CN112630494A - Automatic measuring equipment for security coefficient of anti-direct-current low-voltage current transformer instrument - Google Patents
Automatic measuring equipment for security coefficient of anti-direct-current low-voltage current transformer instrument Download PDFInfo
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- 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
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Abstract
The invention relates to an automatic measuring device for security coefficient of an instrument of a direct current resistant low-voltage current transformer, which relates to the technical field of instrument security coefficient testing devices, and comprises a CPU module, a voltage measuring module, a current measuring module and a UI user interface module which are electrically connected with the CPU module and can realize data bidirectional interaction, and also comprises a program-controlled direct current source module, a program-controlled voltage source module and a program-controlled multi-way switch which are electrically connected with the CPU module and can receive commands from the CPU module, wherein the program-controlled direct current source module and the program-controlled voltage source module are electrically connected with the program-controlled multi-way switch, and the voltage measuring module, the current measuring module and the program-controlled multi-way switch are electrically connected with the instrument to be tested, the invention controls and measures the secondary side limit potential of the instrument to be tested and the security coefficient of the instrument to be tested through, the method has the advantages of simple test and high automation degree.
Description
Technical Field
The invention relates to the technical field of instrument security coefficient testing devices, in particular to automatic measuring equipment for security coefficients of an instrument of an anti-direct-current low-voltage current transformer.
Background
The current transformer for measurement is a current transformer specially used for measuring the current and the electric energy of an electric power system. Under normal operating conditions, it should meet the specified accuracy level requirements to ensure accurate measurements. However, the current transformers used in the power system often have a large overcurrent flowing through the primary winding due to a system fault or operation. Under such a circumstance, it is desirable that the secondary side current does not increase strictly in proportion, so as to prevent instruments and meters connected to the secondary side loop from being subjected to large current impact, and therefore, a requirement is provided for a measuring current transformer for an instrument safety coefficient (FS), wherein the instrument safety coefficient refers to a ratio of an instrument safety current to a rated primary current, and the instrument safety current refers to a minimum primary current value of which a composite error is not less than 10% of the measuring current transformer under a rated secondary side load.
At present, the safety factor of a measuring instrument is obtained by the following method: a) under the condition that a primary winding of the current transformer is open-circuited, applying actual sinusoidal voltage with rated frequency to a secondary side winding by using a voltage regulator; b) measuring the output voltage of the voltage regulator by using a voltmeter, and measuring the exciting current output by the voltage regulator by using the voltmeter when the square-mean root value of the output voltage of the voltage regulator is equal to the secondary side limit induced potential; c) using the obtained exciting current as a numerator, and taking the product of the rated secondary side current and the instrument security coefficient as a denominator, wherein the value of the denominator is equal to or more than 10%; the ammeter and the voltmeter used in the test are AC true effective value tables, and the value error does not exceed +/-3%. The existing testing method has the following technical problems: the invention provides automatic measuring equipment for the safety coefficient of an anti-direct-current low-voltage current transformer instrument, which has the advantages of more required tools, complex process, frequent wire replacement, low manual measuring efficiency and easy error.
Disclosure of Invention
The invention aims to: in order to solve the technical problems in the background art, the invention provides automatic measuring equipment for the safety coefficient of an instrument of an anti-direct-current low-voltage current transformer.
The invention specifically adopts the following technical scheme for realizing the purpose:
the utility model provides an automatic measuring equipment of anti direct current low-voltage current transformer instrument security coefficient, includes the CPU module, still includes and can realize the mutual voltage measurement module, current measurement module and the UI user interface module of data two-way with CPU module electric connection, still includes and can receive programme-controlled direct current source module, programme-controlled voltage source module and the programme-controlled multi-way switch from CPU module order with CPU module electric connection, programme-controlled direct current source module, programme-controlled voltage source module all with programme-controlled multi-way switch electric connection, voltage measurement module, current measurement module and programme-controlled multi-way switch all with the mutual inductor electric connection of being examined.
