DE2231999C3 - Device for determining the translation error and the misalignment of a current transformer - Google Patents

Description

Angle of error of a current transformer according to the differential

the mutual inductance (M) and the secondary winding of the auxiliary transformer (HT) flows through.

only the primary winding of the low-leakage transformer (ZW.,) by flows and which is flow process 25, the secondary winding (W,) of the comparator (K) Created by the German Auslegeschrift current flowing '(I ₂₎ in series, the primary winding 1,264,604 a Bridge arrangement with adjustable

"Diagonal branch became known where the

The current flowing through the secondary winding of the converter to be tested has a normal load and the 30 standard current transformer as a current comparator to display a vanishing differential current between

Secondary current of the current transformer to be tested and

Bridge current on the one hand and secondary current of the Normal current converter on the other hand is formed. Of the

35 current comparator points to a common

The invention relates to the determination of the iron core one of the primary current of the

Translation error and the incorrect angle of a current- the primary winding through which the current transformer flows and

converter by comparison with a normal converter. a secondary winding and a compensation winding

When performing such measurements under- as well as a detector winding, wherein the

if one basically separates between the compensating 40 detector winding to at the same time a magnetic one

tion method and the differential current method. To achieve shielding, on one inside the

In the compensation process, the second aforementioned iron core feeds the inner iron

The core of the current transformer to be tested is wound. The one in the diagonal branch of the

if impedances provided via a first low-leakage intermediate transformer measuring circuit are so

mator and an adjustable current divider set a span 45 that the detector winding of the current

voltage divider circuit, while current flowing through the secondary circuit of the comparator disappears, and

Normal current transformer the primary winding of a two- in this state can be seen from the setting of the

th low-leakage transformer and the primary winding impedances provided in the diagonal branch

development of a counter-bridge arrangement that rotates the phase by 90 degrees, the translation errors and the

inductance are arranged in such a way that the secondary 50 error angle of the current transformer to be tested calculates

winding of the second low-leakage transformer. The current transformer to be tested and the zui

The first voltage divider-slip wire arrangement feeds the application provided current comparators are included

and the secondary winding of the mutual inductance is designed for the same transformation ratios.

feeds the second voltage divider-slip wire arrangement, since the circuit for connecting

the normal current transformers provided with the contact wire tap of the first voltage turn 55

Teilcr-grinding wire arrangement is connected. A train current delivers, in terms of amplitude and phase, mi

The zero indicator is in the branch between the secondary current of the current to be tested

the second voltage divider-slip wire arrangement converter is compared to the one to be expected

and the tap of the voltage divider circuit to check translation errors and phase errors of the

seen to calculate that of the secondary winding of the 60 to be tested current transformer, this must

is fed to the current transformer. '' Reference current supplying standard current transformers high

In the case of one according to the differential current method, little work is done with regard to the correct translation ratio

tend circuit for Finiittlung the translation and lack of scatter be designed. Such demands

The error and angle of a current transformer are high, resulting in high manufacturing costs

the same transformation ratio having 65 normal current transformers. Also arise here

Secondary windings of the Slromwand to be tested - despite the high effort still error 11

lers and the normal converter connected in series, and of the order of 10- '. The invention too

their differential current flows through a cross-resistance, the basic task is to separate itself from diesel

to the construction of a normal flow wall there is, after all, that for the one at the connection point to make high demands free and clamp the secondary winding unc 'the compensation thereby a reduction in the price of the sanitary system to the generation winding of the current comparator flowing off aim and here only errors in the magnitude of the current in relation to Ampcrc number of turns of the same order to reach about 10 "" °. S weight with which the primary winding of the current

There is a device for determining the current flowing through the transmission ratio,

error and the error angle of a current transformer according to the invention is in the following description

the compensation method by comparison with hung is discussed with reference to the figures. from

a normal current transformer which initially shows the characterizing figures

based type is characterized according to the invention »o FIG. 1 is a schematic representation of the

in that the normal current transformer is a current publication in the company sheet »Converter and Bureau

comparator arrangement, consisting of the primary and the measuring device «corresponding mode of operation,

Secondary-side series connection of a with vanishing F i g. 2 shows a first embodiment of the invention,

The magnetic flux in the comparator magnet core is shown in FIG. 3, a second, simplified embodiment

tend current comparator and an auxiliary transformer 15 of the invention and

tors is provided in which the Stromkomparaior. on Fig. 4 to ό further embodiments of the Fr-

an iron core, except for the primary winding.

