CN211979178U - Current transformer polarity measuring device - Google Patents
Current transformer polarity measuring device Download PDFInfo
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- CN211979178U CN211979178U CN202020343345.8U CN202020343345U CN211979178U CN 211979178 U CN211979178 U CN 211979178U CN 202020343345 U CN202020343345 U CN 202020343345U CN 211979178 U CN211979178 U CN 211979178U
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Abstract
The utility model discloses a current transformer polarity measuring device, including power supply, transformer winding and microammeter, transformer winding includes first winding, second winding and the third winding that from left to right sets gradually, two wiring ends of second winding are connected with power supply's positive negative pole electricity respectively, the wiring end of first winding bottom and the wiring end of third winding bottom are connected. The utility model discloses in, transformer winding three-phase short circuit can make the flux linkage that each phase produced offset each other to eliminate the self-induced electromotive force of coil, the return circuit is equivalent to a pure resistance return circuit this moment, the size of electric current only depends on the size of power potential and loop resistance, because the internal resistance of transformer is very little, so the current value will be much bigger than the single-phase coil when adding power, can adjust the size of straight resistance tester output test current according to transformer capacity's size simultaneously, the polarity that microampere table can clear exact CT reflects.
Description
Technical Field
The utility model relates to a technical field is measured to current transformer polarity, specifically is a current transformer polarity measuring device.
Background
The current transformer converts large current into small current in each link of the power system, isolates a secondary circuit connected with a relay and a measuring instrument from a high-voltage system of primary current, and is an essential element in power generation, power transformation, power transmission and power distribution systems. The polarity of the current transformer is closely related to current protection and measurement, and if the polarity is wrong, the wrong measurement and measurement of the protection device caused by the wrong operation of the protection device in the relay protection loop and the metering loop can be caused.
At present, when an oil-filled bushing type current transformer of a large transformer is put into operation to measure polarity, the bushing needs to be disassembled after oil is drained for measurement, the engineering quantity is large, and therefore polarity retesting of the current transformer is very difficult.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a current transformer polarity measuring device to solve the problem that proposes among the above-mentioned background art.
In order to achieve the above object, the utility model provides a following technical scheme:
the utility model provides a current transformer polarity measuring device, includes power supply, transformer winding and microammeter, transformer winding includes first winding, second winding and the third winding that from left to right sets gradually, two wiring ends of second winding are connected with power supply's positive negative pole electricity respectively, the wiring end of first winding bottom and the wiring end of third winding bottom are connected, the wiring end on first winding and third winding top all is connected with power supply's positive pole, first winding, second winding and third winding all match with the current transformer that awaits measuring, and the secondary terminal on the current transformer that awaits measuring is connected with microampere table.
And the winding directions, the winding turns, the winding materials and the intervals of the first winding, the second winding and the third winding are the same.
Wherein, the microammeter is a pointer microammeter.
And the first winding and the third winding form a short-circuit protection loop.
Wherein the output current of the power supply is any one of 2A, 5A or 10A.
Compared with the prior art, the beneficial effects of the utility model are that:
1. the utility model discloses in, transformer winding three-phase short circuit can make the flux linkage that each phase produced offset each other (because large-scale transformer magnetic circuit space is very little, leakage flux can be neglected), thereby eliminate the self-induced electromotive force of coil, the return circuit is equivalent to a pure resistance return circuit this moment, the size of electric current only depends on the size of power potential and return circuit resistance, because the internal resistance of transformer is very little, so the current value will be much bigger than when single-phase coil adds the electricity, can adjust the size of straight resistance tester output test current according to the size of transformer capacity simultaneously, microampere table can clearly correct the polarity of reflecting CT.
2. In the utility model, during measurement, firstly, a microammeter is connected in series between the secondary terminals K3 and K4 of the current transformer (CT2) to measure the polarity of the current transformer, and if the pointer is in positive bias, the current transformer is in polarity reduction; and restoring the wiring of the secondary terminal of the current transformer, connecting the secondary terminal of the current transformer into a (CT1 or CT3) protection loop, connecting a microampere meter in series at the inlet wire of the protection device to measure the CT polarity again, if the deflection direction of the pointer is the same as that of the deflection direction of the pointer when the current transformer (CT2) secondary terminal is measured, namely the pointer is also positively deflected, the wiring of the secondary loop of the current transformer is correct, and otherwise, the wiring is wrong.
