CN105675998B - Footing impedance measuring apparatus and its operating method - Google Patents
Footing impedance measuring apparatus and its operating method Download PDFInfo
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- CN105675998B CN105675998B CN201410658171.3A CN201410658171A CN105675998B CN 105675998 B CN105675998 B CN 105675998B CN 201410658171 A CN201410658171 A CN 201410658171A CN 105675998 B CN105675998 B CN 105675998B
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Abstract
The invention discloses a kind of footing impedance measuring apparatus and its operating methods.One impedance ground of the one alternating current source of grid grounding impedance measurement is electrically connected at and provides an equipment input terminal of an AC power source.The footing impedance measuring apparatus includes a DC power generating circuit and a DC voltage detection circuit.The DC power generating circuit receives the AC power source, and is converted to a DC power supply.The DC power supply makes the impedance ground both ends generate a DC impedance voltage.Using the characteristic of the dc component sum of zero of ac power supply circuit, which measures the DC voltage difference between the equipment input terminal and equipment ground point, that is, is equal to the DC impedance voltage, thus calculates and detect the impedance ground size.
Description
Technical field
It is espespecially a kind of applied to alternating current source the present invention relates to a kind of footing impedance measuring apparatus and its operating method
Footing impedance measuring apparatus and its operating method.
Background technique
Existing electric vehicle, in related international regulations or standard including its charging station, UL 2231-1 standard essentially consists in people
The related specifications of member's protection.Its scope of application is to meet NEC regulation prevention personnel's electric vehicle charging cord needed for by electrical shock hazard
The general norm on road.
Furthermore if in the application of distribution system, usually electricity consumption is set by PE protective wire in expanding application range
Standby all exposed and conductive part is attached, to form complete equipotential link system.Also, due to insulation damages
Caused fault current size and the size of impedance ground value have absolute related, in other words, there is good ground protection,
It could support personnel's Electrical Safety.Therefore, the impedance ground that can accurately detect power end, for Earth Fault Detection with
The realization of ground protection scheme will have very big benifit.
Please refer to the circuit diagram that Figure 1A, Figure 1B and Fig. 1 C are existing common ground impedance detection technology.For Figure 1A and figure
The impedance ground detection mode of alternating current source shown in 1B, current practice are by optic coupling element Op (as shown in Figure 1A) or crystalline substance
Body pipe switch Q1 and resistance R1, the collocation (as shown in Figure 1B) of R2, to detect the impedance ground Rg situation of alternating current source.More
Specifically, it is consistent that duty ratio (duty cycle) will be generated in exit point Pa when impedance ground Rg is short circuit
Square-wave signal, as shown in Figure 2 A.Conversely, when impedance ground Rg is high impedance status (M Ω grade), in exit point Pa institute
The responsibility cycle of the square-wave signal measured will change.Therefore, can whether consistent by the responsibility cycle of the square-wave signal
Or change, it can be learnt that the ground connection situation of impedance ground Rg.In addition, the known practice shown in Fig. 1 C is whole using detecting
Judge whether impedance ground Rg changes in the voltage amplitude size of exit point Pa (non-square-wave signal, as shown in Figure 2 B) after stream
Become, in this way, can roughly judge the impedance ground Rg of the alternating current source according to the output waveform of detection exit point Pa
Situation.However, above-mentioned existing detection method, there are defects below:
1, the size of impedance ground Rg can not be accurately detected out: since existing method is to utilize the detection output end
The waveform of point Pa judges the impedance ground Rg situation of the alternating current source, therefore, square wave consistent for responsibility cycle
Signal can determine whether out that impedance ground Rg is short circuit, however, for exporting the irregular waveform of amplitude size, it just can not be accurately
Judge the degree of impedance ground Rg；
2, the impedance ground Rg of small impedance value can not be detected: since existing method is only capable of detecting 50K Ω mostly
Or the impedance ground Rg of 200K Ω or more, therefore, once the impedance value of impedance ground Rg is lower, it will and cause detection upper serious
Mistake；And
3, the leakage current for flowing back to ground wire is larger, and human electric shock and electrical equipment is be easy to cause to damage.
Therefore, a kind of footing impedance measuring apparatus and its operating method how are designed, the straight of ac power supply circuit is utilized
The characteristic of composition sum of zero is flowed, and being equal to by DC voltage difference between measuring device input terminal and equipment ground point should
DC impedance voltage cooperates the known electric potential source or current source of generation, can be by the way that equipment ground point and remote is precisely calculated
The size of impedance ground between end power supply grounding point is the big class for being intended to row by this case creator and overcoming and solving
Topic.
Summary of the invention
To solve the above-mentioned problems, the present invention provides a kind of footing impedance measuring apparatus, with technology known to overcoming the problems, such as.
