CN201242935Y

CN201242935Y - Electric-theft protection three-phase pulse type precision current mutual-inductor

Info

Publication number: CN201242935Y
Application number: CNU2008201192850U
Authority: CN
Inventors: 王兆秀; 蒋勤
Original assignee: ZHEJIANG JKING POWER-ELECTRONIC Co Ltd; Three Lida Electrical Appliance Co Ltd
Current assignee: ZHEJIANG JKING POWER-ELECTRONIC Co Ltd; Three Lida Electrical Appliance Co Ltd
Priority date: 2008-06-25
Filing date: 2008-06-25
Publication date: 2009-05-20
Anticipated expiration: 2018-06-25

Abstract

The utility model relates to an anti-theft electric device, in particular to an anti-theft electric three-phase pulse type precision current mutual inductor. The anti-theft electric three-phase pulse type precision current mutual inductor comprises an input current detecting mutual inductor, a user current mutual inductor and an impedance converter; wherein, a secondary level of the input current detecting mutual inductor, a primary level of the user current mutual inductor and a primary level of the impedance converter are connected in series to form a loop; the primary level of the input current detecting mutual inductor is connected with an electric network; a secondary level of the user current mutual inductor is connected with a user ammeter; and a secondary level of the impedance converter is connected with a digital pulse self-excited oscillator. The peripheral circuit is simple, as long as oscillation frequency generated by the digital pulse self-excited oscillator is numbered; the system can determine whether electricity-theft occurs and whether the electric network is turned off according to the change of the oscillation frequency; in addition, the input current detecting mutual inductor has obvious change of inductance value during an open-circuit condition and a normal access condition, and so can accurately determine the open-circuit condition.

Description

Anti-electricity-theft three-phase pulse formula precision current instrument transformer

Technical field

The utility model is the signal in a kind of user's of collection electric power meter, to its amplify, comparison, logic determines, in case it is destroyed the three-phase four-wire system balance to occur, with regard to the anti-electricity-theft device of reporting to the police immediately, particularly a kind of induction reactance variation that detects instrument transformer according to input current, produce the self-oscillation signal of different frequency at test lead by control signal, input current is detected the operating state of instrument transformer and differentiated, and carry out the anti-electricity-theft three-phase pulse formula precision current instrument transformer of corresponding alarm.

Background technology

Existing anti-electricity-theft detection principle is to detect feed-in high-frequency signal in the instrument transformer to input current, this high-frequency signal detects at input current and forms resonance in the instrument transformer, when input current detects instrument transformer short circuit or open circuit, impedance, admittance that the capital causes input current to detect instrument transformer change, these variations can cause that the signal amplitude of feed-in changes, and analyze by detecting this variation whether stealing is arranged.The drawback of this detection is that the peripheral circuit complexity requires system to produce a signal, and this signal is passed through to handle back feed-in input current detect instrument transformer, to fetch this signal simultaneously, the signal of fetching is carried out sending into the A/D conversion after the processing at different levels, judge by system; In addition, because the variation of the induction reactance of the open-circuit condition of input current detection instrument transformer and normal access state is very little, so that the variation of signal is also very little, so open-circuit condition is difficult to correctly judge.

Summary of the invention

The purpose of this utility model is in order to overcome existing anti-electricity-theft checkout gear peripheral circuit complexity, open-circuit condition to be difficult to the correct defective of judging, invent a kind of variation that detects instrument transformer induction reactance according to input current, produce the self-oscillation signal of different frequency at test lead by control signal, input current is detected the operating state of instrument transformer and differentiated, and carry out the anti-electricity-theft three-phase pulse formula precision current instrument transformer of corresponding alarm.

The purpose of this utility model realizes as follows: described anti-electricity-theft three-phase pulse formula precision current instrument transformer, comprise that input current detects instrument transformer, user's current transformer and impedance transformer, input current detect instrument transformer secondary, user's current transformer elementary and impedance transformer elementary series connection and constitute the loop, elementary and the electrical network that input current detects instrument transformer is connected, secondary and the electric supply meter of user's current transformer is connected, and the secondary and digit pulse self-excited oscillator of impedance transformer is connected.

Good effect of the present utility model is as follows: the utility model peripheral circuit is simple, as long as the frequency of oscillation that the digit pulse self-excited oscillator is produced counts, system can judge whether that stealing takes place by the variation of frequency of oscillation, and whether electrical network opens circuit; In addition, input current detects instrument transformer at open-circuit condition and normal access state, and the variation of its inductance value is obvious, so can judge soundly to open-circuit condition.

Description of drawings

Fig. 1 is the utility model circuit diagram

Fig. 2 is the short-circuit condition circuit diagram

Fig. 3 is the open-circuit condition circuit diagram

Among the figure: 1 input current detects instrument transformer 2 user's current transformers

3 impedance transformers, 4 electrical networks

5 electric supply meters, 6 digit pulse self-excited oscillators

Embodiment

As shown in Figure 1, described anti-electricity-theft three-phase pulse formula precision current instrument transformer, comprise that input current detects instrument transformer 1, user's current transformer 2 and impedance transformer 3, input current detect instrument transformer 1 secondary, user's current transformer 2 elementary and impedance transformer 3 elementary series connection and constitute the loop, elementary and the electrical network 4 that input current detects instrument transformer 1 is connected, secondary and the electric supply meter 5 of user's current transformer 2 is connected, and the secondary and digit pulse self-excited oscillator 6 of impedance transformer 3 is connected.

Operation principle of the present utility model is as follows: the utility model is that the variation that utilizes input current to detect instrument transformer 1 inductance value can cause this characteristic of variation of the frequency of oscillation of digit pulse self-excited oscillator 3 to monitor whether stealing takes place, and whether electrical network opens circuit.Under normal circumstances, the frequency of oscillation of digit pulse self-excited oscillator 3 is about 25KHz; When stealing takes place, input current detects the secondary meeting of instrument transformer 1 by the short circuit (see figure 2), the secondary inductance value of input current detection instrument transformer 1 that will be caused after the short circuit changes, and then the frequency of oscillation that causes digit pulse self-excited oscillator 3 becomes about 30KHz, can judge have stealing to take place by this variation of frequency of oscillation; When the generation electrical network opens circuit, input current detects the secondary of instrument transformer 1 can be by the open circuit (see figure 3), the secondary inductance value of input current detection instrument transformer 1 that will be caused behind the open circuit changes, and then the frequency of oscillation that causes digit pulse self-excited oscillator 3 becomes about 200KHz, can judge that by this variation of frequency of oscillation electrical network has the generation of opening circuit.

Claims

1. anti-electricity-theft three-phase pulse formula precision current instrument transformer, it is characterized in that: described anti-electricity-theft three-phase pulse formula precision current instrument transformer, comprise that input current detects instrument transformer, user's current transformer and impedance transformer, input current detect instrument transformer secondary, user's current transformer elementary and impedance transformer elementary series connection and constitute the loop, elementary and the electrical network that input current detects instrument transformer is connected, secondary and the electric supply meter of user's current transformer is connected, and the secondary and digit pulse self-excited oscillator of impedance transformer is connected.