EP0521146A1

EP0521146A1 - Measuring converter at high-voltage potential

Info

Publication number: EP0521146A1
Application number: EP19920905577
Authority: EP
Inventors: Adolf Schwab
Original assignee: ABB Patent GmbH
Current assignee: ABB Patent GmbH
Priority date: 1991-01-23
Filing date: 1992-01-21
Publication date: 1993-01-07
Also published as: DE4201434A1; WO1992013278A1; EP0521125A1; DE4101858C1; JPH05508021A; DE4133508C1; JPH05508223A; WO1992013279A1

Abstract

Un transformateur de mesure se trouvant à un potentiel de haute tension est prévu pour une installation de distribution à haute tension dont les signaux de mesure sont amenés depuis le potentiel de haute tension au potentiel de la terre, le transformateur de mesure se trouvant à l'intérieur du contour du conducteur (11). A l'intérieur du conducteur creux (11) est prévu un circuit de couplage de transmission transformant les signaux de mesure électriques en signaux lumineux, lesquels sont guidés par des guides de lumière (27) au potentiel de la terre.A measuring transformer located at a high voltage potential is provided for a high voltage distribution installation whose measurement signals are brought from the high voltage potential to the ground potential, the measuring transformer being located at the inside the conductor outline (11). Inside the hollow conductor (11) is provided a transmission coupling circuit transforming the electrical measurement signals into light signals, which are guided by light guides (27) to earth potential.

Description

Transducers located at high voltage potential

description

The invention relates to a high voltage potential transducer according to the preamble of claim 1.

Measuring transducers of the type mentioned at the outset are used to detect the voltage and / or the current in a high-voltage switchgear, for. B. in a gas or liquid insulated or outdoor high voltage switchgear.

To detect the voltage in gas or liquid-insulated switchgear, capacitive voltage measuring devices are provided in the usual way, which are designed as capacitive voltage dividers and - in principle - from one between the inner conductor and one at a short distance from the inner surface of the outer conductor (metal encapsulation ) and insulated from it there are the high-voltage capacitor located and a low-voltage capacitor, the latter being formed between the measuring layer and the outer conductor. The voltage measurement values are recorded on the undervoltage capacitor.

From DE-OS 25 46 694 a measuring transmitter for high-voltage lines has become known, which has operating potential, ie high-voltage potential, measuring transducers for electrical quantities of the high-voltage line. The output signals of the transducers are fed to a conversion digitizing part which is at operating potential and are transmitted as digital signals to ground potential, for example, by a transmitter. How the transducer is designed cannot be seen from DE-OS 25 46 694. NOT DEPOSED AT SUBMISSION

will wear; For this purpose, one radial bore must be provided in the inner conductor and one in the outer conductor in the case of metal-encapsulated systems. The bore in the outer conductor is to be closed by means of a transparent window.

As mentioned at the outset, DE-OS 37 12 190 discloses a measuring arrangement which is at high voltage potential and whose measuring signals are transmitted as light signals to earth potential. What is important, however, is that the energy supply, on the one hand, and the way in which the measurement signals converted into light signals are carried out, in particular, are designed differently in metal-encapsulated systems.

According to the invention, a transducer unit is thus formed which can be retrofitted in existing systems. Due to the fact that the measuring electrode has an outer diameter which is the same as the outer diameter of the inner conductor, the dielectric strength between the inner conductor in the area of the measuring electrode and the outer conductor does not change if the unit is housed in a metal-encapsulated high-voltage system .

A measuring arrangement is known from JP Abstract 58-124 960, which is arranged in a semicircular cutout in the inner conductor. The sensor is a photo element with which the electrical field inside the recess is detected. In this embodiment, it is important to design and assign the cutout in such a way that where the sensor is located, the greatest concentration of the current is present. In the arrangement according to the JP abstract, this takes place in that the cutout in which the sensor is located is flanked by two further cutouts on the opposite side of the inner conductor, as a result of which an omega-shaped or meander-shaped current path is generated. In addition, it can be seen that the cutouts are inserted so deep that the bottoms of the cutouts lie on the central axis of the inner conductor. In a particularly advantageous embodiment, the light guides are guided in a spiral or meandering shape to the outside through the disk-shaped support insulator to ground potential. This ensures that any creepage distances between the post insulator and the light guides are as long as possible for possible discharges.

It is known from the above-mentioned documents DE-OS 37 12 190 and JP Abstract 58-124 960 to transmit the measurement signals as light signals to earth potential; How the light guides are mechanically guided in support insulators is not shown in either document.