Therefore, the equipment input terminal that the present invention footing impedance measuring apparatus is electrically connected at one AC power source of offer connects with an equipment
Between place, to measure the size of an impedance ground of the alternating current source.The footing impedance measuring apparatus includes a direct current
Source generating circuit and a DC voltage detection circuit.The DC power generating circuit is electrically connected the equipment input terminal and the equipment
Grounding point to receive the AC power source, and converts the AC power source as a DC power supply.The DC power supply makes the impedance ground two
End generates a DC impedance voltage.The DC voltage detection circuit is electrically connected the equipment input terminal with the equipment ground point to survey
Measure a direct current pressure difference between the equipment input terminal and the equipment ground point.Wherein, using the direct current of ac power supply circuit at
The characteristic of part sum of zero, which is the DC impedance voltage for being equal to the impedance ground, to calculate and detect
The impedance ground size out.
To solve the above-mentioned problems, the present invention provides a kind of its operating method of footing impedance measuring apparatus, known to overcome
The problem of technology.Therefore, present invention footing impedance measuring apparatus operating method, one applied to one alternating current source of measurement connects
The size of ground impedance, and be electrically connected between the equipment input terminal and equipment ground point that an AC power source is provided.The behaviour
The step of making method includes: that (a) provides a DC power generating circuit, is electrically connected the equipment input terminal and the equipment ground
Point, to receive the AC power source；(b) AC power source is converted as a DC power supply, which makes the impedance ground both ends
Generate a DC impedance voltage；(c) a DC voltage detection circuit is provided to measure the equipment input terminal and the equipment ground point
Between a direct current pressure difference；And (d) utilize the characteristic of the dc component sum of zero of ac power supply circuit, the DC voltage difference
Value is i.e. equal to the DC impedance voltage of the impedance ground, to detect the impedance ground size.
The present invention utilizes the characteristic of the dc component sum of zero of ac power supply circuit, and passes through measuring device input terminal
DC voltage difference is equal to the DC impedance voltage between equipment ground point, cooperates the known electric potential source or current source of generation,
The size for the impedance ground being precisely calculated between equipment ground point and Remote feeding grounding point can be passed through.
In order to be further understood that technology, means and effect of the invention taken for realization predetermined purpose, please refer to
Following detailed descriptions and accompanying drawings of the present invention, it is believed that the purpose of the present invention, feature and feature, when can thus one deeply and
It is specific to understand, however institute's accompanying drawings are only for reference and description, and are not intended to limit the present invention.
Detailed description of the invention
Figure 1A is the circuit diagram of existing impedance ground detection technique；
Figure 1B is the circuit diagram of another existing impedance ground detection technique；
Fig. 1 C is the circuit diagram of yet another existing impedance ground detection technique；
Fig. 2A is that the impedance ground of corresponding diagram 1A and Figure 1B detect the waveform diagram of output signal；
Fig. 2 B is the waveform diagram that corresponding diagram 1C impedance ground detects output signal；
Fig. 3 is the circuit box schematic diagram of footing impedance measuring apparatus of the present invention；
Fig. 4 A is the circuit diagram that DC power generating circuit of the present invention is a DC current source embodiment；
Fig. 4 B is the circuit diagram that DC power generating circuit of the present invention is a DC voltage source embodiment；
Fig. 4 C is the circuit diagram of DC power generating circuit first embodiment of the present invention；
Fig. 4 D is the circuit diagram of DC power generating circuit second embodiment of the present invention；
Fig. 5 is the circuit diagram of DC voltage detection circuit preferred embodiment of the present invention；
Fig. 6 is microprocessor applications of the present invention in the circuit block diagram of footing impedance measuring apparatus；
Fig. 7 is the detailed circuit diagram that footing impedance measuring apparatus of the present invention is applied to alternating current source；And
Fig. 8 is the flow chart of footing impedance measuring apparatus operating method of the present invention.