Drawings
Fig. 1 is a schematic circuit diagram of a polarity measuring device of a current transformer.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
Referring to fig. 1, the present invention provides a technical solution:
the utility model provides a current transformer polarity measuring device, including power supply, transformer winding and microammeter, transformer winding includes the first winding, second winding and the third winding that from left to right sets gradually, two terminals of second winding are connected with power supply's positive negative pole electricity respectively, the terminal of first winding bottom and the terminal of third winding bottom are connected, the terminal on first winding and third winding top all is connected with power supply's positive pole, first winding, second winding and third winding all match with the current transformer that awaits measuring, and the secondary terminal on the current transformer that awaits measuring is connected with microammeter.
By measuring the polarity of the high-capacity transformer bushing current transformer, the problem that the wiring correctness of a secondary circuit of a CT (current transformer) is verified efficiently by measuring the polarity of the bushing current transformer again on site after the transformer bushing current transformer is assembled is solved. The testing process is simple and reliable, and the method can be applied to the field testing of the polarity and the secondary circuit of the current transformer of various capacities with neutral point lead-out transformers.
The traditional measuring method adopts the series connection between a single-phase winding and a neutral point of a transformer, and because a large-capacity transformer winding has large inductive reactance, the current flowing through a coil is very small when the single-phase measurement is carried out, the current inducted by a current transformer to carry out secondary measurement is smaller, the deflection direction of a pointer cannot be obviously seen from a secondary measurement meter, and therefore the polarity of the transformer cannot be correctly judged. The technical scheme adopts a three-phase short-circuit method for measuring the outer sides (a and c) of the high-voltage sleeve of the transformer winding. The three-phase short circuit of the transformer winding can enable flux linkages generated by each phase to be mutually offset (because the magnetic circuit gap of the large transformer is very small, the leakage flux can be ignored), thereby eliminating the self-induced electromotive force of the coil, at the moment, the loop is equivalent to a pure resistance loop, the current magnitude only depends on the magnitude of the power supply potential and the loop resistance, because the internal resistance of the transformer is very small, the current value is much larger than that of a single-phase coil when being electrified, meanwhile, the magnitude of the output test current of the direct resistance tester can be adjusted according to the magnitude of the transformer capacity, and the microammeter can clearly and correctly reflect the polarity of the CT.
When in measurement, firstly, a microammeter is connected in series between secondary terminals K3 and K4 of a current transformer (CT2) to measure the polarity of the current transformer, and if a pointer is positively biased, the current transformer is in a polarity reduction state; and restoring the wiring of the secondary terminal of the current transformer, connecting the secondary terminal of the current transformer into a (CT1 or CT3) protection loop, connecting a microampere meter in series at the inlet wire of the protection device to measure the CT polarity again, if the deflection direction of the pointer is the same as that of the deflection direction of the pointer when the current transformer (CT2) secondary terminal is measured, namely the pointer is also positively deflected, the wiring of the secondary loop of the current transformer is correct, and otherwise, the wiring is wrong.
The winding direction, the number of winding turns, the winding material and the interval of the first winding, the second winding and the third winding are the same, extra influence factors can be reduced, flux linkages generated after three-phase short circuit of the transformer winding are offset mutually, small current feedback of the secondary side is clearer, and display of a microampere meter is more obvious.
The microammeter is a pointer microammeter, and the polarity of the current transformer can be directly read through swinging deflection of a pointer, so that the microammeter is simple, convenient and quick.
After the transformer winding is connected with a power supply, the flux linkage generated by the first winding and the third winding counteracts the flux linkage generated by the second winding, so that the self-induced electromotive force of the coil is eliminated.
The output current of the power supply is any one of 2A, 5A or 10A, and the power supply is suitable for the detection currents of transformers with different capacities.
