CN113241725A - Residual current transformer coil detection method and device and residual current protection electric appliance - Google Patents
Residual current transformer coil detection method and device and residual current protection electric appliance Download PDFInfo
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- CN113241725A CN113241725A CN202110563161.1A CN202110563161A CN113241725A CN 113241725 A CN113241725 A CN 113241725A CN 202110563161 A CN202110563161 A CN 202110563161A CN 113241725 A CN113241725 A CN 113241725A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
- G01R35/02—Testing or calibrating of apparatus covered by the other groups of this subclass of auxiliary devices, e.g. of instrument transformers according to prescribed transformation ratio, phase angle, or wattage rating
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
The invention discloses a method for detecting a residual current transformer coil. Setting a test coil for the residual current transformer; when the residual current measured value detected by the measuring coil is lower than a preset threshold value, inputting a section of testing signal to the testing coil, if the residual current measured value detected by the measuring coil is still lower than the threshold value, judging that the measuring coil is in failure, otherwise, judging that the measuring coil is in good condition; under the condition that the measuring coil is intact and the main loop has no residual current, the measuring coil is excited by the testing signal, and the residual current measured value detected by the measuring coil is greater than or equal to the threshold value; the threshold value is greater than or equal to the minimum residual current measurement value which can be accurately detected by the measuring coil. The invention also discloses a residual current transformer coil detection device and a residual current protection electric appliance. The invention can realize real-time accurate online detection of the fault of the measuring coil on the premise of ensuring the detection precision of the residual current.
Description
Technical Field
The invention relates to a method for measuring a residual current transformer coil, and belongs to the technical field of low-voltage electrical protection.
Background
The residual current protection electric appliance is an electric device for carrying out leakage protection on an electric circuit, and is used for preventing equipment and electric fire accidents caused by residual current faults and preventing personal electric shock dangerous accidents. The residual current protection electric appliance generally comprises a controller and a residual current transformer, and the key of the residual current protection electric appliance is a residual current transformer detection circuit used for monitoring the working state of the residual current transformer, and the detection circuit needs to operate in a power grid for a long time. In the installation process of the residual current protection electric appliance, the situation that the residual current transformer is forgotten to be connected or has poor contact, falls off and the like sometimes occurs, and when the controller detects that the residual current is zero, the controller cannot judge that the residual current transformer is not connected well, because under the situation that the residual current value is completely connected well, the residual current value can also be zero.
In the existing partial residual current protection electric appliance, in order to detect whether a residual current transformer is disconnected, a certain constant current is added to a sampling unit, and the current is always added to the sampling unit, so that the detection precision of the protection electric appliance on the residual current can be influenced, and finally, the residual current value cannot be accurately detected to cause the misoperation of a protection device. Therefore, a new way is needed to detect the disconnection state of the residual current transformer, and solve the problems in the prior art.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for detecting a residual current transformer coil, which can realize real-time accurate online detection of faults including internal disconnection of a measuring coil and interruption of signal connection between the measuring coil and the outside on the premise of ensuring the residual current detection precision and ensure the correct work of a residual current protection electric appliance.
The invention specifically adopts the following technical scheme to solve the technical problems:
a method for detecting a residual current transformer coil is used for detecting faults of a measuring coil of a residual current transformer; setting a test coil which can couple out a residual current signal in a measuring coil of the residual current transformer under the excitation of an external signal for the residual current transformer; when the residual current measured value detected by the measuring coil is lower than a preset threshold value, inputting a section of test signal to the testing coil, if the residual current measured value detected by the measuring coil is still lower than the threshold value, judging that the measuring coil is in fault, otherwise, judging that the measuring coil is intact; under the condition that the measuring coil is intact and the main loop has no residual current, the residual current measured value detected by the measuring coil under the excitation of the testing signal by the testing coil is greater than or equal to the threshold value; the threshold value is greater than or equal to a minimum residual current measurement value that can be accurately detected by the measurement coil.
Preferably, the measuring coil fault includes a fault in which a wire is broken inside the measuring coil and a fault in which a signal connection of the measuring coil to the outside is interrupted.
Preferably, under the condition that the measuring coil is intact and the main loop has no residual current, the residual current measured value detected by the measuring coil under the excitation of the testing signal by the testing coil is smaller than the difference value between the residual current protection action value and the rated residual no-action current value.