Further, the CPU control module controls the operation of the whole equipment; the voltage measuring module measures the voltage applied to the secondary side of the detected mutual inductor; the current measuring module measures the current on the secondary lateral line of the tested mutual inductor; the UI user interface module is responsible for receiving control input of a user and displaying a measurement result; the program-controlled voltage source module can output alternating-current voltage under the control of the CPU control module; the program-controlled direct current source module can output direct current under the control of the CPU control module; and the program-controlled multi-way switch is used for switching the connection between the program-controlled voltage source module and the program-controlled direct current source module and the mutual inductor to be detected.
A method for measuring by using automatic measuring equipment for security coefficient of an anti-direct current low-voltage current transformer instrument, wherein primary sides of tested transformers are in an open circuit state during testing, comprises the following steps:
step one, measuring a secondary side limit induction potential of a detected mutual inductor, specifically:
(1) measuring the secondary side direct current impedance of the detected mutual inductor: the CPU control module controls the program-controlled multi-way switch to connect the program-controlled direct current source module with the secondary side of the detected mutual inductor, the CPU control module controls the program-controlled direct current source module to output direct current as large as rated current of the secondary side of the detected mutual inductor, and the CPU control module controls the voltage measurement module to measure voltage on a port of the secondary side of the detected mutual inductor;
(2) calculating the direct current internal resistance of the detected mutual inductor: calculating the direct current internal resistance of the detected mutual inductor by using ohm's law according to the voltage value obtained by measuring in the step (1) and the current value output by the program-controlled direct current source module;
(3) measuring the secondary side limit induction potential of the detected mutual inductor: calculating the secondary side limit induced potential of the measured mutual inductor according to the direct current internal resistance of the measured mutual inductor, the rated load of the mutual inductor and the calibrated instrument security coefficient measured in the step one (2), wherein the calculation mode is as follows:
wherein E is the secondary side limit induced potential of the detected mutual inductor, FS is the instrument security system of the detected mutual inductorNumber, InDetermining the secondary side current, R, for the transformer under testdcIs the direct current resistance, R, of the secondary side winding of the detected transformerbResistive component, X, of rated load of the transformer to be testedbThe inductive reactance component is the rated load of the detected transformer;
step two, measuring the instrument security coefficient of the detected mutual inductor, specifically:
(1) the CPU control module controls the program-controlled multi-way switch to connect the program-controlled voltage source module to the secondary side of the detected mutual inductor;
(2) the CPU control module controls the programmable voltage source module to output a voltage value with the amplitude equal to the secondary side limit induced potential of the detected mutual inductor;
(3) the CPU control module controls the current measurement module to measure the exciting current on a line when the limit induction potential is added to the secondary side of the detected mutual inductor;
(4) the CPU control module controls the program-controlled voltage source module to stop outputting;
(5) calculating whether the security coefficient of the instrument is qualified according to the exciting current obtained by measurement in the step (3), and specifically, calculating the security coefficient of the instrument according to the following steps:
wherein, IdThe value of the exciting current measured in the step (3) in the second step, FS is the safety factor value of the instrument calibrated by the detected mutual inductor, InThe secondary side rated current value of the detected mutual inductor is obtained;
(6) if the calculated result in the step (5) meets the inequality in the step (5), the instrument security coefficient of the detected mutual inductor is qualified, otherwise, the instrument security coefficient is judged to be unqualified;
and step three, the CPU control module displays the result of the step two (6) to a user through a UI user interface module.
The working principle and the beneficial effects of the invention are as follows: according to the invention, the secondary side of the detected mutual inductor is connected with the program-controlled direct current source through the program-controlled multi-way switch through the CPU control module, the program-controlled direct current source is controlled to output rated current, the secondary side port voltage of the detected mutual inductor is measured through the voltage measuring module, the direct current internal resistance of the detected mutual inductor is obtained through calculation according to ohm's law, and finally the secondary side ultimate induced potential of the detected mutual inductor is calculated according to the ultimate induced potential formula; the secondary side of the detected mutual inductor is connected with the program-controlled voltage source through the program-controlled multi-way switch, the program-controlled voltage source is controlled to output limit induction voltage, current on a secondary side line of the mutual inductor is measured through the current measuring module, voltage output is stopped, whether the instrument security coefficient is qualified according to the measured exciting current technology or not is judged, and finally the measuring result is displayed to a user through the UI user interface module.