The known circuit shown in Fig. 1 with the same number of turns as the secondary arrangement shows the basic principle of determining the winding and has a detector winding, which 20 translation error and the angle of a current transformer testing the latter preferably has an increased number of turns A 'by means of a normal and expediently one in the interior of the current transformer N after the voltage compensation at the same time acting as a magnetic screen. Here, the converter A 'feeds an intermediate converter ZH' via said iron core arranged inner iron core, and a current divider is wound, and that "the detector winding of the circuit Sz ₁ , which can also be omitted, the current comparator is the input of an amplifier from the voltage divider Sp ₁ and the normal converter N forms a high gain and the compensation via a mutual inductance A / and an intermediate winding of the current comparator in the output of the converter ZW " the amplifier with a slip wire SF as negative feedback winding hene Spamungteilcrschaltunc Sp., while the scan is arranged and at one end the compensating 3 ° secondary winding of the counter inductance Λ / through a tational winding and the Koinpaiatorwick mitein- KC-Klialiune on the sliding wire SΛ cine are connected to each other. the sliding wire voltage U ₁ .- by Q (^ offset chip

A device for determining the translation ί <'λ is generated.

error and the angle of a current transformer according to An as a Feussncr divider circuit with two differential current methods by comparison with 35 -dien / wi-i equal adjustable resistors R _{211 to} a normal current transformer equal conversion. and K ₂ ,, arranged abrasive wire SF formed ratio of the type characterized ISIN voltage divider Sp., the compensation tension Records will according to the invention in that _{k is} a voltage U and to the SThv-ii'üialit .vf the error span normal current transformer a Stromkomparatoranord - Voltage 1 (./,■ tapped, to which the misalignment, consisting of the primary and secondary-side voltage - AJ Λ adds. For example, if a voltage U ₁ - = ± 3 prevails on a series connection of a magnet or sliding wire SF that is disappearing mV. flux in the comparator magnet core - this voltage corresponds to ion voltage provided for a compensating comparator and an auxiliary transformer (Z ₁ = IV is an error range at which the current comparator. on an iron core F = ± 3 °, 0. can also be an winding and a compensation winding vo n, which would correspond to an angle range of Λ = ± 12 'more like the number of turns than the secondary winding. If, on the other hand, the chip is set to have a detector winding, the latter projection divider is set to U _k = 0.1 V. Thus, if the number of turns is increased and the ground wire tensions are expediently the same, the error ranges result moderately around one inside the at the same time as 50 F = ± 3 °, 'o and δ = ± 120'. So that the compensation voltage U _{k of} the inner iron core arranged in the core is wound in the case of a vermagnetic screen acting , the left voltage divider Sp ₁ does not change and the detector winding of the current comparator needs to be changed, the input is through the current divider gate of an amplifier with a high interconnection Si _1, the current in the voltage divider Sp _{1 forms} in the degree of amplification and the compensation winding 55 is reduced from Ii to 1/10 in the above case. In this case, the current comparator at the output of the aforementioned, the current divider circuit St _{1 is designed} so that the amplifier is arranged as a negative feedback winding, its input resistance when there is a change, and at one end the compensation winding is the compensation voltage U ₁ . and so that the measuring and the comparator winding, which is connected to one another, is retained,
are. 60 With the same gear ratio of the two

The advantage achieved by the invention is through current transformers Λ "and N are both voltage

the use of a self-disappearing divider St ₁ and St, in the middle position, for example

Magnetization in the iron core balancing current - with a compensation resistor R _k = 100 Ω, ab-

comparator, with the auxiliary transformer being used, while in the case of unequal transmission ratios

a power-related relief of the left voltage divider St ₁ corresponding to the proportions

waning magnetization working current must be adjusted. The one on the left span

Comparator connected amplifier causes voltage divider St ₁ tapped voltage 17, and the

because in the circuit configuration according to the invention, the sum of the voltages II _k ^J U ₁ 4 ί / Λ = U

via the zero current indicator N! interconnected so that it shows zero when calibrating.

