CN104374985B - A kind of floating ground measurement circuit for two-wire system transducer - Google Patents
A kind of floating ground measurement circuit for two-wire system transducer Download PDFInfo
- Publication number
- CN104374985B CN104374985B CN201410656637.6A CN201410656637A CN104374985B CN 104374985 B CN104374985 B CN 104374985B CN 201410656637 A CN201410656637 A CN 201410656637A CN 104374985 B CN104374985 B CN 104374985B
- Authority
- CN
- China
- Prior art keywords
- resistance
- feet
- circuit
- operational amplifier
- power supply
- 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.)
- Active
Links
Landscapes
- Amplifiers (AREA)
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Abstract
The present invention relates to a kind of floating ground measurement circuit for two-wire system transducer.Tested two-wire system transducer is connected with oscillograph by optical coupling isolation circuit, and tested two-wire system transducer passes through electric current Table A and resistance RSIt is connected with system power supply, optical coupling isolation circuit, oscillograph are connected with system power supply respectively；Optical coupling isolation circuit includes subtraction circuit, voltage feedback loop, voltage follower circuit and light-coupled isolation chip U3；System power supply includes DC source I, DC source II, alternating current power supply.In terms of existing technologies, by optical coupling isolation circuit by tested two-wire system transducer and oscillograph and its power supply isolation, two-wire system transducer is made not come from oscillograph and its power supply effect of noise；By controlling the parameter of optical coupling isolation circuit, V can be madeOUT=VIN, accurately complete the voltage measurement that measured point is with respect to COM end；Meanwhile, the safety of operation is ensure that in floating ground measurement, it is easy to accomplish, cost is relatively low.
Description
Technical field
The present invention relates to integrated circuit fields of measurement, particularly to a kind of floating ground measurement for two-wire system transducer electricity
Road.
Background technology
Two-wire system transducer is extensively applied in the industry.Physical quantity is converted into 4 ~ 20mA electric current by general two-wire system transducer
Export, 4 ~ 20mA electric current is originally powered as transmitter simultaneously.But the presence due to conductor resistance, the reference of two-wire system transducer
Ground level is simultaneously not equal to the ground level of power-supply system, and this brings difficulty to the measurement of two-wire system transducer.
All voltage measurements are all difference measurements, and voltage measurement divides reference ground level measurement and floating ground measurement（Non-reference ground
Level measurement）Two classes.During voltage measurement, most of traditional oscillographs are connected to protective grounding system " signal reference " terminal
On, so all signals being applied to oscillographic signal or oscillograph and providing all can have a points of common connection, and this is public
Junction point is typically oscillograph cabinet, by the Article 3 line ground connection in AC power supply unit power line, to be maintained at (or close)
Zero volt.Directly should not carry out floating ground measurement on the oscillograph with reference to ground level using traditional passive probe during floating ground measurement,
Depending on flowing through the amount of current of reference leads, traditional passive probe can start heating, and when electric current is sufficiently high, it can melt disconnection.
Floating ground measurement technology has isolation input oscillograph, difference detector, voltage isolation device etc..
Content of the invention
In view of the situation of prior art, the invention provides a kind of floating ground measurement circuit for two-wire system transducer, make
The floating neutral system of tested two-wire system transducer is not affected by the earth electrical property, improves the standard carrying out floating ground measurement using oscillograph
Really property and safety.
The present invention is to realize above-mentioned technical purpose, be employed technical scheme comprise that；A kind of floating for two-wire system transducer
Ground measuring circuit, including two-wire system transducer, oscillograph, system power supply it is characterised in that：Also include optical coupling isolation circuit, institute
State tested two-wire system transducer to be connected with oscillograph by described optical coupling isolation circuit, tested two-wire system transducer passes through electric current
Table A and resistance RSIt is connected with system power supply, described optical coupling isolation circuit, oscillograph are connected with system power supply respectively；Described
Optical coupling isolation circuit includes subtraction circuit, voltage feedback loop, voltage follower circuit and light-coupled isolation chip U3；Described system electricity
Source includes DC source I, DC source II, alternating current power supply；Described voltage follower circuit includes adjustable resistance R7 and operation amplifier
Device U2；Described voltage feedback loop comprises resistance R5, resistance R6, electric capacity C1；Described subtraction circuit comprises resistance R1, R2, R3, R4
With operational amplifier U1；Physical circuit is connected as：Resistance R1 mono- tunnel connects 2 feet of operational amplifier U1, separately leads up to resistance R2
Connect 1 foot and 5 feet of operational amplifier U1, resistance R3 mono- tunnel connects 3 feet of operational amplifier U1, separately leads up to resistance R4 and connects computing
4 feet of amplifier U1 and reference ground, the 6 foot connecting resistance R5 of operational amplifier U1, one end of electric capacity C1 and light-coupled isolation chip U3
4 feet, resistance R5 another termination reference ground, 7 feet of operational amplifier U1 connect the electric capacity C1 other end, one end of resistance R6, computing
8 feet of amplifier U1 meet power supply V1+, and 1 foot of light-coupled isolation chip U3 connects reference ground, the other end of 2 foot connecting resistance R6, and 3 feet connect
Power supply V1+, 6 feet meet power supply V2+, and 5 feet connect 3 feet of adjustable resistance R7 one end, operational amplifier U2, another termination of adjustable resistance R7
4 feet of operational amplifier U2 and circuit ground, 1 foot of operational amplifier U2,2 feet are output VOUT, 8 feet meet power supply V2+；Described fortune
Calculate amplifier U1, model OPA2180 of operational amplifier U2, light-coupled isolation chip U3 model TIL300.