Wherein, the reference numerals are as follows:
Rg impedance ground
Op optic coupling element
Q1 transistor switch
R1 resistance
R2 resistance
Pa exit point
10 DC power generating circuits
20 DC voltage detection circuits
202 differential amplifier circuits
204 low-pass filter circuits
206 gain adjustment circuits
30 microprocessors
Ss alternating current source
Sc equipment input terminal
Ls1~Lsn alternating current source firewire
The Ns alternating current source neutral conductor
Lc1~Lcn equipment input terminal firewire
Nc equipment neutral input terminal line
Vdc_RgDC impedance voltage
Idc_RgDC impedance electric current
Rg impedance ground
PE equipment ground point
PEs power supply grounding point
D1~Dn+1 diode
Rdc resistance
Idc DC current
Op_dif differential operational amplifier
Op_fit operational amplifier
Op_gain operational amplifier
Vdif differential voltage
V*dc_RgAdjust DC impedance voltage
S10~S40 step
Specific embodiment
Hereby the technical content and a detailed description for the present invention, cooperation schema are described as follows:
Please refer to the circuit box schematic diagram that Fig. 3 is footing impedance measuring apparatus of the present invention.The footing impedance measuring apparatus
It is the size applied to an impedance ground Rg between the power supply of one equipment ground point PE of measurement and one grounding point PEs.The impedance ground
Measuring device is electrically connected at the equipment input terminal Sc that alternating current source Ss corresponds to phase sequence.In other words, when the AC power source
When for a three-phase four wire system, which has three firewire Ls1~Ls3 and a neutral conductor Ns, the equipment defeated
Enter to hold Sc to be also correspondingly arranged on three firewire Lc1~Lc3 and a neutral conductor Nc.Similarly, when the AC power source is a three-phase three
When linear system is united, which there is three firewire Ls1~Ls3, equipment input terminal Sc to be also correspondingly arranged on three fire
Line Lc1~Lc3.It is worth mentioning, this case footing impedance measuring apparatus can be applied to n phase electric system.Furthermore due to the exchange
Power end Ss and the usually remote distance of equipment input terminal Sc, few then hundreds of meters, more then dozens of kilometres differ, because
This, it is to be disposed adjacent that Fig. 3 illustrates the alternating current source Ss non-with equipment input terminal Sc with double wave wave symbol (≈).Similarly, with
Double wave wave symbol (≈) is illustrated non-between equipment ground point PE and power supply grounding point PEs to be to be disposed adjacent.
The footing impedance measuring apparatus mainly includes a DC power generating circuit 10 and a DC voltage detection circuit 20.
The DC power generating circuit 10 is electrically connected between the equipment input terminal Sc and equipment ground point PE.More specifically,
The side of the DC power generating circuit 10 is electrically connected the route of each phase sequence of equipment input terminal Sc, and the other side is electrical
Connect equipment ground point PE.By taking Fig. 3 as an example, the side of the DC power generating circuit 10 be electrically connected the firewire Lc1~
Lc3 and neutral conductor Nc, and the other side is electrically connected equipment ground point PE.The DC voltage detection circuit 20 is electrically connected
The equipment input terminal Sc and equipment ground point PE, in other words, the side of the DC voltage detection circuit 20 is electrically connected this and sets
The route of the standby any phase sequence of input terminal Sc, and the other side is electrically connected equipment ground point PE.By taking Fig. 3 as an example, the direct current
The side of pressure detection circuit 20 is electrically connected wherein one of the firewire Lc1~Lc3 and neutral conductor Nc.In the present embodiment
In, the side of the DC voltage detection circuit 20 is electrically connected firewire Lc2, therefore, connects remaining described firewire and the neutrality
Line Nc is to be showed with dotted line, and the other side is electrically connected equipment ground point PE.It is worth mentioning, the DC voltage in the present invention
Detection circuit 20 need to connect any phase sequence firewire or neutral conductor Nc.
The DC power generating circuit 10 can be a DC voltage generation circuit or the raw circuit of direct current miscarriage, to generate
The voltage or electric current of dc component.The DC power generating circuit 10 is the power supply for generating dc component, which can be
The both ends impedance ground Rg generate a DC impedance voltage Vdc_RgAnd flow through mono- DC impedance electric current of impedance ground Rg
Idc_Rg.If the DC power supply is a DC current source, the DC impedance electric current I of impedance ground Rg is injecteddc_RgFor
Know, furthermore, due to dc component (DC components) sum of zero, the DC impedance voltage in entire ac power supply circuit
Vdc_RgFirewire Lc1~Lc3 of the size equal to equipment input terminal Sc wherein a phase or neutral conductor Nc and the equipment ground
DC voltage difference between point PE therefore can be by measuring firewire Lc1~Lc3 wherein one at equipment input terminal Sc
Mutually or the DC voltage difference between neutral conductor Nc and equipment ground point PE, you can get it the both ends impedance ground Rg should
DC impedance voltage Vdc_Rg, DC voltage difference without directly measuring the power supply ground terminal PEs Yu equipment ground end PE.
So by calculating DC impedance voltage Vdc_RgWith DC impedance electric current Idc_RgRatio, the equipment ground can be obtained
The size of impedance ground Rg between point PE (user terminal) and distal end power supply grounding point PEs.If the DC power generating circuit
10 be to generate a DC voltage source, then the size of impedance ground Rg can be calculated using simple partial pressure theorem.
