CN111371310A - Control circuit of double-wire alternating current transmitter - Google Patents
Control circuit of double-wire alternating current transmitter Download PDFInfo
- Publication number
- CN111371310A CN111371310A CN201811597801.5A CN201811597801A CN111371310A CN 111371310 A CN111371310 A CN 111371310A CN 201811597801 A CN201811597801 A CN 201811597801A CN 111371310 A CN111371310 A CN 111371310A
- Authority
- CN
- China
- Prior art keywords
- control circuit
- circuit
- constant current
- current source
- monitoring system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/045—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage adapted to a particular application and not provided for elsewhere
- H02H9/046—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage adapted to a particular application and not provided for elsewhere responsive to excess voltage appearing at terminals of integrated circuits
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention discloses a control circuit of a double-wire alternating current transmitter.A field device power line current is isolated and converted into a standard current signal which is changed according to a linear proportion through a constant current source and a voltage stabilizing chip circuit and then is output, the standard current signal is transmitted to an input interface of a monitoring system through a pair of twisted pairs, and the twisted pairs simultaneously transmit a working power supply positioned in the monitoring system to the current transmitter. The control circuit mainly utilizes the input and output characteristics of the voltage stabilizing source and the constant current source, namely, the linear relation, so that the output can be linearly changed along with the input, and the control circuit has the characteristics of high response speed, small error, strong anti-interference capability and the like; and this control circuit makes signal line and power cord unite two into one, has effectively also practiced thrift the cost.
Description
Technical Field
The invention relates to the technical field of transmitters, in particular to a control circuit of a double-wire alternating current transmitter.
Background
Current transducers on the market today are divided into direct current transducers and alternating current transducers. However, most of them are three-wire system (one positive power line, two signal lines, one of which is common to GND) and four-wire system (two positive and negative power lines, two signal lines, one of which is common to GND). When in use, the current transmitter is installed on a power line of field equipment, and a monitoring system taking the single chip microcomputer as a core is positioned in a monitoring room far away from the field of the equipment, wherein the distance between the current transmitter and the monitoring system is dozens of meters to hundreds of meters or even far away. The environment of the equipment site is severe, strong electric signals can generate various electromagnetic interferences, and lightning induction can generate strong surge pulses, so that the monitoring system has large error and high damage rate; and the three-wire system and the four-wire system require more wires, which is not beneficial to judging faults such as power failure, wire breakage and the like. Under the condition, a troublesome problem encountered in the application system of the single chip microcomputer is how to reliably transmit tiny signals in a long distance under a severe environment.
Disclosure of Invention
The invention provides a control circuit of a double-wire alternating current transmitter aiming at solving the problems in the background technology, and aims to transmit a measurement signal and a power supply on a twisted pair wire simultaneously, so that an expensive transmission cable is omitted, the signal is transmitted in a current mode, and the anti-interference capability is greatly enhanced.
In order to achieve the purpose, the invention is realized by the following technical scheme:
a kind of two-wire AC transducer control circuit, the AC transducer is mounted on power line of the field device, the field device is monitored by the remote monitoring system; the power line of the field device is isolated and converted into a standard current signal output according to linear proportion by a constant current source and a voltage stabilizing chip circuit, and the standard current signal is transmitted to an input interface of a monitoring system through a pair of twisted pairs, and the twisted pairs simultaneously transmit a working power supply of the monitoring system to a current transmitter.
As a further embodiment of the invention, the working power supply of the monitoring system supplies power to the constant current source chip, the constant current source chip supplies power to the voltage stabilizing chip, and meanwhile, the constant current source chip is grounded.
As the preferred embodiment of the invention, a power supply circuit of the working power supply for the constant current source chip is connected with a rectifier diode, and a ground circuit of the constant current source chip is connected with the rectifier diode; the purpose of the rectifier diode is to prevent reverse connection from damaging the circuit.
As a further embodiment of the present invention, an ac input signal of the power line of the field device is first converted into a small dc input signal by a circuit, the dc input signal is connected to a dual operational amplifier through a voltage dividing circuit, and a feedback circuit is formed between the dual operational amplifier and a voltage regulator chip.
As a preferred embodiment of the present invention, the alternating current is converted into direct current by a coil and then rectified by a rectifier bridge.
As the preferred embodiment of the invention, the constant current source chip adopts a three-terminal adjustable LM234 device.
As a preferred embodiment of the invention, the voltage-stabilizing source chip adopts a TL431 device.
As a preferred embodiment of the invention, the dual operational amplifier adopts an LM258 device.
As the preferred embodiment of the invention, the current signal output port is additionally provided with a lightning-protection and surge-protection device, thereby being beneficial to safety lightning protection and explosion protection.
