CN203491075U - Current transformer reducing display error of on-site ammeter - Google Patents
Current transformer reducing display error of on-site ammeter Download PDFInfo
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- CN203491075U CN203491075U CN201320393391.9U CN201320393391U CN203491075U CN 203491075 U CN203491075 U CN 203491075U CN 201320393391 U CN201320393391 U CN 201320393391U CN 203491075 U CN203491075 U CN 203491075U
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- iron core
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Abstract
This utility model discloses a current transformer reducing display error of an on-site ammeter, which solves great errors happened when alternating current containing harmonic wave of the secondary side of a current transformer is transmitted faraway and displayed through a current display device. The means of reducing the display errors of distant current is to rectify the alternating current containing the harmonic wave of the secondary side of the current transformer into pulsating direct current and perform smooth wave filtering on ultraharmonics in a loop. The current transformer reducing display error of the on-site ammeter achieves the reduction of the loss of the effective value of the current transmitted by the circuit by reducing adding high harmonic content on the pulsating direct current transmitted afar, reduces the additional error of distant measurement instrument and solves the problem of errors of effective values of relatively big current caused by harmonic wave contained by an amperemeter on the on-site control box and a SCADA data acquisition and monitoring system.
Description
Technical field
The utility model relates to a kind of on-the-spot ammeter effective value display error, SCADA data acquisition and the current transformer of supervisor control to the effective value Acquisition Error of on-the-spot current signal of reducing, in the loop of containing a large amount of high order harmonic components, reduce the current effective value producing after electric current transmits to a distant place and show and Acquisition Error.
Background technology
The effect of current transformer is a larger alternating current of numerical value can be converted to the secondary AC electric current that numerical value is less by certain no-load voltage ratio; be used for protecting, the purposes such as measurement; if contain larger harmonic current and transmission in an alternating current when far away; secondary AC electric current in one end will be decayed excessive because of the electric capacity of circuit in the distance; ammeter demonstration and the current effective value error gathering are larger, have lost the meaning that shows and gather.Most typical example is the ammeter on ammeter on frequency-charger cabinet (be not frequency converter itself with digital ammeter) and field control case, although be in the secondary circuit of same current transformer, but because ammeter is apart from the far and near difference of current transformer, ammeter numerical value on field control case is significantly less than the ammeter on frequency-charger cabinet, and main cause is exactly in current transformer loop, to have larger harmonic current.At present ways of addressing this issue has the AC current transducer of electrified current transformer, though being 4～20mA signal and having many good qualities of its output needs to be replaced by the ammeter with 4～20mA signaling interface at the scene.
SCADA data acquisition and supervisor control signal isolator are generally provided with control room, identical with on-the-spot ammeter situation to the Acquisition Error reason of on-the-spot current signal through signal isolator, thereby the error that description mainly exists with on-the-spot ammeter describes.
Summary of the invention
For solving field control case, show the larger problem of current effective value error, we have taked the simplest treating method, be about to the alternating current that Current Transformer Secondary coil includes harmonic wave and change pulsating direct current electric current into, only radio-frequency component is wherein carried out to smothing filtering, to guarantee the continuous of commutating circuit electric current, the pulsating direct current electric current after smothing filtering transmits to a distant place along former control cables again; For the current effective value loss in compensation rectification and loop, adopted the method at Current Transformer Secondary side minimizing coil turn to compensate, in the Current Transformer Secondary wire loop before commutating circuit, increased voltage protection circuit simultaneously.
The utility model solves the technical scheme that its technical problem adopts:
A kind of energy reduces the current transformer containing harmonic current teletransmission after-current effective value display error, comprise instrument transformer insulating resin housing 1, iron core 2, the leakage current test secondary coil 3 of coiling on iron core, secondary wiring terminals 6, base 7, iron core 2, the leakage current test secondary coil 3 of coiling on iron core, base 7 is cast in instrument transformer insulating resin housing 1, the center of instrument transformer insulating resin housing 1 is provided with iron core center hole, secondary wiring terminals 6 is arranged on instrument transformer insulating resin housing 1 bottom, it is characterized in that, the second tap M in the middle of having on the leakage current test secondary coil 3 of coiling on described iron core
2, in described instrument transformer insulating resin housing 1, also comprising circuit board mounting box 5, described circuit board mounting box 5 has opening cover plate on instrument transformer insulating resin housing 1 surface, and circuit board 4 is arranged in circuit board mounting box 5, and secondary wiring terminals 6 has the first terminal X
1, the second terminal X
2, the 3rd terminal X
3three terminals.