While the two middlemen ZH ', and ZW ₂ can be designed in such a way that they cause a completely negligible measurement error if the secondary currents of the two current transformers X and Λ' are not too different, the error magnitudes of the normal current transformer Λ 'go completely into the measurement a.

This deficiency is eliminated according to the invention in that the normal current converter Λ 'is formed by a sclbslabgleichenden Stronic comparator K , as shown in FIG. 2 is shown.

The Stroinkomparalor K has four windings and two preferably as Tomide ausiiebildete iron cores, said iron core / :, at the same time, the magnetic shield arranged on the inside thereof, serving as a detector core iron core /., Forms, namely the primary winding W _1, Secondary winding H '., And the compensation winding li ^: ., With the same number of turns as H ". ,, which are all wound on the iron core E _x , and the detector winding Ii'" wound on the detector core E., preferably with a higher number of turns . The detector _{winding H / 4} forms the input to the amplifier I-, whose output current J _n feeds the compensation winding M '. The amplifier V has a high gain; as a result, it generates such an output current J _n in the winding Ii '.,. that the amplifier input voltage is low. This means that the magnetic flux in the associated highly permeable iron core also disappears and thus an ampere-turns equilibrium Λ, - H '., T J _n - W., ~ J ^ \ is established. Under the simplifying assumption that H ', = - H'., H '., Let. Then in the primary windings of the counter inductance M and the intermediate converter ZW _{1 is called} the error-free comparator current Ji ₁ -J., - / "- / ,.

Since the current comparator A 'does not transmit any power when the magnetic flux disappears, the auxiliary transformer HT is provided with the same transmission ratio, which takes over the required power transmission. The circuit according to the invention achieves that the secondary current of the converter to be tested Λ "will earn with an error-free secondary current of the comparator A '.

The circuit according to FIG. However, 2 has a disadvantage. This consists in the fact that both the primary winding of the intermediate converter ZW ₂ and that of the mutual inductance M are in the secondary circuit of the amplifier V and that the secondary current J _{1 also} flows through these two windings. As a result, the amplifier Γ must work against a relatively high counter voltage, which is mainly caused by the primary winding of the mutual inductance Λ /. With a more practical one. In the 2nd version, the primary power of the mutual inductance was around 0.625 VA at nominal current and around 2.5 VA at double the nominal current. while the intermediate transformer had an internal consumption of only about 0.1 VA at the nominal current and about 0.4 VA at twice the nominal current.

The grain processor winding H ₁ through which the amplifier current J _n flows is only included in the measurement with its extremely low ohmic resistance. since the current comparator A no longer has a magnetic flux during the adjustment and as a result the inductive resistance of the compensation winding disappears. The same applies to the secondary winding H- ''., Of the current comparator K. The additional load on the amplifier from the compensation winding Ii '., Is given by J _n - Λ., Where J _{n is} in the order of magnitude of niA and / ?., is much smaller than 1 CJ.

To relieve the amplifier from the relatively high load on the part of the mutual inductance.

ίο this is according to the further embodiment of the Ervindune according to Fi g. 3 relocated to the circuit of the auxiliary transformer HT. As a result, it is no longer flowed through by the fault-free current J _r but by a faulty current J. However, the error caused by this is only of the second order of magnitude, since it forms an error from the error, and moreover only affects the measurement of the incorrect angle and not that of the current error Γ.

If the current transformer Λ and the current comparator A 'have the same transformation ratio: · / !, according to a further embodiment of the invention, the auxiliary transformer HT can be replaced by the current transformer Λ, as shown in FIG. 4 is shown. In this circuit, the current transformer undergoes Λ 'by the primary resistance of the Gegeninduktivitäi Λ7 and the resistance of the winding H'., The Komparalors A ", an additional load in the calculation performed by said current load B

3u must be taken into account. The load on the amplifier However, Γ is the same as in the circuit according to FIG. 3.

