CN1085320A - Power frequency test voltage measurer - Google Patents
Power frequency test voltage measurer Download PDFInfo
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- CN1085320A CN1085320A CN 93117914 CN93117914A CN1085320A CN 1085320 A CN1085320 A CN 1085320A CN 93117914 CN93117914 CN 93117914 CN 93117914 A CN93117914 A CN 93117914A CN 1085320 A CN1085320 A CN 1085320A
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Abstract
Measure the measurement mechanism that industrial frequency experiment voltage is used in a kind of electrical equipment AC voltage withstand test, can measure industrial frequency experiment voltage in the low-pressure side of testing transformer.When the low-pressure side electric current passes through it, produce a bucking voltage, can offset " hold and rise " influence that short-circuit impedance causes, adopt the current transformer of measuring the low-pressure side electric current, measurement impedance as its load is adjustable, output transformer is many taps, to be fit to the short-circuit impedance parameter of used testing transformer, makes measurement mechanism have versatility.This measurement mechanism is simple, light, can replace complexity, expensive high-tension measurement equipment, and measuring accuracy reaches 1%.
Description
The present invention relates to measure the measurement mechanism that industrial frequency experiment voltage is used in a kind of electrical equipment AC voltage withstand test, it comprises the architectural feature of measuring impedance and transformer.
Electrical equipment is carried out the power frequency high voltage test, have only when the test product electric capacity is very little, just can approx testing transformer low-pressure side voltage be multiply by voltage ratio K and calculate high-voltage value, when test product electric capacity is big, the trial voltage that is added on the test product will be referred to as " hold and rise " phenomenon usually significantly greater than the value of calculating by voltage ratio K.In fact only when zero load, former and deputy polygonal voltage is just observed the relation of voltage ratio to any transformer.Inevitablely behind the on-load cause output voltage fluctuation by short-circuit impedance, inductive load causes that voltage reduces, and capacitive load causes that voltage raises, the testing transformer band be capacitive load.
According to the circuit analysis of power frequency high voltage test tie lines, can know that the high side voltage that is folded to low-pressure side exceeds reactance voltage than low-pressure side voltage, Here it is so-called " hold and rise " voltage, it increases with the increase of load current.When electric current reaches rated current, can reach about 10% of testing transformer rated voltage, if this moment, trial voltage was 20% of a rated voltage, then " holds liter " and reach 50%, as seen calculate trial voltage and miss by a mile sometimes by voltage ratio K.So the High-Voltage Experimentation chamber of specialty is all carried out direct high-tension measurement in the testing transformer high-pressure side to industrial frequency experiment voltage.Existing high-tension measurement equipment has: ball discharge crack, voltage transformer (VT), capacitive divider, resitstance voltage divider and electrostatic voltmeter etc., these high-tension measurement equipment are not only heavy, and cost an arm and a leg, generally have only the high-tension laboratory of specialty just to possess, in most of medium and small makers' product export tests and in the site test of a lot of power departments, owing to lack suitable measuring equipment, can only calculate high-voltage value by voltage ratio K from low-pressure side voltage, cause trial voltage higher, often specification product are punctured by mistake, cause unnecessary loss.
The testing transformer inside that has has ammeter coil (also claiming to measure winding).By the same token, the ammeter coil can not be measured trial voltage exactly.
For addressing this problem, the method that 1981 the 2nd phase 2-4 of China's " transformer " magazine page or leaf discloses a kind of " measuring industrial frequency experiment voltage in the testing transformer low-pressure side ".This method is to seal in a voltage of measuring in this impedance of impedance (R+jX) to be boosted and fallen mutually by small transformers in the low-pressure side current return of testing transformer, be superimposed on the low voltage voltage, receiving voltage table again measures, this measures Kp/one that impedance equals short-circuit impedance, Kp is the voltage ratio of small transformers, thereby has offset the influence of " hold and rise ".