Described circuit board 4 comprises rectification and high-frequency filter circuit 11, excess voltage protection 12, and described rectification and high-frequency filter circuit 11 comprise D
1～D
4bridge rectifier and the first capacitor C that diode or rectification module form
1, the second capacitor C
2the high-frequency filter circuit forming, the first tap M of the leakage current test secondary coil 3 of coiling on described bridge rectifier input and described iron core
1, the second tap M
2two ends are in parallel, the first described capacitor C
1, the second capacitor C
2be connected in parallel on the output of described bridge rectifier, described rectification and high-frequency filter circuit 11 outputs are connected to the first terminal X of the secondary wiring terminals 6 of described current transformer outlet side
1, the second terminal X
2on two ends;
Described excess voltage protection 12 is also connected in the first tap M of the leakage current test secondary coil 3 of coiling on described iron core
1, the 3rd tap M
3two ends, described excess voltage protection 12 is by bidirectional triode thyristor TV and the first resistance R
1, the second resistance R
2, the 3rd resistance R
3form, the bidirectional triode thyristor TV of described excess voltage protection 12 is connected in parallel on the leakage current test secondary coil 3 the first terminal X of coiling on described iron core
1, the 3rd terminal X
3terminal two ends, the first described resistance R
1, the second resistance R
2after series connection, be attempted by described bidirectional triode thyristor TV two ends, the 3rd described resistance R
3one end is connected to the first described resistance R
1, the second resistance R
2on the intermediate point of series connection, the 3rd described resistance R
3the other end is connected with the control gate level of described bidirectional triode thyristor TV.
On described iron core, be wound with centre tap M
2leakage current test secondary coil 3 be on the basis of the current transformer sizing no-load voltage ratio of national standard, the leakage current test secondary coil of coiling on described iron core 3 number of turn precentagewises are divided for 82%～90% and 10%～18% two part to described leakage current test secondary coil 3 the first terminal X
1with the second terminal X
2between terminal, be 82%～90% of described secondary coil 3 numbers of turn, the second terminal X of described secondary coil 3
2with the 3rd terminal X
3between terminal, be 10%～18% of described secondary coil 3 numbers of turn.
The beneficial effects of the utility model are, the current transformer electric current that can solve containing harmonic wave loop transmits the current effective value greater loss causing to a distant place, cause electric current to show the problem of larger error, make ammeter electric current and the ammeter electric current on field control case of current transformer installation place basically identical, also can make SCADA data acquisition and supervisor control very little to the effective value collection of on-the-spot current signal and major loop actual current effective value error, element in loop is less, simple in structure.
Accompanying drawing explanation
Fig. 1 is current transformer composition diagram of the present utility model
In Fig. 1: 1: instrument transformer insulating resin housing, 2: iron core, 3: the leakage current test secondary coil L of coiling on iron core
1and terminal the first tap M
1, the second tap M
2, the 3rd tap M
3, 4: circuit board, 5: circuit board mounting box, 6: the first terminal X of secondary wiring terminals
1, the second terminal X
2, the 3rd terminal X
3, 7: base.
Fig. 2 is current transformer rectifying and wave-filtering of the present utility model and excess voltage protection theory diagram
In Fig. 2,3: the leakage current test secondary coil L1 of coiling on iron core and terminal the first tap M
1, the second tap M
2, the 3rd tap M
3, 6: the first terminal X of secondary wiring terminals
1, the second terminal X
2, the 3rd terminal X
3, 11: rectification and high-frequency filter circuit, 12: excess voltage protection.
Fig. 3 is current transformer rectifying and wave-filtering of the present utility model and excess voltage protection schematic diagram.
In Fig. 3, L
1: current transformer leakage current test secondary coil 3 and terminal the first tap M
1, the second tap M
2, the 3rd tap M
3; D
1～D
4: rectifier diode; C
1, C
2: the first electric capacity of high-frequency filter capacitor, the second electric capacity, select 0.1 μ F, 0.047 μ F; X
1, X
2, X
3: three terminals of first, second, third with harmonic compensation of secondary wiring of current mutual inductor terminal 6; TV: bidirectional triode thyristor; R
1, R
2, R
3: controllable silicon triggers loop first, second, third resistance.
Embodiment
The electric current with high order harmonic component of induction on current transformer leakage current test secondary coil 3, need to become direct current through bridge rectifier, continuous in order to guarantee the current waveform of bridge rectifier, also due to the little reason of low frequency signal transmission loss, no longer the low frequency signal in transmission current is carried out to filtering, and adopt low frequency pulsating direct current to carry out the transmission to a distant place, only through two high-frequency filter capacitors, high-frequency current component is carried out to smothing filtering, to guarantee there is higher smoothness to the pulsating direct current of distant place transmission, reduce loop higher harmonic current content, in the minimizing high order harmonic component loss in the current delivery of a distant place, and make current delivery process effective value substantially constant.