Drawings
FIG. 1 is a functional block diagram of the present invention;
FIG. 2 is a flow chart of secondary side limit induced potential measurement according to the present invention;
FIG. 3 is a flow chart of the instrument security factor of the measurement transformer of the present invention;
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.
In the description of the embodiments of the present invention, it should be noted that the terms "inside", "outside", "upper", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or orientations or positional relationships conventionally arranged when products of the present invention are used, and are only used for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements indicated must have specific orientations, be constructed in specific orientations, and operated, and thus, cannot be construed as limiting the present invention.
Example 1
As shown in fig. 1-3, an automatic measuring device for security coefficient of instrument of anti-dc low-voltage current transformer comprises a CPU module, a voltage measuring module, a current measuring module and a UI user interface module electrically connected to the CPU module for bidirectional data interaction, a program-controlled dc current source module, a program-controlled voltage source module and a program-controlled multi-way switch electrically connected to the CPU module for receiving commands from the CPU module, the program-controlled direct current source module and the program-controlled voltage source module are electrically connected with the program-controlled multi-way switch, the CPU module adopts BF609 dual-core DSP processor of ADI company, the voltage measurement module analog-to-digital converter adopts AD7608 and 18-bit SAR ADC, and the current measurement module analog-to-digital converter adopts AD7608 and 18-bit SAR ADC.
Further, the CPU control module controls the operation of the whole equipment; the voltage measuring module measures the voltage applied to the secondary side of the detected mutual inductor; the current measuring module measures the current on the secondary lateral line of the tested mutual inductor; the UI user interface module is responsible for receiving control input of a user and displaying a measurement result; the program-controlled voltage source module can output alternating-current voltage under the control of the CPU control module; the program-controlled direct current source module can output direct current under the control of the CPU control module; and the program-controlled multi-way switch is used for switching the connection between the program-controlled voltage source module and the program-controlled direct current source module and the mutual inductor to be detected.
A method for measuring by using automatic measuring equipment for security coefficient of an anti-direct current low-voltage current transformer instrument, wherein primary sides of tested transformers are in an open circuit state during testing, comprises the following steps:
step one, measuring a secondary side limit induction potential of a detected mutual inductor, specifically:
(1) measuring the secondary side direct current impedance of the detected mutual inductor: the CPU control module controls the program-controlled multi-way switch to connect the program-controlled direct current source module with the secondary side of the detected mutual inductor, the CPU control module controls the program-controlled direct current source module to output direct current as large as rated current of the secondary side of the detected mutual inductor, and the CPU control module controls the voltage measurement module to measure voltage on a port of the secondary side of the detected mutual inductor;
(2) calculating the direct current internal resistance of the detected mutual inductor: calculating the direct current internal resistance of the detected mutual inductor by using ohm's law according to the voltage value obtained by measuring in the step (1) and the current value output by the program-controlled direct current source module;
(3) measuring the secondary side limit induction potential of the detected mutual inductor: calculating the secondary side limit induced potential of the measured mutual inductor according to the direct current internal resistance of the measured mutual inductor, the rated load of the mutual inductor and the calibrated instrument security coefficient measured in the step one (2), wherein the calculation mode is as follows:
wherein E is the secondary side limit induced potential of the detected mutual inductor, FS is the instrument security coefficient of the detected mutual inductor, and InDetermining the secondary side current, R, for the transformer under testdcIs the direct current resistance, R, of the secondary side winding of the detected transformerbResistive component, X, of rated load of the transformer to be testedbThe inductive reactance component is the rated load of the detected transformer;
step two, measuring the instrument security coefficient of the detected mutual inductor, specifically:
(1) the CPU control module controls the program-controlled multi-way switch to connect the program-controlled voltage source module to the secondary side of the detected mutual inductor;
(2) the CPU control module controls the programmable voltage source module to output a voltage value with the amplitude equal to the secondary side limit induced potential of the detected mutual inductor;
(3) the CPU control module controls the current measurement module to measure the exciting current on a line when the limit induction potential is added to the secondary side of the detected mutual inductor;
(4) the CPU control module controls the program-controlled voltage source module to stop outputting;
(5) calculating whether the security coefficient of the instrument is qualified according to the exciting current obtained by measurement in the step (3), and specifically, calculating the security coefficient of the instrument according to the following steps:
wherein, IdThe value of the exciting current measured in the step (3) in the second step, FS is the safety factor value of the instrument calibrated by the detected mutual inductor, InThe secondary side rated current value of the detected mutual inductor is obtained;
(6) if the calculated result in the step (5) meets the inequality in the step (5), the instrument security coefficient of the detected mutual inductor is qualified, otherwise, the instrument security coefficient is judged to be unqualified;
and step three, the CPU control module displays the result of the step two (6) to a user through a UI user interface module.
