CN2071396U - Resistance changing anti-sheft alarm for electric wire - Google Patents

Abstract

The utility model relates to a resistance changing anti-theft alarm for electric wire, which is characterized in comprising an impedance transformation sensing circuit, a comparing drive circuit and an alarm circuit. The utility model can alarm guarding against theft whether the power is on or off, having no interference to the surroundings, and is provided with the display of power failure and phase failure. The utility model has the advantage of convenient operation, and can be widely used in the anti-theft field of power line or electric equipment.

Description

Resistance changing anti-sheft alarm for electric wire

The utility model belongs to the power line anti-theft alarm field.

Through inquiry, do not have both at home and abroad to find identical therewith product that the electric power burglar alarm of domestic other type, major defect are to be applied to the left alone without help electricity condition of circuit.

The purpose of this utility model is to overcome the deficiency of above-mentioned prior art, and a kind of new product that all can burglar alarm under left alone without help electricity and electric power thus supplied is provided.

The purpose of this utility model can reach by following measure:

Accompanying drawing is embodiment of the present utility model, is described as follows below in conjunction with the embodiment of accompanying drawing:

Principal character of the present utility model is that by the impedance conversion sensing circuit relatively drive circuit and warning circuit are formed.

As accompanying drawing, A, B, C, O are four binding posts, join T with the three phase mains power line ₁, T ₂, T ₃Be three transformers, its elementary reactive unit that is respectively, C ₁, C ₂, C ₃Be capacitive reactance circuit, T ₁, T ₂, T ₃Elementary reactive unit and C ₁, C ₂, C ₃The capacitive reactance circuit is connected respectively, makes three-phase alternating voltage dividing potential drop step-down respectively, forms every exchanging perfectly straight current circuit, and making at power line has under the electric situation, and the impedance conversion sensing circuit still can constitute DC channel and work.T in addition ₁Secondary to the power rectifier circuit power supply, and T ₁, T ₂, T ₃The secondary indicator light ZD that is connected to ₁, ZD ₂, ZD ₃, can show each mutually left alone without help electric situation in conjunction with alarm condition, or stolen situation.Rectification bridge circuit, integrated package of pressure-stabilizing 7806 and R ₁, C ₄, C ₅Deng forming the direct current supply voltage stabilizing circuit, give the power supply of this instrument, diode D ₇, D ₈Constitute left alone without help direct current electric pond power supply circuits with battery E.

The impedance conversion sensing circuit is by the instrument external accessory reflector sensing resistor R that provides _Anti-1, R _Anti-2, R _Anti-3With the R in the instrument ₂, R ₃, R ₄, R ₅, R ₆Form, the sensing resistor reflector is connected on the far-end that instrument is wanted protected power line outward, and the near-end of power line is connected R with the A of instrument, B, C, O three-phase and four-line terminal _Anti-1, R _Anti-2, R _Anti-3Respectively by diode D ₁-D ₆The forward conduction state and the R of series connection ₅, R ₆Be in parallel, and then respectively and R ₂, R ₃, R ₄After current-limiting resistance is in series, connect dc power supply again.Like this, when the stolen disconnection of power line, the resistance of stolen this branch road is to infinity, R _Anti-1Or R _Anti-2, R _Anti-3With R ₅, R ₆The resistance that closes that is in parallel enlarges markedly, and makes current-limiting resistance R ₂, R ₃, R ₄On the electric current that flows through significantly reduce, pressure drop also significantly reduces, then R ₅, R ₆On the voltage got enlarge markedly, by R ₅, R ₆Sampling obtains the voltage signal that this enlarges markedly on the intersection point, can learn that power line is stolen, and the impedance transformation sensing circuit can be finished the output that the conversion of signals that power line is stolen becomes the signal of telecommunication so thus.

