CN207557333U - A kind of DC current compares measuring device - Google Patents

Abstract

The utility model discloses a kind of DC currents to compare measuring device, belong to the field of current measurement in electrotechnics, including sensing head, exciter transformer, first resistor device, second resistance device, bandpass filter, demodulator, preamplifier, low-pass filter, totalizer, adjuster and power amplifier, the Same Name of Ends polarity inversion of two modulation detection windings is connected in series in the utility model, realize the counteracting of AC ripple induced potential in two modulation detection windings in tested primary current, eliminate the interference to modulator output signal, it ensure that the stable operation of device.The Same Name of Ends polarity of two field windings is with being connected, because two energizing loops are separately independent, more only there is the contact of electricity, will not occur to generate the interference that loop current is formed between two exciting circuits, further ensure the stable operation of device.

Description

A DC Current Comparison Measuring Device

technical field

The utility model belongs to the field of current measurement in the electric technology, and more specifically relates to a direct current comparison measurement device.

Background technique

"Research on Open-loop Characteristics of Dual Magnetic Detector Current Comparator" published in Volume 24, Issue 2 of "Acta Metrology" in April 2003, it organically combines the transmission characteristics of the magnetic modulator and the magnetic amplifier to overcome the traditional magnetic The open-loop transfer characteristic curve of the modulator has several defects and disadvantages of zero crossing. That is, the magnetic amplifier is placed in the magnetic modulator, and they use a common pair of detection iron cores and coils, as well as a common magnetic shielding iron core and feedback windings, forming a dual magnetic detector DC large current sensing theory and method. However, this device has the following disadvantages: the polarities of the same-named ends of the pair of detection core coils are connected in series in the same phase, and the primary DC current of the busbar under test in industrial production inevitably contains AC ripple currents. The electric potential induced by the wave current in a pair of detection core coils not only cannot be offset, but also directly added, and superimposed on the detection signal of the magnetic modulator, causing serious interference to the detection signal of the magnetic modulator and affecting the stable operation of the device. The industrial site use is limited.

It can be seen that the prior art has the technical problem that the detection signal of the magnetic modulator is seriously interfered and it is difficult to operate stably.

Utility model content

Aiming at the above defects or improvement needs of the prior art, the utility model provides a DC current comparison measuring device, thereby solving the technical problems in the prior art that the detection signal of the magnetic modulator is seriously interfered and stable operation is difficult.

In order to achieve the above purpose, the utility model provides a DC current comparison measuring device, including a sensing head, an excitation transformer, a first resistor, a second resistor, a bandpass filter, a demodulator, a preamplifier, a low pass filter, totalizer, regulator, and power amplifier,

The sensor head includes a first annular detection core and a second annular detection core with the same shape, and the first modulation detection winding with the same number of turns is wound on the first annular detection core and the second annular detection core, respectively. The second modulation detection winding, the first modulation detection winding and the second modulation detection winding are coated with an electrostatic shielding layer, and then they are placed as a whole in the cavity of the magnetic shielding iron core with an annular cavity structure, and the magnetic shielding iron A feedback winding is wound outside the core;

The secondary side of the excitation transformer has a first excitation winding and a second excitation winding with the same voltage, the end with the same name of the first excitation winding is connected to the end with the same name of the first modulation detection winding, and the end with the same name of the first excitation winding Connect to one end of the first resistor, the other end of the first resistor is connected to the end of the same name of the first modulation detection winding; the opposite end of the second excitation winding is connected to the opposite end of the second modulation detection winding, the second excitation The same-named end of the winding is connected to one end of the second resistor, and the other end of the second resistor is connected to the same-named end and the ground point of the second modulation detection winding and grounded at the same time; the different-name end of the first modulation detection winding is connected to the second modulation The different-named ends of the detection winding are connected together, the same-named end of the first modulation detection winding is connected to the input end of the band-pass filter, and the output end of the band-pass filter is connected to the input end of the demodulator; the same-named end of the second excitation winding The terminal is connected to the input terminal of the preamplifier, the output terminal of the preamplifier is connected to the input terminal of the low-pass filter, and the output terminal of the low-pass filter and the output terminal of the demodulator are connected to the input terminal of the totalizer at the same time , the output of the totalizer is connected to the input of the regulator, the output of the regulator is connected to the input of the power amplifier, the output of the power amplifier is connected to the same-named end of the feedback winding, and the opposite-named end of the feedback winding is connected to the ground point connected and grounded.