The working principle and the beneficial effects of the invention are as follows: according to the invention, the secondary side of the detected mutual inductor is connected with the program-controlled direct current source through the program-controlled multi-way switch through the CPU control module, the program-controlled direct current source is controlled to output rated current, the secondary side port voltage of the detected mutual inductor is measured through the voltage measuring module, the direct current internal resistance of the detected mutual inductor is obtained through calculation according to ohm's law, and finally the secondary side ultimate induced potential of the detected mutual inductor is calculated according to the ultimate induced potential formula; the secondary side of the detected mutual inductor is connected with the program-controlled voltage source through the program-controlled multi-way switch, the program-controlled voltage source is controlled to output limit induction voltage, current on a secondary side line of the mutual inductor is measured through the current measuring module, voltage output is stopped, whether the instrument security coefficient of the detected mutual inductor is qualified or not is judged automatically according to the measured excitation current technology, and finally the measuring result is displayed to a user through the UI user interface module.
It will be appreciated by those skilled in the art that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed above are therefore to be considered in all respects as illustrative and not restrictive. All changes which come within the scope of or equivalence to the invention are intended to be embraced therein.
Claims (9)
1. The utility model provides an automatic measuring equipment of anti direct current low voltage current transformer instrument security coefficient, its characterized in that includes the CPU module, still includes voltage measurement module, current measurement module and UI user interface module with CPU module electric connection and can realize the two-way mutual of data, still includes programmable direct current source module, programmable voltage source module and the programmable multi-way switch that can receive the order from the CPU module with CPU module electric connection, programmable direct current source module, programmable voltage source module all with programmable multi-way switch electric connection, voltage measurement module, current measurement module and programmable multi-way switch all with the mutual-inductor electric connection that is examined.
2. The automatic measuring equipment for the safety factor of the anti-direct-current low-voltage current transformer instrument according to claim 1, wherein the CPU control module controls the operation of the whole equipment; the voltage measuring module measures the voltage applied to the secondary side of the detected mutual inductor; the current measuring module measures the current on the secondary lateral line of the tested mutual inductor; the UI user interface module is responsible for receiving control input of a user and displaying a measurement result; the program-controlled voltage source module can output alternating-current voltage under the control of the CPU control module; the program-controlled direct current source module can output direct current under the control of the CPU control module; and the program-controlled multi-way switch is used for switching the connection between the program-controlled voltage source module and the program-controlled direct current source module and the mutual inductor to be detected.
3. A method for measuring by using the automatic measuring equipment of the security coefficient of the instrument of the anti-dc low-voltage current transformer according to any one of claims 1-2, wherein the primary sides of the tested transformers are all in an open circuit state during the test, comprising the following steps:
step one, measuring a secondary side limit induction potential of a detected mutual inductor, specifically:
(1) measuring the secondary side direct current impedance of the detected mutual inductor;
(2) calculating the direct current internal resistance of the detected mutual inductor;
(3) measuring the secondary side limit induced potential of the detected mutual inductor;
step two, measuring the instrument security coefficient of the detected mutual inductor, specifically:
(1) measuring the exciting current;
(2) judging the qualification of the security coefficient of the instrument;
and step three, displaying a result.
4. The method for measuring the safety factor of the instrument of the anti-dc low-voltage current transformer according to claim 3, wherein the manner of measuring the secondary side dc impedance of the detected transformer in the first step is specifically as follows: the CPU control module controls the program-controlled multi-way switch to connect the program-controlled direct current source module with the secondary side of the detected mutual inductor, the CPU control module controls the program-controlled direct current source module to output direct current as large as rated current of the secondary side of the detected mutual inductor, and the CPU control module controls the voltage measuring module to measure voltage on a port of the secondary side of the detected mutual inductor.
