CN212723105U

CN212723105U - Adapter is decreased to measurement of loss is situated between to bus ground CVT self excitation method

Info

Publication number: CN212723105U
Application number: CN202021424556.0U
Authority: CN
Inventors: 任守华; 任翔
Original assignee: Ji'nan Fanhua Instrument Equipment Co ltd
Current assignee: Ji'nan Fanhua Instrument Equipment Co ltd
Priority date: 2020-07-20
Filing date: 2020-07-20
Publication date: 2021-03-16
Anticipated expiration: 2030-07-20

Abstract

The utility model discloses a bus grounding CVT self excitation method is situated between and is decreased measurement adapter belongs to data acquisition equipment, the utility model discloses the technical problem who solves for how make the experimenter can be in CVT self excitation method is measured, keeps bus grounding, uses current being situated between to decrease the tester and just can accomplish the experimental measurement simultaneously, ensures not only convenient but also safety, and the technical scheme of adoption is: the structure of the device comprises a box body, wherein a signal input module is arranged on the upper end surface of the box body, and a signal output module is arranged on the lower end surface of the box body; an electromagnetic shielding box is arranged in the box body, a PCB is arranged in the electromagnetic shielding box, and a signal acquisition module is arranged on the PCB; a battery module is arranged on the outer side surface of the box body and supplies power to the signal acquisition module; the signal input module comprises a high-voltage input terminal and an X input terminal; the signal output module comprises a high-voltage output terminal and an output side grounding terminal; the signal acquisition module comprises a high-precision current transformer unit.

Description

Adapter is decreased to measurement of loss is situated between to bus ground CVT self excitation method

Technical Field

The utility model relates to a data acquisition equipment, specifically speaking are bus grounding CVT self excitation method is situated between and is decreased measurement adapter.

Background

A CVT (Capacitor Voltage Transformer) is a Voltage conversion device, which is connected across a high Voltage and a zero line, converts the high Voltage into working voltages of various instruments, and provides important Voltage signals for measurement, control protection, and metering of an electric power system. Existing CVTs are generally constructed with high and low capacitance voltage dividers and electromagnetic units. The capacitor of the high-voltage arm and the low-voltage arm in the capacitive voltage divider is formed by connecting a plurality of capacitors in series.

The CVT self-excitation method is a commonly used measurement method in power systems. The experimental personnel can measure the capacitance value and the dielectric loss value of the capacitor to be measured by using the CVT self-excitation method by using the dielectric loss tester. However, in the using process, the grounding connection of the bus needs to be disconnected sometimes under the influence of a single section or multiple sections of the capacitor to be tested, so that the method is not safe and inconvenient. Specifically, as shown in fig. 4, when the conventional self-excited CVT test is used, the bus ground connection of the C1 capacitor is disconnected. The low-voltage interface of the dielectric loss tester outputs excitation signals to the secondary sides (a-X) of the transformers, and the primary sides (A-X) of the transformers obtain induced high voltage to measure the capacitors C1 and C2. The original signals required to be collected by the dielectric loss tester are the current magnitude and the phase of the capacitor C1 and the capacitor C2, and then data processing is carried out to obtain a result.

In summary, how to enable the experimenter to keep the bus grounded in the measurement of the CVT self-excitation method, and the experimenting measurement can be completed by using the existing dielectric loss tester, so that the problem of convenience and safety is a technical problem to be solved urgently at present.

Disclosure of Invention

The technical task of the utility model is to provide a bus grounding CVT self excitation method is situated between and is decreased measurement adapter, solve how to make experimenter can keep bus grounding in CVT self excitation method is measured, use current the situated between to decrease the tester just can accomplish the experimental survey simultaneously, ensure not only convenient but also safe problem.

The technical task of the utility model is realized in the following way, a bus grounding CVT self-excitation dielectric loss measuring adapter comprises a box body, wherein the upper end surface of the box body is provided with a signal input module, and the lower end surface of the box body is provided with a signal output module; an electromagnetic shielding box is arranged in the box body, a PCB is arranged in the electromagnetic shielding box, and a signal acquisition module is arranged on the PCB; a battery module is arranged on the outer side surface of the box body and supplies power to the signal acquisition module;

the signal input module comprises a high-voltage input terminal and an X input terminal; the signal output module comprises a high-voltage output terminal and an output side grounding terminal; the signal acquisition module comprises a high-precision current transformer unit; the high-voltage input terminal is connected with the high-voltage output terminal through a first lead, the X input terminal is connected with the output side grounding terminal through a second lead, the first lead and the second lead both penetrate through the high-precision current transformer unit, the directions of current signals of the first lead and the second lead are opposite when the first lead and the second lead penetrate through the high-precision current transformer unit, and therefore the current value acquired by the high-precision current transformer unit is the difference value of the current values between the first lead and the second lead.