In the case of the in FIG. 5 shown measuring circuit after the differential current experience for the same translation ratio of the current transformer 'and the comparator * K , an auxiliary transformer // 7 "is provided. In this circuit, the secondary current of the converter X and that of the comparator A' flows through the differential resistance R. ¹ , in the opposite direction. The differential current \ J generates a voltage .1 V at the resistor R 1 to be set according to the measuring range factor, which is compensated for by the voltages LV and UΛ to be set on the sliding wires SF and Λ "Λ. The current transformer .Y. the comparator A and the auxiliary transformer HT have the same transmission ratio.

Otherwise the same voltage ratios as in the circuit according to FIG. 1, it follows that the voltage 1 V occurring across the differential resistor R 1 can have a maximum of a real component of 3 mV and an imaginary component of 3.5 mV. The additional load to that of the converter ZW is therefore extremely low. Furthermore, the error of the intermediate transformer is only a second order in this circuit. This only feeds the sliding wire SF , from which the fault voltage U _{1 is} taken, and no compensation voltage IJ ₁ . is needed where a bug would take full effect.

In the circuit according to FIG. 3, the gcringi measurement error caused by the intermediate transformers ZW , and ZW., Which can be inadmissible when testing precision current transformers, can be eliminated if, according to T- "i ρ d, the intermediate current transformers are also compensated as comparators ZA ', and ZK' .. were carried out

Darstrom is 0.01 A in order to be able to connect the current divider Sf ₁ and the voltage dividers Sp _i and Sp ₂ without shunt resistors.

It is not advisable to save the comparator ZK “ on the right-hand side by designing the comparator K for a secondary current of 0.01 A from the start. In this case,

10

borrowed both the secondary and compensation windings of the comparator have the high number of turns of 120,000 when the comparator should have a number of ampere turns of 1200 AW. The intermediate converters as well as the comparators in contrast, manage with a significantly lower number of ampere-turns.

For this purpose 2 sheets of drawings

Claims (7)