Further, the material of the electrostatic shielding layer is copper foil, and the materials of the first annular detection iron core, the second annular detection iron core and the magnetic shielding iron core are cold-rolled silicon steel sheets.

Further, the resistance values of the first resistor and the second resistor are equal, and the resistance value is less than or equal to 100 ohms.

Generally speaking, compared with the prior art, the above technical solutions conceived by the utility model can achieve the following beneficial effects:

(1) In the utility model, the polarities of the same-named ends of the two modulation detection windings are connected in series in reverse, which realizes the cancellation of the induced potential of the AC ripple in the measured primary current in the two modulation detection windings, and eliminates the influence on the output signal of the modulator. Interference, to ensure the stable operation of the device.

(2) in the utility model, the homonym end polarity of two excitation windings is connected in phase, because two excitation circuits are separate and independent, there is only an electric connection at one point, and the interference that produces loop current formation between two excitation circuits can not occur, further The stable operation of the device is guaranteed.

Description of drawings

Fig. 1 is the outline schematic diagram of the sensor head of the present utility model;

Fig. 2 is a schematic cross-sectional view of a sensor head of the present utility model;

Fig. 3 is a schematic circuit diagram of the utility model.

Detailed ways

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute conflicts with each other.

As shown in Figure 1, the appearance of the sensor head of the utility model is circular, and its cross-section is shown in Figure 2. After being wound with a cold-rolled silicon steel strip, it is annealed to make the first annular detection iron with the same shape. The core C ₁ and the second annular detection core C ₂ are respectively wound with the first modulation _detection winding W _D1 and the second modulation detection winding W _D1 with the same number of turns. Winding W _D2 , after assembly, wrap copper foil on the outside of the first modulation detection winding W _D1 and the second modulation detection winding W _D2 as an electrostatic shielding layer K, and then place them as a whole in a cold-rolled coil with an annular cavity structure In the cavity of the silicon steel magnetic shielding iron core C, a feedback winding W ₂ is wound outside the magnetic shielding iron core C. The busbar W ₁ of the measured primary DC current I ₁ shown in FIG. 3 passes through the central circular hole of the sensing head as shown in FIG. 1 .

As shown in Figure 3, in the utility model, the homonym end of the first excitation winding W _T1 of the excitation transformer T is connected with the opposite end of the first modulation detection winding W D1, and the opposite end of the first excitation winding W _T1 is connected with the first excitation winding W _T1 One end of a resistor _R1 is connected, and the other end of the first resistor _R1 is connected with the end of the same name of the first modulation detection winding _WD1 ; the end of the second excitation winding _WT2 with the same name as the end of the second modulation detection winding _WD2 The opposite end is connected, the end of the same name of the second excitation winding W _T2 is connected to one end of the second resistor _R2 , and the other end of the second resistor _R2 is connected to the end of the same name and the ground point of the second modulation detection winding W _D2 at the same time And grounded, the opposite end of the first modulation detection winding W _D1 is connected with the opposite end of the second modulation detection winding W _D2 , and the same end of the first modulation detection winding W _D1 is connected to the input end of the band-pass filter A , the output of the band-pass filter A is connected to the input of the demodulator B; the same name end of the second excitation winding W _T2 is connected to the input of the preamplifier F, and the output of the preamplifier F is connected to the low-pass filter The input terminal of E is connected, the output terminal of low-pass filter E and the output terminal of demodulator B are connected to the input terminal of totalizer D at the same time, and the output terminal of totalizer D is connected to the input terminal of regulator G, The output terminal of the regulator G is connected to the input terminal of the power amplifier H, the output terminal of the power amplifier H is connected to the same-named end of the feedback winding _W2 , and the opposite-named end of the feedback winding _W2 is connected to the ground point and grounded.

After the device is put into operation, under the action of AC voltage U, the excitation voltage of the two excitation windings W _T1 and W _T2 of the excitation transformer T passes through the resistors R ₁ and R ₂ respectively, and modulates and detects the windings W _D1 and W _D2 , Excite the ring detection iron cores C ₁ and C ₂ , they together form the magnetic modulator working circuit of the double iron core, and obtain the DC detection signal voltage V ₁ of the magnetic modulator from point P; at the same time, the excitation circuit of each iron core winding constitutes _A single-core magnetic amplifier circuit is established, and its exciting current waveform reflects the magnitude of the _{measured DC current, and the magnetic amplifier DC detection signal voltage V 2 is} obtained from point Q; B, after being processed by the preamplifier F and the low-pass filter E, it enters the summator D for superimposition, and obtains the detection signal of the measured primary DC current I ₁ by the magnetic modulator and the magnetic amplifier dual magnetic detector. The detection signal not only comes from the characteristics of high sensitivity and good linearity in the transmission characteristics of the magnetic modulator near zero ampere turns, but also has the characteristics of good homogeneity in the transmission characteristics of the magnetic amplifier, so as to achieve the purpose of eliminating false balance points.

