CN210744729U

CN210744729U - Receiving protection circuit for carrier module of ammeter

Info

Publication number: CN210744729U
Application number: CN201921218361.8U
Authority: CN
Inventors: 赵子文; 周中军
Original assignee: Ningbo Sanxing Electric Co Ltd
Current assignee: Ningbo Sanxing Electric Co Ltd
Priority date: 2019-07-30
Filing date: 2019-07-30
Publication date: 2020-06-12
Anticipated expiration: 2029-07-30

Abstract

The utility model relates to a receive protection circuit for carrier module of ammeter, be used for receiving electric wire netting signal's coupling transformer, the communication module who links to each other with coupling transformer output including the input, still including parallelly connected one-level surge protection device between coupling transformer input and parallelly connected second grade surge protection device between coupling transformer output. By adopting the circuit, the surge protection response speed is improved, and the reliability of the circuit is ensured.

Description

Receiving protection circuit for carrier module of ammeter

Technical Field

The utility model relates to an ammeter field especially relates to a receiving protection circuit for carrier module of ammeter.

Background

The carrier module in the electric meter is one of the main components of the communication system, contains more precise electronic components, but is often interfered by external instantaneous overvoltage, for example, under the conditions of switching on and off an inductive load or switching on and off a high-power load, line faults and the like, the carrier module is easy to generate overvoltage, and natural phenomena such as lightning and the like also easily cause lightning surge of the carrier module.

This type of overvoltage (current) is commonly referred to in the art as a surge voltage (current), which is a transient disturbance that can seriously affect the normal operation of the communication system. In order to prevent the surge voltage (current) from damaging the electronic equipment, a shunt method is generally adopted for preventive protection, that is, the surge voltage is in short circuit with the ground within a very short time, so that the surge current flows into the ground, and the purpose of weakening or eliminating the overvoltage and the overcurrent is achieved.

Most of the prior art uses a gas discharge tube or TVS tube as a single element for surge protection. When the voltage loaded to the two ends of the internal electrode reaches the voltage which makes the gas of the gas discharge tube breakdown, the gas discharge tube starts to discharge and is changed from high resistance to low resistance, so that the voltage at the two ends of the electrode does not exceed the breakdown voltage; the core part of the TVS tube is a PN junction with a larger cross section area, and the PN junction has stronger pulse absorption capacity when working in an avalanche state. Although this type of design has some effect, it has a problem that the accuracy of the operating voltage is low and the follow-up current is generated.

SUMMERY OF THE UTILITY MODEL

In view of the above, an object of the present invention is to provide a reception protection circuit for a carrier module of an electricity meter, which has a fast response time and high operation accuracy.

In order to achieve the above object, the utility model adopts the following technical scheme: a receiving protection circuit for a carrier module of an electric meter comprises a coupling transformer with an input end used for receiving a power grid signal and a communication module connected with an output end of the coupling transformer, and is characterized in that:

the protection circuit also comprises a primary surge protection device connected between the input ends of the coupling transformers in parallel and a secondary surge protection device connected between the output ends of the coupling transformers in parallel.

Furthermore, the primary surge protection device is a solid discharge tube.

Further, the secondary surge protection device is a TVS tube.

Further, the coupling transformer output end comprises a first output end serving as a receiving end for receiving the converted power grid signal and transmitting the converted power grid signal to the communication module, and a second output end serving as a transmitting end for transmitting the signal from the communication module;

and the first output end and the second output end are both connected with the secondary surge protection device in parallel.

Furthermore, the first output end is connected with a voltage dividing resistor in parallel after the secondary surge protection device.

Further, the voltage dividing resistor comprises a first resistor and a second resistor which are respectively and correspondingly connected in series between the positive electrode and the negative electrode of the first output end, and a third resistor which is connected in series with the first resistor and the second resistor and connected in parallel between the positive electrode and the negative electrode.

Further, a high-pass filter is connected in parallel to the first output end after the voltage dividing resistor.

Further, the high-pass filter comprises a first capacitor and a second capacitor which are respectively connected in series between the positive pole and the negative pole of the first output end, and a first inductor which connects the first capacitor and the second capacitor in series and connects the first capacitor and the second capacitor in parallel between the positive pole and the negative pole.