Preferably, after a period of test signal is input to the test coil, if the residual current measurement value detected by the measurement coil within a preset time is still lower than the threshold value, it is determined that the measurement coil is faulty, otherwise, it is determined that the measurement coil is intact, and the test signal is no longer input to the test coil of the residual current transformer.
Preferably, the preset time is greater than or equal to the time from inputting the test signal to the test coil to inducing the residual current by the measuring coil.
Based on the same inventive concept, the following technical scheme can be obtained:
a residual current transformer coil detection device is used for detecting faults of a measuring coil of a residual current transformer; the method comprises the following steps:
the test coil can couple out a residual current signal in the measurement coil of the residual current transformer under the excitation of an external signal; the detection module is used for carrying out the following detection judgment: when the residual current measured value detected by the measuring coil is lower than a preset threshold value, inputting a section of test signal to the testing coil, if the residual current measured value detected by the measuring coil is still lower than the threshold value, judging that the measuring coil is in fault, otherwise, judging that the measuring coil is intact; the threshold value is greater than or equal to a minimum residual current measurement value which can be accurately detected by the measuring coil;
a test signal generation circuit for generating the test signal; and under the condition that the measuring coil is intact and the main loop has no residual current, the residual current measured value detected by the measuring coil under the excitation of the test signal by the testing coil is greater than or equal to the threshold value.
Preferably, the measuring coil fault includes a fault in which a wire is broken inside the measuring coil and a fault in which a signal connection of the measuring coil to the outside is interrupted.
Preferably, under the condition that the measuring coil is intact and the main loop has no residual current, the residual current measured value detected by the measuring coil under the excitation of the testing signal by the testing coil is smaller than the difference value between the residual current protection action value and the rated residual no-action current value.
Preferably, after a period of test signal is input to the test coil, if the residual current measurement value detected by the measurement coil within a preset time is still lower than the threshold value, it is determined that the measurement coil is faulty, otherwise, it is determined that the measurement coil is intact, and the test signal is no longer input to the test coil of the residual current transformer.
Preferably, the preset time is greater than or equal to the time from inputting the test signal to the test coil to inducing the residual current by the measuring coil.
A residual current protection electric appliance comprises a residual current transformer and a residual current transformer coil detection device according to any one of the technical schemes.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
the invention can realize accurate on-line detection of the fault of the measuring coil of the residual current transformer, and can not generate adverse effect on the residual current detection precision; the technical scheme of the invention is simple to realize, the testing coil and the testing signal generating circuit can directly utilize the inherent residual current protection testing device of partial residual current protection electric appliances, only the software part needs to be updated, the adaptability is stronger, and the realization cost is lower.
Detailed Description
Aiming at the defects in the prior art, the invention provides a solution for exciting a simulation residual current signal which can be measured under normal conditions in a residual current transformer by using an additional testing coil when the residual current measurement value is too low, and if the corresponding correct residual current measurement value can be detected, the residual current transformer is proved not to have the fault of disconnection inside the measuring coil and the fault of interruption of signal connection between the measuring coil and the outside, otherwise, the fault of the measuring coil is proved to be generated.
Specifically, the technical scheme provided by the invention is as follows:
a method for detecting a residual current transformer coil is used for detecting faults of a measuring coil of a residual current transformer; setting a test coil which can couple out a residual current signal in a measuring coil of the residual current transformer under the excitation of an external signal for the residual current transformer; when the residual current measured value detected by the measuring coil is lower than a preset threshold value, inputting a section of test signal to the testing coil, if the residual current measured value detected by the measuring coil is still lower than the threshold value, judging that the measuring coil is in fault, otherwise, judging that the measuring coil is intact; under the condition that the measuring coil is intact and the main loop has no residual current, the residual current measured value detected by the measuring coil under the excitation of the testing signal by the testing coil is greater than or equal to the threshold value; the threshold value is greater than or equal to a minimum residual current measurement value that can be accurately detected by the measurement coil.
