CN110488215A - Current transformer tests circuit, method and device - Google Patents
Current transformer tests circuit, method and device Download PDFInfo
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- CN110488215A CN110488215A CN201910889496.5A CN201910889496A CN110488215A CN 110488215 A CN110488215 A CN 110488215A CN 201910889496 A CN201910889496 A CN 201910889496A CN 110488215 A CN110488215 A CN 110488215A
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- current transformer
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- pumping signal
- excitation
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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
Abstract
The invention discloses a kind of current transformers to test circuit, and the circuit includes current transformer, excitation application module, core channel module and self-test module；Wherein, excitation applies module, for applying pumping signal to current transformer according to predetermined period；Core channel module, for detecting the sampled value and reference value of the pumping signal；Self-test module obtains difference, judges whether the current transformer is in normal operating conditions according to the difference and preset threshold for asking poor to the sampled value and the reference value.The invention also discloses a kind of current transformer test method and devices, by applying excitation to current transformer to detect open circuit and short circuit in technical solution of the present invention, the test for realizing electric-leakage detection circuit does not need artificially to manipulate, improves the safety of electric-leakage detection circuit.
Description
Technical field
The present invention relates to detection of electrical leakage technical field, in particular to a kind of current transformer tests circuit, method and device.
Background technique
Current transformer in leakage current detection protection circuit in use, is easy to occur due to components loosening, electricity
Local electrical resistance caused by pressure disturbs increases, and will cause the failure of short circuit or open circuit.Artificial detection mutual inductor state is time-consuming and laborious,
Heavy workload at high cost；Additional circuit is arranged in leakage current detection protection circuit to detect current transformer, improves
The complexity of circuit, cost high power consumption are big.In order to solve the above technical problems, need one kind to can be carried out self-test while not influencing to leak
The current transformer measuring technology of electro-detection protection circuit original function.
Summary of the invention
The main object of the present invention is to provide a kind of current transformer test circuit, method and device, it is intended to realize electric current
The automatic fault selftesting of mutual inductor.
To achieve the above object, the present invention proposes a kind of current transformer test circuit, and the circuit includes Current Mutual Inductance
Device, excitation apply module, core channel module and self-test module；Wherein,
Excitation applies module, for applying pumping signal to current transformer according to predetermined period；
Core channel module, for detecting the sampled value and reference value of the pumping signal；
Self-test module obtains difference, according to the difference and in advance for asking poor to the sampled value and the reference value
If whether current transformer described in threshold decision is in normal operating conditions.
Preferably, the output end that the excitation applies module is connected with the current transformer；The current transformer
Output end is connected with the receiving end of the core channel module；The output end and the self-test module of the core channel module
Receiving end connection.
To achieve the above object, the present invention also proposes a kind of current transformer test method, and the method includes walking as follows
It is rapid:
Excitation applies module and applies pumping signal to current transformer according to predetermined period；
Core channel module detects the sampled value and reference value of the pumping signal；
Self-test module asks poor to the sampled value and the reference value, difference is obtained, according to the difference and default threshold
Value judges whether the current transformer is in normal operating conditions
Preferably, the excitation applies the step of module applies pumping signal to current transformer according to predetermined period, tool
Body includes:
Excitation, which applies module and controls the pumping signal according to predetermined period, carries out switching, and by the pumping signal
It is applied to the current transformer.
Preferably, the excitation apply the step of module applies pumping signal to current transformer according to predetermined period it
Before, the method also includes:
Excitation applies module and issues pumping signal, and the pumping signal is continuous current excitation signal, low-frequency excitation signal and height
At least one of frequency pumping signal three；
The low-frequency excitation signal, frequency value range is in 0.1Hz~49Hz or 51~59Hz or 61Hz~1KHz；
The high-frequency excitation signal, frequency value range is in 500Hz~10KHz.
Preferably, before the core channel module detects the step of sampled value and reference value of the pumping signal, institute
State method further include:
Core channel module is filtered pumping signal, to separate the pumping signal of different frequency
Preferably, the core channel module detects the step of sampled value and reference value of the pumping signal, specific to wrap
It includes:
When applying the pumping signal, the sampled value of the pumping signal is obtained by filtering algorithm；
When closing the pumping signal, the reference value of the pumping signal is obtained by filtering algorithm.