But this method requires to measure the short-circuit impedance R of impedance (R+jX) and used testing transformer
k+ JX
kReal part, imaginary part proportional respectively, and it allows electric current to be not less than rated current of testing transformer, and various testing transformer rated current and short-circuit impedance have nothing in common with each other, thereby test the impedor parameter of the supporting measurement of transformer for each bench teat and also have nothing in common with each other.Prepare measuring sensor separately so can only test transformer, can not make in batches, form the standardization product, therefore fundamentally limited applying of this method for a certain bench teat.
The objective of the invention is to avoid above-mentioned the deficiencies in the prior art part and provide a kind of measure the fexible unit of industrial frequency experiment voltage in low-pressure side, its only needs simple debugging just can be used for all testing transformers.
Purpose of the present invention can reach by following measure:
1, Current Transformer becomes testing transformer low-pressure side electric current into the electric current that is not more than 5A, feeds and measures impedance, measures impedance like this and can unify to design by the 5A current capacity.
2, the element of measuring impedance is made adjustablely, can be transferred to the numerical value that the short-circuit impedance with used testing transformer adapts during use.
3, output transformer is made many taps, and convertible tap is to adapt to the requirement of the different impedance voltages of various testing transformers during use.
Purpose of the present invention also can reach by following measure:
1, adjustable measurement impedance (R+jX) since adjustable resistance (R) and regulative reactance (X) be composed in series;
2, adjustable measurement impedance (R+jX) is connected to the primary side of transformer (P.T.); Or one of them branch that is connected to the secondary side of transformer (P.T.) connects.
3, can take testing transformer low pressure winding to measure industrial frequency experiment voltage; Maybe can take testing transformer ammeter coil to measure industrial frequency experiment voltage.
The present invention compared with prior art has following advantage:
1, volume, weight and the price of common high-tension measurement equipment increase rapidly with voltage increases, and size of this device and cost and high side voltage are irrelevant, only are equivalent to 1/10～1/100 of high pressure measuring equipments such as voltage transformer (VT), capacitive divider.
2, this device has versatility, only needs simple debugging, just applicable to all testing transformers, can be developed into the standardization industrial products, can make in batches, be convenient to promote.
The drawing of accompanying drawing is described as follows:
Fig. 1 takes testing transformer low pressure winding to measure the measurement mechanism tie lines figure of industrial frequency experiment voltage.
Fig. 2 takes testing transformer ammeter coil to measure the measurement mechanism tie lines figure of industrial frequency experiment voltage.
Wherein 1 is current transformer (C.T.); 2,3 is a terminal of (C.T.); 4,5 is the secondary terminal of (C.T.); 6 is adjustable measuring resistance (R), and 7 is adjustable measurement reactance (X), and 8 is transformer (P.T.); 9,10 is the secondary terminal of (P.T.); 11 is voltage table (V), and 12 is testing transformer (T), and 13 is protective resistance (R
1), 14 is test product electric capacity (C), 15 is pressure regulator (V.R.), 16,17 be respectively the low-pressure side electric current (
1) and voltage (
1), 18 be the voltage table measuring voltage (
V), 19 be (P.T.) secondary voltage (
P), 20 is the testing transformer of charged table coil, and 21 is ammeter coil (W
3), 22 be the ammeter coil terminal voltage (
3).
By reference to the accompanying drawings content of the present invention is described further:
1, measure test voltage at the testing transformer primary side:
In Fig. 1, in the frame of broken lines for measuring network: no-load voltage ratio be Kc current transformer (C.T.) 1 once hold 2,3 to insert in the primary current loop of testing transformers 12, (C.T.) 1 load is adjustable measurement impedance Z=R+jX. No-load voltage ratio is that the additive polarity transformer (P.T.) 8 of Kp is used for the measurement impedance powered on to press being elevated to impedance voltage
1（R
K+R
1′+jX
K), and paraphase. R whereinKAnd XKBe respectively the testing transformer short-circuit resistance that is folded to low-pressure side and the value of short-circuit reactance, R1' for being folded to the protective resistance value of low-pressure side.