A residual current transformer coil detection device is used for detecting faults of a measuring coil of a residual current transformer; the method comprises the following steps:
the test coil can couple out a residual current signal in the measurement coil of the residual current transformer under the excitation of an external signal; the detection module is used for carrying out the following detection judgment: when the residual current measured value detected by the measuring coil is lower than a preset threshold value, inputting a section of test signal to the testing coil, if the residual current measured value detected by the measuring coil is still lower than the threshold value, judging that the measuring coil is in fault, otherwise, judging that the measuring coil is intact; the threshold value is greater than or equal to a minimum residual current measurement value which can be accurately detected by the measuring coil;
a test signal generation circuit for generating the test signal; and under the condition that the measuring coil is intact and the main loop has no residual current, the residual current measured value detected by the measuring coil under the excitation of the test signal by the testing coil is greater than or equal to the threshold value.
The measuring coil faults include faults of broken wires inside the measuring coil and faults of signal connection interruption between the measuring coil and the outside.
Part of the existing residual current protection electric appliances are provided with a testing device for testing the residual current protection function, and the principle is that the residual current exceeding the residual current protection action value is simulated in the residual current transformer through a testing coil so as to verify whether the residual current protection electric appliances can realize the normal protection function. For the residual current protection electric appliance, the technical scheme of the invention can directly utilize the existing residual current protection testing device to generate the testing signal, and only a small amount of adjustment is needed to be carried out on the software of the controller.
In order to prevent the superposition of the real residual current of the main loop and the simulated residual current signal generated by the test signal in the test signal application process from exceeding the residual current protection action value, thereby causing protection misoperation, the simulated residual current signal generated by the test signal should not be too large, and the following test signal configuration principle is preferably adopted: and under the condition that the measuring coil is intact and the main loop has no residual current, the residual current measured value detected by the measuring coil under the excitation of the test signal by the testing coil is smaller than the difference value between the residual current protection action value and the rated residual immobility current value.
For the public understanding, the technical scheme of the invention is explained in detail by a specific embodiment:
in the control and protection switching device in this embodiment, the residual current protection switching device includes a controller, a residual current transformer, and a residual current transformer coil detection device for detecting a fault of a measurement coil of the residual current transformer; the residual current transformer coil detection device comprises a test coil and a test signal generation circuit controlled by a controller, wherein the test coil is a single-turn or multi-turn coil wound on a magnetic core of the residual current transformer and can couple a residual current signal in a measurement coil of the residual current transformer under the excitation of an external signal; the measuring coil of the residual current transformer outputs a residual current signal to the controller, the controller samples and calculates the residual current signal in real time to obtain a residual current measured value, and once the residual current measured value reaches a residual current protection action value, the controller controls an executing mechanism (usually a magnetic flux converter) to act, so that residual current protection is realized.
In this embodiment, the rated residual inoperative current value and the residual current protection setting value of the residual current protection electrical appliance are respectively 0.5IΔn1And IΔn1I.e. when the residual current measurement is less than 0.5IΔn1No residual current protection action is performed, and the residual current is greater than or equal to IΔn1The residual current protection action is carried out at any time, and the specific residual current protection action value can be 0.5I according to the actual requirementΔn1～IΔn1In this example, 0.75I is takenΔn1. The minimum residual current measurement value which can be accurately detected by the residual current protection electric appliance through the measuring coil is about 0.1IΔn1Therefore, a slightly larger current value, for example 0.2I, may be taken as the threshold valueΔn1(ii) a I.e. when the residual current measurement is below 0.2IΔn1When the residual current transformer is considered to be possible to have a measuring coil fault, further confirmation by applying a test signal is required. I isΔn1Can be set according to the requirements of protection circuits, I in the embodimentΔn1Take 40mA as an example.
The residual current signal generated by the applied test signal is ensured to be accurately measured under normal conditions, and therefore, the test signal satisfies the following requirements: under the condition that the measuring coil is intact and the main loop has no residual current, the residual current measured value detected by the measuring coil under the excitation of the test signal by the testing coil is greater than or equal to the threshold value (the threshold value is 0.2I in the embodiment)Δn1I.e., 8 mA). In addition, in order to prevent the superposition of the real residual current of the main loop and the simulated residual current signal generated by the test signal in the test signal applying process from exceeding the residual current protection action value, thereby causing protection misoperation, the test signal preferably also needs to satisfy the following conditions: under the condition that the measuring coil is intact and the main loop has no residual current, the residual current measured value detected by the measuring coil under the excitation of the test signal by the testing coil is smaller than the difference value between the residual current protection action value and the rated residual immobility current value, which is 0.75I in the embodimentΔn1-0.5IΔn1＝0.25IΔn1(i.e., 10mA) such that the actual residual current in the main loop is less than 0.5IΔn1The motion value of 0.75I is not reached at the time of (20 mA)Δn1(i.e., 30mA) and does not malfunction. Therefore, the magnitude of the test signal should be within the interval that it can produce an additional residual current measurement of greater than or equal to 0.2IΔn1(i.e. 8mA) less than 0.25IΔn1(i.e., 10 mA).
