Matsuo MQT8H 25XB

Temperature control devices are used to regulate temperature within a specified range, with loads that can be heaters (heat sources) or coolers (cooling units, fans). Thermal devices include electronic, bimetallic, liquid-expansion, thermal-magnetic, and thermal fuse types. The two primary functions of thermal devices are control and protection.

• Electronic thermostat: Maintains temperature within a specified range; common products are electronic thermostats, requiring small on/off temperature differential, high accuracy, and long service life.
• Temperature Power Sensor (TPS): Consists of a sharp snap-action spring for semi-permanent use, a flat bimetal strip with no material strain, and two flat bimetal strips for enhanced sensitivity; enables precise temperature regulation as a replacement for electronic thermostats.
• Capillary thermostat (liquid expansion type): Predominant controller type before electronic thermostats entered the market; used in industrial and consumer appliances, but declining in adoption due to large physical size and thermal interference defects in the capillary.
• TRS thermal reed switch (magnetic type): Contact capacity limited to less than 0.5A; contacts are non-snap-action with no trip mechanism; difficult to control additive elements and sintering temperature of thermosensitive magnets (sintered components) for specific operating temperature ranges; not suitable for planned production.
• Disc-type thermal protector: Simple structure, low cost, accounting for 80% of the global bimetal thermal protector market; however, large temperature differential, gradual drift of specified temperature, and unsuitability for use as a controller.
• Thermal fuse: Single-use, a primitive type of protector; demand for this safety device will persist due to its simplicity and low cost.
• TPS operating principle: Specifically designed and manufactured for precision control applications, featuring miniaturization and low cost; composed of a spring with near-infinite service life and sharp, distinct trip characteristics, combined with non-deforming flat bimetal strips; uses two bimetal strips in combination for enhanced sensitivity. Narrow temperature differential and sharp snap-action spring play a critical role in achieving ideal thermostat response; the snap-action spring opens and closes within an extremely small distance (approx. 0.05mm) or temperature range (approx. 3°C); the beryllium copper snap-action spring withstands at least 2 million operations.
• Disc-type thermal protector operating principle: Achieves snap action by forming the bimetal strip into a dome shape (hemispherical, disc-shaped); simple structure suited for mass production; accounts for 80% of the global bimetal thermal protector market due to low cost. However, the physical properties of the bimetal material are similar to ordinary steel — not inherently a spring material — causing gradual deformation through repeated trip cycles; service life is generally limited to a few thousand to tens of thousands of operations; while nearly ideal as a protector, it is not suitable for use as a controller.