Preferably, the self-test module asks poor to the sampled value and the reference value, difference is obtained, according to the difference
Value and preset threshold judge the step of whether current transformer is in normal operating conditions, specifically include:
Self-test module asks poor to the sampled value and the reference value, obtains difference；
When the difference is less than the low value of default short-circuit decision threshold, judge the current transformer for failed shorted shape
State；
When the difference is greater than the high level of default open circuit decision threshold, judge the current transformer for failed open shape
State.
Preferably, the step of self-test module asks poor to the sampled value and the reference value, obtains difference, it is described
Method further include:
DC channel, low frequency channel and high frequency channel in the self-test module respectively believe excitation corresponding with access
Number the sampled value and the reference value ask poor.
To achieve the above object, the present invention also proposes a kind of current transformer testing device, the current transformer test
Device includes that above-mentioned current transformer test circuit or described device apply above-mentioned current transformer test method.
Technical solution of the present invention applies module, core channel module and self-test mould by setting current transformer, excitation
Block forms a kind of current transformer test circuit.Excitation applies module, for being applied according to predetermined period to current transformer
Pumping signal；Core channel module, for detecting the sampled value and reference value of the pumping signal；Self-test module, for pair
The sampled value and the reference value ask poor, obtain difference, judge the current transformer according to the difference and preset threshold
Whether normal operating conditions is in.The present invention is by applying excitation to current transformer to carry out to the current transformer state
Detection, realizes the self-test of current transformer circuit, electric-leakage detection circuit is utilized predominantly detects access, reduces into
Originally reduce power consumption, reduce the complexity of circuit.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with
The structure shown according to these attached drawings obtains other attached drawings.
Fig. 1 is the functional block diagram that current transformer of the present invention tests circuit first embodiment；
Fig. 2 is the electrical block diagram that current transformer of the present invention tests circuit first embodiment；
Fig. 3 is the flow diagram of current transformer test method first embodiment of the present invention；
Fig. 4 is the flow diagram of current transformer test method second embodiment of the present invention；
Drawing reference numeral explanation:
The embodiments will be further described with reference to the accompanying drawings for the realization, the function and the advantages of the object of the present invention.
| Label | Title | Label | Title |
| 100 | Current transformer | R1~R3 | First resistor is to 3rd resistor |
| 200 | Excitation applies module | C1~C3 | First capacitor is to third capacitor |
| 300 | Core channel module | D1 | First diode |
| 400 | Self-test module | D2 | Second diode |
| SCR | Control terminal | D3 | First light emitting diode |
| VDD | First power end | Q1 | It is silicon-controlled |
| GND | Ground terminal | U1 | Chip |
| VDD2 | Second source end | EOL | Warning end |
| CT | Mutual inductance end |
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiment is only a part of the embodiments of the present invention, instead of all the embodiments.Base
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts it is all its
His embodiment, shall fall within the protection scope of the present invention.
It is to be appreciated that the directional instruction (such as up, down, left, right, before and after ...) of institute is only used in the embodiment of the present invention
In explaining in relative positional relationship, the motion conditions etc. under a certain particular pose (as shown in the picture) between each component, if should
When particular pose changes, then directionality instruction also correspondingly changes correspondingly.
In addition, the description for being related to " first ", " second " etc. in the present invention is used for description purposes only, and should not be understood as referring to
Show or imply its relative importance or implicitly indicates the quantity of indicated technical characteristic." first ", " are defined as a result,
Two " feature can explicitly or implicitly include at least one of the features.In addition, the technical solution between each embodiment can
It to be combined with each other, but must be based on can be realized by those of ordinary skill in the art, when the combination of technical solution occurs
It is conflicting or when cannot achieve should people think that the combination of this technical solution is not present, also not the present invention claims protection
Within the scope of.
The present invention proposes a kind of current transformer test circuit.
Referring to figs. 1 to Fig. 2, Fig. 1 is the functional block diagram that current transformer of the present invention tests circuit first embodiment；Fig. 2
For the electrical block diagram of current transformer testing device first embodiment of the present invention；
In embodiments of the present invention, current transformer test circuit function module is as shown in Figure 1；
The current transformer test circuit includes: current transformer 100, excitation application module 200, core channel module
300, self-test module 400；The excitation applies the output end of module 200 and the current transformer 100 connects；The electric current
The output end of mutual inductor 100 is connected with the receiving end of the core channel module 300；The output of the core channel module 300
End is connected with the receiving end of the self-test module 400；Wherein,
The current transformer 100 after coupling, is exported to the core channel module for receiving the pumping signal
300.In the present embodiment, the turn ratio of the current transformer 100 is 1:1000, firewire and zero curve from the current transformer
It is passed through in 100.