The adjusting of measuring resistance value is determined by following formula:
R＝（R
K+R
1′）Kc/Kp（1）
X＝X
KKc/Kp（2）
During Power Frequency High Voltage Test, (C.T.) 1 secondary current
/ Kc flows through and measures voltage that impedance (R+jX) produces and boost and paraphase is through (P.T.) 8:
Formula (1), (2) substitution formula (3) are got:
Formula (4) shows
Equal the impedance voltage phasor of paraphase.
This shows that the voltage that voltmeter 11 records is:
When testing transformer 12(is not inserted this measurement mechanism) circuit analysis when making the power frequency high-potting, the high side voltage that is folded to low-pressure side as can be known is:
In the formula
Be respectively the high side voltage and the voltage ratio of testing transformer 12 with K.This formula shows the high side voltage that is folded to low-pressure side
With low-pressure side voltage
The difference impedance voltage
Comparison expression (5) and formula (6) be as can be known:
That is: U
2=KUv(7)
Formula (7) shows: in the measurement tie lines of Fig. 1, the reading Uv of low-pressure side voltage table 11 multiply by voltage ratio K and just obtains the high-potting voltage U
2, so just realized purpose with low-pressure side voltage table measurement high-pressure side trial voltage.
2, at testing transformer ammeter coil experiment with measuring voltage:
In Fig. 2, the testing transformer 20 with ammeter coil 21 comes down to a kind of three-winding transformer, and the terminal voltage that is folded to three winding ammeter coils 21 of primary side is:
In the formula: R
K2, X
K2Be the secondary coil short-circuit impedance, be about first and second short-circuit impedance R
K, X
K2/3 of value.
With formula (8) two ends divided by the voltage ratio K between, three time
13, the voltage that obtains being folded to the ammeter coil sides is:
In the formula
For being folded to the U of three sides
2Value.
Formula (9) is similar with formula (6), shows ammeter coil voltage U
3The scaled value that is not equal to high pressure
", its difference is the secondary side impedance voltage that is folded to three sides
1(R
K2+ R
1'+jX
K2)/K
13Here it is, and the ammeter coil can not accurately be measured the reason of high side voltage.
Measure the value of impedance and press the following formula adjusting:
R＝（R
K2+R
1′）Kc/Kp/K
13（10）
X＝X
K2Kc/Kp/K
13（11）
As shown in Figure 2:
Formula (10), (11) substitution formula (12) are got:
Voltage table 11 records voltage:
Comparison expression (14), (9) are as can be known:
Be U
2=K
23Uv
This shows: the reading Uv of voltage table 11 multiply by voltage ratio K
23Just equal high-pressure side trial voltage U
2It is the same measuring with the device of measuring in low-pressure side at the ammeter coil, just parameter setting difference.
Voltage ratio K between general high voltage side and the ammeter coil
23Make integer 1000, the voltage voltage that records at the ammeter coil just in time is the kilovolt number of high side voltage like this, and Here it is uses the convenience of ammeter coil.
If in the test higher harmonic resonance takes place, then resonance current is reflected to by (C.T.) and measures in the impedance, makes the scaled value of measurement mechanism export resonance voltage.So this measurement mechanism can correctly reflect resonance phenomena.