Preferably, the high-precision current transformer unit comprises a high-precision current transformer, a feedback coil and an operational amplifier, current exists on a lead penetrating through the high-precision current transformer unit, a secondary coil of the high-precision current transformer generates induced voltage, the induced voltage is amplified by the operational amplifier and induced current is generated on the feedback coil, and the induced current can just offset the current on the lead penetrating through the high-precision current transformer, so that the magnetic core of the high-precision current transformer works in a zero-magnetic-flux state, and the circuit precision is improved.

Preferably, the signal acquisition module further comprises a signal conditioning unit, and the high-precision current transformer unit transmits the acquired current signal to the signal conditioning unit.

Preferably, the signal conditioning unit comprises an operational amplifier, and the operational amplifier is used for amplifying the phase of the current signal and adjusting the phase of the current signal so that the output current is equal to the difference value of the current values between the first conducting wire and the second conducting wire.

Preferably, the signal output module further comprises a Cx output terminal, and the signal conditioning unit is connected with the Cx output terminal and outputs the current signal through the Cx output terminal.

Preferably, the signal input module further includes an input side ground terminal for grounding.

Preferably, the battery module comprises a lithium battery, a charging socket, an electric quantity display lamp group and a switch key, the lithium battery is arranged in the box and above the electromagnetic shielding box, the charging socket, the switch key and the electric quantity display lamp group are arranged on the outer side face of the box, and the switch key is used for controlling the lithium battery to start or cut off external power supply.

Preferably, the electromagnetic shielding box is a box body made of a galvanized iron plate.

The utility model discloses a bus grounding CVT self excitation method is situated between and is decreased measurement adapter has following advantage:

when the CVT self-excitation method is used for measurement, the bus can be prevented from being removed, the field workload is reduced, and the safety of the test work is improved;

(two) the utility model discloses make the experimenter can keep bus grounding and obtain accurate measuring result in CVT self-excitation method is measured, and use current dielectric loss tester just can accomplish the experiment and measure, and is both convenient and safe.

The utility model has the characteristics of reasonable in design, simple structure, easily processing, small, convenient to use, a thing is multi-purpose etc, therefore, has fine popularization and use value.

Drawings

The present invention will be further explained with reference to the accompanying drawings.

FIG. 1 is a schematic structural diagram of a bus grounding CVT self-excitation dielectric loss measurement adapter;

FIG. 2 is a block diagram of a signal acquisition module;

FIG. 3 is a schematic circuit diagram of a signal acquisition module;

FIG. 4 is a schematic diagram of the conventional CVT self-excitation method (bus grounding needs to be disconnected);

figure 5 is the wiring schematic diagram that uses the utility model discloses carry out CVT self excitation method test.

In the figure: 1. the high-voltage power supply comprises a high-voltage input terminal, 2, an input side grounding terminal, 3, an X input terminal, 4, a charging socket, 5, an electric quantity display lamp bank, 6, a switch key, 7, a Cx output terminal, 8, a high-voltage output terminal, 9, an output side grounding terminal, 10, an electromagnetic shielding box, 11, a lithium battery, 12, a box body, 13, a high-precision current transformer unit, 14, a signal conditioning unit, 15, a PCB board, 16, a dielectric loss tester, 17, a first wire, 18, a second wire, 19 and a transformer.

Detailed Description

The bus grounding CVT self-excitation dielectric loss measurement adapter of the present invention is described in detail below with reference to the drawings and the specific embodiments.