And after the controller works on the power supply, detecting and sampling the output signal of the measuring coil of the residual current transformer in real time, and calculating the residual current value.
When the residual current value detected by the controller is less than the predetermined threshold value 0.2IΔn1(i.e. 8mA), the controller sends a test signal to the test coil through the test signal generating circuit, and then judges the residual current. If it is within a predetermined time after the test signal is emitted (the predetermined time is longer than or equal to the time from the input of the test signal to the test coil to the induction of the residual current in the measurement coil), for exampleIf the residual current value is not detected to be greater than or equal to 0.2I within 0.5sΔn1(namely 8mA), judging that the measuring coil of the residual current transformer is disconnected or the signal connection between the measuring coil and the controller is disconnected; otherwise, the residual current transformer measuring coil is judged to be intact, the measuring coil is normally connected with an external signal, and the controller does not send a test signal to the residual current transformer measuring coil any more.
The case analysis is as follows:
1. the residual current transformer has a fault of disconnection inside the measuring coil or a fault of interruption of signal connection between the measuring coil and the outside;
the controller detects that the residual current measurement value is less than 0.2IΔn1(8 mA), sending a test signal to the test coil, and if the controller detects that the residual current is less than 0.2I within 0.5s after the test signal is sentΔn1(namely 8mA), the residual current transformer measuring coil is judged to have faults (including the conditions of wire breakage and the like) or faults that the signal connection between the measuring coil and the outside is interrupted (namely the signal connection between the measuring coil and the controller is disconnected).
2. The residual current transformer measuring coil has no fault of internal disconnection of the measuring coil or fault of signal connection interruption between the measuring coil and the outside;
(1) no residual current or residual current less than 0.2IΔn1(i.e. 8mA) in the case of
The controller detects that the residual current is less than 0.2IΔn1(i.e., 8mA), a test signal is sent to the test coil and the measurement coil is able to couple out a residual current signal, so the controller will detect a value greater than or equal to the decision threshold of 0.2IΔn1(i.e., 8mA) and less than 0.45IΔn1(i.e., 18mA) residual current value, (here 0.45I)Δn1I.e. 0.2IΔn1+0.25IΔn1) Judging that a measuring coil of the residual current transformer is intact (the conditions such as wire breakage and the like do not occur), and normally connecting the measuring coil with an external signal; the detected residual current can not reach the action value of 0.5I of residual current protectionΔn1(i.e., 20mA) and therefore does not cause malfunction of the residual current protection。
(2) Residual current greater than or equal to 0.2IΔn1(i.e., 8mA), the controller detects a residual current of greater than or equal to 0.2IΔn1(namely 8mA), directly judging that the measuring coil of the residual current transformer is intact, and normally connecting the measuring coil with an external signal; at the moment, a test signal does not need to be sent to the test coil, and the accuracy of residual current detection can be ensured.
Claims (11)
1. A method for detecting a residual current transformer coil is used for detecting faults of a measuring coil of a residual current transformer; the method is characterized in that a test coil which can couple out a residual current signal in a measurement coil of the residual current transformer under the excitation of an external signal is arranged for the residual current transformer; when the residual current measured value detected by the measuring coil is lower than a preset threshold value, inputting a section of test signal to the testing coil, if the residual current measured value detected by the measuring coil is still lower than the threshold value, judging that the measuring coil is in fault, otherwise, judging that the measuring coil is intact; under the condition that the measuring coil is intact and the main loop has no residual current, the residual current measured value detected by the measuring coil under the excitation of the testing signal by the testing coil is greater than or equal to the threshold value; the threshold value is greater than or equal to a minimum residual current measurement value that can be accurately detected by the measurement coil.
2. The method for detecting a residual current transformer coil of claim 1, wherein the measuring coil faults comprise faults of broken wires inside the measuring coil and faults of interrupted signal connection between the measuring coil and the outside.
