Temperature detection control circuit of electric kettle

Temperature detection control circuit of electric kettle

Shown is the temperature detection and control circuit of the electric kettle .
    Connect the AC 220 V power supply. The L (live wire) end of the AC power supply is added to the water boiling heater through the steam-type automatic power-off switch , thermostat ST and thermal fuse FU.
One end of the EH forms a loop through the water boiling heater and the N (neutral) end of the AC power supply, so that there is AC
current at both ends of the heater and starts heating.
    There are three levels of protection in the electric kettle: The first level is a steam-type automatic power-off switch. When the water in the electric kettle boils, steam will be generated,
which will heat and deform the metal sheet in the steam switch, automatically pop up the switch, and disconnect the circuit. ; The second level is the thermostat, which plays
a role in preventing boiling and drying out in the electric kettle. When the steam-type automatic power-off switch does not work, the water in the kettle will continue to decrease. When the water level is too low or appears to be burning.
state, the bimetallic piece in the thermostat will work to disconnect the circuit; the third kettle thermal fuse, when the above-mentioned switches lose their function,
as the temperature rises (around 139°C), the thermal fuse The fuse will blow, causing the electric kettle to lose power.
    The indicator light (neon tube) HL and the current limiting resistor R are connected in series and are in parallel with the water boiling heater. When the electric kettle circuit is in the open and
boiling state, the boiling heater has voltage to withstand operation. HL will light up to indicate the heating status of boiling water. When the water temperature is higher than 96°C, after the steam-type automatic
power-off switch is turned off, the electric kettle circuit is in an open circuit state and the indicator light HL goes out.