The excitation applies module 200, applies pumping signal to current transformer 100 according to predetermined period.The excitation
Apply module 200 for exporting default pumping signal.In the present embodiment, the excitation applies module 200, the core access mould
Block 300 and the self-test module 400 are all integrated in chip U1, and the chip U1 is in leakage current detection protection circuit, packet
Containing earth leakage protective and self-test function, the current transformer tests the main of the circuit multiplexer leakage current detection protection circuit
Detection path.In specific implementation, the excitation applies module 200, the core channel module 300 and the self-test module
400, which can also be used as circuit module, is implemented separately, and can also be partially integrated in the middle part of chip and be allocated as external circuit, the present invention is not
This is limited.
In the present embodiment, the self-test of current transformer 100 is realized using earth leakage protective chip, is realizing earth leakage protective
In the case where function, while peripheral circuit of arranging in pairs or groups realizes the self-test of the important electronic component such as silicon-controlled, to simplify electric appliance
The circuit structure of equipment, can reduce the production cost of electrical equipment, carry out the progress of earth leakage protective while to solve
100 self-test of current transformer is needed using additional circuit, can exist in cost and complexity in circuit design compared with
The problem of big cost.
It should be noted that in the chip U1 further include: pressure stabilizing and power supply module are described steady for pressure stabilizing and power supply
Pressure is connected with power supply module with the first power end VDD of the chip U1；Test synchronization module is for after obtaining halfwave rectifier
Shape information extracts AC synchronous information from the shape information, minus in alternating-current magnitude according to AC synchronous information
Self-test is carried out in period, to confirm whether the protection circuit and current transformer are normal；Creepage protection function module is used
In realization creepage protection function；Silicon-controlled testing control module judges for receiving the AC synchronous signal of half-wave rectifying circuit
It is detected when the alternating-current magnitude of the AC synchronous signal is less than zero to silicon-controlled.In the chip U1, above-mentioned module is executed
It is not interfere with each other when corresponding function, partial circuit multiplexing.
It should be noted that the mutual inductance end CT of the chip U1 is connected with the input terminal of the current transformer 100, to institute
It states current transformer 100 and applies pumping signal.It should be noted that pumping signal is actually point for including different frequency
Amount, may include direct current, the one or more of low frequency or high-frequency signal, or even may include many in pumping signal
The different signal of kind, and when detection and test, it can choose one or more kinds of signals in the frequency range using target, come
Carry out the test to current transformer.Due to digital filtering, when several pumping signals exist simultaneously, phase between different frequency component
It does not interfere with independently mutually, and the frequency of the pumping signal avoids the main frequency section as leakage protection circuit work.Institute
It states pumping signal and the current transformer 100 is applied to according to predetermined period.For example, predetermined period is 1200ms, then it is described to swash
It encourages signal and applies 600ms, turn off 600ms.Ramp signal perhaps square-wave signal or other can be used in the pumping signal
The signal of what amplitude controlled change.The problem of selecting ramp signal can be to avoid the abundant high fdrequency component of square-wave signal.
The core channel module 300 detects the sampled value and reference value of the pumping signal.The core channel module
300 receive the pumping signal that the current transformer 100 exports, and detect to the pumping signal.When the pumping signal
When application, stablizes to the pumping signal, detect the sampled value of the pumping signal；When pumping signal shutdown, to institute
It states pumping signal to stablize, detects the reference value.The sampled value and the reference value are that different excitations is calculated by filtering
Method obtains.For example, predetermined period is 1200ms, the pumping signal applies 600ms, and when 100ms, the pumping signal is stablized,
Detect the sampled value of the pumping signal；After the pumping signal applies 600ms, 600ms is turned off, when 700ms, the excitation
Signal stabilization detects the reference value.