In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and for simplification of description. And are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example (b):

as shown in the attached

drawings

1 and 2, the bus grounding CVT self-excitation dielectric loss measurement adapter mainly comprises a box body 12, a signal input module, a signal output module, a signal acquisition module and a battery module. The signal input module is positioned on the upper end surface of the box body 12, and the signal output module is positioned on the lower end surface of the box body 12; an electromagnetic shielding box 10 is arranged in the box body 12, a PCB 15 is arranged in the electromagnetic shielding box 10, and the signal acquisition module is welded on the PCB 15; the battery module is located the lateral surface of box 12, and the battery module is the power supply of signal acquisition module. The battery module includes lithium cell 11, socket 4 that charges, electric quantity display banks 5 and switch button 6, and lithium cell 11 installs in box 12 and is located the top of electromagnetic shield box 10, and socket 4, switch button 6 and electric quantity display banks 5 that charge install on box 12 lateral surface, and switch button 6 is used for controlling the lithium cell to start external power supply or cuts off external power supply. The electromagnetic shielding case 10 is a case made of a galvanized iron plate. The signal input module comprises a high-voltage input terminal 1, an input side grounding terminal 2 and an X input terminal 3; the signal output module comprises a high-voltage output terminal 8, an output side grounding terminal 9 and a Cx output terminal 7; the high voltage input terminal 1, the input side ground terminal 2, the X input terminal 3, the high voltage output terminal 8, the output side ground terminal 9, and the Cx output terminal 7 are each led out from the PCB 15 and pass through the electromagnetic shield case 10 and extend to the outside of the case 12. The signal acquisition module comprises a high-precision current transformer unit 13 and a signal conditioning unit 14, and the high-precision current transformer unit 13 and the signal conditioning unit 14 are respectively welded on the PCB 15. The high-voltage input terminal 1 is connected with the high-voltage output terminal 8 through a first lead 17, the X input terminal 3 is connected with the output side grounding terminal 9 through a second lead 18, the first lead 17 and the second lead 18 both penetrate through the high-precision current transformer unit 13, the mounting directions of the first lead 17 and the second lead 18 are adjusted, the directions of current signals of the first lead 17 and the second lead 18 are opposite when the first lead 17 and the second lead 18 penetrate through the high-precision current transformer unit 13, and the current value acquired by the high-precision current transformer unit 13 is the difference value of the current values between the first lead 17 and the second lead 18; the high-precision current transformer unit 13 transmits the acquired current signals to the signal conditioning unit 14, the signal conditioning unit 14 is connected with the Cx output terminal 7, the Cx output terminal 7 outputs the current signals, namely, the signal acquisition module performs difference calculation on the current signals passing through the high-voltage input terminal 1 and the X input terminal 3, and then the difference current is output by the Cx output terminal 7. The signal conditioning unit 14 includes an operational amplifier for amplifying the current signal and adjusting the phase of the current signal so that the output current is equal to the difference in current value between the first conductor 17 and the second conductor 18.

The circuit schematic diagram of the signal acquisition module is shown in fig. 3, wherein C1 is a capacitor, R1, R2 and R3 are resistors, R4 and R5 are adjustable resistors, an L high-precision current transformer, T1 is a secondary coil of the L high-precision current transformer, T2 is a feedback coil, and U1 and U2 are operational amplifiers. When a current is present through the lead wire of the high-precision current transformer unit 13, the secondary coil T1 of the high-precision current transformer L generates an induced voltage, which is amplified by the operational amplifier U1 to generate an induced current on the feedback coil T2. The induced current on the feedback coil T2 can just cancel the current on the wire passing through the high-precision current transformer L, so that the magnetic core of the high-precision current transformer L works in a zero-flux state, thereby improving the circuit precision. The output end of the high-precision current transformer L is connected with an operational amplifier U2 of the signal conditioning unit 14, the operational amplifier U2 amplifies the induced current generated by the high-precision current transformer L, the adjustable resistor R4 is used for fine adjustment of the current amplification factor, and the combination of the adjustable resistor R5 and the capacitor C1 can adjust the phase of the current signal. The amplified current is drawn from the Cx output terminal 7. The output terminal of the operational amplifier U2 of the signal conditioning unit 14 is connected to the output-side ground terminal 9. The operational amplifiers U1 and U2 are OPA 2277.

As shown in fig. 5, when measuring, the utility model discloses the generating line of the C1 electric capacity that will await measuring carries out ground connection, and the A interface that transformer 19 once inclines (A-X) is connected to the other end. The utility model discloses a high voltage input terminal 1 is connected to the electric capacity C2 one end that awaits measuring, and the A interface that transformer 19 once inclines (A-X) is connected to the other end. The utility model discloses a X input terminal 3 and the X interface connection of transformer 19 side (A-X), input side ground terminal 2 ground connection, high-voltage output terminal 8 connects the high-voltage interface that the loss tester 16 is situated between. The Cx interface that decreases tester 16 contains signal line and shielded wire, and wherein the signal line is connected the utility model discloses a Cx output terminal 7, shielded wire are connected and are decreased tester 16's output side ground terminal 9. In addition, the low voltage interface of the dielectric loss tester 16 is connected to the secondary side (a-x) of the transformer 19 to generate the excitation signal, as in the conventional lateral approach.

