CN204028280U - A kind of secondary loop of mutual inductor failure detector - Google Patents
A kind of secondary loop of mutual inductor failure detector Download PDFInfo
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- CN204028280U CN204028280U CN201420342229.9U CN201420342229U CN204028280U CN 204028280 U CN204028280 U CN 204028280U CN 201420342229 U CN201420342229 U CN 201420342229U CN 204028280 U CN204028280 U CN 204028280U
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Abstract
A kind of secondary loop of mutual inductor failure detector, comprise primary processor CPU, signal amplification circuit, Current Transmit 1, return signal modulate circuit, return signal amplifying circuit, bandwidth-limited circuit, AD/DA circuit, described Current Transmit 1 is dual signal output current transformer, comprise metering coil and signal coil, metering coil is done metering, and signal coil is used as input; Described signal amplification circuit is connected with the signal coil of Current Transmit 1; The described Current Transmit 1 of stating is connected with detected foreign current mutual inductor CT0.Admittance detection method is applied to the equipment such as load management terminal by the design, in order to the real-time intelligent diagnostic design to state under the normal operation of secondary loop of mutual inductor and failure condition.Can find the fault of secondary circuit, reduce the generation of energy loss and security incident.
Description
Technical field
The design relates to secondary loop of mutual inductor failure detector, belongs to current transformer technical field.
Background technology
When current transformer (CT) charging operation, secondary returning trackside breaks down and will produce serious potential safety hazard, and affects electric energy metrical, and main manifestations is open circuit and short circuit two states.Current transformer poor contact of contacts in service, contact are damaged, artificially the fault such as short circuit or disconnection, mutual inductor damage all can be summed up as open circuit or short circuit phenomenon in current return.When Verification of Measuring Current Transformer fault, will directly affect the accuracy of electric energy metrical, secondary side people in various degree, for short circuit is also stealing conventional means, opens a way and easily causes electric power safety accident simultaneously.Detect in real time the on-the-spot ruuning situation of current return and process and be very important in time.Finally all can be reflected as the variation of current return admittance (admittance) (inverse of impedance (impedance)) value for aforementioned fault, admittance value in loop is detected in real time, can diagnose the ruuning situation in whole secondary circuit.
Summary of the invention
For above-mentioned requirements, the design is according to admittance ratio juris, magnetic test coil is designed to dual signal output current transformer CT1, by existing signal amplification circuit, electric current return signal modulate circuit, return signal amplifying circuit, bandwidth-limited circuit, AD/DA circuit and dual signal output current transformer CT1 combination, provide a kind of secondary loop of mutual inductor failure detector, in time the ruuning situation of detection reaction Current Transmit 0.
For achieving the above object, the design realizes by following technological means:
A kind of secondary loop of mutual inductor failure detector, comprise primary processor CPU, signal amplification circuit, Current Transmit 1, return signal modulate circuit, return signal amplifying circuit, bandwidth-limited circuit, AD/DA circuit, signal amplification circuit includes signal conversion circuit, return signal amplifying circuit includes low-pass filter circuit, AD/DA circuit includes ac-dc converter circuit, it is characterized in that: described Current Transmit 1 is dual signal output current transformer, comprise metering coil and signal coil, metering coil is done metering, signal coil is used as input, described signal amplification circuit is connected with the signal coil of Current Transmit 1, described Current Transmit 1 is connected with detected foreign current mutual inductor CT0.
Preferably, described a kind of secondary loop of mutual inductor failure detector, is characterized in that: described primary processor CPU sends PWM square-wave signal to signal amplification circuit.
Preferably, described a kind of secondary loop of mutual inductor failure detector, is characterized in that: the frequency of described PWM square-wave signal is 20KHz.
Preferably, described a kind of secondary loop of mutual inductor failure detector, is characterized in that: the signal that described signal amplification circuit flows to Current Transmit 1 signal coil is sine wave signal.
Preferably, described a kind of secondary loop of mutual inductor failure detector, is characterized in that: the enlargement factor of described return signal amplifying circuit is 50 times.