Compared with the prior art, the invention has the following beneficial effects:
(1) the control circuit mainly utilizes the input and output characteristics of the voltage stabilizing source and the constant current source, namely the linear relation, so that the output can be linearly changed along with the input, and the control circuit has the characteristics of high response speed, small error, strong anti-interference capability and the like.
(2) The control circuit improves the wire system, so that a signal wire and a power wire are combined into a whole, and a rectifier diode is connected to the power input end and the ground end, so that the equipment is prevented from being damaged by misoperation of a customer, the service life of the product is prolonged, and the cost is also saved.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a control circuit diagram of the present invention.
Detailed Description
In order to make the purpose and function, implementation technical scheme and advantages of the embodiments of the present invention easily understood and appreciated, the present invention will be fully described in detail with reference to the accompanying drawings of the embodiments. It is obvious that the described embodiments are a part of the present invention, not all embodiments, and all other embodiments obtained by those of ordinary skill in the art without any inventive work are within the scope of the present invention.
Example (b):
as shown in figure 1, the control circuit of the double-wire alternating current transmitter converts the current isolation of a field device power line into a standard current signal which is 4-20 mA and changes according to a linear proportion, and then the standard current signal is transmitted to an input interface of a monitoring system through a pair of twisted pairs, and the twisted pairs simultaneously transmit a 24V working power supply positioned in the monitoring system to the current transmitter.
The specific working principle is as follows: and a three-end adjustable constant current source device LM234 and a voltage stabilizing source device TL431 are adopted to convert the power line current into standard current information which changes linearly.
A power supply section:
the 24V working power supply of the monitoring system supplies power to the constant current source chip LM234 through a rectifier diode D7 (the diode is used for protecting a circuit and preventing the circuit from being damaged due to reverse connection, and the same principle is adopted in the D9), and the output voltage of a pin 6 of the LM234 chip supplies power to the dual operational amplifier chip LM 258; meanwhile, the LM234 chip output voltage is output through the adjusting resistor R20 and constantly flows through the coupling capacitor C2 to the ground.
The signal flow direction is as follows:
alternating current input (within the range of 0-400A) of the power line of the external field equipment is subjected to current transformation by a 3000N coil and then rectified by a rectifier bridge consisting of D1-D4, so that a large alternating current input signal is changed into a small direct current input signal, and the change process is changed linearly. Wherein, C3 is step-down electric capacity, and R2-R4 and R17-R19 are bleeder resistance, and the electric energy of C3 energy storage just releases through bleeder resistance after the input disconnection, if there is no bleeder resistance, the electric capacity of its energy storage causes the electric shock to the human body very easily. After the current changes, a voltage division circuit formed by R1 and R5 provides an inverting input for an operational amplifier unit of the dual operational amplifier LM258, the inverting input of the operational amplifier unit is grounded, and R9 is a feedback resistor and feeds back the output end of the operational amplifier unit to the input end. In addition, the output is transmitted to the equidirectional input end of the second operational amplifier unit through an amplitude modulation potentiometer GIN, the output end of the second operational amplifier unit is amplified through the current of an NPN triode KTC4378 and then provides input for a precise voltage-stabilized power supply TL431 through R22, R21 is a regulating resistor matched with the TL431, the output of the TL431 is connected to the equidirectional input end of the second operational amplifier unit of the operational amplifier LM258 through a zero-setting resistor GIN to form negative feedback, and the feedback system has very important significance for the stability of the work of the alternating current transmitter, the accuracy of data, the interference resistance and the like.
In the circuit of the invention, the zero setting resistor (GIN) and the amplitude modulation resistor (OFS) are mutually influenced, but the influence of the GIN on the OFS is different from the influence of the OFS on the GIN. The zero potentiometer GIN is up to 1M and the amplitude modulated potentiometer OFS is only 50K, which results in a large amplitude impact when the GIN varies greatly. In addition, when the emitter output of the transistor KTC4378 fluctuates, the output of the constant current source, that is, the current output of the entire system is affected, and thus it can be seen that the output changes linearly with the input. The control circuit can accurately control the input alternating current, overcomes the defect of poor stability, and realizes the simplification and cost reduction of the circuit board.
Claims (9)
1. The control circuit of the double-wire alternating current transmitter is characterized in that the alternating current transmitter is arranged on a power line of field equipment, and the field equipment is monitored by a remote monitoring system; the method is characterized in that: the power line of the field device is isolated and converted into a standard current signal output according to linear proportion by a constant current source and a voltage stabilizing chip circuit, and the standard current signal is transmitted to an input interface of a monitoring system through a pair of twisted pairs, and the twisted pairs simultaneously transmit a working power supply of the monitoring system to a current transmitter.
