Regarding the use of temperature sensors to control the start and stop of fans
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The start and stop of the fan are controlled using the dry contact signal from the temperature sensor; this is achieved through a relay circuit. Multiple high-temperature switches connected in parallel activate the coil of the intermediate relay, which in turn supplies a signal to the fan’s secondary control circuit to start the fan. Multiple low-temperature switches connected in series activate the coil of the intermediate relay, which supplies a signal to the fan’s secondary control circuit to stop the fan. The fan control circuit is kept in its current state. After the temperature shutdown switch outputs a signal, the temperature does not drop immediately; the interlock signal from the temperature switch remains active until the temperature falls below the high-temperature interlock value, at which point the switch is reset. However, due to the self-holding feature of the fan’s secondary circuit, the fan continues to run until the temperature reaches the low-temperature interlock value, at which point the temperature switch stops the fan by sending a signal. Until the temperature rises again to the low-temperature interlock value, the signal from the temperature switch remains active, and it is only when the temperature reaches that value that the switch is reset, starting the cycle over again. I’m not sure if the operation of the aforementioned temperature switch is like this
Yes, your description of the temperature switch controlling the start and stop of the fan is correct. When the temperature reaches the set high-temperature threshold, the high-temperature switch closes and activates the fan through an intermediate relay. The fan continues to operate under the self-holding control circuit; even if the temperature drops slightly but does not fall below the high-temperature interlock value, the fan will not stop. Only when the temperature drops to the set low-temperature threshold do the multiple low-temperature shutdown fan switches connected in series close, thereby cutting off the relay and stopping the fan from operating. Only when the temperature rises above the low-temperature interlock value again does the low-speed fan switch return to its normal state and become ready for the next start, and this cycle repeats itself. This design ensures that the fan can operate effectively within an appropriate temperature range. .