The present invention has advantages below：The present invention in terms of existing technologies, by optical coupling isolation circuit by tested two
Line transmitter and oscillograph and its power supply isolation, make two-wire system transducer not come from oscillograph and its power supply
Effect of noise；By controlling the parameter of optical coupling isolation circuit, V can be madeOUT=VIN, accurately complete measured point with respect to COM
The voltage measurement at end；Meanwhile, the present invention ensure that the safety of operation in floating ground measurement, it is easy to accomplish, cost is relatively low.
Brief description
Fig. 1 is that slowdown monitoring circuit of the present invention connects block diagram；
Fig. 2 is the circuit theory diagrams of the present invention.
Specific embodiment
The current measurement circuit below in conjunction with the accompanying drawings and the specific embodiments present invention being provided is described in further detail.
As shown in Figure 1 and Figure 2, a kind of floating ground measurement circuit for two-wire system transducer, including two-wire system transducer, shows
Ripple device, system power supply, also include optical coupling isolation circuit, tested two-wire system transducer is by described optical coupling isolation circuit and oscillography
Device connects, and tested two-wire system transducer passes through electric current Table A and resistance RSIt is connected with system power supply, optical coupling isolation circuit, oscillography
Device is connected with system power supply respectively.
Optical coupling isolation circuit includes subtraction circuit, voltage feedback loop, voltage follower circuit and light-coupled isolation chip U3；System
System power supply includes DC source I, DC source II, alternating current power supply.
Voltage follower circuit includes adjustable resistance R7 and operational amplifier U2；Voltage feedback loop comprises resistance R5, resistance
R6, electric capacity C1；Subtraction circuit comprises resistance R1, R2, R3, R4 and operational amplifier U1.
Physical circuit is connected as：Resistance R1 mono- tunnel connects 2 feet of operational amplifier U1, separately leads up to resistance R2 and connects computing and puts
1 foot of big device U1 and 5 feet, resistance R3 mono- tunnel connects 3 feet of operational amplifier U1, separately leads up to resistance R4 and meet operational amplifier U1
4 feet and reference ground, 4 feet of the 6 foot connecting resistance R5, one end of electric capacity C1 and light-coupled isolation chip U3 of operational amplifier U1, electricity
Resistance R5 another termination reference ground, 7 feet of operational amplifier U1 meet the electric capacity C1 other end, one end of resistance R6, operational amplifier U1
8 feet meet power supply V1+, 1 foot of light-coupled isolation chip U3 connects reference ground, the other end of 2 foot connecting resistance R6, and 3 feet meet power supply V1+, 6
Foot meets power supply V2+, and 5 feet connect 3 feet of adjustable resistance R7 one end, operational amplifier U2, adjustable resistance R7 another termination operation amplifier
4 feet of device U2 and circuit ground, 1 foot of operational amplifier U2,2 feet are output VOUT, 8 feet meet power supply V2+.
Operational amplifier U1, model OPA2180 of operational amplifier U2, light-coupled isolation chip U3 model TIL300.
Adjustable resistance R7 is accurate adjustable resistance, and its maximum value is 1.5 times of resistance R5.
Resistance R1, R2, R3, R4 meet R1=R2, R3=R4.
The ceiling voltage that DC source I and DC source II provides is 48V, and alternating current power supply provides 220V alternating current.Actual
In application, DC source I and DC source II can be selected for Switching Power Supply.
Due to resistance R in practical applicationSPresence, VCOMIt is not equal to V1-, if necessary to measurement is tested two-wire system pick-up
The tested point voltage of device, with respect to the voltage at COM end, if not using isolation, when directly being measured using oscillograph, easily will
The interference of outside the earth introduces tested two-wire system transducer；If directly carrying out floating ground measurement using oscillograph（I.e. ground wire not with greatly
Ground is connected）, it is possible to during measurement damage circuit or impact personal safety.The present invention is using easy the solving of optical coupling isolation circuit
This problem.
