Working principle of the temperature control switch in a hair dryer

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This post was last edited by goldliyang on 2020-5-12 08:32. A temperature control switch is also known as a temperature protector or temperature controller; it is simply referred to as a thermostat. It is a type of automatic control element that can undergo physical deformation within its switch structure in response to changes in the temperature of the working environment, thereby generating certain special effects and enabling the switch to either conduct or disconnect power. The switch of a hair dryer is generally controlled by a bimetallic temperature controller. This controller consists of a bimetallic strip and contact switches; the shape of the bimetallic strip changes as the temperature varies. At normal temperatures, the contacts of the bimetallic strip remain closed, but when the temperature rises and reaches the set point, the bimetallic strip deforms and the contacts break apart, thereby achieving temperature control. When the hair dryer is turned off, the two contacts of the bimetallic temperature controller ST are in a connected state. When the hair dryer is powered on and set to the high-temperature setting, it operates normally. Once a certain temperature is reached, the two contacts of the bimetallic temperature controller separate, resulting in an open circuit; the hair dryer then stops heating and enters a heat-retention mode. When its temperature drops to a certain level, the metal spring inside the bimetallic temperature controller becomes connected again, allowing the hair dryer to start heating once more.