Preferably, described a kind of secondary loop of mutual inductor failure detector, is characterized in that: described bandwidth-limited circuit is considered the noise signal except 20KHz, and the sine wave signal of 20KHz is transferred to AD/DA circuit.
The invention has the beneficial effects as follows: admittance detection method is applied to the equipment such as load management terminal by the design, in order to the real-time intelligent diagnostic design to state under the normal operation of secondary loop of mutual inductor and failure condition.It can operate in underloading and overload (in the normal measures range of mutual inductor) can accurately detect at current transformer.Node-pair method is opened application in short circuit and can help to find the fault of secondary circuit at current return secondary side, reduces the generation of energy loss and security incident.
Brief description of the drawings
Fig. 1 is the design's the electric circuit constitute schematic diagram, and Fig. 2 is Current Transmit 1 structural representation.
Embodiment
Below in conjunction with Figure of description, design is further described.
The design is according to admittance detection method principle, magnetic test coil is designed to dual signal output current transformer CT1, by existing signal amplification circuit, electric current return signal modulate circuit, return signal amplifying circuit, bandwidth-limited circuit, AD/DA circuit and dual signal output current transformer CT1 combination, in order to the ruuning situation of detection reaction Current Transmit 0.
As shown in Figure 1, 2, in the time that terminal device normally moves, its current return is made up of with terminal inner Current Transmit l the Current Transmit 0 of end product outside, in design, requiring the current transformer elements that terminal is selected is dual signal output current transformer, metering (being referred to as to measure coil) is done in one tunnel output, and input (being referred to as signal coil) is used as in the output of～road.The variation that Current Transmit 0 secondary circuit is normal, open circuit, three kinds of state variation of short circuit finally can be reflected to the admittance value (resistance value) that current transformer shows circuit (CT1).Detect the method that admittance value can adopt the external signal that superposes on the secondary signal coil of CTl, reflect the variation of CT0 by metering coil, after circuit conversion becomes DC voltage, judge again the secondary side state of current return by AD sampled value.
Terminal signaling translation circuit, wherein PWM ripple is the square-wave signal of frequency 20 kHz of primary processor CPU output.Current transformer can be counted as a constant current source in linear work region, its internal resistance infinity, and the output between secondary is not subject to the impact of secondary load impedance variation.When secondary impedance continues to increase, make secondary excitation voltage reach current transformer saturation point, mutual inductor work will enter nonlinear area, and exciting current increases, and the electric current of inferior load side is shunted by energized circuit gradually.
The factor that affects secondary circuit impedance (admittance) size is mainly determined by loaded impedance and excitation property.Under normal circumstances, loaded impedance remains unchanged substantially, and excitation impedance (admittance) changes with the variation of secondary excitation voltage.
Sine wave signal is added on the signal coil of Current Transmit l, along with current return secondary side CT0
Normally, the change of the state such as open circuit, short circuit, also there is variation in the admittance value feeding back on CTl, resistance value changes, sine wave signal also can change.
When PWM square-wave signal process translation circuit is to a signal coil sine wave signal of stack (sin), this signal feeds back on metering coil through primary coil again, the signal amplitude that metering coil induces is very little, and with clutter (wherein containing 50 Hz power frequency components), therefore need first through amplifying circuit, signal to be amplified to 50 times
, then carry out low-pass filter circuit and carry out filtering.Signal output current wave after low-pass filtering after amplifying, it shows normally, open circuit and short-circuit condition waveform frequency are 20 kHz.
Bandwidth-limited circuit, the noise signal beyond filtering 20 kHz left and right.The 20 kHz square waves that produced by CPU obtain corresponding signal after Current Transmit l feedback amplification filtering, finally isolate good sine wave signal by bandpass filter.
Waveform after bandpass filter is the sine wave of standard, and amplitude sinusoidal wave under the various states of current return is difference, then through AC signal turn direct current signal by the A/D sampled signal of CPU be diagnosable go out current return secondary side open short trouble.