5. The method for measuring the security coefficient of the instrument of the anti-dc low-voltage current transformer according to claim 4, wherein the manner of calculating the dc internal resistance of the detected transformer in the first step is specifically as follows: and calculating the direct current internal resistance of the detected mutual inductor by using ohm's law according to the measured voltage value and the current value output by the program control direct current source module.
6. The method for measuring the safety factor of the instrument of the anti-dc low-voltage current transformer according to claim 5, wherein the measuring of the secondary side limit induced potential of the detected instrument in the first step is performed by: calculating the secondary side limit induction potential of the tested mutual inductor according to the measured direct current internal resistance of the tested mutual inductor, the rated load of the mutual inductor and the calibrated instrument security coefficient, wherein the calculation mode is as follows:
wherein E is the secondary side limit induced potential of the detected mutual inductor, FS is the instrument security coefficient of the detected mutual inductor, and InDetermining the secondary side current, R, for the transformer under testdcIs the direct current resistance, R, of the secondary side winding of the detected transformerbResistive component, X, of rated load of the transformer to be testedbThe inductance component is the rated load of the detected transformer.
7. The method for measuring the security coefficient of the anti-dc low-voltage current transformer instrument according to claim 3, wherein the excitation current in the second step is measured by:
(1) the CPU control module controls the program-controlled multi-way switch to connect the program-controlled voltage source module to the secondary side of the detected mutual inductor;
(2) the CPU control module controls the programmable voltage source module to output a voltage value with the amplitude equal to the secondary side limit induced potential of the detected mutual inductor;
(3) the CPU control module controls the current measurement module to measure the exciting current on a line when the limit induction potential is added to the secondary side of the detected mutual inductor;
(4) the CPU control module controls the program control voltage source module to stop outputting.
8. The method for measuring by the automatic measuring equipment of the safety coefficient of the instrument of the anti-direct current low-voltage current transformer according to claim 3, wherein the judgment of the qualification of the safety coefficient of the instrument in the second step is specifically as follows:
wherein, IdThe value of the exciting current measured in the step (1) is FS, the value of the security coefficient of the instrument calibrated by the detected mutual inductor, InThe secondary side rated current value of the detected transformer is obtained.
9. The method for measuring the security coefficient of the anti-dc low-voltage current transformer instrument according to claim 7, wherein the result in the third step is displayed in a specific manner: the CPU control module displays the judgment result of the security coefficient of the instrument to a user through the UI user interface module.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011461658.4A CN112630494A (en) | 2020-12-11 | 2020-12-11 | Automatic measuring equipment for security coefficient of anti-direct-current low-voltage current transformer instrument |
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| CN202011461658.4A CN112630494A (en) | 2020-12-11 | 2020-12-11 | Automatic measuring equipment for security coefficient of anti-direct-current low-voltage current transformer instrument |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101545963A (en) * | 2008-03-25 | 2009-09-30 | 扬州博达电气设备有限公司 | High-performance current transformer intelligent analyzer |
| CN201514474U (en) * | 2009-07-03 | 2010-06-23 | 武汉义天科技有限公司 | Parameter test instrument of current transformer |
| CN105974348A (en) * | 2016-04-29 | 2016-09-28 | 国网山东省电力公司电力科学研究院 | Low-voltage current transformer integrated detection system and method thereof |
-
2020
- 2020-12-11 CN CN202011461658.4A patent/CN112630494A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101545963A (en) * | 2008-03-25 | 2009-09-30 | 扬州博达电气设备有限公司 | High-performance current transformer intelligent analyzer |
| CN201514474U (en) * | 2009-07-03 | 2010-06-23 | 武汉义天科技有限公司 | Parameter test instrument of current transformer |
| CN105974348A (en) * | 2016-04-29 | 2016-09-28 | 国网山东省电力公司电力科学研究院 | Low-voltage current transformer integrated detection system and method thereof |
Non-Patent Citations (1)
| Title |
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| 李静，沙玉洲，张有和: "测量用电流互感器仪表保安系数的计算和控制", 变压器, 31 October 2002 (2002-10-31), pages 1 - 5 * |
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