The utility model connects the polarities of the two modulation detection windings W _D1 and W _D2 in series in reverse, and realizes the cancellation of the induced potential of the AC ripple in the measured current I ₁ in the two modulation detection windings, eliminating the need for modulation The interference of the output signal of the device ensures the stable operation of the device; the polarities of the same-named terminals of the two excitation windings W _T1 and W _T2 are connected in the same phase, because the two excitation circuits are separated and independent, and there is only one point of electrical connection, so there will be no two The interference formed by the loop current generated between the excitation circuits further ensures the stable operation of the device.

The dual detection signal output by the totalizer D passes through the regulator G and the power amplifier H to obtain the feedback current I ₂ and flows through the feedback winding W ₂ to obtain the magnetic potential balance I ₁ W of the ampere-turn of the measured primary current and the ampere-turn of the secondary feedback current ₁ = I ₂ W ₂ , usually W ₁ is one turn, W ₂ is multi-turn, so that the secondary current can accurately reflect the primary current I ₂ = (W ₁ /W ₂ )·I ₁ , and its ratio coefficient is fixed turns ratio.

Those skilled in the art can easily understand that the above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements and modifications made within the spirit and principles of the utility model Improvements and the like should all be included within the protection scope of the present utility model.

Claims (3)

1. a kind of DC current compares measuring device, which is characterized in that including sensing head, exciter transformer, first resistor device, Two resistors, bandpass filter, demodulator, preamplifier, low-pass filter, totalizer, adjuster and power amplifier,

The sensing head includes first annular detection iron core, the second annular detection iron core, the first modulation detection winding, the second modulation Detection winding, electrostatic screen layer, magnetic screen iron core and feedback winding, the first annular detection iron core and the second annular detection iron The shape of core is identical, is wound with the first identical modulation inspection of the number of turn on first annular detection iron core and the second annular detection iron core respectively Survey the outside cladding electrostatic screen of winding, the second modulation detection winding, the first modulation detection winding and the second modulation detection winding Layer is placed in the cavity of the magnetic screen iron core with toroidal cavity structure, and feedback winding is wound with outside magnetic screen iron core；

The pair side of the exciter transformer has identical the first field winding and the second field winding of voltage, and described first is excitatory The Same Name of Ends of winding is connected with the different name end of the first modulation detection winding, the different name end of the first field winding and first resistor device One end connects, and the other end of first resistor device is connected with the Same Name of Ends of the first modulation detection winding；The different name of second field winding End is connected with the different name end of the second modulation detection winding, and the Same Name of Ends of the second field winding is connect with one end of second resistance device, The other end of second resistance device connect and is grounded simultaneously with the Same Name of Ends and earth point of the second modulation detection winding；First modulation inspection The different name end and the different name end of the second modulation detection winding for surveying winding link together, and the Same Name of Ends of the first modulation detection winding connects The input terminal of bandpass filter is connected to, the output terminal of bandpass filter is connected to the input terminal of demodulator；Second field winding Same Name of Ends is connected to the input terminal of preamplifier, and the output terminal of preamplifier is connected with the input terminal of low-pass filter, low The output terminal of bandpass filter and the output terminal of demodulator, while the input terminal of totalizer is connected to, the output terminal connection of totalizer To the input terminal of adjuster, the output terminal of adjuster is connected to the input terminal of power amplifier, the output terminal of power amplifier with The Same Name of Ends connection of feedback winding, the different name end of feedback winding is connected and is grounded with earth point.

2. a kind of DC current as described in claim 1 compares measuring device, which is characterized in that the material of the electrostatic screen layer Expect for copper foil, the material of the first annular detection iron core, the second annular detection iron core and magnetic screen iron core is cold-reduced silicon sheet.

3. a kind of DC current as claimed in claim 1 or 2 compares measuring device, which is characterized in that the first resistor device Equal with the resistance value of second resistance device, the resistance value is less than or equal to 100 ohm.