The input of subtraction circuit connects COM end and the measured point of tested two-wire system transducer, the output of subtraction circuit respectively
VOUT’=(R4/R3)*(VIN-VCOM)；And VIN-VCOMBe need measurement tested two-wire system transducer tested point voltage with respect to
The voltage at COM end, adjusting respective resistivity values makes VOUT’=VIN-VCOM.
The effect of feedback circuit is to maintain the brightness stability of light emitting diode in optical coupling isolation circuit, and follower U2 makes Vo end
Driving force strengthen；The final output V of optical coupling isolation circuitOUT≈VOUT', i.e. VOUT≈VIN-VCOM.By adjusting adjustable resistance
The resistance of R7, can make VOUT=VIN-VCOM.
Operational amplifier U1, U2 can be realized by two-way operational amplifier OPA2180, and U3 is by light-coupled isolation chip TIL300
Realize；DC source can adopt 24V Switching Power Supply；By adjusting the above circuit parameter, make the defeated of optical coupling isolation circuit
Go out VOUTEqual to tested two-wire system transducer tested point voltage with respect to COM end voltage, oscillograph can accurately measure this
Magnitude of voltage, can also measure the parameters such as respective waveforms and time.
Measuring principle
In Fig. 1, two-wire system transducer is tested instrument, and COM end is the datum of two-wire system transducer（Floating ground）, need
Measure the voltage that measured point is with respect to COM end.One input V of optical coupling isolation circuitCOMConnect two-wire system transducer
COM end, another input V of optical coupling isolation circuitINConnect the measured point of two-wire system transducer.DC source I becomes for two-wire system
Send device to power, also power near the part of two-wire system transducer for optical coupling isolation circuit, as shown in figure V1+, V1-.Light-coupled isolation
The outfan V of circuitOUTConnect oscillographic test point CH, alternating current power supply is powered for oscillograph, DC source II is light-coupled isolation
The close oscillographic part of circuit is powered, as shown in figure V2+, V2-.The V2- end of DC source II and the GND of alternating current power supply
（Greatly）Connect.
During two-wire system transducer work, need to measure the voltage with respect to COM end of measured point, if directly using oscillography
Device measures, and oscillographic GND end can introduce the interference coming from the earth, the accuracy of the tested point voltage that impact is measured.And
Optical coupling isolation circuit can make output voltage equal with the voltage of measured point, i.e. VOUT=VIN, and the use of light-coupled isolation chip,
So that two-wire system transducer is kept apart with the earth, be not subject to noise jamming.After application optical coupling isolation circuit, due to VOUT=VIN, oscillography
V measured by deviceOUTIt is the voltage that measured point is with respect to COM end.
Claims (1)
1. a kind of floating ground measurement circuit for two-wire system transducer, including two-wire system transducer, oscillograph, system power supply, its
It is characterised by：Also include optical coupling isolation circuit, tested two-wire system transducer passes through described optical coupling isolation circuit with oscillograph even
Connect, tested two-wire system transducer passes through electric current Table A and resistance RSIt is connected with system power supply, described optical coupling isolation circuit, oscillography
Device is connected with system power supply respectively；Described optical coupling isolation circuit includes subtraction circuit, voltage feedback loop, voltage follower circuit
With light-coupled isolation chip U3；Described system power supply includes DC source I, DC source II, alternating current power supply, and DC source I includes
V1+, V1-, DC source II includes V2+, V2-, and alternating current power supply is E, L, N, is that oscillograph is powered；Described voltage follower circuit bag
Include adjustable resistance R7 and operational amplifier U2；Described voltage feedback loop comprises resistance R5, resistance R6, electric capacity C1；Described subtraction
Circuit comprises resistance R1, R2, R3, R4 and operational amplifier U1；Physical circuit is connected as：Resistance R1 mono- tunnel meets operational amplifier U1
2 feet, separately lead up to 1 foot and 5 feet that resistance R2 meets operational amplifier U1, resistance R3 mono- tunnel connects 3 feet of operational amplifier U1,
Separately lead up to 4 feet and the reference ground that resistance R4 meets operational amplifier U1, the 6 foot connecting resistance R5 of operational amplifier U1, electric capacity C1
Termination light-coupled isolation chip U3 4 feet, resistance R5 another termination reference ground, it is another that 7 feet of operational amplifier U1 meet electric capacity C1