Theoretical according to rectification filtering circuit, input and output effective value current ratio is 0.9COS α, for guaranteeing commutating circuit electric current basic continous, be that COS α is for getting large value, can adopt reduce the Current Transformer Secondary side number of turn 10%～18% method compensation rectified current reduce lose with loop, wherein 10%～15% loss causing for rectification 0.9COS α, 1%～8% for other loss of compensation circuit
Fig. 1 has adopted plain edition current transformer structure, is provided with described secondary wiring of current mutual inductor intermediate terminal M
2changed Current Transformer Secondary side umber of turn, be used for compensating rectification and loop loss, current transformer for secondary side rated current 5A, secondary side winding turn ratio is original reduces 13%, the wherein 10% current effective value loss that is used for compensating switching process 0.9COS α, other loss of 3% compensation circuit; For the current transformer of secondary side rated current 1A, secondary side winding turn ratio is original reduces 12%, the wherein 10% current effective value loss that is used for compensating switching process, other loss of 2% compensation circuit.
Described rectification and high-frequency filter circuit 11, the loop that is 5A for Current Transformer Secondary side rated current, adopts the D of average rectified current 5A, peak-inverse voltage 1000V
1～D
4four rectifier diodes form bridge rectifiers, and the loop that is 1A for Current Transformer Secondary side rated current adopts the D of average rectified current 1.5A, peak-inverse voltage 1000V
1～D
4four rectifier diodes form bridge rectifier, Current Transformer Secondary lateral coil L
1on containing the alternating current of harmonic wave, be rectified into the direct current of pulsation, C
1, C
2be respectively the high-frequency filter capacitor of 0.1 μ F, 0.047 μ F, the direct current that contains high fdrequency component become to the pulsating direct current electric current that contains less high fdrequency component.
Described excess voltage protection 12, the loop that is 5A for Current Transformer Secondary side rated current, the bidirectional triode thyristor of employing 8A, withstand voltage 600V, is attempted by Current Transformer Secondary coil, and circuits for triggering adopt 4k Ω, 50 Ω, tri-resistance of 20 Ω; The loop that is 1A for Current Transformer Secondary side rated current, the bidirectional triode thyristor of employing 4A, withstand voltage 600V, circuits for triggering adopt 4k Ω, 30 Ω, tri-resistance of 10 Ω.Under normal circumstances, Current Transformer Secondary side voltage is below 20V, and excess voltage protection electric current is below several milliamperes; When outside overcurrent, lightning impulse, secondary coil loop, the mutual device of electric current loop open circuit or loose contact; overvoltage protection set point is between 100～150V; while reaching overvoltage set point, bidirectional triode thyristor triggering and conducting, by Current Transformer Secondary coil short; bidirectional triode thyristor current over-zero turn-offs; voltage reaches set point conducting, and overvoltage disappears, after bidirectional triode thyristor zero passage disconnects; no longer conducting, does not affect circuit and normally works.
In practicality, diode bridge current rectifying and wave filtering circuit and excess voltage protection concentrate on a circuit board 4, and described circuit board 4 is fixed on described in current transformer in circuit board mounting box 5, and lid is detachable, and lid downside arranges output the first terminal X
1, the second terminal X
2, the 3rd terminal X
3, when there is harmonic wave in loop, output cable is connected on the first terminal X of the secondary wiring terminals 6 of described current transformer outlet side
1, the second terminal X
2when above, loop is without harmonic wave, output cable is connected on the first terminal X of the secondary wiring terminals 6 of described current transformer outlet side
1, the 3rd terminal X
3upper, convenient on-the-spot installation and wiring.
The ammeter that can reflect alternating current-direct current is installed at the scene, if rectification is ammeter, digital ammeter, all can be met the requirement that on-the-spot ammeter correctly shows main circuit current effective value.
Claims (3)
1. the current transformer that can reduce on-the-spot ammeter display error, comprise instrument transformer insulating resin housing (1), iron core (2), the leakage current test secondary coil (3) of coiling on iron core, secondary wiring terminals (6), base (7), iron core (2), the leakage current test secondary coil (3) of coiling on iron core, base (7) is cast in instrument transformer insulating resin housing (1), the center of instrument transformer insulating resin housing (1) is provided with iron core center hole, secondary wiring terminals (6) is arranged on instrument transformer insulating resin housing (1) bottom, it is characterized in that, the second tap M in the middle of having on the leakage current test secondary coil (3) of coiling on described iron core
2in described instrument transformer insulating resin housing (1), also comprise circuit board mounting box (5), described circuit board mounting box (5) has opening cover plate on instrument transformer insulating resin housing (1) surface, circuit board (4) is arranged in circuit board mounting box (5), and secondary wiring terminals (6) has the first terminal X
1, the second terminal X
2, the 3rd terminal X
3three terminals.