More than show and described the design's ultimate principle, principal character and advantage.The technician of the industry should understand; the design is not restricted to the described embodiments; the principle that the design is just described of describing in above-described embodiment and instructions; do not departing under the prerequisite of the design's spirit and scope; the design also has various changes and modifications, and these changes and improvements all fall within the scope of claimed the design.The claimed scope of the design is defined by appending claims and equivalent thereof.
Claims (6)
1. a secondary loop of mutual inductor failure detector, comprise primary processor CPU, signal amplification circuit, Current Transmit 1, return signal modulate circuit, return signal amplifying circuit, bandwidth-limited circuit, AD/DA circuit, signal amplification circuit includes signal conversion circuit, return signal amplifying circuit includes low-pass filter circuit, AD/DA circuit includes ac-dc converter circuit, it is characterized in that: described Current Transmit 1 is dual signal output current transformer, comprise metering coil and signal coil, metering coil is done metering, signal coil is used as input, described signal amplification circuit is connected with the signal coil of Current Transmit 1, described Current Transmit 1 is connected with detected foreign current mutual inductor CT0.
2. a kind of secondary loop of mutual inductor failure detector as claimed in claim 1, is characterized in that: described primary processor CPU sends PWM square-wave signal to signal amplification circuit.
3. a kind of secondary loop of mutual inductor failure detector as claimed in claim 2, is characterized in that: the frequency of described PWM square-wave signal is 20KHz.
4. a kind of secondary loop of mutual inductor failure detector as claimed in claim 1, is characterized in that: the signal that described signal amplification circuit flows to Current Transmit 1 signal coil is sine wave signal.
5. a kind of secondary loop of mutual inductor failure detector as claimed in claim 1, is characterized in that: the enlargement factor of described return signal amplifying circuit is 50 times.
6. a kind of secondary loop of mutual inductor failure detector as claimed in claim 1, is characterized in that: described bandwidth-limited circuit is considered the noise signal except 20KHz, and the sine wave signal of 20KHz is transferred to AD/DA circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420342229.9U CN204028280U (en) | 2014-06-26 | 2014-06-26 | A kind of secondary loop of mutual inductor failure detector |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201420342229.9U CN204028280U (en) | 2014-06-26 | 2014-06-26 | A kind of secondary loop of mutual inductor failure detector |
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| CN201420342229.9U Expired - Fee Related CN204028280U (en) | 2014-06-26 | 2014-06-26 | A kind of secondary loop of mutual inductor failure detector |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104865481A (en) * | 2015-06-18 | 2015-08-26 | 烟台东方威思顿电气股份有限公司 | Detecting method for load management to terminal external CT secondary side loop states |
| CN107037303A (en) * | 2016-11-07 | 2017-08-11 | 北京博纳电气股份有限公司 | Detection means and detection method for tested CT secondary side circuit states outside ammeter |
| CN112285618A (en) * | 2019-12-20 | 2021-01-29 | 青岛鼎信通讯股份有限公司 | Scheme for detecting CT secondary side wiring state |
| CN113640727A (en) * | 2021-01-21 | 2021-11-12 | 青岛鼎信通讯股份有限公司 | CT secondary circuit detection method based on PWM excitation and fixed frequency analysis |
-
2014
- 2014-06-26 CN CN201420342229.9U patent/CN204028280U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104865481A (en) * | 2015-06-18 | 2015-08-26 | 烟台东方威思顿电气股份有限公司 | Detecting method for load management to terminal external CT secondary side loop states |
| CN107037303A (en) * | 2016-11-07 | 2017-08-11 | 北京博纳电气股份有限公司 | Detection means and detection method for tested CT secondary side circuit states outside ammeter |
| CN107037303B (en) * | 2016-11-07 | 2019-06-07 | 北京博纳电气股份有限公司 | For being tested the detection device and method of CT secondary side circuit state outside ammeter |
| CN112285618A (en) * | 2019-12-20 | 2021-01-29 | 青岛鼎信通讯股份有限公司 | Scheme for detecting CT secondary side wiring state |
| CN113640727A (en) * | 2021-01-21 | 2021-11-12 | 青岛鼎信通讯股份有限公司 | CT secondary circuit detection method based on PWM excitation and fixed frequency analysis |
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