Household appliances electric water heater temperature regulating circuit circuit

  
Electric water heater temperature control circuit, with water level indication, temperature and anti-dry, leakage power automatic protection function, safe and reliable. (1) Th
Household appliances electric water heater temperature regulating circuit circuit - schematic

e circuit electric water heater temperature control circuit from the power circuit, leakage circuit protection, temperature control circuit, a level indicative of anti-dry circuit, as shown in Figure 1-56. Power circuit from the power transformer T, rectifier bridge pile UR, filter capacitor c1, Cz and three-terminal voltage regulator integrated circuit lCl composition. Leakage protection circuit current transformer TA, dual time-base integrated circuit IC2 (ICZa, ICZb) an internal timebase circuits and related peripheral components and parts. Temperature control circuit by the time-base integrated circuit IC2 double inside another time base circuit, thermistor RT, transistor VT, relay K, potentiometer RP and associated external components. EH electric heater; LED1 work status indicator LEDs. LED6 electric heater indicator light-emitting diodes. (2) After the power switch circuit principle Sl, AC 220V voltage after T Buck, UR rectifier, C. After filtering and regulator IC1, at both ends of C2 + 12y generate voltage as leakage protection, temperature control, water level indication and anti-dry circuit power supply. Thousands of low temperature in the tank 40 (water temperature is set lower limit temperature), IC2 pin voltage is lower than V {i:/3, feet high output, the transistor VT conduction, the relay pull-K, its normally open contact connected to the electric heater EH energizes work, LED6 light. When the water temperature is heated to 45t (set temperature upper limit temperature), 1C2 of a pin goes low, the VT end, K release, EH stop heating. LED6 extinguished. When the water temperature drops until less than 40, EH and start working, LED1 light, so the cycle, the tank temperature constant at 40 to between 45. When the electric heater EH is working properly, the current flowing through the transformer winding WI TAs, W2 more stable operating current, the winding W3 on the induced voltage is 0, IC2 pin voltage is greater than 2Vcc:/3, pin voltage is low dry 2Vcc/3, feet high output, the light emitting diode LED1 lit, indicating EH normal operation, no leakage phenomenon. When EH leakage occurs, will lead to flow through the windings Wl TAs, W2 in operating current suddenly increases, resulting in a sense of winding W3 will be voltage, feet of IC2 goes high, pin goes low level, LED1 off, indicating the presence of EH leakage. Meanwhile diode VD2 conduction, IC2 of ? pin goes low, a pin output low, the VT end, K release, the EHs power supply cut off, to achieve a leakage protection. S2 for the leakage protection test button. When the button is pressed, the horse Zouren resistor circuit, the winding Wl TAs, W2 in a short-circuit current, voltage is induced in the winding W3, lC2 the pin goes high, feet from the high variant low, LED1 lit by the state variable is off, indicating that the leakage protection circuit can play Bei electrical protection... Water level indicator circuit with anti-dry south level detection circuit electrode AE, resistors horses, horse 2, Rl. Light emitting diode LED2, LED5 and analog electronic switch integrated circuit IC3 composition. 1C3 four control terminal ( feet, feet, feet and feet) water level detecting electrode, respectively, A - D is connected. When the water tank, the water level rises to the electrode at D, the main electrode E (for the ground, and + f ,: connected) through the water and electricity Xi phase D then make the IC3 feet high, inside the feet to analog electronic switch is turned ON, the IC3 O pin goes high, indicating a low level light emitting diode l. ED2 lit, while ? feet of IC2 goes high, the temperature control circuit controls EH work (when the water level is below the electrode D, EH does not work, EH to prevent damage due to dry). The water level continues to rise to the electrodes C, B, A when, IC3s feet, feet and legs have also changed to high level, the water level indicator LED LED3, LED4 and LED5 also have been lit. When leakage, diode VD2 conduction, so that the 1C2 ? pin goes low, a pin output low, the VT end, K release, the EHs power supply cut off, to achieve a leakage protection.




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