2. current transformer according to claim 1, is characterized in that: described circuit board (4) comprises rectification and high-frequency filter circuit (11), excess voltage protection (12), and described rectification and high-frequency filter circuit (11) comprise D
1～D
4bridge rectifier and the first capacitor C that diode or rectification module form
1, the second capacitor C
2the high-frequency filter circuit forming, the first tap M of the leakage current test secondary coil (3) of coiling on described bridge rectifier input and described iron core
1, the second tap M
2two ends are in parallel, the first described capacitor C
1, the second capacitor C
2be connected in parallel on the output of described bridge rectifier, described rectification and high-frequency filter circuit (11) output is connected to the first terminal X of the secondary wiring terminals (6) of described current transformer outlet side
1, the second terminal X
2on two ends;
Described excess voltage protection (12) is also connected in leakage current test secondary coil (3) the first tap M of coiling on described iron core
1, the 3rd tap M
3two ends, described excess voltage protection (12) is by bidirectional triode thyristor TV and the first resistance R
1, the second resistance R
2, the 3rd resistance R
3form, the bidirectional triode thyristor TV of described excess voltage protection (12) is connected in parallel on leakage current test secondary coil (3) the first terminal X of coiling on described iron core
1, the 3rd terminal X
3terminal two ends, the first described resistance R
1, the second resistance R
2after series connection, be attempted by described bidirectional triode thyristor TV two ends, the 3rd described resistance R
3one end is connected to the first described resistance R
1, the second resistance R
2on the intermediate point of series connection, the 3rd described resistance R
3the other end is connected with the control gate level of described bidirectional triode thyristor TV.
3. current transformer according to claim 1, is characterized in that: the second tap M in the middle of being wound with on described iron core
2leakage current test secondary coil (3) be on the basis of the current transformer sizing no-load voltage ratio of national standard, leakage current test secondary coil (3) number of turn precentagewise of coiling on described iron core is divided for 82%～90% and 10%～18% two part to described leakage current test secondary coil (3) the first terminal X
1with the second terminal X
2between terminal, be 82%～90% of described secondary coil (3) number of turn, the second terminal X of described secondary coil (3)
2with the 3rd terminal X
3it between terminal, is 10%～18% of described secondary coil (3) number of turn.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320393391.9U CN203491075U (en) | 2013-07-01 | 2013-07-01 | Current transformer reducing display error of on-site ammeter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320393391.9U CN203491075U (en) | 2013-07-01 | 2013-07-01 | Current transformer reducing display error of on-site ammeter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203491075U true CN203491075U (en) | 2014-03-19 |
Family
ID=50261886
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201320393391.9U Expired - Fee Related CN203491075U (en) | 2013-07-01 | 2013-07-01 | Current transformer reducing display error of on-site ammeter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203491075U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104215928A (en) * | 2014-09-11 | 2014-12-17 | 国家电网公司 | Analytical model method for current conversion ratio and phase difference of open-type current transformer |
| CN108987082A (en) * | 2018-06-28 | 2018-12-11 | 江阴市星火电子科技有限公司 | A kind of open-close type current transformer and its assembly method equipped with electro-magnetic screen layer |
| CN110907797A (en) * | 2018-09-18 | 2020-03-24 | 施耐德电气工业公司 | Method and apparatus for circuit detection |
-
2013
- 2013-07-01 CN CN201320393391.9U patent/CN203491075U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104215928A (en) * | 2014-09-11 | 2014-12-17 | 国家电网公司 | Analytical model method for current conversion ratio and phase difference of open-type current transformer |
| CN104215928B (en) * | 2014-09-11 | 2017-02-15 | 国家电网公司 | Analytical model method for current conversion ratio and phase difference of open-type current transformer |
| CN108987082A (en) * | 2018-06-28 | 2018-12-11 | 江阴市星火电子科技有限公司 | A kind of open-close type current transformer and its assembly method equipped with electro-magnetic screen layer |
| CN110907797A (en) * | 2018-09-18 | 2020-03-24 | 施耐德电气工业公司 | Method and apparatus for circuit detection |
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| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140319 Termination date: 20160701 |