The self-test module 400 asks poor to the sampled value and the reference value, difference is obtained, according to the difference
The state of the current transformer is judged with preset threshold.The core channel module 300 is by the reference value and the sampling
DC channel, low frequency channel and high frequency channel point of the value output to the self-test module 400, in the self-test module 400
Other to ask poor to the sampled value of corresponding pumping signal and the reference value, the difference can be continuous current excitation, low
The component of frequency excitation and high frequency pumping one of which, is also possible to a variety of combinations.After obtaining the difference, by the difference and
Preset threshold is compared, and the state of current transformer is judged according to result.For example, when the difference is less than default short circuit judgement
The low value of threshold value, then the current transformer is in failed shorted state, when the difference is greater than default open circuit decision threshold
High level, then the current transformer is in failed open state.
It should be noted that current transformer is tested circuit and is applied in leakage protection circuit, and electric leakage in the present embodiment
Protection circuit shares a set of preamplifier, ADC module and a part of digital filter, runs and leaks in leakage current detection protection circuit
When electric protection function, the fault test of current transformer can be periodically carried out simultaneously, multiplexing is realized on frequency domain.Starting
When test function, the excitation just starts to be applied to the current transformer 100.
The present invention applies module 200, core channel module 300, self-test mould by setting current transformer 100, excitation
Block 400 forms a kind of current transformer test circuit, realizes the self-test of current transformer, electric-leakage detection circuit is utilized
Access is predominantly detected, that is, test signal and earth leakage protective detection signal share a set of preamplifier, ADC module and one
Part number filter, reduces costs, and reduces the complexity of circuit, has saved the power consumption of circuit.
It is the electrical block diagram that current transformer of the present invention tests circuit first embodiment referring to Fig. 2, Fig. 2.
In the present embodiment, the excitation applies module 200, the core channel module 300 and the self-test module 400
It is all integrated in chip U1, the chip U1 further include: ground terminal GND, control terminal SCR, the first power end VDD, the second electricity
Source VDD2 and warning end EOL.The output end of the current transformer 100 is connected with the first end of third capacitor C3, and described
The second end of three capacitor C3 is connected with the second source end VDD2, the second end of the third capacitor C3 and second resistance R2's
Second end connection, the second end of the second resistance R2 connects with the second source end VDD2, and the of the second resistance R2
One end is connected with the cathode of the second diode D2, and the anode of the second diode D2 is connected with firewire, and the firewire is from described
It is passed through in current transformer 100.The output end of first power end VDD and the current transformer 100, the third capacitor C3
First end connection, the first power end VDD also connect with the zero curve, and the first power end VDD is grounded, the third
The first end of capacitor C3 is grounded.
It include earth leakage protective and self-test function it should be noted that the chip U1 is in leakage current detection protection circuit,
The current transformer test circuit multiplexer leakage current detection protection circuit predominantly detects access.In specific implementation,
The excitation, which applies module 200, the core channel module 300 and the self-test module 400, can also be used as circuit module
It is implemented separately, can also be partially integrated in the middle part of chip and be allocated as external circuit, the present invention limits not to this.
It should be noted that the firewire is connected with the anode of the first diode D1, the of the first resistor R1
One end is connected with the cathode of the first diode D1 with the anode of silicon-controlled Q1, the minus earth of the silicon-controlled Q1, described
The cathode of silicon-controlled Q1 is also connected with the zero curve.The second end of the first resistor R1 is connected with ground terminal GND, the ground connection
End GND is also connected with the second end of the second capacitor C2, the first end of the second capacitor C2 and the second end of the first resistor
And the first power end VDD connection, the second end of the first capacitor C1 are connected with the control terminal SCR and the silicon-controlled Q1,
The first end of the first capacitor C1 is connected with the input terminal of the current transformer 100, the first end of the first capacitor C1
Also connected with the second end of the ground terminal GND and the second capacitor C2.
Technical solution of the present invention by setting current transformer 100, excitation apply module 200, core channel module 300 and
Self-test module 400 forms a kind of current transformer test circuit.Excitation applies module 200, according to predetermined period to electric current
Mutual inductor 100 applies pumping signal；Core channel module 300 detects the sampled value and reference value of the pumping signal；Self-test
Module 400 asks poor to the sampled value and the reference value, obtains difference, judges electric current according to the difference and preset threshold
The state of mutual inductor.The present invention is motivated by applying to current transformer to be detected to the current transformer state,
The self-test for realizing current transformer circuit, be multiplexed electric-leakage detection circuit predominantly detects access, reduces costs reduction
Power consumption, reduces the complexity of circuit.
The present invention also proposes a kind of current transformer test method, is current transformer of the present invention test referring to Fig. 3, Fig. 3
The flow diagram of method first embodiment.