If by taking the DC power generating circuit 10 is the DC current generation circuit as an example, the DC power generating circuit 10
It is to generate a DC current Idc, and DC current Idc injects impedance ground Rg as DC impedance electric current Idc_Rg,
And DC impedance voltage V is generated at the both ends impedance ground Rgdc_Rg。
It is worth mentioning, it is not limitation with above-described embodiment that actual circuit, which is applied upper, and in other words, which generates
The input side and outlet side of circuit 10 can also be electrically connected at wantonly two in the firewire Lc1~Lc3 and neutral conductor Nc
Between person, then cooperates and outlet side is connected to equipment ground point PE, by the voltage or electric current of the generated dc component,
It similarly may be implemented to accurately calculate the impedance ground Rg between equipment ground point PE and distal end power supply grounding point PEs
Size.
As for the detailed circuit and its mode of operation of the DC power generating circuit 10 and the DC voltage detection circuit 20,
It will be in further specified hereinafter.
In the present invention, which can be a DC current source or a DC voltage source.It please refers to
Fig. 4 A is the circuit diagram of the DC current source embodiment for DC power generating circuit of the present invention.From the above, the DC power supply
Generation circuit 10 is electrically connected between the equipment input terminal Sc and equipment ground point PE, directly to receive the equipment input terminal
The alternating voltage of Sc.Therefore, the alternating voltage that equipment input terminal Sc is converted by the DC power generating circuit 10, can be defeated
A DC current Idc out.In addition, it is a DC voltage source embodiment that please refer to Fig. 4 B, which be DC power generating circuit of the present invention,
Circuit diagram.As described above, the DC power generating circuit 10 directly receives the alternating voltage of equipment input terminal Sc, and convert
The alternating voltage of equipment input terminal Sc and export a DC voltage Vdc.Wherein, it is pure straight to be not limited to one by DC voltage Vdc
Galvanic electricity pressure, also can for one it is rectified and/or filtering after a resulting DC voltage.Fig. 4 C is please referred to as the DC power supply of the invention
The circuit diagram of generation circuit first embodiment.The DC power generating circuit 10 includes multiple diode D1~Dn+1 and a resistance
Rdc.Multiple diode D1~Dn+1 is the corresponding three firewire Lc1~Lc3 for being electrically connected at equipment input terminal Sc
With neutral conductor Nc.By taking Fig. 4 C as an example, the anode tap of multiple diode D1~Dn+1 is that the corresponding equipment that is electrically connected inputs
Hold the three firewire Lc1~Lc3 and neutral conductor Nc of Sc.One end of resistance Rdc is to be electrically connected multiple diode
The cathode terminal of D1~Dn+1.Due to the connection framework of multiple diode D1~Dn+1 and resistance Rdc, when the equipment
The alternating voltage of input terminal Sc is after multiple diode D1~Dn+1, it will is rectified into a DC voltage source, and passes through
It crosses resistance Rdc and is connected to equipment ground point PE.It therefore, can be real by multiple diode D1~Dn+1 and resistance Rdc
Existing DC power generating circuit.It is worth mentioning, above-described embodiment also need to can only use single diode, the correspondingly connected equipment
A wherein phase of input terminal Sc, to generate a dc component power supply.In the present embodiment, since diode D2 is with right
Firewire Lc2 should be connected, therefore, is expressed with solid line in figure 4 c；Conversely, remaining multiple diode then can with dotted line expression
It is selectively connected the firewire and neutral conductor Nc.
Please refer to the circuit diagram that Fig. 4 D is the DC power generating circuit second embodiment of the invention.Fig. 4 D and Fig. 4 C is maximum
Difference be that the cathode terminal of multiple diode D1~Dn+1 is corresponding described three for being electrically connected equipment input terminal Sc
Firewire Lc1~Lc3 and neutral conductor Nc.One end of resistance Rdc is electrically connected the anode tap of multiple diode D1~Dn+1.
Due to the reversing of multiple diode D1~Dn+1, when the alternating voltage of equipment input terminal Sc is by multiple
After diode D1~Dn+1, it will be rectified into DC voltage source, and connect by resistance Rdc with the equipment ground point.
The difference of the second embodiment and the aforementioned first embodiment is only that direction and Fig. 4 C direct current of DC current Idc
Flow the contrary of Idc.In other words, Fig. 4 C is corresponding with Fig. 4 D these diodes D1~Dn+1 rectifies equipment input terminal Sc's
Positive and negative half cycle alternating voltage generates the DC power supply using resistance Rdc.So passing through multiple diode D1~Dn+1
It is same as resistance Rdc that DC power generating circuit can be achieved.
It is worth mentioning, in the present invention, although only providing Fig. 4 C and two kinds of embodiments of Fig. 4 D, however, in practical applications,
The DC power generating circuit 10 can be used and can convert alternating voltage and be realized by the circuit of DC current or DC voltage, example
As current mirroring circuit (current mirror circuit) or other from design circuit, therefore, not with Fig. 4 C and Fig. 4 D circuit
For limitation.