The working principle is as follows:
by measuring the polarity of the high-capacity transformer bushing current transformer, the problem that the wiring correctness of a secondary circuit of a CT (current transformer) is verified efficiently by measuring the polarity of the bushing current transformer again on site after the transformer bushing current transformer is assembled is solved. The testing process is simple and reliable, and the method can be applied to the field testing of the polarity and the secondary circuit of the current transformer of various capacities with neutral point lead-out transformers.
The traditional measuring method adopts the series connection between a single-phase winding and a neutral point of a transformer, and because a large-capacity transformer winding has large inductive reactance, the current flowing through a coil is very small when the single-phase measurement is carried out, the current inducted by a current transformer to carry out secondary measurement is smaller, the deflection direction of a pointer cannot be obviously seen from a secondary measurement meter, and therefore the polarity of the transformer cannot be correctly judged.
The three-phase short circuit of the transformer winding can enable flux linkages generated by each phase to be mutually offset (because the magnetic circuit gap of the large transformer is very small, the leakage flux can be ignored), thereby eliminating the self-induced electromotive force of the coil, at the moment, the loop is equivalent to a pure resistance loop, the current magnitude only depends on the magnitude of the power supply potential and the loop resistance, because the internal resistance of the transformer is very small, the current value is much larger than that of a single-phase coil when being electrified, meanwhile, the magnitude of the output test current of the direct resistance tester can be adjusted according to the magnitude of the transformer capacity, and the microammeter can clearly and correctly reflect the polarity of the CT.
When in measurement, firstly, a microammeter is connected in series between secondary terminals K3 and K4 of a current transformer (CT2) to measure the polarity of the current transformer, and if a pointer is positively biased, the current transformer is in a polarity reduction state; and restoring the wiring of the secondary terminal of the current transformer, connecting the secondary terminal of the current transformer into a (CT1 or CT3) protection loop, connecting a microampere meter in series at the inlet wire of the protection device to measure the CT polarity again, if the deflection direction of the pointer is the same as that of the deflection direction of the pointer when the current transformer (CT2) secondary terminal is measured, namely the pointer is also positively deflected, the wiring of the secondary loop of the current transformer is correct, and otherwise, the wiring is wrong.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (5)
1. The utility model provides a current transformer polarity measuring device, includes power supply, transformer winding and microammeter, its characterized in that: the transformer winding comprises a first winding, a second winding and a third winding which are sequentially arranged from left to right, two wiring ends of the second winding are respectively and electrically connected with the positive electrode and the negative electrode of a power supply, the wiring end of the bottom end of the first winding is connected with the wiring end of the bottom end of the third winding, the wiring ends of the top ends of the first winding and the third winding are respectively connected with the positive electrode of the power supply, the first winding, the second winding and the third winding are matched with a current transformer to be tested, and a secondary terminal on the current transformer to be tested is connected with a microampere meter.
2. The polarity measuring device of claim 1, wherein: and the winding directions, the winding turns, the winding materials and the intervals of the first winding, the second winding and the third winding are the same.
3. The polarity measuring device of claim 1, wherein: the microammeter is a pointer microammeter.
4. The polarity measuring device of claim 1, wherein: the first winding and the third winding form a short-circuit protection loop.
5. The polarity measuring device of claim 1, wherein: the output current of the power supply is any one of 2A, 5A or 10A.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020343345.8U CN211979178U (en) | 2020-03-18 | 2020-03-18 | Current transformer polarity measuring device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020343345.8U CN211979178U (en) | 2020-03-18 | 2020-03-18 | Current transformer polarity measuring device |
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| Publication Number | Publication Date |
|---|---|
| CN211979178U true CN211979178U (en) | 2020-11-20 |
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| CN202020343345.8U Active CN211979178U (en) | 2020-03-18 | 2020-03-18 | Current transformer polarity measuring device |
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| CN (1) | CN211979178U (en) |
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2020
- 2020-03-18 CN CN202020343345.8U patent/CN211979178U/en active Active
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