In current transformer test method first embodiment, the current transformer test method the following steps are included:
Step S10, excitation apply module 200 and apply pumping signal to current transformer 100 according to predetermined period.
It should be noted that current transformer testing device is applied in leakage protection circuit in the present embodiment, and electric leakage
Protection circuit shares a set of preamplifier, ADC module and a part of digital filter, runs and leaks in leakage current detection protection circuit
When electric protection function, the fault test of current transformer, when starting test function, the excitation can be periodically carried out simultaneously
Just start to be applied to the current transformer 100.
It should be noted that the excitation applies module 200, the core channel module 300 and institute in the present embodiment
Self-test module 400 is stated all to be integrated in chip U1, the mutual inductance end CT of the chip U1 and the current transformer 100
Input terminal connection, Xiang Suoshu current transformer 100 apply pumping signal.100 turn ratio of current transformer in the present embodiment is
1:1000, firewire and zero curve are passed through from the current transformer 100, not to the number of turns of current transformer 100 in specific implementation
It is limited.
It is arranged it should be noted that the predetermined period applies module 200 by excitation, the pumping signal may be direct current
One of pumping signal, low-frequency excitation signal and high-frequency excitation signal or a variety of combinations.It is several to swash due to digital filtering
When encouraging signal and existing simultaneously, do not interfered with independently of each other between different frequency component.The low-frequency excitation signal, frequency value
Range is in 0.1Hz~49Hz or 51~59Hz or 61Hz~1KHz；The high-frequency excitation signal, frequency value range exist
500Hz~10KHz.
Step S20, core channel module 300 detect the sampled value and reference value of the pumping signal.
It should be noted that the core channel module 300 receives the pumping signal that the current transformer 100 exports,
The pumping signal is detected.For example, be applied with continuous current excitation signal and low-frequency excitation signal simultaneously, then it is right simultaneously respectively
The sampled value and the reference value of the signal are detected.Due to digital filtering, the continuous current excitation signal and described
Low-frequency excitation signal does not interfere with independently of each other, has respectively obtained the institute of the continuous current excitation signal and the low-frequency excitation signal
State sampled value and the reference value.
Step S30, self-test module ask poor to the sampled value and the reference value, difference are obtained, according to the difference
Judge whether the current transformer is in normal operating conditions with preset threshold
It can be readily appreciated that the self-test module 400 has received the sampling that the core channel module 300 transmits
Value and the reference value, and poor is asked to the sampled value and the reference value, to obtain difference, according to preset threshold and the difference
Value may determine that the state of current transformer 100.In the present embodiment, by taking leakage protection circuit as an example, when the difference is less than
The low value of default short circuit decision threshold, then the current transformer is in failed shorted state, when the difference is greater than default open
The high level of road decision threshold, then the current transformer is in failed open state.
The present embodiment technical solution applies module 200, core channel module 300 by setting current transformer 100, excitation
And self-test module 400 forms a kind of current transformer test circuit.Excitation applies module 200, according to predetermined period to electricity
Current transformer 100 applies pumping signal；Core channel module 300 detects the sampled value and reference value of the pumping signal；From survey
Die trial block 400 asks poor to the sampled value and the reference value, obtains difference, judges electricity according to the difference and preset threshold
Current transformer whether normal work.The test for realizing electric-leakage detection circuit does not need artificially to manipulate, has been multiplexed detection of electrical leakage
Circuit predominantly detects access, reduces the complexity of circuit, reduces lower power consumption cost, improves the peace of electric-leakage detection circuit
Quan Xing.
Further, as shown in figure 4, proposing Current Mutual Inductance of the present invention based on current transformer test method first embodiment
Device test method second embodiment, in the present embodiment, the step S10, comprising:
Step S101: excitation, which applies module and controls the pumping signal according to predetermined period, carries out switching, and by institute
It states pumping signal and is applied to the current transformer.
Apply and turn off it should be noted that the pumping signal is controlled according to the predetermined period, for example, predetermined period
For 1200ms, while it being applied with the high-frequency excitation signal of 500Hz and the low-frequency excitation signal of 25Hz, the pumping signal applies
600ms turns off 600ms, successively repeatedly.It is without restriction in signal type the present embodiment of the pumping signal, specific implementation
In the signal of square-wave signal or other any amplitude controlled changes can be used.In the present embodiment, the pumping signal is
Ramp signal avoids the problem of square-wave signal bring enriches high fdrequency component.
