Abstract: The present disclosure discloses a T-shaped three-level overload operating system, including a three-level topology and an overload mode switching system. The topology is connected with a first device group and a second device group which form a T shape; the first device group is designed with an overload capacity, and the second device group is designed with a rated capacity; and the overload mode switching system is configured for being connected to the topology to control the first device group to perform overload two-level operation on the topology, or to control the second device group to perform normal three-level operation on the topology, so that the number of device groups of the overload design can be effectively reduced, and then the cost of the system can be reduced. A working method of the T-shaped three-level overload operating system is further disclosed. The topology can be rapidly switched among working modes according to an output current of the topology.

Abstract: The present disclosure discloses a T-shaped three-level overload operating system, including a three-level topology and an overload mode switching system. The topology is connected with a first device group and a second device group which form a T shape; the first device group is designed with an overload capacity, and the second device group is designed with a rated capacity; and the overload mode switching system is configured for being connected to the topology to control the first device group to perform overload two-level operation on the topology, or to control the second device group to perform normal three-level operation on the topology, so that the number of device groups of the overload design can be effectively reduced, and then the cost of the system can be reduced. A working method of the T-shaped three-level overload operating system is further disclosed. The topology can be rapidly switched among working modes according to an output current of the topology.

Abstract: A surface-mounted polymer PTC overcurrent protection element having a small package size, comprising a PTC chip, an insulating layer (30), end electrodes (41, 42), and at least one conductive member (60). A dividing gap is designed on a first conductive electrode (21) to form first and second conductive areas (211, 212); the conductive member (60) is arranged at the edge or at least a corner of the first conductive area (211) side of the PTC chip, is used for conducting the first conductive area (211) and a second conductive electrode (22) on the PTC chip, and is not in contact with the end electrodes (41, 42); the main portion comprised in the dividing gap (70) of the first conductive electrode (21) is parallel to the longitudinal direction of the first end electrode (41) and the second end electrode (42). Also provided is a preparation method for the protection element. Thus, the miniaturized overcurrent protection element can satisfy the current PCB process to achieve requirements of mass production.