3, the wiring of measurement mechanism and debugging:
Measurement mechanism has polarity, and wiring rules is as shown in Figure 1, works as electric current
116 terminals 2 by (C.T.) enter Measurement Network, and the secondary terminal 10 of P.T. connects noble potential, and the other end 9 connects voltage table 11, another termination electronegative potential of voltage table 11.In Fig. 2, terminal 10 connects the noble potential of ammeter coil, and terminal 9 connects voltage table 11.If polarity connects instead, the voltage table indication does not only increase " hold and rise " part, deducts it on the contrary, will compare U
2' much lower.If press and test product to be punctured by mistake by this value additional examination electrical verification.So when measurement mechanism and used testing transformer are supporting, need to use after the debugging.Now adjustment method is described in down:
Carry out tie lines by Fig. 1; and with testing transformer 12 high-pressure sides through protective resistance 13 short circuits; add rated current in low-pressure side; as protective resistance overheatedly can suitably reduce electric current, earlier the shunting switch with (P.T.) 8 switches to the Kp minimum position; adjustable measuring resistance (R) 6 and adjustable measurement reactance (X) 7 zero setting; transfer big (R) and value (X) then gradually; reduce as voltage table 11 indicated values thereupon; illustrate that polarity is correct; otherwise should check (C.T.) 1 or (P.T.) 8 polarity, debugging again after the correction.Adjusting (R), (X) value make voltage table 11 be designated as zero or approaching zero minimum value repeatedly.As (R) or (X) be tuned to the maximal value of this element, voltage table 11 is nulling not still, the tap of (P.T.) 8 can be switched to next big shelves of Kp, debugging again.After mixing up R is got final product with (X) the element sliding point is fixing.Because high-pressure side short circuit during debugging, what low-pressure side added is exactly impedance voltage
1(R
K+ R
1'+jX
K).
The explanation of voltage table 11 nullings:
Just in time copy the phasor of the impedance voltage of paraphase, (4), (5), (7) formula are all set up, thereby satisfied the condition of this method.After measuring impedance setting, measurement mechanism just becomes the corollary apparatus of this testing transformer special use.And protective resistance (R
1) value can not change again, otherwise should debug again.This short-circuit test method also can be used as the verification means of this device.
4, other forms of adjustable measurement impedance:
One of them branch that adjustable measurement impedance (R+jX) also can be connected to the secondary of (P.T.) 8 connects.Amount to principle by two impedances of transformer, what the value ratio of impedance this moment (R+jX) was connected to (P.T.) 8 once holds 4,5 o'clock the big K of value
2P times, Kp is the voltage ratio of the tap that connects.The capacity of (P.T.) 8 is also wanted corresponding increase simultaneously.
5, the voltage table internal resistance is to the influence of measuring accuracy:
With output capacity was relevant, the precision of this device was also relevant with output capacity, thereby relevant with the internal resistance Rv of applied voltage table as the precision of voltage transformer (VT).According to circuit analysis, the relative error of its measurement as can be known:
δ＝（V
2′-Uv）/U
2′≈RK
2 P/Rv×100%（16）
Hence one can see that:
A should select internal resistance Rv higher voltage table for use for reducing this error.
B is because (R) with protective resistance (R
1) increase and increase, so select for use excessive protective resistance (R1) will cause the measuring error increase, press the relevant specification of high-voltage engineering specialty, should be by testing transformer rated impedance (U
1H/ I
1H) a few percent choose the protective resistance value.Can see that in the following embodiments when choosing the protective resistance value like this, measuring error is an acceptable.
C should preferentially select the little transformer tap of Kp for use in the debugging.
Embodiment:
Select low-voltage bus bar formula current transformer for use, rated load is 0.4 Ω, 0.5 grade.A rated current when secondary rated current 5A, a hollow circle has 100,150,200,300,400,500,600 and 800 amperes of eight kinds of specifications.Product just is divided into eight kinds of models by rated primary current like this.Increase the hollow number of turn and can reduce a rated current to needs numerical value.
Measuring resistance element (R): 0～0.33 Ω is adjustable, electric current 5A.
Measure reactance component (X): 0～0.22 Ω is adjustable,
Electric current 5A.