Please refer to the circuit diagram that Fig. 5 is the DC voltage detection circuit preferred embodiment of the invention.DC voltage detection
Circuit 20 mainly includes a differential amplifier circuit 202 and a low-pass filter circuit 204.The differential amplifier circuit 202 is poor by one
Operational amplifier Op_dif, multiple resistance and multiple capacitors is divided to be formed.More specifically, differential operational amplifier Op_
Dif has an inverting input terminal and a non-inverting input, which is electrically connected equipment ground point PE；This is anti-
Phase input terminal is electrically connected the firewire Lc1~Lc3 or neutral conductor Nc wherein one of equipment input terminal Sc.The difference is put
Big circuit 202 be to capture firewire Lc1~Lc3 wherein a phase or the voltage difference of neutral conductor Nc and equipment ground point PE,
To export a differential voltage Vdif.The low-pass filter circuit 204 is electrically connected the differential amplifier circuit 202.Low-pass filtering electricity
Road 204 is made of an operational amplifier Op_fit, multiple resistance and multiple capacitors.More specifically, the operation amplifier
Device Op_fit has an inverting input terminal and a non-inverting input, which is electrically connected calculus of differences amplification
Device Op_dif, to receive differential voltage Vdif.Operational amplifier Op_fit is to capture the straight of differential voltage Vdif
Composition is flowed, in other words, it is DC impedance voltage V that operational amplifier Op_fit, which exports the dc component voltage,dc_Rg。
Therefore, when the DC voltage detection circuit 20 obtains DC impedance voltage Vdc_RgAfterwards, it may be output to a micro process
Device 30 carries out operation, can accurately calculate the size of impedance ground Rg.
In addition, the DC voltage detection circuit 20 further includes a gain adjustment circuit 206, and the gain adjustment circuit
206 are electrically connected between the low-pass filter circuit 204 and the microprocessor 30.The gain adjustment circuit 206 is put by an operation
Big device Op_gain is formed with multiple resistance.More specifically, operational amplifier Op_gain have an inverting input terminal with
One non-inverting input, the non-inverting input are electrically connected operational amplifier Op_fit, to receive the DC impedance voltage
Vdc_Rg.The gain adjustment circuit 206 is to adjust DC impedance voltage Vdc_RgGain be a DC impedance voltage V*dc_Rg,
So that DC impedance voltage V* adjusteddc_RgSuitable for voltage signal size or letter handled by the microprocessor 30 of rear end
Number resolution (resolution).
Please referring to Fig. 6 is microprocessor applications of the present invention in the circuit block diagram of footing impedance measuring apparatus.Due to the friendship
Galvanic electricity source size is upset condition, therefore the microprocessor 30 receives the AC information of equipment input terminal Sc, and root
It is changed according to the alternating voltage, corresponding output DC impedance voltage Vdc_RgOr DC impedance voltage V*dc_Rg, so that calculating
The impedance ground Rg size come maintains definite value, is not influenced by alternating voltage variation.
Please referring to Fig. 7 is the detailed circuit diagram that the footing impedance measuring apparatus of the invention is applied to alternating current source.At this
In figure, mainly by the DC voltage detection circuit 20 of the DC power generating circuit 10 of Fig. 4 C and Fig. 5 specifically in Fig. 3
Middle exposure, a preferred embodiment of this case footing impedance measuring apparatus.So, from the above, the DC power generating circuit 10
Can have a different embodiments, and or the DC voltage detection circuit 20 can be also implemented with equivalent circuit.It is worth mentioning,
In the preferred embodiment, non-inverting input provided by the differential amplifier circuit 202 of the DC voltage detection circuit 20
End connection equipment ground point PE；In addition, the inverting input terminal provided by the differential amplifier circuit 202 can connect the firewire
Lc1~Lc3 wherein voltage of a phase or neutral conductor Nc.In fig. 7, it is with the anti-phase input of the differential amplifier circuit 202
For end connection firewire Lc2.In other words, which is to capture firewire Lc1~Lc3 wherein phase
The voltage difference of voltage or neutral conductor Nc and equipment ground point PE, and pass through the processing of the DC voltage detection circuit 20, it obtains
Obtain DC impedance voltage Vdc_RgOr adjustment DC impedance voltage V*dc_Rg。
So the major technique spirit of this case, which focuses on, designs the footing impedance measuring apparatus, and pass through the impedance ground
The alternating voltage of equipment input terminal Sc is converted to a DC voltage by the DC power generating circuit 10 of measuring device, so that
DC impedance voltage V is generated at the both ends impedance ground Rgdc_Rg.Recycle the dc component sum of zero of ac power supply circuit
Characteristic so that a direct current between the equipment input terminal and equipment ground point measured by the DC voltage detection circuit 20
Pressure difference is equal to DC impedance voltage Vdc_RgThe equipment can be so precisely calculated by the microprocessor and connect for size
The size of impedance ground Rg between place PE (user terminal) and distal end power supply grounding point PEs.
Finally, please referring to the flow chart that Fig. 8 is footing impedance measuring apparatus operating method of the present invention.The grid grounding impedance measurement
Device operating method, the size of the impedance ground applied to one alternating current source of measurement, and be electrically connected and the AC power source
Hold the equipment input terminal and equipment ground point of corresponding phase sequence.The step of operating method includes: firstly, providing a direct current
Source generating circuit is electrically connected the equipment input terminal and the equipment ground point, to receive an AC power source of the equipment input terminal
(S10).When the AC power source is a three-phase four wire system, which has three firewires and a neutral conductor, should
Equipment input terminal is also correspondingly arranged on three firewires and a neutral conductor.It, should when the AC power source is a three-phase three wire system
Alternating current source has three firewires, which is also correspondingly arranged on three firewires.
Then, the AC power source is converted as a DC power supply, which makes the impedance ground both ends generate a direct current
Impedance voltage (S20).In the present invention, which can be a DC current source or a DC voltage source.It should
DC power generating circuit is electrically connected between the equipment input terminal and equipment ground point, directly to receive equipment input
The alternating voltage at end.Therefore, the alternating voltage of the equipment input terminal is converted by the DC power generating circuit, can export one
DC current or the DC power generating circuit directly receive the alternating voltage of the equipment input terminal, and convert the equipment
The alternating voltage of input terminal and export a DC voltage.Wherein, DC voltage Vdc is not limited to a pure DC voltage, also may be used
For one it is rectified and/or filtering after a resulting DC voltage.
A DC voltage detection circuit is provided, to measure the direct current between the equipment input terminal and the equipment ground point
Pressure difference (S30).The DC voltage detection circuit mainly includes a differential amplifier circuit and a low-pass filter circuit.The difference is put
Big circuit is made of a differential operational amplifier, multiple resistance and multiple capacitors.More specifically, which amplifies
Device has an inverting input terminal and a non-inverting input, which is electrically connected the equipment ground point；The reverse phase
Input terminal is electrically connected the firewire wherein one of the equipment input terminal.The differential amplifier circuit is to capture the firewire wherein
The voltage difference of the voltage of one phase and the equipment ground point, to export a differential voltage.The low-pass filter circuit is electrically connected the difference
Divide amplifying circuit.The low-pass filter circuit is made of an operational amplifier, multiple resistance and multiple capacitors.It is more specific and
Speech, the operational amplifier have an inverting input terminal and a non-inverting input, which is electrically connected the difference
Operational amplifier, to receive the differential voltage.The operational amplifier is the dc component to capture the differential voltage, changes speech
It, it is the DC impedance voltage which, which exports the dc component voltage,.
Finally, the characteristic of the dc component sum of zero using ac power supply circuit, which is equal to this
DC impedance voltage of impedance ground, to calculate and detect the impedance ground size (S40).When the DC voltage detects electricity
After road obtains the DC impedance voltage, it may be output to a microprocessor and carry out operation.More specifically, which, which calculates, is somebody's turn to do
DC impedance voltage and the DC impedance electric current for flowing through the impedance ground, that is, the DC current, can accurately calculate
The size of the impedance ground.
In addition, the DC voltage detection circuit further includes a gain adjustment circuit, and the gain adjustment circuit electrically connects
It is connected between the low-pass filter circuit and the microprocessor.The gain adjustment circuit is by an operational amplifier and multiple resistance institutes
Composition.More specifically, which has an inverting input terminal and a non-inverting input, non-inverting input electricity
Property connects the operational amplifier, to receive the DC impedance voltage.The gain adjustment circuit is to adjust the DC impedance voltage
Gain be a DC impedance voltage so that the DC impedance voltage adjusted be suitable for the rear end microprocessor handled by
Voltage signal size or signal resolution degree (resolution).
In conclusion the present invention has the advantage that
1, since the footing impedance measuring apparatus can be applied to multi-phase power system, impedance ground survey can be improved
Measure the adaptability and obdurability of device application；
2, the DC power generating circuit 10 is designed using passive electronic component, can reduce circuit development cost and letter
Change the design of control circuit；
3, using the characteristic of the dc component sum of zero of ac power supply circuit, and pass through measurement equipment input terminal Sc
A direct current pressure difference is equal to DC impedance voltage V between equipment ground point PEdc_Rg, the DC power supply is cooperated to generate electricity
Equipment ground point PE can be precisely calculated by the microprocessor and (used for the known electric potential source or current source that road 10 generates
Family end) and distal end power supply grounding point PEs between impedance ground Rg size, and small impedance value can be accurately detected out
Impedance ground Rg；And
4, the leakage current for flowing back to ground wire is small, is capable of providing the protection of human body and electrical equipment.
The above, the detailed description and schema of preferred embodiment only of the present invention, however feature of the invention is simultaneously
It is not limited to this, it is not intended to limit the invention, all ranges of the invention should be subject to following claims, all together in this
The embodiment of spirit variation similar with its of invention claim, should all be included in scope of the invention, any this field skill
Art personnel within the field of the present invention, can think easily and changes or modifications can all cover the scope of the patents in following this case.
Claims (22)
1. a kind of footing impedance measuring apparatus is electrically connected at the equipment input terminal for providing an AC power source and an equipment ground
Between point, to measure the size of an impedance ground of the alternating current source, which includes:
One DC power generating circuit is electrically connected the equipment input terminal and the equipment ground point, to receive the AC power source, and
Be converted to a DC power supply；The DC power supply makes the impedance ground both ends generate a DC impedance voltage；And
One DC voltage detection circuit is electrically connected the equipment input terminal and the equipment ground point, to measure the equipment input terminal
With the direct current pressure difference between the equipment ground point；
Wherein, using the characteristic of the flip-flop sum of zero of ac power supply circuit, which is equal to the ground connection
DC impedance voltage of impedance, to calculate and detect the impedance ground size.
2. footing impedance measuring apparatus as described in claim 1, wherein the DC power generating circuit includes:
An at least diode is electrically connected the equipment input terminal；And
One resistance is electrically connected an at least diode.
3. footing impedance measuring apparatus as claimed in claim 2 wherein the cathode terminal of the diode is electrically connected to each other, then connects
Connect one end of the resistance；The anode tap of the diode is corresponding to be electrically connected the equipment input terminal.
4. footing impedance measuring apparatus as claimed in claim 2 wherein the anode tap of the diode is electrically connected to each other, then connects
Connect one end of the resistance；The cathode terminal of the diode is corresponding to be electrically connected the equipment input terminal.
5. footing impedance measuring apparatus as described in claim 1, wherein the DC power generating circuit generates a DC voltage source.
6. footing impedance measuring apparatus as claimed in claim 5, also includes:
One microprocessor receives the DC impedance voltage, and calculates this according to the DC voltage source and the DC impedance voltage
Impedance ground size.
7. footing impedance measuring apparatus as described in claim 1, wherein the DC power generating circuit generates a DC current source.
8. footing impedance measuring apparatus as claimed in claim 7, also includes:
One microprocessor receives the DC impedance voltage, and calculates the ratio of the DC impedance voltage and the DC current source, with
Calculate the impedance ground size.
9. footing impedance measuring apparatus as described in claim 1, wherein the DC voltage detection circuit includes:
One differential amplifier circuit, including a differential operational amplifier, multiple resistance and multiple capacitors；The differential operational amplifier
Corresponding wherein a firewire or the neutral conductor for being electrically connected the equipment ground point and the equipment input terminal of two input terminals, to capture this
The voltage difference of the voltage of firewire and the equipment ground point, and then export a differential voltage；And
One low-pass filter circuit, including an operational amplifier, multiple resistance and multiple capacitors；The low-pass filter circuit receives should
Differential voltage and the differential voltage is filtered, to obtain the DC impedance voltage.
10. footing impedance measuring apparatus as claimed in claim 9, the wherein DC voltage detection circuit further include:
One gain adjustment circuit, including an operational amplifier and multiple resistance；The gain adjustment circuit receives DC impedance electricity
Pressure is an adjustment DC impedance voltage to adjust the gain of the DC impedance voltage.
11. the footing impedance measuring apparatus as described in claim 6 or 8, wherein the microprocessor changes shape according to the AC power source
Condition, corresponding received DC impedance voltage, so that the impedance ground size calculated maintains definite value.
12. a kind of footing impedance measuring apparatus operating method, the size of the impedance ground applied to one alternating current source of measurement,
And be electrically connected between the equipment input terminal and equipment ground point that an AC power source is provided, the step of operating method, wraps
It includes:
(a) DC power generating circuit is provided, the equipment input terminal and the equipment ground point are electrically connected at, to receive the friendship
Galvanic electricity source；
(b) AC power source is converted as a DC power supply, which makes the impedance ground both ends generate DC impedance electricity
Pressure；
(c) a DC voltage detection circuit is provided, to measure a DC voltage between the equipment input terminal and the equipment ground point
Difference；And
(d) using the characteristic of the flip-flop sum of zero of ac power supply circuit, which is equal to direct current resistance
Reactance voltage, to calculate and detect the impedance ground size.
13. footing impedance measuring apparatus operating method as claimed in claim 12, wherein the DC power generating circuit includes:
An at least diode is electrically connected the equipment input terminal；And
One resistance is electrically connected an at least diode.
14. footing impedance measuring apparatus operating method as claimed in claim 13, wherein the cathode terminal of the diode is electric each other
Property connection, reconnect one end of the resistance；The anode tap of the diode is corresponding to be electrically connected the equipment input terminal.
15. footing impedance measuring apparatus operating method as claimed in claim 13, wherein the anode tap of the diode is electric each other
Property connection, reconnect one end of the resistance；The cathode terminal of the diode is corresponding to be electrically connected the equipment input terminal.
16. footing impedance measuring apparatus operating method as claimed in claim 12, wherein the DC power generating circuit generates one
DC voltage source.
17. footing impedance measuring apparatus operating method as claimed in claim 16, also includes:
One microprocessor is provided, receives the DC impedance voltage, and calculate according to the DC voltage source and the DC impedance voltage
The impedance ground size out.
18. footing impedance measuring apparatus operating method as claimed in claim 12, wherein the DC power generating circuit generates one
DC current source.
19. footing impedance measuring apparatus operating method as claimed in claim 18, also includes:
One microprocessor is provided, the DC impedance voltage is received, and calculates the DC impedance voltage and the ratio of the DC current source
Value, to calculate the impedance ground size.
20. footing impedance measuring apparatus operating method as claimed in claim 12, wherein the DC voltage detection circuit includes:
One differential amplifier circuit, including a differential operational amplifier, multiple resistance and multiple capacitors；The differential operational amplifier
Corresponding wherein a firewire or the neutral conductor for being electrically connected the equipment ground point and the equipment input terminal of two input terminals, to capture this
The voltage difference of the voltage of firewire and the equipment ground point, and then export a differential voltage；And
One low-pass filter circuit, including an operational amplifier, multiple resistance and multiple capacitors；The low-pass filter circuit receives should
Differential voltage and the differential voltage is filtered, to obtain the DC impedance voltage.
21. footing impedance measuring apparatus operating method as claimed in claim 20, the wherein DC voltage detection circuit further include:
One gain adjustment circuit, including an operational amplifier and multiple resistance；The gain adjustment circuit receives DC impedance electricity
Pressure is an adjustment DC impedance voltage to adjust the gain of the DC impedance voltage.
22. the footing impedance measuring apparatus operating method as described in claim 17 or 19, wherein the microprocessor is according to the exchange
Power supply variation, corresponding received DC impedance voltage, so that the impedance ground size calculated maintains definite value.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201410658171.3A CN105675998B (en) | 2014-11-18 | 2014-11-18 | Footing impedance measuring apparatus and its operating method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410658171.3A CN105675998B (en) | 2014-11-18 | 2014-11-18 | Footing impedance measuring apparatus and its operating method |
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| CN105675998A CN105675998A (en) | 2016-06-15 |
| CN105675998B true CN105675998B (en) | 2019-05-17 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107328997A (en) * | 2017-07-10 | 2017-11-07 | 西安兴汇电力科技有限公司 | A kind of grid grounding impedance measurement method |
| KR102254776B1 (en) * | 2019-10-14 | 2021-05-24 | 주식회사 민테크 | Impedance measuring device |
| CN111308206B (en) * | 2020-02-21 | 2022-04-15 | 苏州华兴源创科技股份有限公司 | Impedance detection device and detection method thereof |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6281664B1 (en) * | 1999-01-13 | 2001-08-28 | Honda Giken Kogyo Kabushiki Kaisha | Generator and generator apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5576960A (en) * | 1978-12-06 | 1980-06-10 | Masami Fujii | Method of measuring low grounding resistance |
| FR2655156B1 (en) * | 1989-11-24 | 1992-01-10 | Merlin Gerin | PERMANENT CONTROL SYSTEM FOR THE ELECTRICAL CONDUCTION OF A NETWORK. |
| CN201281729Y (en) * | 2008-09-11 | 2009-07-29 | 中国北车集团大同电力机车有限责任公司 | Grounding resistance tester |
| US9046560B2 (en) * | 2012-06-04 | 2015-06-02 | Eaton Corporation | System and method for high resistance ground fault detection and protection in power distribution systems |
| JP6126930B2 (en) * | 2013-07-19 | 2017-05-10 | 矢崎総業株式会社 | Insulation state detector |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6281664B1 (en) * | 1999-01-13 | 2001-08-28 | Honda Giken Kogyo Kabushiki Kaisha | Generator and generator apparatus |
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