Before the step S10, further includes:
Step S100: excitation applies module and issues pumping signal, and the pumping signal is continuous current excitation signal, low-frequency excitation
At least one of signal and high-frequency excitation signal three；
May include direct current it should be noted that pumping signal is actually the component for including different frequency, low frequency or
The one or more of person's high-frequency signal.It may include various signal even in pumping signal.And it detects and surveys
When examination, it can choose one or more kinds of signals in the frequency range using target, to carry out the test to current transformer.
The low-frequency excitation signal, frequency value range is in 0.1Hz~49Hz or 51~59Hz or 61Hz~1KHz；The high frequency swashs
Signal is encouraged, frequency value range is in 500Hz~10KHz.The frequency of the pumping signal avoids leakage protection circuit
Working frequency will not influence earth leakage protective function.
In the present embodiment, before the step S20, further includes:
Step S200: core channel module is filtered pumping signal, to separate the pumping signal of different frequency.
It can be readily appreciated that the frequency that the exciting signal frequency of the current transformer and earth leakage protective device work is different,
The signal of different frequency is separated by filter, does not interfere with earth leakage protective function while testing current transformer.
In the present embodiment, the step S20, specifically includes:
Step S201: when applying the pumping signal, the sampling of the pumping signal is obtained by filtering algorithm
Value；When closing the pumping signal, the reference value of the pumping signal is obtained by filtering algorithm.
It should be noted that stablizing to the pumping signal when the pumping signal applies, detecting the pumping signal
Sampled value；When pumping signal shutdown, stablizes to the pumping signal, detect the reference value.The sampled value and
The reference value is that different excitations is obtained by filtering algorithm.For example, the pumping signal is continuous current excitation signal and low
Frequency pumping signal, predetermined period T are 1200ms, and the pumping signal 1/2T applies, 1/2T shutdown, alternately and repeatedly, in 100ms+
When NT, the pumping signal is stablized, and detects the sampled value of the pumping signal；The pumping signal shutdown, in 700ms+NT
The pumping signal is stablized, and the reference value (N=0,1,2 ...) are detected.Simultaneously as digital filtering, the continuous current excitation
Signal and the low-frequency excitation signal do not interfere with independently of each other, have respectively obtained the continuous current excitation signal and the low frequency swashs
Encourage the sampled value and the reference value of signal.
In the present embodiment, the step S30, specifically includes:
Step S301: self-test module 400 asks poor to the sampled value and the reference value, obtains difference；
It should be noted that the core channel module 300 by the reference value and the sampled value export to it is described from
Test module 400, DC channel, low frequency channel and the high frequency channel in the self-test module 400 are respectively to corresponding
The sampled value and the reference value of pumping signal ask poor, and the difference can be continuous current excitation, low-frequency excitation and high frequency and swash
One of component is encouraged, a variety of combinations is also possible to.
Step S302: when the difference is less than the low value of default short-circuit decision threshold, judge that the current transformer is
Failed shorted state；When the difference is greater than the high level of default open circuit decision threshold, judge the current transformer for failure
Open-circuit condition.
It should be noted that the difference and preset threshold are compared, judged according to result after obtaining the difference
The state of current transformer.For example, judging that current transformer is when the difference is less than the low value of default short-circuit decision threshold
Short circuit；When the difference is greater than the high level of default open circuit decision threshold, judge current transformer for open circuit.For example, obtaining straight
The sampled value for flowing pumping signal is DC ACT, and the reference value for obtaining the continuous current excitation signal is DC REF, and obtaining difference is DC
DIFF, the difference are greater than the low value of the default short-circuit decision threshold, then judge current transformer short circuit.
It can be readily appreciated that the judgement that the different differences carries out this step can be configured, the preset threshold can be with
It is configured according to the actual situation, in the present embodiment with no restrictions.
The present embodiment technical solution solves judgement current transformer by applying pumping signal to current transformer 100
The problem of malfunction.The problem of pumping signal is ramp signal, avoids the abundant high fdrequency component of square-wave signal；Multiplexing
The major avenues of approach of leakage protection circuit and D/A converting circuit, have merged function, save the space of device；The excitation letter
The combination that number can be continuous current excitation signal, low-frequency excitation signal and high-frequency excitation signal one or more of them, avoids leakage
The detection frequency band of electric protection circuit while realizing creepage protection function, can carry out the self-test of current transformer simultaneously,
Improve the accuracy of detection.