It is also known from DE-OS 32 07 306 how light guides can be guided from high to low voltage potential. However, the known insulator is not a disk-shaped support insulator located within a gas-insulated, metal-encapsulated system, but a porcelain insulator with plates for extending the creepage distances. In addition, the light guides are on the outer surface and they run helically, but not spirally.

A further embodiment of the invention can be found in claim 4, which indicates how the measuring electrode is held in the recess.

The fact that the so-called measuring coating of the measuring capacitor is kept at a distance within the depression by the thin insulating material webs and that its length is shorter than that of the depression means that the dielectric of the measuring capacitor is essentially the same dielectric is like that inside the metal encapsulation. As a result, the transmission ratio of the capacitive voltage divider and thus the measuring signals of the measuring capacitor are primarily temperature-independent.

The measuring coating of the capacitive transducer does not have to extend over the entire circumference of the high-voltage conductor. In particular in the case of three-phase encapsulated high-voltage systems, it proves to be expedient to form the measurement covering only over part of the circumference, so that the voltages of the individual conductors can be measured separately.

In order to create a so-called combined current-voltage converter, the inner conductor according to claim 5 similarly has a circumferential additional depression, which is covered by a cylinder which adjoins one edge of the depression and ends at a distance from the other edge; In the inner space between the bottom of the depression and the inner wall of the cylinder, a coil is preferably arranged, the signals of which can be fed to the transmission circuit arrangement.

A further embodiment of the invention can be found in the characterizing features of claim 6. Thereafter, a capacitor arrangement is also provided for the voltage supply of the transmission circuit arrangement within the outer surface of the conductor, which arrangement is formed in that the conductor has a circumferential recess in which an electrode insulates at a distance from the bottom of the recess is arranged. The outside diameter of the electrode corresponds to the outside diameter of the conductor. This configuration is thus the same as the measuring arrangement, except for the fact that a different dimensioning may be required for the voltage supply.

The voltage picked up by the transducer or the current taken up by the transducer is in itself an analog signal, and accordingly the circuit arrangement is expediently designed as an analog / digital converter with a light transmitter which converts the analog measurement signal into a digital light signal converts which is transmitted by means of the light guide to an evaluation unit located outside the encapsulation.

The measured values can additionally be transmitted in an analog form with a further light guide section into the outside space to the evaluation unit in order to be able to record the phase angle precisely. The transmission circuit arrangement, or in short the measuring electronics, is located within the inner conductor and thus at high potential. For technical reasons, for example with high load currents or solar radiation, the temperature of the inner conductor can reach 80 ° C. Temperature rises up to 130 ° C cannot be excluded. The reliable functioning of the transmission circuit arrangement designed as microelectronics and the associated optoelectronics with which the data are converted into light signals is only guaranteed up to limit values for the operating temperature, which are 75 ° C. and in special cases 125 ° C. .

For cooling, the entire measuring arrangement, ie. H. the transmission circuit arrangements may each be mounted on a Peltier element serving as a cooler, which may be supplied with current by a corresponding current transformer.

For the keyword "Peltier element", reference is made to Meyers Lexicon of Technology and the Exact Natural Sciences, Volume 3, 1970, Biographical Institute, Mannheim / Vienna / Zurich.

As indicated above, the invention is applicable to all types of systems in which currents and voltages flowing in conductors at high voltage potential are to be measured. These systems can be open-air systems or metal-encapsulated, gas or liquid-insulated switchgear.

The invention and further advantageous refinements and improvements of the invention are to be explained and described in more detail with reference to the drawing, in which some exemplary embodiments of the invention are shown.

Show it:

Figure 1 is a schematic representation of a capacitive

Transducer within a high-voltage switchgear, FIG. 2 shows a schematic illustration of a current transformer, similar to the illustration according to FIG. 1,

3 shows a combi converter consisting of a current and a voltage converter according to FIGS. 1 and 2, likewise in a schematic representation, and

Figure 4 shows the transducer of Figure 1 with a Peltier element for cooling.

The same parts in the figures have the same reference numbers.

A metal-encapsulated, gas-insulated high-voltage switchgear, as shown in FIG. 1, has an outer encapsulation 10 located at earth potential, in which a hollow inner conductor 11 located at high voltage potential is arranged concentrically. The outer encapsulation 10 is composed of two encapsulation parts 12, 13, at the ends of which a flange 14 or 15 is provided, between which a disk-shaped support insulator 16 for the inner conductor 11 is clamped. Instead of an inner conductor 11, a number of inner conductors corresponding to the number of phases can of course also be provided in multiphase-encapsulated switchgear.

