CN105445537A - Instrument transformer detection device and method - Google Patents
Instrument transformer detection device and method Download PDFInfo
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- CN105445537A CN105445537A CN201511004844.4A CN201511004844A CN105445537A CN 105445537 A CN105445537 A CN 105445537A CN 201511004844 A CN201511004844 A CN 201511004844A CN 105445537 A CN105445537 A CN 105445537A
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- 238000001514 detection method Methods 0.000 title claims abstract description 49
- 238000000034 method Methods 0.000 title abstract description 11
- 238000005070 sampling Methods 0.000 claims description 16
- 238000012360 testing method Methods 0.000 claims description 12
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 206010035148 Plague Diseases 0.000 description 1
- 241000700159 Rattus Species 0.000 description 1
- 241000607479 Yersinia pestis Species 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
-
- 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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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
The invention discloses an instrument transformer detection device and method and belongs to the electronic circuit technical field, in particular, the technical field of the detection of current or leakage current detection instrument transformers in power distribution boxes. The instrument transformer detection device provided by the invention includes a current detection circuit and a control circuit; the current detection circuit has a first mode and a second mode, wherein the first mode is used for outputting signals reflecting the magnitude of the current of an instrument transformer to be detected, and the second mode is used for outputting signals reflecting the work state of the instrument transformer to be detected; the control circuit is used for calculating the mean value of the signals reflecting the magnitude of the current of the instrument transformer to be detected when the current detection circuit works under the first mode, and switches the work state of the current detection circuit to the second state when the mean value is 0 and is maintained 0 for a certain time period; and the work state of the instrument transformer to be detected can be a normal state, a short-circuited state or an open-circuited state.
Description
Technical field
The present invention relates to the detection technique of electric current or leakage current test mutual inductor in electronic circuit technology field, particularly panel box.
Background technology
In low-voltage alternating-current system, the parameter such as examination and controlling electric current, electric leakage is the indispensable means of electric power supervisory control, generally all can use current transformer during detection.
Testing process is such: by the cable in panel box through current transformer, the electric current that current transformer is coupled in tested cable by a rated transformation ratio, measure the size of couple current again thus extrapolate electric current or the electrical leakage of test line, and being exported by display or network.
But when aging circuit, the worm plague of rats and conduction dust or foreign matter etc. cause current transformer to produce the fault of short circuit or broken string, the size of current detected will be 0 always.
This type of fault, can not the very first time timely handling failure to be found by manual inspection and eliminating, and then causes Electrical Safety hidden danger.
Summary of the invention
Technical matters to be solved by this invention is: for above-mentioned Problems existing, a kind of mutual inductor Working state checking circuit and method are provided, when occur external impressed current or creepage mutual inductor short circuit, broken string fault time, can automatically detect, and export different magnitudes of voltage so that maintenance personal judges the state of mutual inductor according to the magnitude of voltage exported, fix a breakdown in time.
A kind of mutual inductor testing apparatus provided by the invention, comprising:
Current detection circuit, has first mode and the second pattern; First mode is used for the signal of output-response to-be-tested transformer size of current; Second pattern is used for the signal of output-response to-be-tested transformer duty;
Control circuit, for calculating the average of the signal of described reaction to-be-tested transformer size of current when current detection circuit is operated in first mode, when described average be 0 and certain time time, the duty of current detection circuit is switched to the second pattern;
To-be-tested transformer duty is normal, short circuit or open circuit.
Further, current detection circuit comprises the first detection resistance, the second detection resistance and gate-controlled switch;
One end ground connection of described first detection resistance, the other end is connected with second one end detecting resistance by gate-controlled switch; Second other end detecting resistance is connected with direct supply;
First detection resistance is in parallel with to-be-tested transformer; The first described other end detecting resistance is connected to the AD Sampling Interface of control circuit;
The control end of gate-controlled switch is connected to the IO pin of control circuit.
Further, AD sample circuit is also comprised;
Current detection circuit comprises the first detection resistance, second and detects resistance and gate-controlled switch;
One end ground connection of described first detection resistance, the other end is connected with second one end detecting resistance by gate-controlled switch; Second other end detecting resistance is connected with direct supply;
First detection resistance is in parallel with to-be-tested transformer; The first described other end detecting resistance is connected to the AD Sampling Interface of AD sample circuit;
The control end of gate-controlled switch is connected to the IO pin of control circuit; AD sample circuit and control circuit have signal and are connected.
Further, described control circuit for calculate AD sample circuit output signal average, and for when described average be 0 and certain time time to gate-controlled switch output control signal by gate-controlled switch conducting.
Present invention also offers a kind of mutual inductor detection method, comprising:
Current detection step, detects and the signal of output-response to-be-tested transformer size of current;
Mean value computation step, calculates the average of the signal of reaction to-be-tested transformer size of current;
Null value determining step, judges whether described average is 0;
To-be-tested transformer state detecting step, when described average is 0 and maintains certain hour, detects further mutual inductance to be measured and is normal, open circuit or short-circuit condition and output detections result.
