CN2435873Y - Overvoltage and undervoltage protective device for domestic electrical equipment - Google Patents

Abstract

The utility model relates to an over-voltage and under-voltage protective device for domestic electric appliances, which comprises a shell, a transformer, a rectification circuit, an over-voltage protection circuit and an under-voltage protection circuit, wherein, the over-voltage and the under-voltage protection circuits all use two triodes, three relays and one voltage stabilizing tube. In the device, the three relays are jointly used by the over-voltage and the under-voltage protection circuits; the two triodes in the over-voltage protection circuit and the under-voltage protection circuit all have the connection method that the collector electrode of one triode is mutually connected with the base electrode of the other triode. The device has the advantages of compact structure and favorable performance, and ensures that the domestic electric appliances can be safely operated within the range of assigned voltage. The utility model can prolong the service life of the domestic electric appliances.

Description

Household electrical appliance over-and under-voltage protective device

The utility model relates to a kind of household electrical appliance over-and under-voltage protective device.

Along with the raising of people's living standard, the kind and the quantity of household electrical appliance are increasing, normally move in order to make household electrical appliance; need overvoltage, under-voltage protection device; existing protective device performance is not really desirable, therefore, is necessary to provide a kind of over-and under-voltage protective device simple in structure.

The purpose of this utility model provides a kind of household electrical appliance over-and under-voltage protective device, and this apparatus structure compactness, performance are good.

For achieving the above object, the utility model is taked following design: a kind of household electrical appliance over-and under-voltage protective device comprises: housing, transformer, commutating circuit, overvoltage crowbar, under-voltage protecting circuit, described overvoltage crowbar comprises: triode T ₂, T ₁, T ₂The c utmost point and T ₁The b utmost point join T ₂The b utmost point and the electric resistance partial pressure loop between meet a voltage-stabiliser tube D ₂, T ₁The e utmost point succeed electrical equipment SR ₂Coil L ₂And relay SR ₃Contact K ₃, SR ₂Contact K ₂With SR ₁Coil L1 serial connection, be subjected to coil L ₁The contact K of control ₁Join with the output of earth leakage protective device, described under-voltage protecting circuit comprises: triode T ₃, T ₄, T ₄The c utmost point and T ₃The b utmost point join T ₄The b utmost point and the electric resistance partial pressure loop between meet voltage-stabiliser tube D ₄, at triode T ₃The e utmost point meet a relay SR ₃Coil L ₃, SR ₃Contact K ₃With SR ₂Coil L ₂Serial connection, SR ₂Contact K ₂With SR ₁Coil L ₁Serial connection.

The utility model is described in further detail below in conjunction with accompanying drawing.

Fig. 1 is the utility model circuit theory diagrams

As shown in Figure 1, L, N are the output of earth leakage protective device, connect L, the N end of transformer respectively, and the E end is the protective wire contact, and it succeeds electrical equipment SR ₁Contact K ₁, resistance R ₁Connect the L end of transformer again.Q is the bridge rectifier loop, has comprised overvoltage crowbar and under-voltage protecting circuit among the figure, and wherein overvoltage crowbar has triode T ₂, T ₁, T ₂The c utmost point (collector electrode) and T ₁The b utmost point (base stage) join T ₂The b utmost point (base stage) and electric resistance partial pressure loop (R3, R5, R4 form) between meet a voltage-stabiliser tube D ₂, T ₁The e utmost point (emitter) succeed electrical equipment SR ₂Coil L ₂And relay SR ₃Contact K ₃, SR ₂Contact K2 and SR ₁Coil L ₁Serial connection.

Course of action: when line voltage is lower than 240V, voltage-stabiliser tube D ₂Not conducting, triode T ₂End T ₁Conducting, and with relay SR ₂L ₂With relay SR ₃Contact K3 constitutes loop, SR ₂Adhesive, K ₂The contact is often opened by normally closed change, at this moment, and relay SR ₁L ₁There is not electric current to pass through, K ₁Be in normally open, the earth leakage protective device operate as normal.When line voltage rises to 240 volts, D ₂Conducting, R ₂Main electric current through D ₂And T ₂The be utmost point, T ₁The b pole tension descend T ₁End, because T ₁Can not with SR ₂L ₂With the K on the SR3 ₃Produce the loop, do not have electric current to pass through, SR ₂K ₂Become normally closed by open circuit, SR ₁L ₁Pass through SR ₂K ₂Produce current circuit, SR ₁Adhesive, SR ₁K ₁Become closed by often opening, from power firestreak through R ₁, SR ₁K ₁To protection ground wire E, produced the loop, the simulation electric leakage, the earth leakage protective device outage of tripping is immediately protected all electrical appliances.K among the figure _AThe effect of knob: it belongs to experiment button, K _ADuring connection, D ₂By short circuit, T ₁End T ₂Work, earth leakage protective device begin tripping operation, and power supply is cut off.Can this key switch both can have been tested earth leakage protective device and trip, but the circuit of testing fixture operate as normal whether again.

Under-voltage protecting circuit comprises: triode T ₃, T ₄, T ₄The c utmost point (collector electrode) and T ₃The b utmost point (base stage) join T ₄The b utmost point (base stage) and electric resistance partial pressure loop (R ₉, R ₁₀, R ₁₁Composition) meets voltage-stabiliser tube D between ₄, also have at T ₃The e utmost point meet a relay SR ₃Coil L ₃, SR ₃Contact K ₃With SR ₂Coil L ₂Serial connection, SR ₂Contact K ₂With SR ₁Coil L ₁Serial connection.

Course of action: when line voltage was reduced to 180 volts by normal power supply, this device began protection, D ₄Voltage-stabiliser tube ends, T ₄Not conducting, T ₄Ce utmost point no current flows through, and T ₃Work, its ce utmost point has electric current to flow through, SR ₃L ₃Through T ₃The ce utmost point produce path, and have electric current to flow through the ce utmost point and SR ₃L ₃End, SR ₃Adhesive, SR ₃By normally closed change open circuit, make SR ₂L ₂Open circuit SR with the ground end ₂On K ₂Be closure, SR ₁K ₁Closure, then power firestreak is through R1, SR ₁K ₁To E end generation electric leakage analog loopback, earth leakage protective device tripping operation outage, and make electrical appliance obtain safeguard protection.

The utility model advantage: this apparatus structure compactness, performance is good, can make household electrical appliance at the assigned voltage model Enclose interior safety operation, prolong the service life of household electrical appliance.

Claims (1)

1, a kind of household electrical appliance over-and under-voltage protective device, it is characterized in that: it comprises: housing, transformer, commutating circuit, overvoltage crowbar, under-voltage protecting circuit, described overvoltage crowbar comprises: triode T ₂, T ₁, T ₂The c utmost point and T ₁The b utmost point join T ₂The b utmost point and the electric resistance partial pressure loop between meet a voltage-stabiliser tube D ₂, T ₁The e utmost point succeed electrical equipment SR ₂Coil L ₂And relay SR ₃Contact K ₃, SR ₂Contact K ₂With SR ₁Coil L ₁Serial connection is subjected to coil L ₁The contact K of control ₁Join with the output of earth leakage protective device, described under-voltage protecting circuit comprises: triode T ₃, T ₄, T ₄The c utmost point and T ₃The b utmost point join T ₄The b utmost point and the electric resistance partial pressure loop between meet voltage-stabiliser tube D ₄, at triode T ₃The e utmost point meet a relay SR ₃Coil L ₃, SR ₃Contact K ₃With SR ₂Coil L ₂Serial connection, SR ₂Contact K ₂With SR ₁Coil L ₁Serial connection.

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