The conductor 11 has a first circumferential recess 17, on the bottom of which insulating webs 18 and 19 are arranged, by means of which a measuring coating or a measuring electrode 20 is supported in an insulated manner with respect to the conductor 11. A measuring capacitor 21 is thus formed between the measuring coating 20 and the bottom of the recess 17; with the capacitance 22 located between the measuring coating 20 and the encapsulation part 12, the measuring capacitor or capacitance 21 forms a capacitive voltage divider.

Connection lines 23 and 24 are connected to the measuring pad 20 on the one hand and to the inner surface of the hollow conductor 11, which lead to a circuit arrangement 25 of a transmission circuit arrangement arranged in the interior of the conductor 11, in which the through the conductors 23 and 24 to the circuit arrangement 25, the analog measuring signals of the measuring capacitor 21 are converted into digital signals. Accordingly, the circuit arrangement 25 is an analog / digital converter. On the analog / digital converter 25 there is a light transmitter 26 of the transmission circuit arrangement which, after conversion into light signals, transmits the digital signals to a light guide arrangement 27 which, as shown schematically in FIG. 1, is led out in a spiral through the post insulator 16 to the outside . The individual cross sections of the light guide arrangement 27 can be seen in FIG. 1. The light guide arrangement 27 is connected to an evaluation circuit 28 in which the light signals are evaluated. The converter 25 is supplied with voltage by means of a capacitor arrangement which is similar to the measuring capacitor. This capacitor arrangement 29 has a third recess 30, on the bottom of which webs 31 and 32 are applied, which hold a capacitor electrode 33, as a result of which a supply capacitor 34 of this second capacitor arrangement is formed. The capacitance located between the electrode 33 and the encapsulation part 10 has the reference number 35. The electrode 33 on the one hand and the inner conductor 11 on the other hand are connected to the converter 25 by means of electrical lines 36 and 37.

Figure 2 shows another embodiment of a transducer.

A further depression 40 is introduced within the inner conductor 11, which is covered by an edge 41 of the depression protruding toward the outer surface except for a gap 43. A coil 45 is accommodated in the interior 44 through the cylinder 42 and the bottom of the depression 40, which coil is designed, for example, as a Rogowski coil and the measurement signals of which are fed to the converter 25. The voltage supply for the converter 25 is provided by the capacitor 34 of the capacitive voltage divider 34, 35, which is constructed in the same way as the voltage divider used to supply the voltage to the measuring transducer 21/22 and therefore has the same reference numbers. The remaining structural design of the arrangement according to FIG. 2 corresponds to the arrangement according to FIG. 1. FIG. 3 shows a combination of the two transducers according to FIGS. 1 and 2.

This combination has the transducer 50, which corresponds to the current transformer shown in FIG. 2, and the transducer 51, which corresponds to the capacitive transducer according to FIG. 1. To supply power to the two circuit arrangements (converters) 52 and 53, which correspond to the circuit arrangements 25, the supply capacitance 29 is provided, which is to be dimensioned such that it can supply the two converters 52 and 53 evenly with voltage. Both the converter 52 with the light transmitter 54 and the converter 53 with the light transmitter 55 emit their light signals to the two light guides 56 and 57, which correspond to the light guide 27 in FIGS. 1 and 2. Both light guides 56 and 57 run spirally through the post insulator 16 to an evaluation unit 58 which corresponds to the evaluation circuit 28 in an adapted form.

There is of course also the possibility that the voltage supply for the transducers 25 and the light transmitters 26 is provided by the transducers themselves and not by means of an additional supply capacity.

An additional light guide is not shown, which is assigned to the capacitive transducer 21 and the inductive transducer 45 and which feeds the signals generated by the respective transducer in analog form to the evaluation circuit. These additional light guide arrangements would also be passed spirally through the post insulator 26; With these analog signals, which are in the same phase with the quantity to be measured, the phase angle can be detected precisely.

The invention can be used in gas- or liquid-insulated metal-encapsulated high-voltage switchgear and in open-air systems, and overall has a comparatively small space requirement and can also be produced with little effort. The description of the figures shows only a single conductor within the metal encapsulation; If the high-voltage system is a multi-phase encapsulated system, then the measuring surface of the capacitive measuring transducer, such as that with reference number 20, can only be formed over part of the circumference, so that the voltages of the individual conductors can be measured separately.

Due to the design of the arrangement according to FIGS. 1 to 3, the inside of each transducer or supply capacitance contains the same dielectric as inside the outer encapsulation 10, so that the measurement signals are temperature-dependent in a first approximation.