Deliver to the comparison drive circuit from the signal of telecommunication that the impedance transformation sensing circuit picks up, relatively drive circuit is by reference voltage circuit R ₇, R ₈, amplifier or comparator IC ₁, transistor BG ₁, the NAND gate ic chip ₂(also can be made of resolution element transistor etc.) etc. formed.The signal of telecommunication and amplifier or the comparator IC that send here by the impedance transformation sensing circuit ₁In-phase input end 3 link to each other R ₇And R ₈Constitute reference voltage circuit, reference voltage is sent into IC ₁2 ends, when power line is stolen, then the sampling voltage signal that enters 3 ends by the impedance transformation sensing circuit will significantly increase, and must be significantly higher than reference voltage signal, comparator upset, IC ₁1 end by original output low level, become high level, and then drive BG ₁Transistor turns, BG ₁Collector terminal voltage reduce IC then ₂The output of NAND gate obtains to drive the high level signal of warning circuit.

Warning circuit is by ZD ₄Alarm lamp (light-emitting diode or other kind indicator light) and warning integrated circuit (IC) ₃(for example four tones of standard Chinese pronunciation warning circuit 9561), driving transistors BG ₂, BG ₃, loudspeaker are formed.Compare drive circuit transistor BG ₁Collector electrode by load resistance R ₁₀With alarm lamp ZD ₄Link to each other, relatively the IC of drive circuit ₂The NAND gate output links to each other the output of warning integrated circuit and BG with the trigger end of warning integrated circuit (for example four tones of standard Chinese pronunciation warning circuit 9561) ₂, BG ₃Driving transistors links to each other, and then connects loudspeaker.When power line is stolen, compare the BG of drive circuit ₁Conducting, collector electrode step-down level, alarm lamp is bright, and is stolen by the light warning power line, simultaneously, compares the IC of drive circuit ₂NAND gate becomes high level by low level at ordinary times, triggers to drive warning circuit IC ₃, and then IC ₃Output is by driving transistors BG ₂, BG ₃, drive loudspeaker and send chimes of doom, constitute power line jointly when stolen, acousto-optic is warning circuit simultaneously, makes the guard scene that arrives in the very nick of time, and handles and the safety of defendance power circuit, and the utility model also can be used for the electric equipment burglar alarm.

The utility model has following advantage compared to existing technology:

1, rely on the impedance conversion of circuit because of it, irrelevant with left alone without help electric power supply state, and be provided with every exchanging perfectly straight current circuit, so all can use under power supply and the left alone without help electric situation.

How 2, have phase failure indication, institute is so that differentiate broken string or outage or mutually stolen different situations.

When 3, working near electrical equipment there is not any interference.

The utility model test effect is good, has dressed up many in model machine, has practical reference value.

Claims (5)

1, a kind of power line anti-theft alarm device is primarily characterized in that by the impedance conversion sensing circuit, and relatively drive circuit and warning circuit are formed.

2,, it is characterized in that said impedance conversion sensing circuit is the annex sensing resistor reflector by the instrument outside, R according to the said power line anti-theft alarm device of claim 1 _Anti-1, R _Anti-2, R _Anti-3By every exchanging perfectly straight current circuit and sample resistance R ₅, R ₆Be in parallel, and then and current-limiting resistance R ₂, R ₃, R ₄After the series connection, connect dc power supply respectively.Disconnect the impedance conversion that causes by power line, thereby make R ₅, R ₆Intersection point obtain the signal of telecommunication of variation.

3, it is characterized in that saidly every exchanging perfectly straight current circuit according to the said power line anti-theft alarm device of claim 2, is by transformer T ₁, T ₂, T ₃Primary inductance induction reactance and capacitor C ₁, C ₂, C ₃Capacitive reactance be in series and make ac buck, direct current passes through, and then connects D again ₁-D ₆Further constitute tight isolation interchange and pass through DC circuit.

4,, be primarily characterized in that said relatively drive circuit is by sample resistance R according to the said power line anti-theft alarm device of claim 1 ₅, R ₆, reference voltage circuit R ₇, R ₈, amplifier or comparator IC ₁Be connected, work as R ₅, R ₆During the marked change of intersection point sampling output voltage, cause amplifier or comparator IC ₁Overturn and the driving warning circuit.

5,, be primarily characterized in that said warning circuit is by the audible alarm integrated circuit (IC) according to the said power line anti-theft alarm device of claim 1 ₃With light indication warning circuit ZD ₄Common formation sound light alarming circuit.