Further, the first output end is connected with a low-pass filter in parallel after the high-pass filter.

Further, the low-pass filter includes a third capacitor connected in parallel between the positive and negative poles of the first output terminal, a second inductor and a third inductor located behind the third capacitor and respectively connected in series between the positive and negative poles of the first output terminal, and a fourth capacitor connected in series with the second inductor and the third inductor and connected in parallel between the positive and negative poles.

Compared with the prior art, the utility model has the advantages of: the input end of the coupling transformer is provided with the solid discharge tube, the output end of the coupling transformer is provided with the TVS tube which is respectively used as a primary surge protection device and a secondary surge protection device, and through the cooperation of the solid discharge tube and the secondary surge protection device, the problems of high residual voltage, slow response time and low action precision of the gas discharge tube can be well solved, the discharge response time is prolonged, the characteristics of the two devices are fully utilized, and the reliable protection of a circuit is realized.

Drawings

Fig. 1 is a block diagram of the receiving protection circuit of the carrier module for the electricity meter of the present invention.

Fig. 2 is a circuit diagram of a preferred embodiment of the receiving protection circuit of the carrier module for the electricity meter of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present invention, and should not be construed as limiting the present invention.

Fig. 1-2 show a preferred example of the receiving protection circuit of the carrier module for an electricity meter according to the present invention, as shown in fig. 1, the receiving protection circuit includes a coupling transformer 2 having an input end for receiving signals of an electricity grid 1, a communication module 3 connected to an output end of the coupling transformer 2, a first-stage surge protection device 4 connected in parallel between the input ends of the coupling transformer 2, and a second-stage surge protection device 5 connected in parallel between the output ends of the coupling transformer 2. The input of the receiving protection circuit for the carrier module receives information from the power grid and converts it into internally recognizable information, and is connected to the mains for receiving voltage, which is well known to those skilled in the art and therefore not described in detail herein.

In this embodiment, the primary surge protection device 4 is a solid discharge tube VD12, and the secondary surge protection device 5 is a TVS tube. As can be seen in detail from fig. 2, the output terminal of the coupling transformer 2 includes a first output terminal 21 serving as a receiving terminal for receiving the converted signal of the power grid 1 and transmitting the signal to the communication module 3, and a second output terminal 22 serving as a transmitting terminal for transmitting the signal from the communication module 3, and the first output terminal 21 and the second output terminal 22 are both connected in parallel with the secondary surge protection device 5, that is, connected in parallel with the TVS tubes VD11 and VD10, respectively.

In order to ensure the stability of the rear end circuit of the coupling transformer, the first output end 21 is further connected in parallel with a voltage dividing resistor 6 after the secondary surge protection device 5, and the voltage dividing resistor 6 includes a first resistor R121 and a second resistor R122 respectively connected in series between the positive and negative poles of the first output end 21, and a third resistor which connects the first resistor R121 and the second resistor R122 in series and connects the first resistor R121 and the second resistor R122 in parallel between the positive and negative poles, wherein the third resistor is composed of a resistor R123 and a resistor R124 connected in series in the present embodiment.

Meanwhile, the first output terminal 21 is connected in parallel with a high-pass filter 7 after the voltage dividing resistor 6 to allow the wave of a specific frequency band to pass through and shield other frequency bands. The high-pass filter 7 includes a first capacitor C123 and a second capacitor C124 respectively connected in series between the positive and negative poles of the first output terminal 21, and a first inductor L123 connecting the first capacitor C123 and the second capacitor C124 in series and itself connected in parallel between the positive and negative poles. Of course, the back end of the circuit may also be connected in parallel with a plurality of high pass filters to better achieve the filtering effect, as shown in fig. 2, as indicated by

reference numerals

71 and 72.

The first output 21 is further connected in parallel with a low pass filter 8 after the high pass filter 7 to allow the waves of a specific frequency band to pass and to shield other frequency bands. The low-pass filter 8 comprises a third capacitor C121 connected in parallel between the positive and negative poles of the first output terminal 21, a second inductor L121 and a third inductor L122 located behind the third capacitor C121 and respectively connected in series between the positive and negative poles of the first output terminal 21, and a fourth capacitor C122 connecting the second inductor L121 and the third inductor L122 in series and itself connected in parallel between the positive and negative poles.