Measure the maximal value of impedance:
Z＝（R
2+X
2）
1/2＝（0.33
2+0.22
2）
1/2＝0.397Ω＜0.4Ω
Rated voltage 2V of transformer (P.T.), capacity 5VA, secondary are provided with 6 taps and can supply to switch: 20V, 30V, 50V, 60V, 70V and 100V.Voltage ratio is respectively 10,15,25,30,35 and 50.So that the needs of the different impedance voltages of adequacy test transformer.
For investigating the versatility of this measurement mechanism, calculate its component parameters and measuring error when being used for 10 kinds of common testing transformers, list in the table 1,2,3.
According to the product description of domestic testing transformer main manufacturer, table 1 has been listed the parameter that 10 kinds of model tests commonly used become device.
Symbolic significance about the testing transformer parameter in the table 1 is described as follows:
U
1n-rated primary voltage (V).
I
1n-primary side rated current (A).
u
k%-impedance voltage percentage.
U
K-be folded to the impedance voltage (V) of primary side.
Z
K-be folded to the short-circuit impedance (Ω) of primary side
Φ
K-Z
KAngle of impedance.
Each parameter of transformer has been used following formula in the reckoner 1:
K＝U
2n/U
1n
U
K＝U
1nu
K%
Z
K＝U
K/I
1n
R
K＝Z
KCosΦ
K
X
K＝Z
KSinΦ
K
R′
1＝R
1/K
2
Protective resistance R in the table 1
1Value be by (U
1n/ I
1n) 5-7% of value chooses.
Table 2 has been listed the device of these 10 kinds of testing transformers usefulness embodiment when primary side experiment with measuring voltage, the parameter that measuring sensor should be adjusted.R, X, value are calculated by formula (1), (2).The rated current of current transformer C.T. is selected to such an extent that be slightly less than a rated current of testing transformer in sequence number 1 and the 10 liang of hurdles, is to use because current transformer allows to be no more than 120% rated current.
Table 3 has been listed the device of these 10 kinds of testing transformers usefulness embodiment when ammeter coil sides experiment with measuring voltage, the measuring sensor parameter.R in the table
K2, X
K2Press R respectively
K, X
K2/3 calculate.R, X, value are calculated by formula (10), (11).
Observe table 2, each hurdle of table 3 as can be known: for the testing transformer of different model, no matter be to measure, as long as suitably choose the no-load voltage ratio K of transformer P.T. at primary side or at the ammeter coil
P, can make measurement impedance parameter R＜0.33 Ω that calculates by formula (1), (2) or (10), (11); X＜0.22 Ω; Z＜0.4 Ω, thereby can use the measurement mechanism of embodiment.
The T10-V type voltage table that uses Guilin ammeter factory to produce, the internal resistance of its 150V, 300V, 600V shelves is respectively 20k Ω, 40k Ω, 80k Ω.The internal resistance R of the used shelves of T10-V type voltage table has been listed on last two hurdles of table 2, table 3
VWith the error delta of calculating by formula (18).
All in-0.25%, the error in the table 3 is all in-0.13% for error in the table 2.Measure because used K at the ammeter coil
PBe worth lessly, error is also little.So when testing transformer has the ammeter coil, should measure at the ammeter coil as far as possible.
T10-V type voltage table full scale electric current is 7.5mA.The lower voltage table full scale electric current of common internal resistance can reach 30mA.Be that internal resistance only is the former 1/4.Can calculate by formula (18), promptly use this low internal resistance voltage table, the measuring error δ in the table 2,3 is also in-1%.As use peak-reading voltmeter, because its internal resistance is very high, measuring error δ can ignore.
Increase the rated load of current transformer C.T., can allow to increase and measure impedance, thereby reduce K
PValue can make the error delta of calculating by formula (18) further reduce.For example the rated load of current transformer C.T. is increased to 0.8 Ω, and then the error delta in the table 2,3 reduces half.
The precision of this device reaches 1%.Satisfy among the standard GB 311-83 about the Transmission System for High Voltage Measurements error less than 3% requirement.
