the loop switching method comprises the following steps that the connection of the second loop is controlled; the controllable switching tube is triggered to be connected; the disconnection of the direct current contactor is controlled after the controllable switching tube is connected; and the disconnection of the controllable switching tube is triggered after the direct current contactor is disconnected. According to the loop switching method, the device and the system, the connection heat losses can be reduced and the switching speed can be accelerated.