Refrigerator power protection circuit

  
5 min circuit can continue to operate in the state of the power outage, the role to protect the refrigerator. Refrigerator power protection circuit 1136 as shown in FIG. T for
Refrigerator power protection circuit - schematic

the power transformer, 220V voltage by the rectifier bridge VD1 ~ fM Ct charge of power supply voltage control circuit + 1ZV, for the first time. Since there is no charge on the G, VT2 off, A point of high potential., VT3 deadline, TRIAC VTHZ due VD7 triggered by conduction, the load is energized, Refrigerator start work. At the same time, R2 to c2 charged and the B point potential rise by R, VTH1 triggered thyristor conduction. Relay K pull its normally open contact K is closed; the G diode VD5 charging voltage of + 12y, the circuit is in standby power protection. Once the power circuit, the relay K energized. Normally open contacts K release, since the c: 1 charged with a charge voltage of + 12V, is applied to the gate of VT2 pole. Because the pole, no current links between the gate and source-drain. Therefore, the charge on C3 remains substantially unchanged. C3 on the voltage applied to the VT2 between the gate-source, so that VGS is greater than the threshold voltage VT2 U, so that the drain and source of the field effect transistor conductive channel between a certain way, although there is no power supply voltage, but the drain between panels D and the source S, equivalent to a closed switch state. During this time, if the power to call, VT2 place in the conduction state, the A point at a low potential, HL lights that delay protection. Transistor VT3 conduction, C point at a high potential, the diode VD7 off, triac trigger current VTH2 be less than the cut-off, the refrigerator does not work. during this time. The R6 always sampled voltage of the transistor f ] turned, B point is low, does not trigger the thyristor VTH1, following appliances K does not pull, the normally open contacts K is not action, maintaining A point low. A point of time to maintain low potential may be adjusted to control the wind. With C3 for acupuncture discharge. Reducing the charge on G, the field effect transistor VT2 drain, source current is gradually reduced, sampling voltage reduction on R less, eventually leading to VT1 end, B point potential rise, triggering VTH1 turn, relay K energized, normally open contact. K is closed,. VTZ Wei stop. A point to a high potential, C point into low, diode VD7 trigger, VTH2 conduction, refrigerator electrical work. Zener granted tube vs. For protecting the field effect transistor VT2 past, Rg, C4 in series and in parallel i VS2 protection bidirectional thyristor has VTHZ, Shu, HL indication of the delay circuit.




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