3. The method for detecting the residual current transformer coil as claimed in claim 1, wherein under the condition that the measuring coil is intact and the main circuit has no residual current, the residual current measured value detected by the measuring coil under the excitation of the test signal by the testing coil is smaller than the difference value between the residual current protection action value and the rated residual no-action current value.
4. The method for detecting the coil of the residual current transformer as claimed in claim 1, wherein after the test signal is inputted to the test coil, if the residual current measurement value detected by the measurement coil is still lower than the threshold value within a preset time, the fault of the measurement coil is determined, otherwise, the measurement coil is determined to be intact, and the test signal is no longer inputted to the test coil of the residual current transformer.
5. The method as claimed in claim 4, wherein the predetermined time is a time taken from inputting the test signal to the test coil to sensing the residual current in the measurement coil.
6. A residual current transformer coil detection device is used for detecting faults of a measuring coil of a residual current transformer; it is characterized by comprising:
the test coil can couple out a residual current signal in the measurement coil of the residual current transformer under the excitation of an external signal;
the detection module is used for carrying out the following detection judgment: when the residual current measured value detected by the measuring coil is lower than a preset threshold value, inputting a section of test signal to the testing coil, if the residual current measured value detected by the measuring coil is still lower than the threshold value, judging that the measuring coil is in fault, otherwise, judging that the measuring coil is intact; the threshold value is greater than or equal to a minimum residual current measurement value which can be accurately detected by the measuring coil;
a test signal generation circuit for generating the test signal; and under the condition that the measuring coil is intact and the main loop has no residual current, the residual current measured value detected by the measuring coil under the excitation of the test signal by the testing coil is greater than or equal to the threshold value.
7. The residual current transformer coil detection device of claim 6, wherein the measuring coil faults include faults of broken wires inside the measuring coil and faults of interrupted signal connection of the measuring coil and the outside.
8. The device for detecting the residual current of a coil of a current transformer as claimed in claim 6, wherein when the measuring coil is intact and the main circuit has no residual current, the residual current measured value detected by the measuring coil under the excitation of the test signal by the testing coil is smaller than the difference between the residual current protection action value and the rated residual no-action current value.
9. The device for detecting the coil of the residual current transformer as claimed in claim 6, wherein after a test signal is inputted to the test coil, if the residual current measurement value detected by the measurement coil is still lower than the threshold value within a preset time, the fault of the measurement coil is determined, otherwise, the measurement coil is determined to be intact, and the test signal is no longer inputted to the test coil of the residual current transformer.
10. The device for detecting the winding of a residual current transformer according to claim 9, wherein the predetermined time is a time taken from the time when the test signal is inputted to the test winding to the time when the residual current is induced in the measurement winding.
11. A residual current protection device comprising a residual current transformer, characterized in that it further comprises a coil detection device of a residual current transformer according to any one of claims 6 to 10.
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| CN202110563161.1A CN113241725B (en) | 2021-05-24 | 2021-05-24 | Residual current transformer coil detection method and device and residual current protection electric appliance |
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| CN202110563161.1A CN113241725B (en) | 2021-05-24 | 2021-05-24 | Residual current transformer coil detection method and device and residual current protection electric appliance |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113985158A (en) * | 2021-09-18 | 2022-01-28 | 河北工业大学 | Residual current protection inspection method, inspection device, electronic device and storage medium |
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| CN1732605A (en) * | 2002-11-08 | 2006-02-08 | 伊顿电气有限公司 | Residual current devices |
| CN204065253U (en) * | 2014-04-30 | 2014-12-31 | 西门子公司 | Earth leakage protective device and the test circuit for this earth leakage protective device |
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2021
- 2021-05-24 CN CN202110563161.1A patent/CN113241725B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1732605A (en) * | 2002-11-08 | 2006-02-08 | 伊顿电气有限公司 | Residual current devices |
| CN204065253U (en) * | 2014-04-30 | 2014-12-31 | 西门子公司 | Earth leakage protective device and the test circuit for this earth leakage protective device |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113985158A (en) * | 2021-09-18 | 2022-01-28 | 河北工业大学 | Residual current protection inspection method, inspection device, electronic device and storage medium |
| CN113985158B (en) * | 2021-09-18 | 2023-09-12 | 河北工业大学 | Residual current protection inspection method, inspection device, electronic apparatus, and storage medium |
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