In sum, owing to have employed technique scheme, the invention has the beneficial effects as follows:
When the switches are opened, circuit of the present invention equally with common current sample circuit carries out normal panel box cable current, leakage current samples and calculate.When current sampling data is 0 for a long time, now the present invention is by turn on-switch, and sampling magnitude of voltage now, provides basis for estimation for judging that mutual inductor connects whether to break down.
Accompanying drawing explanation
Examples of the present invention will be described by way of reference to the accompanying drawings, wherein:
Fig. 1 is the circuit theory diagrams of the present invention's specific embodiment.
Embodiment
All features disclosed in this instructions, or the step in disclosed all methods or process, except mutually exclusive feature and/or step, all can combine by any way.
Arbitrary feature disclosed in this instructions, unless specifically stated otherwise, all can be replaced by other equivalences or the alternative features with similar object.That is, unless specifically stated otherwise, each feature is an example in a series of equivalence or similar characteristics.
Circuit of the present invention comprises current detection circuit, has first mode and the second pattern; First mode is used for the signal of output-response to-be-tested transformer size of current; Second pattern is used for the signal of output-response to-be-tested transformer duty;
Control circuit, for calculating the average of the signal of described reaction to-be-tested transformer size of current when current detection circuit is operated in first mode, when described average be 0 and certain time time, the duty of current detection circuit is switched to the second pattern;
To-be-tested transformer duty is normal, short circuit or open circuit.
As shown in Figure 1, in the present invention's specific embodiment, current detection circuit comprises detection resistance R1, detects resistance R2 and controllable switch S; One end ground connection SGND of described detection resistance R1, the other end is connected with the one end detecting resistance R2 by controllable switch S; The other end detecting resistance R2 is connected with direct supply VCC; Detect resistance R1 in parallel with to-be-tested transformer CT; The described other end detecting resistance R1 is connected to AD Sampling Interface, and the control end of gate-controlled switch is connected with control pin.
In another specific embodiment, the control end C of gate-controlled switch is connected to an IO pin of control circuit.Described AD Sampling Interface is the interface of AD sample circuit, and AD sample circuit and control circuit have signal and be connected.
Described control circuit can be realized by single-chip microcomputer.When the single-chip microcomputer selected carries AD conversion function, the described other end detecting resistance R1 is connected to the AD Sampling Interface of single-chip microcomputer.
Control circuit for calculating the average of AD sample circuit output signal, and controls controllable switch S conducting when equaling 0 when average.
Introduce the principle of work of foregoing circuit below, better to understand the present invention.
Current detection circuit has first mode and the second pattern, and these two kinds of patterns are switched by controllable switch S.
During use, the electric current that cable to be measured passes through through mutual inductor CT, mutual inductor CT coupling test line.Controllable switch S disconnects, current detection circuit is operated in first mode, the no-load voltage ratio of the electric current I that couple current i and test line pass through and mutual inductor CT is relevant, couple current i is by detecting resistance R1, detect resistance R1 and coupling current signals is converted to voltage signal, obtain by AD sampling the magnitude of voltage reacting size of current in cable to be measured again, at least one cycle of sampling can restore the oscillogram of cable current to be measured.Under normal circumstances, the AD signal obtained of sampling is 50Hz AC signal.
Follow-up handling procedure can calculate mean value to sampled value, and now mean value may be 0 and not be 0 two kinds of situations.When mean value is not 0, provable mutual inductor circuit is intact, does not now need to detect.
When mean value is 0, now can not judge that the actual current that test line passes through is 0 or causes sampled value to be 0 because of the fault that mutual inductor short circuit or broken string cause.Be after 0 when mean value continues for some time, the control pin of single-chip microcomputer exports " 1 ", and control controllable switch S conducting, current detection circuit is switched to the second pattern.
Now AD sampled result has 3 kinds of situations (setting ground SGND voltage as 0):
1. normal: to represent that external mutual inductor normally accesses, the result of now AD sampling is:
// be sign of operation in parallel, r is the internal resistance of mutual inductor CT.
2. short circuit: the result of now AD sampling is:
Vo＝0。
3. open circuit: the result of now mutual inductor CT internal resistance r=+ ∞, AD sampling is:
Therefore, different by the magnitude of voltage of sampling out, subsequent conditioning circuit can judge the state that mutual inductor is different.If there is fault to make corresponding fault cues; If non-fault, close analog switch and continue to detect current value.
The present invention is not limited to aforesaid embodiment.The present invention expands to any new feature of disclosing in this manual or any combination newly, and the step of the arbitrary new method disclosed or process or any combination newly.