One end, one end of resistance R6,8 feet of operational amplifier U1 meet the V1+ of DC source I, and 1 foot of light-coupled isolation chip U3 connects reference
Ground, the other end of 2 foot connecting resistance R6,3 feet meet the V1+ of DC source I, and 6 feet meet the V2+ of DC source II, and 5 feet connect adjustable resistance
R7 one end, 3 feet of operational amplifier U2,4 feet of adjustable resistance R7 another termination operational amplifier U2 and circuit ground, operation amplifier
1 foot of device U2,2 feet are output VOUT, 8 feet meet the V2+ of DC source II；Described operational amplifier U1, the type of operational amplifier U2
Number be OPA2180, light-coupled isolation chip U3 model TIL300.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410656637.6A CN104374985B (en) | 2014-11-18 | 2014-11-18 | A kind of floating ground measurement circuit for two-wire system transducer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410656637.6A CN104374985B (en) | 2014-11-18 | 2014-11-18 | A kind of floating ground measurement circuit for two-wire system transducer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104374985A CN104374985A (en) | 2015-02-25 |
| CN104374985B true CN104374985B (en) | 2017-03-01 |
Family
ID=52554023
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410656637.6A Active CN104374985B (en) | 2014-11-18 | 2014-11-18 | A kind of floating ground measurement circuit for two-wire system transducer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104374985B (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5373410A (en) * | 1992-03-27 | 1994-12-13 | Tandy Corporation | Single string resistive divider network for a digital multimeter |
| CN202503366U (en) * | 2012-02-04 | 2012-10-24 | 南京因泰莱电器股份有限公司 | Intelligent ring network measurement and control terminal |
| CN203133243U (en) * | 2013-02-05 | 2013-08-14 | 上海宏测半导体科技有限公司 | Floating-ground test system |
| CN204214936U (en) * | 2014-11-18 | 2015-03-18 | 中环天仪股份有限公司 | A kind of floating ground measurement circuit |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9482698B2 (en) * | 2010-10-07 | 2016-11-01 | Raritan Americas, Inc. | Methods and apparatus for resistive voltage sensing in an isolated power distribution unit |
-
2014
- 2014-11-18 CN CN201410656637.6A patent/CN104374985B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5373410A (en) * | 1992-03-27 | 1994-12-13 | Tandy Corporation | Single string resistive divider network for a digital multimeter |
| CN202503366U (en) * | 2012-02-04 | 2012-10-24 | 南京因泰莱电器股份有限公司 | Intelligent ring network measurement and control terminal |
| CN203133243U (en) * | 2013-02-05 | 2013-08-14 | 上海宏测半导体科技有限公司 | Floating-ground test system |
| CN204214936U (en) * | 2014-11-18 | 2015-03-18 | 中环天仪股份有限公司 | A kind of floating ground measurement circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN104374985A (en) | 2015-02-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102841260B (en) | DC microresistivity measuring system | |
| CN103529342A (en) | Line detection device | |
| CN103487767B (en) | A kind of load driving circuits and electronic load | |
| CN106405209B (en) | Accumulator voltage detection device | |
| CN102822684A (en) | Measuring arrangement for detecting alternating currents | |
| CN105699764A (en) | Hall-sensor-based electric energy meter | |
| CN206515387U (en) | Current sensing means and current detecting system | |
| CN207689656U (en) | A kind of multi-epitope direct-current electric energy meter calibrating device | |
| CN203117295U (en) | Resistance value detection circuit and device | |
| CN108169568A (en) | Milliohm resistance measuring circuit | |
| CN104316896A (en) | Method for calibrating errors of electric energy meter under influence of direct currents and even-order harmonic | |
| CN104374985B (en) | A kind of floating ground measurement circuit for two-wire system transducer | |
| CN105911394B (en) | PIN-FET light-receiving component Auto-Test System | |
| CN204214936U (en) | A kind of floating ground measurement circuit | |
| CN205450108U (en) | Electric energy meter based on hall sensor | |
| US8907658B2 (en) | System and method of measuring power produced by a power source | |
| CN204228946U (en) | A kind of electric energy meter error calibrating installation | |
| CN207424104U (en) | Vibration amplifier sensor capacitance amount detecting device | |
| CN106556737A (en) | A kind of digital current voltmeter interface circuit based on Hall current sensor | |
| CN108196159A (en) | A kind of DC leakage flow detection device | |
| CN201194016Y (en) | AC current detection circuit | |
| CN204302353U (en) | A kind of power detection system based on Hall element | |
| CN202182914U (en) | A circuit utilizing a linear optical coupler to realize accurate measurement of AC zero passage signals | |
| CN104076301A (en) | Separating type monitoring circuit of alternating/direct current aliasing magnetic field | |
| CN207992320U (en) | Milliohm resistance measuring circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |