CN105510679A - High-reliability and high-precision current measuring method and device - Google Patents
High-reliability and high-precision current measuring method and device Download PDFInfo
- Publication number
- CN105510679A CN105510679A CN201610039717.6A CN201610039717A CN105510679A CN 105510679 A CN105510679 A CN 105510679A CN 201610039717 A CN201610039717 A CN 201610039717A CN 105510679 A CN105510679 A CN 105510679A
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- Prior art keywords
- shielded cable
- current
- current transformer
- precision
- amplifier
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/02—General constructional details
- G01R1/18—Screening arrangements against electric or magnetic fields, e.g. against earth's field
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
- G01R15/183—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core
- G01R15/185—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core with compensation or feedback windings or interacting coils, e.g. 0-flux sensors
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
- Measurement Of Current Or Voltage (AREA)
Abstract
The invention provides a high-reliability and high-precision current measuring method and device. A current measuring sensor is a zero-flux current transformer, and is connected into a current loop in a non-opening through connecting mode, flux leakage does not exist, an electrical connection point of the current loop is intuitive and visible, and open-circuit risks do not exist. The device has a multistage protecting function and is provided with a shielding circuit, the sensor and the circuit are protected from open-circuit damage under extreme conditions, the current measurement range is simple and adjustable, the precision is hardly influenced by temperature, and the 0.02-stage level is reached. According to the method, a secondary current loop can be connected into a transformer substation site conveniently, online current measurement is carried out by means of long-term networking, and the online monitoring level is improved.
Description
Technical field
The present invention relates to Electric Measurement Technology field, is specifically related to reliability high-precision current measuring method and device.
Background technology
In transformer station's online monitoring system, need the parameters such as the secondary loop current to equipment in transformer station, Leakage Current to carry out real-time on-line measurement, because current measurement needs long-term hanging net operation, to the reliability and precision measuring access, there is very high requirement.Existing mode generally adopts the mode of directly series connection to access, and tie point is positioned at device inside, can not intuitive judgment loop state, and the maintenance of measurement mechanism has influence on the connection of secondary circuit.
Summary of the invention
Technical matters to be solved by this invention is for Problems existing in above-mentioned background technology, a kind of reliability high-precision current measuring method and device are provided, can under substation field ensures the precondition of reliability, realize the high-acruracy survey of loop current, facilitate repair and maintenance and measure test.
For solving the problems of the technologies described above, the technical solution used in the present invention is: a kind of reliability high-precision current measuring device, comprise zero-flux current transformer, it is characterized in that, zero-flux current transformer adopts not opening punching connected mode access current return, zero-flux current transformer is wrapped up by metal shielding, metal shielding connects shielded cable, zero-flux current transformer is connected change-over circuit by shielded cable with shielded cable joint, described shielded cable joint is between shielded cable and switching current, and shielded cable joint is integrated with normally closed travel switch.Opening does not refer to that the magnetic material of mutual inductor is closed into ring.
Described change-over circuit adopts amplifier to build I/V translation circuit, and Current Transformer Secondary side electric current flows through amplifier output terminal through platinum resistance, and the input end of amplifier is by two 1N4148 diode clamp protection amplifiers.
When shielded cable joint and change-over circuit disconnect, automatic short circuit current mutual inductor secondary side circuit, described change-over circuit is connected with shielded cable joint by Connection Block.
Reliability high-precision current measuring method, comprises the following steps:
Zero-flux current transformer, metal shielding, shielded cable, shielded cable joint and Connection Block are installed on outside device, amplifier is arranged at device inside, current return adopts not opening punching connected mode to pass zero-flux current transformer, the number of turn adjustable of punching; Adopt shielded cable to connect shielding case and shielding protection is carried out to zero-flux current transformer secondary side circuit; The built-in normally closed travel switch of shielded cable joint; When shielded cable joint and Connection Block disconnect, the closed guarantee Current Transformer Secondary side loop of travel switch is not opened a way, when shielded cable joint connects Connection Block, in Connection Block, contact pushes down normally closed travel switch shell fragment, and Current Transformer Secondary side loop is linked change-over circuit; Described change-over circuit is amplifier positive and negative terminal, and Current Transformer Secondary side electric current flows through amplifier output terminal through platinum resistance, adopts platinum resistance to realize I/V conversion.Device refers to that one is carried out the equipment of Collect conversion to electric current and voltage data, and device inside refers to the inside of this equipment; Change-over circuit is linked on the interface (interface is connected with shielded cable joint) of this device, the cable connected outside device interface is the shielded cable with screen layer, Connection Block is arranged on the shell of device, and change-over circuit is connected to zero-flux current transformer current return by interface, shielded cable joint, shielded cable.
Change the number of turn of zero-flux current transformer punching, and the multiplying power of the inner amplifier I/V conversion of device is to change measurement range.
The input end of amplifier when current transformer overcurrent or device do not power on, can not damage amplifier by two 1N4148 diode clamp protections.
The I/V translation circuit of amplifier and shielded cable effectively inhibit common mode interference, and the precision of I/V conversion depends on current transformer precision and platinum resistance precision.
Compared with prior art, the present invention has following beneficial effect:
The present invention under the condition not changing the connection of on-the-spot secondary circuit, realize the high-precision measurement of loop current, and device can possess multi-stage protection function, and guarantee open circuit, power-off do not affect sensor, circuit.
Accompanying drawing explanation
Fig. 1 is reliability high-precision current measuring device structural drawing of the present invention;
Wherein 1 zero-flux current transformer, 2 current returns, 3 shielding cases, 4 shielded cables, 5 normally closed travel switches, 6 joints, 7 Connection Blocks, 8 measurement mechanisms are inner, 9 diodes, 10 platinum resistance.
Embodiment
Below in conjunction with accompanying drawing, the present invention is further described.
(1) current return 2 adopts not opening punching connected mode to pass zero-flux current transformer 1, and the number of turn of punching is variable.Current transformer punching one circle no-load voltage ratio is 1000:1, and two circles are 2000:1, by that analogy.If measure electric current to be 6A to the maximum, then can design punching two circle, Current Transformer Secondary side electric current is 12mA to the maximum, and peak-to-peak value is 17mA.Opening does not refer to and refers to that the magnetic material of mutual inductor is closed into ring, can not open.
(2) Current Transformer Secondary side electric current is less, and when primary side current is 250mA, secondary side current is 125uA, adopts shielded cable 4 to connect shielding case 3 pairs of secondary side current loops and carries out shielding protection.
(3) the built-in normally closed travel switch 5 of the joint 6 of shielded cable, when disconnecting with Connection Block 7, travel switch closes, ensure that Current Transformer Secondary side current return is not opened a way, when connecting Connection Block, in Connection Block, contact is pushed down normally closed travel switch shell fragment normally closed travel switch is disconnected, and Current Transformer Secondary side loop is linked amplifier positive and negative terminal.Secondary side circuit is two output lines of mutual inductor.
(4) due to the empty short characteristic of amplifier, Current Transformer Secondary side is equivalent to short-circuit condition, and secondary side current flows through amplifier output terminal through platinum resistance 10, and the magnitude of voltage U=-I*R of amplifier output terminal, I are Current Transformer Secondary side electric current.The precision of output valve is mainly relevant with the precision of the precision of Zero flux mutual inductor, resistance, adopt zero-flux current transformer and 0.01% precision, the temperature drift 500 Europe platinum resistance that are ± 2PPM/ DEG C of 0.01%, whole device precision can be made to reach 0.02 grade, and output area 0 ~ 6V(exchanges).Amplifier need select Low-bias Current, and the device of high cmrr, as OPA277.
(5) due under abnormal conditions, may there is overcurrent or device not power-up state in Current Transformer Secondary side, and therefore the input end of amplifier designs two reverse diode protection amplifier input potential difference (PD) and can not exceed tolerance.Diode 9 must select the device of low junction capacity, ensures that diode can not produce additional effect to the phase place of circuit under normal circumstances.
A kind of reliability high-precision current measuring method, current metering sensor is zero-flux current transformer, and adopt not opening punching connected mode access current return, current return electric connecting point (i.e. shielded cable joint) is intuitively visual; Device has multi-stage protection function and screened circuit, protects sensor (i.e. current transformer), circuit can not under extreme conditions because of open circuit breakage; Current measuring range is simply adjustable; Current measurement precision is subject to the impact of temperature hardly, reaches the level of 0.02 grade.
Zero-flux current transformer access adopts punching connected mode, electric terminal (i.e. shielded cable joint) is not inner at device, does not increase extra electric terminal, does not change the wire diameter in original loop, increase only the loop length of several centimetres, increase 0.2VA load.Device has multi-stage protection function and screened circuit.In order to ensure that electric terminal is not inner at device, sensor is not mounted in device inside, sensor has metal screen layer, sensor is connected by shielded cable with change-over circuit, the integrated short circuiting switch of shielded cable joint (i.e. normally closed travel switch), when sensor connector (i.e. shielded cable joint) disconnects with change-over circuit, automatic short circuit current transformer circuit.Change-over circuit adopts amplifier to build I/V translation circuit, and the input end of amplifier when current transformer overcurrent or device do not power on, can not damage amplifier by two 1N4148 diode clamp protections.Current measuring range is simply adjustable.Current transformer change multiplying power into 1000:1, change the number of turn of external current transformer punching, and inner I/V convert multiplying power, can measurement range be changed.Generally the maximum punching number of turn is 8.Current measurement precision is subject to the impact of temperature hardly, reaches the level of 0.02 grade.The I/V translation circuit of operational amplifier design and screen layer effectively inhibit common mode interference, and design use noninductive platinum resistance realizes I/V conversion, and U=-I*R, the precision of conversion is only subject to the impact of current transformer precision and platinum resistance precision.
By present invention achieves a kind of reliability high-precision current measuring method and device; can under the condition not changing the connection of on-the-spot secondary circuit; realize the high-precision measurement of loop current; and device possesses multi-stage protection function; guarantee open circuit, power-off do not affect sensor, circuit; measurement device precision is high, reaches 0.02 grade of level.
The above is only the preferred embodiment of the present invention; be noted that for those skilled in the art; under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (7)
1. a reliability high-precision current measuring device, comprise zero-flux current transformer, it is characterized in that, zero-flux current transformer adopts not opening punching connected mode access current return, zero-flux current transformer is wrapped up by metal shielding, metal shielding connects shielded cable, zero-flux current transformer is connected change-over circuit by shielded cable with shielded cable joint, described shielded cable joint is between shielded cable and switching current, and shielded cable joint is integrated with normally closed travel switch.
2. a kind of reliability high-precision current measuring device according to claim 1; it is characterized in that; described change-over circuit adopts amplifier to build I/V translation circuit; Current Transformer Secondary side electric current flows through amplifier output terminal through platinum resistance, and the input end of amplifier is by two 1N4148 diode clamp protection amplifiers.
3. a kind of reliability high-precision current measuring device according to claim 1, it is characterized in that, when shielded cable joint and change-over circuit disconnect, automatic short circuit current mutual inductor secondary side circuit, described change-over circuit is connected with shielded cable joint by Connection Block.
4. adopt the reliability high-precision current measuring method of the device described in claim 1-3 any one, it is characterized in that, comprise the following steps:
Zero-flux current transformer, metal shielding, shielded cable, shielded cable joint and Connection Block are installed on outside device, amplifier is arranged at device inside, current return adopts not opening punching connected mode to pass zero-flux current transformer, the number of turn adjustable of punching; Adopt shielded cable to connect shielding case and shielding protection is carried out to zero-flux current transformer secondary side circuit; The built-in normally closed travel switch of shielded cable joint; When shielded cable joint and Connection Block disconnect, the closed guarantee Current Transformer Secondary side loop of travel switch is not opened a way, when shielded cable joint connects Connection Block, in Connection Block, contact pushes down normally closed travel switch shell fragment, and Current Transformer Secondary side loop is linked change-over circuit; Described change-over circuit is amplifier positive and negative terminal, and Current Transformer Secondary side electric current flows through amplifier output terminal through platinum resistance, adopts platinum resistance to realize I/V conversion.
5. reliability high-precision current measuring method according to claim 4, is characterized in that, changes the number of turn of zero-flux current transformer punching, and the multiplying power of the inner amplifier I/V conversion of device is to change measurement range.
6. reliability high-precision current measuring method according to claim 4, is characterized in that, the input end of amplifier when current transformer overcurrent or device do not power on, can not damage amplifier by two 1N4148 diode clamp protections.
7. reliability high-precision current measuring method according to claim 4, is characterized in that, the I/V translation circuit of amplifier and shielded cable effectively inhibit common mode interference, and the precision of I/V conversion depends on current transformer precision and platinum resistance precision.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610039717.6A CN105510679A (en) | 2016-01-21 | 2016-01-21 | High-reliability and high-precision current measuring method and device |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201610039717.6A CN105510679A (en) | 2016-01-21 | 2016-01-21 | High-reliability and high-precision current measuring method and device |
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| CN105510679A true CN105510679A (en) | 2016-04-20 |
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| CN201610039717.6A Pending CN105510679A (en) | 2016-01-21 | 2016-01-21 | High-reliability and high-precision current measuring method and device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111952043A (en) * | 2020-08-10 | 2020-11-17 | 广东电网有限责任公司 | Portable power supply device utilizing flexible mutual inductor to obtain energy from cable |
| CN112276431A (en) * | 2020-09-11 | 2021-01-29 | 深圳市启玄科技有限公司 | Current collecting device and current collecting method |
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|---|---|---|---|---|
| US4616174A (en) * | 1983-09-15 | 1986-10-07 | Danfysik A/S | Detector circuit for current measurements |
| JPH06267396A (en) * | 1993-03-16 | 1994-09-22 | Hitachi Ltd | Zero-phase current transformer |
| CN1658344A (en) * | 2005-03-10 | 2005-08-24 | 上海Mwb互感器有限公司 | Low-power electronic current mutual inductor |
| CN101131406A (en) * | 2006-08-21 | 2008-02-27 | 致茂电子股份有限公司 | High-frequency high-voltage current measuring apparatus |
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| JPH06267396A (en) * | 1993-03-16 | 1994-09-22 | Hitachi Ltd | Zero-phase current transformer |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111952043A (en) * | 2020-08-10 | 2020-11-17 | 广东电网有限责任公司 | Portable power supply device utilizing flexible mutual inductor to obtain energy from cable |
| CN112276431A (en) * | 2020-09-11 | 2021-01-29 | 深圳市启玄科技有限公司 | Current collecting device and current collecting method |
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Application publication date: 20160420 |
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