2. The control circuit of claim 1, wherein: the working power supply of the monitoring system supplies power to the constant current source chip, the constant current source chip supplies power to the voltage stabilizing chip, and meanwhile the constant current source chip is grounded.
3. The control circuit of claim 2, wherein: the power supply circuit of the working power supply for the constant current source chip is connected with a rectifier diode, and the ground circuit of the constant current source chip is connected with a rectifier diode.
4. A control circuit as claimed in claim 2 or 3, wherein: an alternating current input signal of the field device power line is converted into a small direct current input signal through a circuit, the direct current input signal is connected with a double operational amplifier through a voltage division circuit, and a feedback circuit is formed between the double operational amplifier and a voltage stabilizing source chip.
5. The control circuit of claim 4, wherein: the alternating current is converted into direct current through the coil and then rectified through the rectifier bridge.
6. The control circuit of claim 4, wherein: the constant current source chip adopts a three-end adjustable LM234 device.
7. The control circuit of claim 4, wherein: the voltage-stabilizing source chip adopts a TL431 device.
8. The control circuit of claim 4, wherein: the dual operational amplifier adopts an LM258 device.
9. The control circuit of claim 1, wherein: the current signal output port is additionally provided with a lightning and surge protection device, so that safety, lightning and explosion protection are facilitated.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811597801.5A CN111371310A (en) | 2018-12-26 | 2018-12-26 | Control circuit of double-wire alternating current transmitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811597801.5A CN111371310A (en) | 2018-12-26 | 2018-12-26 | Control circuit of double-wire alternating current transmitter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111371310A true CN111371310A (en) | 2020-07-03 |
Family
ID=71211460
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811597801.5A Pending CN111371310A (en) | 2018-12-26 | 2018-12-26 | Control circuit of double-wire alternating current transmitter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111371310A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113447049A (en) * | 2021-07-30 | 2021-09-28 | 福建顺昌虹润精密仪器有限公司 | Alternating current signal transmitter |
| CN115454192A (en) * | 2022-10-10 | 2022-12-09 | 盈帜科技（常州）有限公司 | Two-bus circuit |
-
2018
- 2018-12-26 CN CN201811597801.5A patent/CN111371310A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113447049A (en) * | 2021-07-30 | 2021-09-28 | 福建顺昌虹润精密仪器有限公司 | Alternating current signal transmitter |
| CN115454192A (en) * | 2022-10-10 | 2022-12-09 | 盈帜科技（常州）有限公司 | Two-bus circuit |
| CN115454192B (en) * | 2022-10-10 | 2023-07-07 | 盈帜科技（常州）有限公司 | Two-bus circuit |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111371310A (en) | Control circuit of double-wire alternating current transmitter | |
| US7046157B2 (en) | Short circuit detector for shield conductor in a fieldbus network | |
| CN206161092U (en) | Oil mass remote monitoring system | |
| WO2022134379A1 (en) | Bus communication circuit and device | |
| CN109238557A (en) | A kind of intelligent self-diagnosing formula pressure transmitter device | |
| CN110887597B (en) | Two-wire system intelligent differential pressure controller transmitter digital display instrument | |
| US5805052A (en) | Cable system for signal transmission | |
| WO2022135024A1 (en) | Pulse signal output circuit and flowmeter | |
| CN214251201U (en) | Pulse signal output circuit and flowmeter | |
| CN104848895A (en) | Anti-intensive-impact and high-voltage-resistant temperature pressure sensor combined device | |
| CN113542925A (en) | Transmission system and transmission method for transmitter signal power information | |
| US8963735B2 (en) | Turbine meter pre-scaling terminal block electronics | |
| CN209345011U (en) | Two-wire exchanges transmitter control circuit | |
| CN204902874U (en) | Anti thump and high pressure resistant temperature and pressure sensor composite set | |
| CN208887835U (en) | A kind of intelligent self-diagnosing formula pressure transmitter device | |
| CN204188699U (en) | Transformer iron core grounding current on-line monitoring system | |
| CN212872833U (en) | Fault detection circuit device for switching value input port of multifunctional instrument | |
| CN209246930U (en) | A kind of sensor coding circuit based on partial pressure method | |
| CN208984687U (en) | Electric energy metering device and electric energy meter | |
| CN212305301U (en) | PWM isolation control output 4-20mA circuit | |
| CN204214936U (en) | A kind of floating ground measurement circuit | |
| CN111351543A (en) | Wet-type water meter M-BUS BUS photoelectric direct-reading sensor | |
| CN204116443U (en) | Square electric current is bored a hole the AC current transducer of anti-strong electromagnetic | |
| CN203359721U (en) | Elevator brake shoe gap detection device | |
| JP2014186709A (en) | Temperature monitoring system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |