CN116338556A - Error tracing device and method for wide-range standard current transformer - Google Patents
Error tracing device and method for wide-range standard current transformer Download PDFInfo
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Abstract
The invention discloses an error tracing device and method of a wide-range standard current transformer, wherein the error tracing device of the wide-range standard current transformer is arranged on the periphery of the wide-range standard current transformer; the error tracing method of the wide-range standard current transformer is also provided, and the error under the condition of measuring rated current by adopting sectional tracing is adopted. The invention shields the whole secondary coil of the wide-range standard current transformer on one hand, and adds the isolation transformer between the voltage regulator and the current booster on the other hand, thereby reducing the influence of the stray capacitance of the whole system on the measurement error under 0.1-1% of rated current and realizing the accurate measurement and tracing of the wide-range current transformer within the range of 0.1-200% of rated current.
Description
Technical Field
The invention relates to the field of wide-range standard current transformers, in particular to an error tracing device and method of a wide-range standard current transformer.
Background
With the high proliferation of urban residents and the rapid development of urban industry, the electricity load of urban power grids is increased year by year, the highest accuracy level of a current transformer for metering adopted in a current power system is 0.2S level, in fact, the variation range of the load of a plurality of users is very large, the current transformer often works under extremely small current and overload current, the measurement requirements of large current signals and small current signals cannot be met at the same time, and the secondary induction current of the transformer is far smaller than the current value which should be used for metering, so that the metering deviation of electric charge is caused;
mutual inductor technical Specification section 1 for Q/GDW 10572.1-2020: the accurate level 0.5SS and 0.2SS of the wide-range current transformer are newly added in the low-voltage current transformer, and the range of the internal error limit value is between 0.1 and 200 percent of rated current; however, the accurate measurement of the wide-range current transformer is a problem to be solved in the field urgently at present due to the range limitation of the error verification system.
Disclosure of Invention
This section is intended to outline some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section as well as in the description summary and in the title of the application, to avoid obscuring the purpose of this section, the description summary and the title of the invention, which should not be used to limit the scope of the invention.
The present invention has been made in view of the above and/or problems with the metering of existing wide-range current transformers.
Therefore, the invention aims to solve the problem of providing an error tracing device of a wide-range standard current transformer and providing a tracing method for verifying the wide-range current transformer.
In order to solve the technical problems, the invention provides the following technical scheme:
in a first aspect, an embodiment of the present invention provides an error tracing apparatus for a wide-range standard current transformer, where the apparatus is disposed on a wide-range standard current transformer T 0 Peripheral, the error traceability device is characterized in that: the wide-range standard current transformer T 0 The device comprises an iron core, a coil assembly, a shielding layer, an insulating layer and a box body; the iron core comprises a main iron core and a shielding iron core, the shielding iron core is arranged outside the main iron core and comprises an inner shielding iron core, an outer shielding iron core, an upper shielding iron core and a lower shielding iron core; the coil assembly comprises a compensation coil uniformly wound on the main iron core, a primary coil wound on the shielding iron core, and a secondary coil wound on the primary coil, wherein the tap of the primary coil
The other taps of the primary coil are all nonpolar terminals, the taps of the secondary coil are +.>
Is a polar endThe other taps of the secondary coil are all nonpolar ends; the polarity end and the nonpolar end of the compensation coil are connected into the corresponding secondary coils according to the requirements of the zero magnetic flux compensation technology, and the compensation coil and the secondary coils are led out by shielding wires; the shielding layer is arranged between the secondary coil and the primary coil, and the outgoing line of the shielding layer is grounded; the insulating layer is arranged on the outer side of the iron core, and the coil assemblies are all provided with interlayer insulating layers; the primary coil and the secondary coil are in a multi-winding form; error traceability device includes voltage regulator T 1 Flow rising device T 2 Compensation type current comparator T 3 Error measuring device HE, current load box Z, voltage source zeroing device S and two-stage current transformer +.>
The voltage regulator T 1 The output end is connected with an isolation transformer T s Is connected with the input end of the isolation transformer T s The output end of (1) is connected with a current booster T 2 And the low voltage side of the output end is grounded; the upflow device T 2 The output ends of the (B) are respectively connected with a wide-range standard current transformer T 0 Primary coil non-polar end and compensation type current comparator T 3 Is a non-polar end of the primary coil; the wide-range standard current transformer T 0 The primary coil polarity end of (C) is connected with a compensation type current comparator T 3 Is arranged at the primary coil polarity end; the compensation type current comparator T 3 The polarity end of the primary compensation coil of (a) is connected with a compensation type current comparator T 3 And a compensation type current comparator T 3 The non-polar end of the primary compensation coil of (a) is grounded.
Another object of the present invention is to provide an error tracing method for a wide-range standard current transformer, including: the method adopts sectional tracing to measure the error under the condition of rated current, including the error under the condition of 0.1-120% of rated current and the error under the condition of 120-200% of rated current.
As a preferable scheme of the error tracing method of the wide-range standard current transformer, the invention comprises the following steps: 0.1% -120% of rated value is measuredConnection of errors in the current situation, including, compensation current comparator T 3 Polar ends of secondary coil and secondary compensation coil of (C) and wide-range standard current transformer T 0 After the polarity end of the secondary coil is connected, the differential flow signal is connected to the K terminal of the error measuring device HE from the polarity end of the compensation coil; wide-range standard current transformer T 0 The non-polar end of the secondary coil of the (E) is connected with a current load box Z and then is connected with an error measuring device HE
Terminal, compensation type current comparator T 3 Is connected with the non-polar end of the secondary coil of the transformer 0 The terminal, the nonpolar end of the secondary compensation coil is connected with the voltage source zeroing device S and then connected with the D terminal of the error measuring device HE; the transmission line of the differential stream signal is a shielding line, and the outgoing line of the shielding layer is connected with the D terminal of the error measuring device HE, and the D terminal is connected with the grounding end of the error measuring device HE.
As a preferable scheme of the error tracing method of the wide-range standard current transformer, the invention comprises the following steps: the operation steps for measuring the error under the condition of 0.1-120% rated current comprise the steps of adjusting the voltage regulator T 1 Output voltage change up-converter T of (a) 2 Outputting current to make the current percentage in the error measuring device HE reach a preset detection point, and regulating the voltage source zeroing device S to make the compensation type current comparator T 3 The voltage on the zero-pointing coil is zero, and the reading in the error measurement device HE is the error value of the wide-range current transformer under the current percentage.
As a preferable scheme of the error tracing method of the wide-range standard current transformer, the invention comprises the following steps: connection for measuring errors under the condition of 120-200% rated current, comprising the following steps of passing through a high-precision two-stage current transformer
Setting up the second stage of the multiplication circuit, the transformation ratio of the second stage is +.>
Wide-range standard current mutualSensor T 0 The polarity end of the secondary coil of the (B) is connected with a two-stage current transformer +.>
The primary coil polarity end of the transformer is connected with a current load box Z and then connected with a two-stage current transformer +.>
Is a non-polar end of the primary coil; double-stage current transformer->
The polarity end of the primary compensation coil is connected with the polarity end of the primary coil, and the nonpolar end is grounded; double-stage current transformer->
The polarity ends of the secondary coil and the compensation coil of the (C) are connected with a compensation type current comparator T 3 After the polarity ends of the secondary coil and the compensation coil, the secondary coil and the compensation coil are connected with a compensation current comparator T 3 The polarity end of the compensation coil of the (2) is connected with a differential flow signal into a K terminal of an error measurement device HE; double-stage current transformer->
Is connected to the non-polar side of the secondary winding of the error measuring device HE>
The non-polar end of the compensation coil is grounded; compensation type current comparator T 3 Is connected to the T of the error measuring device HE by a nonpolar terminal of the secondary coil 0 A terminal, a D terminal of the nonpolar termination error measuring device HE of the compensation coil; the transmission line of the differential stream signal is a shielding line, and the outgoing line of the shielding layer is connected with the D terminal of the error measuring device HE, and the D terminal is connected with the grounding end of the error measuring device HE.
As a preferable scheme of the error tracing method of the wide-range standard current transformer, the invention comprises the following steps: the operation step of measuring the error under the condition of 120-200% rated current comprises the following steps of passing through a voltage regulator T 1 Output-regulated up-converter T 2 Output current, error measuring deviceThe percentage of current shown in HE is set at the actual setpoint
Adjusting the voltage source zeroing means S so that the compensated current comparator T 3 The voltage on the zero-pointing coil is zero, and the reading in the error measuring device HE is the wide-range standard current transformer T 0 At->
Error values at times the current percentage.
As a preferable scheme of the error tracing method of the wide-range standard current transformer, the invention comprises the following steps: compensation type current comparator T 3 The accuracy grade is 0.001 grade; double-stage current transformer
The accuracy rating is 0.001S.
The invention has the beneficial effects that: the invention provides an error tracing device and a method for a wide-range standard current transformer, which are used for shielding the whole secondary coil of the wide-range standard current transformer on one hand and a voltage regulator T on the other hand 1 Adding an isolation transformer T between the current booster and the current booster s The influence of the stray capacitance of the whole system on the measurement error of 0.1-1% of rated current is reduced, and accurate measurement and tracing of the wide-range current transformer in the range of 0.1-200% of rated current are realized.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein:
FIG. 1 shows a wide-range standard current transformer T in embodiment 1 0 Is an internal structural diagram of the (c).
FIG. 2 shows a wide-range standard current transformer in example 1T 0 Is a structural schematic diagram of the (c).
FIG. 3 shows a wide-range standard current transformer T in embodiment 1 0 Error tracing circuit at 0.1% -120% measuring point.
FIG. 4 shows a wide-range standard current transformer T in embodiment 1 0 And (3) an error tracing line at 120% -200% of measurement points.
FIG. 5 shows a wide-range standard current transformer T in embodiment 1 0 Error tracing line is at current ware T that rises 2 And the input end is reversely connected with the wiring diagram.
FIG. 6 shows a wide-range standard current transformer T used in example 2 0 And (5) making a test wiring diagram for standard verification of the wide-range current transformer.
Detailed Description
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways other than those described herein, and persons skilled in the art will readily appreciate that the present invention is not limited to the specific embodiments disclosed below.
Further, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic can be included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
Example 1
Referring to fig. 1 to fig. 5, in a first embodiment of the present invention, an error tracing device for a wide-range standard current transformer is provided, where the wide-range standard current transformer includes: iron core, coil assembly, shielding layer, insulating layer and box.
Wherein the iron core comprises a main iron core and a shielding iron core, and the shielding iron core is provided withThe main iron core is arranged outside the main iron core and comprises an inner shielding iron core, an outer shielding iron core, an upper shielding iron core and a lower shielding iron core; the coil assembly comprises a compensation coil uniformly wound on the main iron core, a primary coil wound on the shielding iron core, and a secondary coil wound on the primary coil, as shown in FIG. 2, the polarity end B of the compensation coil 1 And a nonpolar end B 2 The compensation coil and the secondary coil are led out by shielding wires; the shielding layer is arranged between the secondary coil and the primary coil, and the outgoing line of the shielding layer is grounded; the insulating layer set up in the iron core outside, the coil assembly all is equipped with the interlayer insulating layer.
Furthermore, the invention discloses a wide-range standard current transformer T 0 The whole secondary coil of the transformer is shielded, the outgoing line and the shielding layer are made of copper foil, and the outgoing line of the shielding layer is grounded.
Further, the tap of the primary coil
The other taps L of the primary coil are polar ends 2 ~L N Are all nonpolar ends, tap of secondary coil +.>
The rest taps K of the secondary coil are polar ends 2 ~K M Are all nonpolar ends. Tap B of compensation coil 1 For the polar end, tap B of the compensation coil 2 Is a non-polar end.
Wherein, wide range standard current transformer's error traceability device includes, voltage regulator T 1 Flow rising device T 2 Compensation type current comparator T 3 Error measuring device HE, current load box Z, voltage source zeroing device S and two-stage current transformer
The method comprises the steps of carrying out a first treatment on the surface of the Voltage regulator T 1 The output end is connected with an isolation transformer T s Is connected with the input end of the isolation transformer T s Is connected with the output end of (a)Riser T 2 And the output is grounded at a low voltage side.
Riser T 2 The output ends of the (B) are respectively connected with a wide-range standard current transformer T 0 Primary coil non-polar end and compensation type current comparator T 3 Is a non-polar end of the primary coil.
Wide-range standard current transformer T 0 The primary coil polarity end of (C) is connected with a compensation type current comparator T 3 Is a primary coil polarity terminal, a compensation type current comparator T 3 The polarity end of the primary compensation coil of (a) is connected with a compensation type current comparator T 3 And a compensation type current comparator T 3 The non-polar end of the primary compensation coil of (a) is grounded.
Referring to fig. 3 and fig. 4, the embodiment further provides an error tracing method for a wide-range standard current transformer, which includes the steps of measuring an error under the condition of rated current by adopting sectional tracing, and measuring an error under the condition of 0.1% -120% of rated current and an error under the condition of 120% -200% of rated current.
Wherein, when measuring the error under the condition of 0.1% -120% rated current, a test wiring diagram shown in figure 3 is adopted.
A0.001-level compensation type current comparator is selected as a standard, and a primary coil polarity end of a wide-range standard current transformer and a compensation type current comparator T are adopted 3 Primary coil N of (2) 1 After the polar ends are connected, the nonpolar ends are respectively connected with the current rising device T 2 Is provided.
Compensation type current comparator T 3 Primary compensation coil N of (2) D Polarity termination compensation type current comparator T 3 Primary coil N of (2) 1 Compensation type current comparator T at the polar end of (2) 3 Primary compensation coil N of (2) D Is grounded.
Compensation type current comparator T 3 Secondary coil N of (2) 2 And a secondary compensation coil N B Polar end of (a) and wide-range standard current transformer T 0 After the polar ends of the secondary coils of (2) are connected, the secondary compensation coil N B The polarity end of (1) is connected with the differential flow signal into an error measuring device HEK terminal, shield wire for differential current outgoing line, and D terminal of error measuring device HE.
Wide-range standard current transformer T 0 The non-polar end of the secondary coil of the (E) is connected with a current load box Z and then is connected with an error measuring device HE
And a terminal.
Compensation type current comparator T 3 Secondary coil N of (2) 2 Non-polar terminal access T 0 Terminal, secondary compensation coil N B The nonpolar terminal voltage source zeroing device S is connected to the D terminal of the error measuring device HE, the D terminal is connected with the grounding end of the error measuring device HE and then grounded, wherein the transmission line of the differential flow signal is a shielding line, the outgoing line of the shielding layer is connected with the D terminal of the error measuring device HE, and the D terminal is connected with the grounding end of the error measuring device HE.
Further, compensation type current comparator T 3 Primary loop and wide range standard current transformer T 0 Primary circuits of (1) are connected in series by an up-converter T 2 The working current of the error measuring device HE is controlled by a wide-range standard current transformer T 0 Is provided by the secondary circuit of the compensation type current comparator T 3 N on the zero-pointing coil d When the voltage of the current comparator is zero, the main iron core of the current comparator is in a zero magnetic flux state, and the comparator has almost no error.
Further, the error operation steps under the condition of measuring 0.1% -120% of rated current include:
by adjusting voltage regulator T 1 Output voltage change up-converter T of (a) 2 And outputting current to enable the current percentage in the error measurement device HE to reach a preset detection point.
During testing, the voltage source zeroing device S in the secondary compensation coil loop is regulated to enable the voltage on the zero coil of the compensation current comparator T3 under the corresponding working current test point to be zero, and the reading in the error measuring device HE is the wide-range standard current transformer T 0 Error values at this current percentage.
In the current transformer verification circuit commonly used at present, stray capacitances exist among turns of windings, layers and the whole test system of the current transformer, when the primary circuit is in a normal working state, voltage differences exist at two ends of the stray capacitances, so that leakage current is caused, if the current enters a differential measurement circuit, the error measurement result is influenced, the influence quantity is related to the voltage value on the primary circuit, and the influence quantity is obvious when the measurement is carried out under 0.1% rated current.
Further, voltage regulator T 1 The input end of the power supply is connected with a 220V power frequency power supply, and the output end is connected with a current booster T 2 Riser T 2 The output of the power supply is directly connected with the primary loop, so that the 220V power frequency power supply has direct influence on the voltage value on the primary loop.
In the verification wiring diagram shown in fig. 3, the voltage regulator T 1 And a riser T 2 An isolation transformer with the transformation ratio of 250V/250V is additionally arranged between the two circuits, the low-voltage side of the output end of the isolation transformer is grounded, power supply filtering is realized, the power supply is isolated from the verification circuit, and the voltage value on the primary circuit is reduced, so that the leakage current in the verification circuit is reduced.
When the flow rises T 2 When the input ends are respectively connected in the positive and negative directions, the reverse connection circuit is shown in FIG. 5, and the current direction of the primary loop has two conditions, and the corresponding secondary induced current and differential current also have two flow directions, namely
And->
。
Further, since the space voltage difference and the stray capacitance are unchanged, the generated leakage current remains unchanged.
According to the working principle of the error measuring device HE, a wide-range standard current transformer T 0 The test error of (1) is a differential stream signal flowing into the K end of the error checking instrument
And inflow T 0 The operating current of the terminal->
Ratio of the two components.
At the upflow device T 2 In both the forward and reverse cases, due to leakage current
Is present such that the test error is
Or->
。
Leakage current
Remains substantially unchanged, but the differential stream signal +.>
And operating current->
As the current detection point increases.
According to the proportional relation, the smaller the operating current, the larger the influence amount of the leakage current on the error data, so that the measurement errors caused at the 0.1% and 0.5% detection points cannot be ignored.
If a voltage difference exists between the primary coil loop and the secondary coil loop as shown in fig. 3, the stray capacitance can generate leakage current, if the current enters the differential measurement loop, the error measurement result can be influenced, the smaller the working current is, the larger the influence is, and the influence is the largest when the rated current is 0.1%.
Furthermore, in order to reduce the influence of leakage current on the error measurement of the wide-range standard current transformer, shielding measures are adopted for the whole secondary coil of the wide-range standard current transformer, most of leakage current flows to the ground through shielding, and the leakage current entering the differential current loop is very little, so that the influence of the leakage current on the measurement error caused by stray capacitance is further reduced.
In order to verify the influence of the shielding layer on the 0.01 SS-level wide-range standard current transformer, the current boosters T can be respectively tested at the small current verification point 2 Test errors generated by positive connection and negative connection
And->
Additional error when due to leakage current in both the positive and reverse connection case +.>
Does not exceed the detected current transformer +.>
At 1/10 of the error limit, the additional error that is expected to occur is negligible.
The method is also suitable for a test line based on the wide-range standard current transformer serving as a standard verification current transformer.
Further, when the error is measured under the condition of 120% -200% rated current, a test wiring diagram shown in fig. 4 is adopted.
Further, compensation type current comparator T 3 The accuracy rating is 0.001.
Through a high-precision two-stage current transformer
Setting up the second stage of the multiplication circuit, the transformation ratio of the second stage is +.>
Wide-range standard current transformer T 0 Is connected to the two-stage current transformer by the polarity of the secondary coil>
The polarity end of the primary coil of the wide-range standard current transformer is connected with the two-stage current transformer after the non-polarity end of the secondary coil of the wide-range standard current transformer is connected with the current load box Z/>
Is a non-polar end of the primary coil.
Double-stage current transformer
The polarity end of the primary compensation coil is connected with the polarity end of the primary coil, and the nonpolar end of the primary compensation coil is connected with the ground.
The existing error measurement system is basically designed according to 120% rated current, and the conditions that the measurement accuracy is affected and even equipment is damaged due to current overload can occur at 150% and 200% detection points.
Therefore, a multiplication circuit is adopted in the tracing method, namely, a wide-range standard current transformer is used for cascading a two-stage current transformer, and the two-stage current transformer is used for cascading the two-stage current transformer
Is->
The general test is 25A/5A or 10A/5A, and the compensation type current comparator T 3 Is +.>
The transformation ratio of the double wide-range standard current transformer.
The transformation ratio of the standard equipment and the detected equipment is the same, the wide-range standard current transformer reduces the secondary loop current in a cascading two-stage current transformer mode, and the error measuring device HE and the compensation type current comparator T are used at the moment 3 And the working current range is not exceeded.
For example, the transformation ratio of the two-stage current transformer cascaded with the wide-range standard current transformer is 10A/5A, namely
And the reading of 100% of measurement points displayed by the error measurement device HE is the error of the wide-range standard current transformer under the condition of 200% of rated current, and the like.
Due to the cascade of doubleThe stage current transformer itself has errors, so the exact stage of the dual stage current transformer needs to be considered. Assume that the current ratio of the wide-range standard current transformer is
Error is->
Current ratio of two-stage current transformer +.>
Error is->
Then, according to the current transfer relation, the specific formula is:
wherein, the liquid crystal display device comprises a liquid crystal display device,
primary current of the wide-range standard current transformer; />
Secondary current of wide-range standard current transformer
Wherein, the secondary current of the wide-range standard current transformer is obtained
As the primary current of the two-stage current transformer,
secondary current output by the two-stage current transformer;
the method can obtain the following steps:
the current ratio of the whole cascade line is thus
Error is->
Neglecting trace +.>
The error of the cascade current transformer is +.>
。
In order to ensure verification accuracy, the accuracy level of the two-stage current transformer is two levels higher than that of the wide-range standard current transformer, and can be ignored.
Therefore, the two-stage current transformer can be selected from 0.001S-stage current transformers and above.
In summary, the error tracing device and the method of the wide-range standard current transformer provided by the invention are used for shielding the whole secondary coil of the wide-range standard current transformer on one hand and on the other hand, the error tracing device and the method of the wide-range standard current transformer are used for shielding the whole secondary coil of the wide-range standard current transformer on the voltage regulator T 1 And a riser T 2 The isolation transformer is added between the two devices, so that the influence of the stray capacitance of the whole system on the measurement error under the rated current of 0.1% -1% is reduced, a specific test scheme of the influence is provided, and the accurate measurement and tracing of the wide-range current transformer in the rated current range of 0.1% -200% are realized.
Example 2
Referring to fig. 6, table 1 and table 2, for the second embodiment of the present invention, in order to verify the advantageous effects thereof, a comparison description of error data with the HLS-20G2 precision current transformer is provided, including an experiment based on a test line using the wide-range standard current transformer of the present invention as a standard verification current transformer and a comparison with the HLS-20G2 precision current transformer.
When the current transformer is detected by adopting the test wiring diagram shown in fig. 6, the wide-range standard current transformer T 0 The wiring taps are mutually connected according to the detected currentSensor(s)
The number of turns of the same current ratio is selected.
Further, the current transformer to be inspected in fig. 6
The accurate level of the current transformer is 0.02S level, and the wide-range standard current transformer T of the invention 0 Is of the order of 0.01 SS.
Wide-range standard current transformer T 0 Current transformer with detected
After the polar ends of the primary coils of the transformer are connected, the non-polar ends are respectively connected with the current rising device T 2 Is provided.
After the polar ends of the secondary coils are connected, the secondary coils are connected with the current transformer to be detected
Leading out a differential flow signal to a K terminal of an error measurement device HE, wherein a shield wire is used for the differential flow lead-out wire, and a shield layer is connected with a D terminal of the error measurement device HE; the D terminal is connected to the ground terminal of the error measurement device HE and then grounded.
Current transformer to be inspected
Is connected to the error measuring device HE after the non-polar access to the current load box Z>
End, wide-range standard current transformer T 0 T of the non-polar termination to the error measuring device HE 0 An end; the reading of the error measuring device HE is the detected current transformer +.>
Error of (2); the method comprises the following steps:
the following table is the error data of the wide-range current transformer with the rated current ratio of 300A/5A, the rated load of 5VA and the power factor of 0.8.
Table 1 error data for calibrating wide range current transformers using HLS-20G2 precision current transformers
Table 2 error data of wide-range current transformers calibrated by adopting the wide-range standard current transformers of the present invention
The comparison data can obviously show that the leakage current has a larger influence on the measurement of the ratio difference of the wide-range current transformer, and the influence quantity of the leakage current on the error measurement is obviously reduced after the wide-range standard current transformer is used.
Table 1 shows that the HLS-20G2 precise current transformer has an additional ratio error of-0.022% caused by leakage current at the 0.1% rated current ratio measuring point, and has a large influence on error measurement.
While as the primary current value increases, the leakage current remains substantially unchanged, so that the additional error caused by it decreases in a proportional relationship, being substantially negligible at the 1% measurement point.
The wide-range standard current transformer of the invention is used, and the voltage regulator in the verification line
And upflow device->
An isolation transformer is additionally arranged between the two>
After grounding, the additional error measured at the 0.1% rated current ratio measurement point in table 2 has been reduced to-0.002%, with substantially negligible impact on the error measurement.
It should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or substituted without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered in the scope of the claims of the present invention.
Claims (7)
1. Error tracing device of wide-range standard current transformer, the device is set up in wide-range standard current transformer T 0 Peripheral, the error traceability device is characterized in that:
the wide-range standard current transformer T 0 The shielding iron core comprises a main iron core and a shielding iron core, wherein the shielding iron core is arranged outside the main iron core and comprises an inner shielding iron core, an outer shielding iron core, an upper shielding iron core and a lower shielding iron core; the coil assembly comprises a compensation coil uniformly wound on the main iron core, a primary coil wound on the shielding iron core, and a secondary coil wound on the primary coil, wherein the tap of the primary coil
The other taps of the primary coil are all nonpolar terminals, the taps of the secondary coil are +.>
The secondary coil is a polar end, and the other taps of the secondary coil are all nonpolar ends; the polarity end and the nonpolar end of the compensation coil are connected into the corresponding secondary coils according to the requirements of the zero magnetic flux compensation technology, and the compensation coil and the secondary coils are led out by shielding wires; the shielding layer is arranged between the secondary coil and the primary coil, and the outgoing line of the shielding layer is grounded; the insulating layer is arranged on the outer side of the iron core, and the coil assemblies are all provided with interlayer insulating layers;
error traceability device includes voltage regulator T 1 Flow rising device T 2 Compensation type current comparator T 3 Error measuring device HE, current load box Z, voltage source zeroing device S and two-stage current transformer
The voltage regulator T 1 The output end is connected with an isolation transformer T s Is connected with the input end of the isolation transformer T s The output end of (1) is connected with a current booster T 2 And the low voltage side of the output end is grounded; the upflow device T 2 The output ends of the (B) are respectively connected with a wide-range standard current transformer T 0 Primary coil non-polar end and compensation type current comparator T 3 Is a non-polar end of the primary coil; the wide-range standard current transformer T 0 The primary coil polarity end of (C) is connected with a compensation type current comparator T 3 Is arranged at the primary coil polarity end; the compensation type current comparator T 3 The polarity end of the primary compensation coil of (a) is connected with a compensation type current comparator T 3 And a compensation type current comparator T 3 The non-polar end of the primary compensation coil of (a) is grounded.
2. The error tracing method for the wide-range standard current transformer is based on the error tracing device for the wide-range standard current transformer, and is characterized in that: comprising the steps of (a) a step of,
the error in the case of measuring the rated current by means of a sectional trace source, including,
an error under the condition of 0.1% -120% rated current and an error under the condition of 120% -200% rated current are measured.
3. The error tracing method of the wide-range standard current transformer according to claim 2, wherein the error tracing method comprises the following steps: the connection of the errors under the condition of 0.1 to 120 percent of rated current comprises,
the compensation type current comparator T 3 Polar ends of secondary coil and secondary compensation coil of (C) and wide-range standard current transformer T 0 After the polarity end of the secondary coil is connected, the differential flow signal is connected to the K terminal of the error measuring device HE from the polarity end of the compensation coil;
the wide-range standard current transformer T 0 Secondary coil non-pole of (2)The sex end is connected with a current load box Z and then is connected with an error measuring device HE
Terminal, compensation type current comparator T 3 Is connected with the non-polar end of the secondary coil of the transformer 0 The terminal, the nonpolar end of the secondary compensation coil is connected with the voltage source zeroing device S and then connected with the D terminal of the error measuring device HE;
the transmission line of the differential stream signal is a shielding line, and the outgoing line of the shielding layer is connected with the D terminal of the error measuring device HE, and the D terminal is connected with the grounding end of the error measuring device HE.
4. The error tracing method of the wide-range standard current transformer according to claim 3, wherein the error tracing method comprises the following steps: the error operation step under the condition of 0.1% -120% rated current comprises the following steps of,
by adjusting voltage regulator T 1 Output voltage change up-converter T of (a) 2 Outputting current to enable the current percentage in the error measurement device HE to reach a preset detection point;
adjusting the voltage source zeroing means S so that the compensated current comparator T 3 The voltage on the zero-pointing coil is zero;
the reading in the error measuring device HE is the error value of the wide-range current transformer under the current percentage.
5. The error tracing method of the wide-range standard current transformer according to claim 4, wherein the error tracing method comprises the following steps: the connection of the errors under the condition of measuring 120-200% of rated current comprises,
through a high-precision two-stage current transformer
Setting up the second stage of the multiplication circuit, the transformation ratio of the second stage is +.>
，
Wide-range standard current transformer T 0 The secondary coil polar end of the transformer is connected with a two-stage current transformer
The primary coil polarity end of the transformer is connected with a current load box Z and then connected with a two-stage current transformer +.>
Is a non-polar end of the primary coil;
the two-stage current transformer
The polarity end of the primary compensation coil is connected with the polarity end of the primary coil, and the nonpolar end is grounded; the polarity ends of the secondary coil and the compensation coil are connected with a compensation type current comparator T 3 After the polarity ends of the secondary coil and the compensation coil, the secondary coil and the compensation coil are connected with a compensation current comparator T 3 The polarity end of the compensation coil of the (2) is connected with a differential flow signal into a K terminal of an error measurement device HE;
double-stage current transformer
Is connected to the non-polar side of the secondary winding of the error measuring device HE>
The non-polar end of the compensation coil is grounded; compensation type current comparator T 3 Is connected to the T of the error measuring device HE by a nonpolar terminal of the secondary coil 0 A terminal, a D terminal of the nonpolar termination error measuring device HE of the compensation coil;
the transmission line of the differential stream signal is a shielding line, and the outgoing line of the shielding layer is connected with the D terminal of the error measuring device HE, and the D terminal is connected with the grounding end of the error measuring device HE.
6. The error tracing method of the wide-range standard current transformer according to claim 5, wherein the error tracing method comprises the following steps: the error operation step under the condition of measuring 120% -200% rated current comprises the following steps,
by pressure regulationDevice T 1 Output-regulated up-converter T 2 Outputting a current so that the current percentage displayed in the error measuring device HE is the actual detection point
；
Adjusting the voltage source zeroing means S so that the compensated current comparator T 3 The voltage on the zero-pointing coil is zero;
reading in the error measuring device HE is the wide-range standard current transformer T 0 At the position of
Error values at times the current percentage.
7. The error tracing method of the wide-range standard current transformer according to claim 6, wherein the error tracing method comprises the following steps: the compensation type current comparator T 3 The accuracy grade is 0.001 grade;
the two-stage current transformer
The accuracy rating is 0.001S.
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