Patent claims: 1. Device for determining the translation error and the error angle of a current transformer according to the Konipensationsverfahren by comparison with a normal current transformer, in which the secondary circuit of the current transformer to be tested (A ") possibly via a first low-leakage intermediate transformer (ZW ₁ ) and an adjustable current divider (St ₁ ) feeds a voltage divider circuit (Sp ₁ ) and in the secondary circuit of the normal current transformer (N) the primary winding of a second low-leakage transformer (ZW ₂ ) and the primary winding of a mutual inductance (M) rotating the phase by 90 ° are arranged and in which the secondary winding of the second low-leakage Transformer (ZW ₂ ) feeds a first voltage divider slip wire arrangement (SF) and the secondary winding of the mutual inductance (M ) feeds a second voltage divider slip wire arrangement (S δ) , which is connected to the slip wire tap of the first voltage divider slip wire arrangement (SF ) is connected, with a zero indicator (NI) in the connecting branch between the tap of the voltage divider circuit (5P ₁ ) and the second voltage divider contact wire arrangement (Sd) is arranged, characterized in that a current comparator arrangement, consisting of the primary and secondary-side series circuit of a with vanishing magnetic flux in the normal current transformer (N) Komparatormagnetkem working current comparator (K) and an auxiliary transformer (HT) is provided, in which the current comparator (/ i _{) is wound on an iron core (E 1} ), apart from the primary winding (H ^ ₁ ), a secondary winding (W ₂ ) and a compensation winding (W ₃ ) has the same number of turns as the secondary winding (W.,) and a detector winding (W ₄ ), the latter preferably having a higher number of turns and expediently arranged around an inside of the aforementioned iron core (E ₁ ), which also acts as a magnetic screen inner iron core (E.,) is wound, and that the detector winding (W ₄ ) of the Stromkom parators (K) forms the input of an amplifier (V) of high gain and the compensation winding (W _{: i} ) of the current comparator (K) is arranged in the output of said amplifier (V) as a negative feedback winding and at one end the compensation winding (W _{: l} ) and the comparator winding (W.,) are connected to one another. 2. Device according to claim 1, characterized in that the interconnected terminals of the secondary winding (W.,) and the compensation winding (W.,) of the comparator (K) withdrawn current 60 nen terminals of the secondary winding (W ₂ ) and the compensation winding (W ₃ ) of the comparator (K) withdrawn current W ₁ W. the primary winding of the Gcgcnindukten (M) and the second low-energy intermediate transformer (ZW ₂ ) flows through in series (Fig. 2). 3. Device according to claim 1, characterized in that the connected to the primary winding of the second low-leakage intermediate transformer (ZW ₂ ) flows through and the secondary winding (W ₂ ) of the comparator (K) and the secondary winding of the auxiliary transformer (HT) flowing through in series Current (Z ₂ ) only flows through the primary winding of the mutual inductance (M) (FIG. 3). 4. Device according to claim 3, wherein the current transformer (X) and the current comparator (K) have the same transformation ratio, characterized in that the secondary winding of the current transformer to be tested (X) and a burden (B) and the secondary winding (W ₂ ) of the comparator (K) and the primary winding of the mutual inductance (M) are connected in series and thereby the current transformer to be tested (Λ ') also acts as an auxiliary transformer (HT) (Fig. 4). 5. Device according to claim 1, characterized in that the two low-leakage intermediate transformers (ZW ₁ ) are formed by two self-balancing current comparators (ZZi ₁ and ZK ₂ ) (Fig. 6). 6. Device for determining the translation error and the error angle of a current transformer (X) according to the differential current method by comparison with a standard current transformer (N) with the same transformation ratio, with the secondary winding of the current transformer to be tested (X) and the secondary winding of the standard transformer (N) in series are switched and their differential current flows through a transverse resistance (R 1) and in which the secondary current of the standard converter flows through the primary winding of a low-leakage transformer (ZW ₂ ) and the primary winding of a 90 "rotating mutual inductance (M) and in which the secondary winding of the low-leakage Transformer (ZW.,) A ¹ ; first voltage control slip wire arrangement (SF) and the secondary winding of the mutual inductance (M ) feeds a second voltage divider slip wire arrangement (Sd) and the slip wire tap of the first voltage divider slip wire arrangement (5F) With the second voltage divider-slip wire arrangement (S (>) v is erbunden and a zero indicator ir the connecting branch between the differential resistance (R I) and the second voltage divider-slip wire arrangement (5 ()) is arranged, as characterized in that as a normal current converter (/ V) a current comparator arrangement, be standing from the primary - and secondary-side series connection of a with vanishing magnetic flux in the comparator magnet core work the current comparator (K) and an auxiliary transformer (HT) is provided in which the current comparator (Λ '), on an iron core (E ₁ ) gcwik kclt, except for the primary « winding (W ₁ ) has a secondary winding (W.,) and a compensation winding (W.,) with the same number of turns as the secondary winding (W.,) and a detector _{winding (IF 4} , soft the latter preferably has an increased number of turns and is expediently U.N one inside the at the same time as magnetic and creates a voltage gradient across it. The aforementioned iron core (E ₁ ) acting on the screen flows through the secondary current of the normal converter uie arranged inner iron core (E ₂ ) is wound, the primary winding of a low-leakage transformer and that the detector _{winding (W 4} ) of the current - the primary winding of a 90 degree phase comparator ( K) the input einns amplifier 5 rotating mutual inductance, and the secondary winding (V) forms a high gain and the development of the low-leakage transformer feeds a first compensation winding (W ₃ ) of the current comparator voltage divider slip wire arrangement and the setors (Ä!) is the output of said amplifier of the mutual inductance kundärwicklung a second (V) arranged as a feedback winding voltage divider abrasive wire assembly, wherein said at one end and the compensation winding io Schleifdrahtabgriff the first voltage divider grinding """-'■'■" ·· ■ wire arrangement with the second voltage divider Abrasive wire arrangement is connected. A zero indicator is arranged on the connection branch between the differential resistance and the second voltage divider terminals of the secondary winding (W.,) and 15 sliding wire arrangement,
of the compensation winding (W.) of the Kompara- The publication »Wandler und Bürdenmeß device "type MEWK the company Hartmann & Braun, Frankfurt, published April 1958, shows such according to the compensation method processing-30 tend measurement circuits to determine the translation error and the Feh'.winkels both CT as aach voltage transformers.
To determine the translation error and the (W ₃ ) and the comparator winding (W.,) are connected to one another. 7. Device according to claim 6, characterized in that the interconnected tors (K) drawn current