CN2178957Y

CN2178957Y - Safety device for electrical equipment of household

Info

Publication number: CN2178957Y
Application number: CN 94201938
Authority: CN
Inventors: 赵维增; 赵红增
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-01-28
Filing date: 1994-01-28
Publication date: 1994-10-05
Anticipated expiration: 2004-01-28

Abstract

The utility model belongs to a protector for household electrical appliances, which comprises a power plug, a socket, a working power supply circuit, an overvoltage shutdown circuit and a light (empty) loading time delay switch off circuit. The overvoltage shutdown circuit comprises a voltage sample circuit, an overvoltage discrimination circuit, a transistor switching circuit and an electricity failure executive circuit. The light (empty) loading time delay switch off circuit comprises a current sample circuit, switching elements and a delay circuit. The utility model has the characteristics of reliable and sensitive overvoltage protection and automatic break of mains supply when household electrical appliances are light-loaded or shut-down.

Description

Safety device for electrical equipment of household

The utility model relates to a kind of protector for household electrical appliances, can cut off the protector of household electrical appliance input power supply when being characterized in a kind of overvoltage and zero load, underloading.

In the vast rural area of China; the fluctuation of line voltage is very big; when power consumption is big; supply voltage can be reduced to volt more than 100; power consumption hour; supply voltage can rise to volt more than 300; this just gives civil electric appliance; particularly household electrical appliance bring very big harm; as too high voltage the transformer of electrical appliance is burnt; even cause fire; the effective means that addresses this problem is between electrical appliance and mains electricity input end overvoltage protector to be set; but existing overvoltage protector normally takes out the overvoltage signal with the overvoltage sample circuit and directly drives electronic switch or drive relay cut-out input voltage through amplifier; this overvoltage protector is only when rising appears jumping in line voltage; could effectively cut off alternating current input power supplying; if line voltage slowly rises to the electronic switch critical condition or when making amplifier be in the amplification region; disconnected phenomenon when opening when electronic switch or relay will take place; shorten the useful life of electrical appliance; and overvoltage protector does not possess when electrical appliance shuts down like this, thereby cuts off the function that the electrical appliance that can not cut off the power supply fully when mains supply prevents those shutdown suffers overvoltage harm automatically.

The purpose of this utility model provides a kind of protector for household electrical appliances that can overcome above-mentioned overvoltage protector defective fully.

For achieving the above object, the utility model comprises attaching plug, socket, working power circuit and has the overvoltage shutdown circuit of voltage sample circuit, it is characterized in that also comprising that light (sky) carries time-delay shutdown circuit, this circuit is made up of current sampling circuit, switch element and delay circuit, the current sampling circuit input is serially connected in the power supply input circuit of supply socket, the input of output and switch element joins, and delay circuit is connected between the input of transistor switching circuit of switch element output and overvoltage shutdown circuit.Described overvoltage shutdown circuit with voltage sample circuit also has overvoltage judging circuit, transistor switching circuit and outage executive circuit, the overvoltage judging circuit is connected between the input of voltage sample circuit output and transistor switching circuit, the outage executive circuit is made of one-way SCR and the parallel connection of circuit breaker winding, and the control end of one-way SCR (being trigger electrode and negative electrode) joins with the output of transistor switching circuit.The contact of described relay and switch knob also connect, and seal in the power supply output loop of attaching plug.

The utility model is compared with existing overvoltage protector, and it is reliable to have an overvoltage protection, the advantage of cut-out mains supply automatically when sensitive and household electrical appliance underloading or shutdown.

Fig. 1 is a circuit diagram of the present utility model.

Below in conjunction with accompanying drawing the utility model is described in detail.