In the embodiment according to FIG. 2, the cylinder 42 ends at a distance from the next edge of the depression 40, as a result of which the gap 43 is formed. This is very important in order to avoid short-circuit currents which cause magnetic shielding of the coil. The cylinder 42 serves only as a shield for the coil 45, whereby measurement errors caused by capacitive interference are avoided. The coil 45 is expediently designed as a Rogowski coil.

In the known voltage transformers, in which the measuring capacitance is at earth potential or in the region of the earth potential, there is a risk that in the event of a short-circuit, in the event of a short circuit, arcing from the measuring device to earth occurs because the encapsulation is transient is placed on high voltage potential. In addition, there is also an electromagnetic compatibility problem in the known arrangements; these problems do not exist in the arrangement according to the invention, both according to FIGS. 1 and 3 and according to FIG. 2.

Both the capacitive transducer with the voltage supply and the current transformer with the capacitive voltage supply and, moreover, also the combination transformer according to FIG. 3 can be readily prepared and prefabricated as a unit in the factory. The fact that the supply of the transducers 25 or 52 and 53 is designed as a voltage supply is due to the fact that voltage is always present or the voltage leads the current. This has the advantage that the supply of the transducers 25, 52 and 53 and the associated light transmitter 26, 54, 55 is always ensured.

Figure 4 shows a transducer with cooling.

On a shoulder 60 inside the inner conductor 11 a Pel¬ tier element, which is designated in its entirety with 61, is placed. As is known, the Peltier element 61 has conductor materials of different electrical conductivity, as is known, for example, from Meyers Lexicon of Technology and the Exact Natural Sciences, volume 3, page 1916, so that the composition need not be discussed in more detail here.

In order to reduce the operating temperatures, the transmission circuit arrangements are or are thermally contacted with the cold surface of the Pelier element 61.

The Peltier element 61 is supplied with current by means of a suitably dimensioned current transformer 62 surrounding the inner conductor 11 via lines 63 and 64, so that a sufficient cooling effect can be achieved for the transmission circuit arrangement 25/26. Of course, the power supply 29 could also be used. It goes without saying that a rectifier must be provided and is not shown in more detail in FIG. 4.

Claims

1. Measuring transducers located at high voltage potential, in particular for a metal-encapsulated, gas-insulated high-voltage switchgear assembly, with at least one conductor located at high voltage potential and possibly an outer conductor surrounding it, with a conductor provided inside the hollow, which Electrical measurement signals converting transmission circuit arrangement into light signals, the light signals being conducted from high voltage potential to earth potential, characterized in that a depression (17) is introduced on the outer circumference of the conductor (11), in which a measuring electrode (11) is insulated from the conductor (11). 20) is provided, the length of which in the longitudinal direction of the conductor (11) is smaller than the length of the recess (17) and the outside diameter of which is equal to the outside diameter of the conductor (11), and that between the measuring electrode (20 ) and the conductor (11) located capacitance (21) generates the measurement signals.

2. Transducer according to claim 1, characterized in that the light guide (27) in a metal-encapsulated, gas or liquid-insulated switchgear with support insulators for supporting the inner conductor with respect to the outer conductor in a spiral or meandering shape through the adjacent post insulator (16) towards au¬ are grounded.

3. A transducer according to claim 1, characterized in that the measurement signals are transmitted to earth potential in the form of a light beam.

4. Transducer according to one of claims 1 to 3, thereby ge indicates that webs (18, 19) made of insulating material are attached to the bottom of the recess (17), on which the measuring electrode (20) is applied.

5. Transducer according to one of claims 1 to 4, characterized ge indicates that the conductor (11) has a circumferential further recess (40) which is electrically conductive by means of an edge of the further recess (40) adjoining and ending at a distance from the other edge cylinder (42) is covered, the wall thickness is thin and the outer circumference corresponds to the outer circumference of the conductor, and that in the interior between the bottom of the further recess (40) and the inner wall of the cylinder (42) a coil (45) is arranged, the signals of which can be fed to the transmission circuit arrangement (25, 26).

6. Transducer according to one of the preceding claims, characterized in that within the outer contour egg-ne third Ver¬ depression _^ . (30) is provided in which a further capacitor arrangement (31 to 34), as in the claims 1 to 3, whose voltage signals serve to supply the transmission circuit arrangement (25, 26) and are dimensioned for this purpose.

7. Transducer according to one of the preceding claims, characterized in that the transmission circuit arrangement (25, 26) is an analog / digital converter or a voltage / frequency converter.

8. Transducer according to one of the preceding claims, characterized in that at least one Peltier element (61) serving as a cooling element is provided within the hollow inner conductor (11), which is connected to the transmission circuit arrangement (25, 26) is in thermally close contact and is possibly supplied with current by means of a current transformer (62) surrounding the inner conductor (11).