The utility model discloses an inside box 12, high-pressure input terminal 1 passes through a 17 lug connection with high-pressure output terminal 8, then transmits the high-pressure side of losing the tester 16 for being situated between, so electric capacity C2's electric current size compares with the phase place signal and does not change with the conventional mode. Therefore, the current information of the capacitor C2 to be measured acquired by the dielectric loss tester 16 is not changed compared with the conventional measurement method.

On the primary side of the transformer 19, the current flowing through the A-X terminal of the transformer 19 is equal to the sum of the currents flowing through the capacitors C1 and C2, so that the C1 current is equal to the difference between the A-X terminal current and the C2 current. The utility model discloses an inside box 12, high-pressure input terminal 1 passes through wire 17 with high-pressure output terminal 8 and is connected, and X input terminal 3 passes through wire two 18 with input side ground terminal 2 and is connected, and the electric current in wire 17 and the wire two 18 flows through signal acquisition module with opposite direction, and signal acquisition module's output is the electric current difference in wire 17 and the wire two 18, is the electric current of C1 promptly. And then transmitted to the Cx interface of the dielectric loss tester through the Cx output terminal 7 and the output side ground terminal 9. Therefore, the current information of the capacitor C1 to be measured acquired by the dielectric loss tester 16 is not changed compared with the conventional measurement method.

Therefore use the utility model discloses, guaranteed under bus ground's state, the sampling signal that the loss of dielectric tester 16 obtained electric capacity C1 and electric capacity C2 that await measuring is the same with using traditional mode completely, and the measuring result that final data processing reachs can not change.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.

Claims

1. A bus grounding CVT self-excitation dielectric loss measurement adapter is characterized by comprising a box body, wherein a signal input module is arranged on the upper end face of the box body, and a signal output module is arranged on the lower end face of the box body; an electromagnetic shielding box is arranged in the box body, a PCB is arranged in the electromagnetic shielding box, and a signal acquisition module is arranged on the PCB; a battery module is arranged on the outer side surface of the box body and supplies power to the signal acquisition module;

2. The bus-grounded CVT self-excited dielectric loss measurement adapter of claim 1, wherein the high-precision current transformer unit includes a high-precision current transformer, a feedback coil, and an operational amplifier, wherein a current is present on a wire passing through the high-precision current transformer unit, and wherein a secondary coil carried by the high-precision current transformer generates an induced voltage which is amplified by the operational amplifier and generates an induced current on the feedback coil.

3. The bus-grounded CVT self-excited dielectric loss measurement adapter according to claim 1 or 2, wherein the signal acquisition module further comprises a signal conditioning unit, and the high-precision current transformer unit transmits the acquired current signals to the signal conditioning unit.

4. The bus-grounded CVT self-excited dielectric loss measurement adapter of claim 3, wherein the signal conditioning unit includes an operational amplifier for amplifying the current signal and adjusting the phase of the current signal so that the output current is equal to the difference in current values between wire one and wire two.

5. The busbar grounding CVT self-excitation dielectric loss measurement adapter according to claim 4, wherein the signal output module further comprises a Cx output terminal, and the signal conditioning unit is connected to the Cx output terminal and outputs a current signal from the Cx output terminal.

6. The bussed CVT self-excited dielectric loss measurement adapter of claim 1, wherein the signal input module further comprises an input side ground terminal for grounding.

7. The bus grounding CVT self-excitation dielectric loss measurement adapter according to claim 1, wherein the battery module comprises a lithium battery, a charging socket, a power display lamp set and a switch button, the lithium battery is arranged in the box body and located above the electromagnetic shielding box, the charging socket, the switch button and the power display lamp set are arranged on the outer side face of the box body, and the switch button is used for controlling the lithium battery to be started to supply power to the outside or cut off the power to the outside.

8. The bus-grounded CVT self-excitation dielectric loss measurement adapter according to claim 1, 6 or 7, wherein the electromagnetic shielding box is a box body made of galvanized iron plate.