Moreover, in order to ensure the normal communication of the circuit, the circuit is also provided with a safety capacitor C101 at the front end of the coupling transformer 1 to limit the working current, the capacitor is generally selected to be nF grade safety capacitor, and the withstand voltage value is higher than the power supply voltage. Schottky diodes VD3 and VD5 are arranged behind the low-pass filter 8 to play a role in voltage limiting and stabilizing, and the stable work of the rear-end communication module is ensured.

This application parallelly connected solid discharge tube VD12 between the coupling transformer input, as one-level surge protection device, can bear big surge current, and respectively connect a TVS pipe in parallel at coupling transformer output, be VD10 respectively, VD11, as second grade protection device, can produce the response to surge voltage in ps level time range, because its response is fast, the action precision is high, can be in the twinkling of an eye bar overvoltage accurate control at certain level, thereby through the cooperation of the two, the solution gas discharge tube that can be fine is incomplete high, response time is slow, the problem that the action precision is low, discharge response time has been improved, and the characteristics of these two kinds of devices of make full use of, the reliable protection of circuit has been realized. In addition to the above-mentioned modifications, other similar modifications are also included in the scope of the present invention, and are not described herein in detail. While embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A receiving protection circuit for a carrier module of an electric meter comprises a coupling transformer (2) with an input end for receiving a power grid (1) signal, and a communication module (3) connected with an output end of the coupling transformer (2), and is characterized in that:

the protection circuit also comprises a primary surge protection device (4) connected in parallel between the input ends of the coupling transformer (2) and a secondary surge protection device (5) connected in parallel between the output ends of the coupling transformer (2).

2. The receive protection circuit of claim 1, for a carrier module of an electricity meter, characterized in that:

the primary surge protection device (4) is a solid discharge tube (VD 12).

3. The receive protection circuit of claim 1, for a carrier module of an electricity meter, characterized in that:

the secondary surge protection device (5) is a TVS tube (VD10, VD 11).

4. The receive protection circuit of claim 3, wherein:

the output end of the coupling transformer (2) comprises a first output end (21) serving as a receiving end for receiving the converted power grid (1) signal and transmitting the converted power grid signal to the communication module (3), and a second output end (22) serving as a transmitting end for transmitting the signal from the communication module (3);

the first output end (21) and the second output end (22) are connected with the secondary surge protection device (5) in parallel.

5. The receive protection circuit of claim 4, wherein:

and the first output end (21) is also connected with a voltage dividing resistor (6) in parallel after the secondary surge protection device (5).

6. The receive protection circuit of claim 5, wherein:

the voltage division resistor (6) comprises a first resistor (R121) and a second resistor (R122) which are respectively connected in series between the positive pole and the negative pole of the first output end (21), and a third resistor which connects the first resistor (R121) and the second resistor (R122) in series and connects the first resistor (R121) and the second resistor (R122) in parallel between the positive pole and the negative pole.

7. The receive protection circuit of claim 5, wherein:

the first output end (21) is also connected with a high-pass filter (7) in parallel after the voltage dividing resistor (6).

8. The receive protection circuit of claim 7, for a carrier module of an electricity meter, characterized by:

the high-pass filter (7) comprises a first capacitor (C123) and a second capacitor (C124) which are respectively connected in series between the positive pole and the negative pole of the first output end (21), and a first inductor (L123) which connects the first capacitor (C123) and the second capacitor (C124) in series and connects the first capacitor (C123) and the second capacitor (C124) in parallel between the positive pole and the negative pole.

9. The receive protection circuit of claim 7, for a carrier module of an electricity meter, characterized by:

the first output (21) is further connected in parallel with a low-pass filter (8) after the high-pass filter (7).

10. The receive protection circuit of claim 9, wherein:

the low-pass filter (8) comprises a third capacitor (C121) connected in parallel between the positive pole and the negative pole of the first output end (21), a second inductor (L121) and a third inductor (L122) which are positioned behind the third capacitor (C121) and respectively connected in series between the positive pole and the negative pole of the first output end (21), and a fourth capacitor (C122) which connects the second inductor (L121) and the third inductor (L122) in series and connects the second inductor (L121) and the third inductor (L122) in parallel between the positive pole and the negative pole.