Claims (6)
1, a kind of power frequency test voltage measurer comprises that by one the two-port network of measuring impedance (R+jX) and transformer (P.T.) constitutes, and is characterized in that:
The inlet of a, network is a current transformer (C.T.) of measuring the low-pressure side electric current,
The load of b, current transformer (C.T.) is adjustable measurement impedance (R+jX),
The output transformer (P.T.) of voltage is many taps in c, the measurement impedance.
2, device according to claim 1 is characterized in that described adjustable measurement impedance (R+jX) is by adjustable resistance (R) formation of connecting with regulative reactance (X).
3, device according to claim 1 and 2 is characterized in that adjustable measurement impedance (R+jX) is connected to the primary side of transformer (P.T.).
4, device according to claim 1 and 2 is characterized in that adjustable measurement impedance (R+jX) is connected to a tap of transformer (P.T.) secondary side.
5, device according to claim 1, it is characterized in that when taking testing transformer low pressure winding to measure industrial frequency experiment voltage, transformer (P.T.) terminal 10 connects the noble potential of testing transformer low pressure winding, the other end 9 connects voltage table, the electronegative potential of another termination testing transformer low pressure winding of voltage table.
6, device according to claim 1, it is characterized in that when taking testing transformer ammeter coil to measure industrial frequency experiment voltage, transformer (P.T.) terminal 10 connects the noble potential of ammeter coil, and the other end 9 connects voltage table, the electronegative potential of another termination ammeter coil of voltage table.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 93117914 CN1085320A (en) | 1993-10-07 | 1993-10-07 | Power frequency test voltage measurer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 93117914 CN1085320A (en) | 1993-10-07 | 1993-10-07 | Power frequency test voltage measurer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1085320A true CN1085320A (en) | 1994-04-13 |
Family
ID=4992206
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 93117914 Pending CN1085320A (en) | 1993-10-07 | 1993-10-07 | Power frequency test voltage measurer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1085320A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103245834A (en) * | 2013-05-16 | 2013-08-14 | 国家电网公司 | Site testing method for transformer winding deformation low-voltage impedance |
| CN103454480A (en) * | 2013-08-09 | 2013-12-18 | 国家电网公司 | Method for measuring and calculating transformer invading lightning voltage waveforms with transformer bushing |
| CN112067896A (en) * | 2020-09-08 | 2020-12-11 | 福建育巢信息科技有限公司 | Integrated intelligent tester for transformation ratio direct resistance on-load impedance |
| CN112260599A (en) * | 2020-10-10 | 2021-01-22 | 国网山东省电力公司烟台供电公司 | Capacity and pressure regulating predictive control method |
-
1993
- 1993-10-07 CN CN 93117914 patent/CN1085320A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103245834A (en) * | 2013-05-16 | 2013-08-14 | 国家电网公司 | Site testing method for transformer winding deformation low-voltage impedance |
| CN103454480A (en) * | 2013-08-09 | 2013-12-18 | 国家电网公司 | Method for measuring and calculating transformer invading lightning voltage waveforms with transformer bushing |
| CN103454480B (en) * | 2013-08-09 | 2016-04-20 | 国家电网公司 | A kind of method utilizing bushing shell for transformer to calculate transformer invasion lightning voltage waveform |
| CN112067896A (en) * | 2020-09-08 | 2020-12-11 | 福建育巢信息科技有限公司 | Integrated intelligent tester for transformation ratio direct resistance on-load impedance |
| CN112067896B (en) * | 2020-09-08 | 2023-04-21 | 安康陕变智能电力装备制造有限公司 | Transformation ratio direct resistance on-load impedance integrated intelligent tester |
| CN112260599A (en) * | 2020-10-10 | 2021-01-22 | 国网山东省电力公司烟台供电公司 | Capacity and pressure regulating predictive control method |
| CN112260599B (en) * | 2020-10-10 | 2022-07-15 | 国网山东省电力公司烟台供电公司 | Capacity and pressure regulating predictive control method |
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