The present invention also proposes a kind of current transformer testing device, which includes as described above
Current transformer tests circuit, which tests the specific structure of circuit referring to above-described embodiment, since this electric current is mutual
Sensor test device uses whole technical solutions of above-mentioned all embodiments, therefore at least with the technical side of above-described embodiment
All beneficial effects brought by case, this is no longer going to repeat them.
The above description is only a preferred embodiment of the present invention, is not intended to limit the scope of the invention, all at this
Under the inventive concept of invention, using equivalent structure transformation made by description of the invention and accompanying drawing content, or directly/use indirectly
It is included in other related technical areas in scope of patent protection of the invention.
Claims (10)
1. a kind of current transformer tests circuit, which is characterized in that the circuit include current transformer, excitation apply module,
Core channel module and self-test module；Wherein,
Excitation applies module, for applying pumping signal to current transformer according to predetermined period；
Core channel module, for detecting the sampled value and reference value of the pumping signal；
Self-test module obtains difference, according to the difference and default threshold for asking poor to the sampled value and the reference value
Value judges whether the current transformer is in normal operating conditions.
2. current transformer as described in claim 1 tests circuit, which is characterized in that the excitation applies the output end of module
It is connected with the current transformer；The output end of the current transformer is connected with the receiving end of the core channel module；Institute
The output end for stating core channel module is connected with the receiving end of the self-test module.
3. a kind of current transformer test method, which is characterized in that described method includes following steps:
Excitation applies module and applies pumping signal to current transformer according to predetermined period；
Core channel module detects the sampled value and reference value of the pumping signal；
Self-test module asks poor to the sampled value and the reference value, obtains difference, is sentenced according to the difference and preset threshold
Whether the current transformer that breaks is in normal operating conditions.
4. current transformer test method as claimed in claim 3, which is characterized in that the excitation applies module according to default
The step of period applies pumping signal to current transformer, specifically includes:
Excitation applies module and controls the pumping signal progress switching according to predetermined period, and the pumping signal is applied
To the current transformer.
5. current transformer test method as claimed in claim 3, which is characterized in that the excitation applies module according to default
Before the step of period applies pumping signal to current transformer, the method also includes:
Excitation applies module and issues pumping signal, and the pumping signal is that continuous current excitation signal, low-frequency excitation signal and high frequency swash
Encourage at least one of signal three；
The low-frequency excitation signal, frequency value range is in 0.1Hz~49Hz or 51~59Hz or 61Hz~1KHz；
The high-frequency excitation signal, frequency value range is in 500Hz~10KHz.
6. current transformer test method as claimed in claim 3, which is characterized in that described in the core channel module detection
Before the step of sampled value and reference value of pumping signal, the method also includes:
Core channel module is filtered pumping signal, to separate the pumping signal of different frequency.
7. current transformer test method as claimed in claim 3, which is characterized in that described in the core channel module detection
It the step of sampled value and reference value of pumping signal, specifically includes:
When applying the pumping signal, the sampled value of the pumping signal is obtained by filtering algorithm；
When closing the pumping signal, the reference value of the pumping signal is obtained by filtering algorithm.
8. current transformer test method as claimed in claim 7, which is characterized in that the self-test module is to the sampling
Value and the reference value ask poor, obtain difference, judge whether the current transformer is according to the difference and preset threshold
The step of normal operating conditions, specifically includes:
Self-test module asks poor to the sampled value and the reference value, obtains difference；
When the difference is less than the low value of default short-circuit decision threshold, judge the current transformer for failed shorted state；
When the difference is greater than the high level of default open circuit decision threshold, judge the current transformer for failed open state.
9. current transformer test method as claimed in claim 8, which is characterized in that the self-test module is to the sampling
The step of value and the reference value ask poor, obtain difference, the method also includes:
DC channel, low frequency channel and high frequency channel in the self-test module are respectively to pumping signal corresponding with access
The sampled value and the reference value ask poor.
10. a kind of current transformer testing device, which is characterized in that the current transformer testing device includes that right such as is wanted
The described in any item current transformer test circuits of the 1-2 asked or described device application claim 3-9 are described in any item
Current transformer test method.
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Application publication date: 20191122 |