Claims (5)
1. a mutual inductor testing apparatus, is characterized in that, comprising:
Current detection circuit, has first mode and the second pattern; First mode is used for the signal of output-response to-be-tested transformer size of current; Second pattern is used for the signal of output-response to-be-tested transformer duty;
Control circuit, for calculating the average of the signal of described reaction to-be-tested transformer size of current when current detection circuit is operated in first mode, when described average is 0 and continues for some time, switches to the second pattern by the duty of current detection circuit;
To-be-tested transformer duty is normal, short circuit or open circuit.
2. a kind of mutual inductor testing apparatus according to claim 1, is characterized in that, current detection circuit comprises the first detection resistance, second and detects resistance and gate-controlled switch;
One end ground connection of described first detection resistance, the other end is connected with second one end detecting resistance by gate-controlled switch; Second other end detecting resistance is connected with direct supply;
First detection resistance is in parallel with to-be-tested transformer; The first described other end detecting resistance is connected to the AD Sampling Interface of control circuit;
The control end of gate-controlled switch is connected to the IO pin of control circuit.
3. a kind of mutual inductor testing apparatus according to claim 1, is characterized in that, also comprises AD sample circuit;
Current detection circuit comprises the first detection resistance, second and detects resistance and gate-controlled switch;
One end ground connection of described first detection resistance, the other end is connected with second one end detecting resistance by gate-controlled switch; Second other end detecting resistance is connected with direct supply;
First detection resistance is in parallel with to-be-tested transformer; The first described other end detecting resistance is connected to the AD Sampling Interface of AD sample circuit;
The control end of gate-controlled switch is connected to the IO pin of control circuit; AD sample circuit and control circuit have signal and are connected.
4. a kind of mutual inductor testing apparatus according to Claims 2 or 3, it is characterized in that, described control circuit for calculate AD sample circuit output signal average, and for when described average be 0 and certain time time to gate-controlled switch output control signal by gate-controlled switch conducting.
5. a mutual inductor detection method, is characterized in that, comprising:
Current detection step, detects and the signal of output-response to-be-tested transformer size of current;
Mean value computation step, calculates the average of the signal of reaction to-be-tested transformer size of current;
Null value determining step, judges whether described average is 0;
To-be-tested transformer state detecting step, when described average be 0 and certain time time, detect further mutual inductance to be measured and be normal, open circuit or short-circuit condition and output detections result.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201511004844.4A CN105445537A (en) | 2015-12-29 | 2015-12-29 | Instrument transformer detection device and method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201511004844.4A CN105445537A (en) | 2015-12-29 | 2015-12-29 | Instrument transformer detection device and method |
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| CN105445537A true CN105445537A (en) | 2016-03-30 |
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| CN201511004844.4A Pending CN105445537A (en) | 2015-12-29 | 2015-12-29 | Instrument transformer detection device and method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108572344A (en) * | 2017-03-10 | 2018-09-25 | 恩智浦美国有限公司 | Detect the device and method of Current Transformer Secondary side disconnecting |
Citations (5)
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| CN102680851A (en) * | 2012-05-30 | 2012-09-19 | 深圳市英威腾电气股份有限公司 | Current leakage detecting method and current leakage detecting device |
| CN203396891U (en) * | 2013-06-28 | 2014-01-15 | 上海电科电器科技有限公司 | Transformer wire fracture detection device |
| CN104297611A (en) * | 2014-01-14 | 2015-01-21 | 河南许继智能控制技术有限公司 | Transformer sampling circuit |
| CN104793100A (en) * | 2015-05-13 | 2015-07-22 | 上海盛善电气有限公司 | Detection device for circuit breakage and short circuit of secondary coil of electric leakage mutual inductor |
| CN204666760U (en) * | 2015-05-26 | 2015-09-23 | 蚌埠依爱消防电子有限责任公司 | Residual current transformer failure detector circuit |
-
2015
- 2015-12-29 CN CN201511004844.4A patent/CN105445537A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102680851A (en) * | 2012-05-30 | 2012-09-19 | 深圳市英威腾电气股份有限公司 | Current leakage detecting method and current leakage detecting device |
| CN203396891U (en) * | 2013-06-28 | 2014-01-15 | 上海电科电器科技有限公司 | Transformer wire fracture detection device |
| CN104297611A (en) * | 2014-01-14 | 2015-01-21 | 河南许继智能控制技术有限公司 | Transformer sampling circuit |
| CN104793100A (en) * | 2015-05-13 | 2015-07-22 | 上海盛善电气有限公司 | Detection device for circuit breakage and short circuit of secondary coil of electric leakage mutual inductor |
| CN204666760U (en) * | 2015-05-26 | 2015-09-23 | 蚌埠依爱消防电子有限责任公司 | Residual current transformer failure detector circuit |
Non-Patent Citations (1)
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| 朱波 等: "《现代材料处理工艺工程计算机控制》", 30 November 2014, 哈尔滨工业大学出版社 * |
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| CN108572344A (en) * | 2017-03-10 | 2018-09-25 | 恩智浦美国有限公司 | Detect the device and method of Current Transformer Secondary side disconnecting |
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Application publication date: 20160330 |