In Fig. 1, underloading (zero load) time-delay shutdown circuit is made up of current sampling circuit, switch element and delay circuit, and current sampling circuit comprises resistance R ₁, R ' ₁, adjustable resistance R _WWith reversed polarity diode connected in parallel D ₁, D ₂, and resistance R ₂Resistance R ₁, diode D ₁, D ₂And resistance R ' ₁Adjustable resistance R _WSeries circuit interrelated (one end ground connection) constitutes the input of current sampling circuit, is serially connected in the power supply input circuit of supply socket CZ resistance R ₁An end (an earth-free end) and resistance R ₂An end connect resistance R ₂The other end and ground constitute the output of current sampling circuit and triode V as switch element ₁Base stage, emitter (input of switch element) join.Delay circuit is a resistance R ₃, capacitor C ₂The capacitance-resistance charge-discharge circuit that constitutes, delay capacitor C ₂Be connected on triode V ₁Between the input of the crystal switch circuit in output (collector electrode, emitter) and the overvoltage shutdown circuit.The electrical equipment shutdown that inserts when socket or when being in the remote-control closedown state, resistance R ₁Two ends do not have voltage or voltage to be lower than 0.7 volt, triode V ₁End, electric current passes through R ₃To capacitor C ₂C is worked as in charging ₂When the charging voltage at two ends is higher than 1.4 volts, triode V ₂Conducting triggers unidirectional controllable silicon S CR conducting, so just makes the short circuit in winding of relay J, can not continue its contact of adhesive, thereby cut off civil power.

The overvoltage shutdown circuit is made up of voltage sample circuit, overvoltage judging circuit, transistor switching circuit and outage executive circuit, and voltage sample circuit is made of LED and potentiometer W serial connection, and the overvoltage judging circuit is by voltage stabilizing didoe D _WWith diode D ₄Differential concatenation constitutes, and the negative pole of voltage stabilizing didoe is connected diode D with the adjustable end of potentiometer W ₄Negative pole and the triode V of transistor switching circuit ₂Base stage connects.Transistor switching circuit also comprises resistance R ₄, R ₅, triode V ₂Emitter and the unidirectional controllable silicon S CR control utmost point be connected, and pass through resistance R ₄Be connected with the negative electrode of SCR.Unidirectional controllable silicon S CR formation outage in parallel with the winding of relay J executive circuit, this circuit passes through R ₅Join with the output of working power circuit.When overpressure situation occurring, judging circuit utilizes voltage-stabiliser tube D _WThe reverse breakdown voltage value differentiate whether overvoltage, as voltage greater than voltage-stabiliser tube D _WReverse breakdown voltage, D _WThe snowslide conducting makes triode V ₂Conducting, its emitter current potential raises, and triggers the controllable silicon SCR conducting, short circuit the relay J winding in parallel with it, the contact of relay J is disconnected, thereby has cut off the mains supply of electrical equipment, avoided the infringement of overvoltage to electrical equipment.

In Fig. 1: working power circuit is by transformer B, rectifier diode D ₁And capacitor C ₁Form.Start push switch AN and relay contact J _KBack in parallel is serially connected in the output loop of attaching plug CT by fuse F.Capacitor C elsewhere ₃Playing anti-power surges disturbs.Piezo-resistance RU plays voltage when too high, and resistance reduces the effect of blowout.

The utility model can also increase a voltage regulator or pressurizer to improve adaptability of the present utility model between attaching plug CT and supply socket CZ.

Claims

1, a kind of protector for household electrical appliances, comprise attaching plug, socket, working power circuit and have the overvoltage shutdown circuit of voltage sample circuit, it is characterized in that: comprise that also light (sky) carries time-delay shutdown circuit, this circuit is made up of current sampling circuit, switch element and delay circuit, the current sampling circuit input is serially connected in the power supply input circuit of supply socket, the input of output and switch element joins, and delay circuit is connected between the input of transistor switching circuit of switch element output and overvoltage shutdown circuit; Described overvoltage shutdown circuit with voltage sample circuit also has overvoltage judging circuit, transistor switching circuit and outage executive circuit, the overvoltage judging circuit is connected between the input of voltage sample circuit output and transistor switching circuit, the outage executive circuit is made of one-way SCR and the parallel connection of relay winding, the control end of one-way SCR and the output of transistor switching circuit join, the contact of described relay and shift knob and connect after seal in the power supply output loop of attaching plug.

2, protector for household electrical appliances according to claim 1 is characterized in that: described overvoltage judging circuit is by voltage stabilizing didoe (D _W) and diode (D ₄) the differential concatenation composition.

3, protector for household electrical appliances according to claim 1 is characterized in that: the switch element that light (sky) carries in the time-delay shutdown circuit is a transistor.

4, protector for household electrical appliances according to claim 1 is characterized in that: be pressed into a voltage regulator or pressurizer between attaching plug and supply socket.