Fusible alloy type thermal-links are available in two types, Axial type and Radial type.The operating principle and structure for the two types is basically the same.
Tin plated soft copper wire are welded to a fusible alloy with a lower melting point. For fusible alloy surely melting at the functioning on the surface, after coating the special rosin then insert in the insulation case. The structure is sealed completely by sealant on the case opening part.
|Fusible alloy||Special rosin||Insulation case||Sealant||Lead wire|
When thermal-links sense a abnormal heat cause by abnormal operation of component/equipment through thermal-links body and lead wire, the fusible alloy melt by reaching at the temperature of the melting point of the alloy.
An electrical circuit of the thermal-links is opened with forming two separate balls at the edges of the lead by surface tension of the melted fusible alloy.
Special resin accelerate the surface tension of the melted fusible alloy.
This thermal-links adopted metal casing and sense temperature material of organic compound pellet.
This is a completely seal off structure by sealant, and in the metalic case it has be installed with insulation bush and spring, movable contact, disc and thermal pellet.
|Thermal pellet||Metal case||Disk||Spring 1||Movable contact|
|Spring 2||Insulator bushing||Sealant||Lead wire1||Lead wire2|
The current has flowed by the route of lead wire ⇔ movable contact ⇔ metallic case ⇔ lead wire before it functions.
The thermal pellet perceives heat when the ambient temperature rises, and it melts.
Spring expands when the thermal pellet melts, the movable contact pushes and separated from the lead, and the current is intercepted.
|Insulation case||Sealant||Resistor||Thermal-Links||Lead wire|