WO1992013279A1

WO1992013279A1 - High tension current transformer

Info

Publication number: WO1992013279A1
Application number: PCT/EP1992/000112
Authority: WO
Inventors: Adolf Schwab
Original assignee: Abb Patent Gmbh
Priority date: 1991-01-23
Filing date: 1992-01-21
Publication date: 1992-08-06
Also published as: DE4201434A1; WO1992013278A1; EP0521125A1; EP0521146A1; DE4101858C1; JPH05508021A; DE4133508C1; JPH05508223A

Abstract

The invention concerns a high-tension measuring transformer, in particular for metal-encapsulated, gas-insulated high-tension switching devices, which generates signals which are guided from high voltage to earth potential, the measuring transformer being located within the contour of a high-tension power line (11). Fitted inside the hollow line (11) is a transformation circuit (25, 26) which converts the electrical transducer signals into light signals, the light signals being conducted to earth by a fibre-optic cable (27). The transformation circuit (25, 26) is mounted on a Peltier element (61) to cool it. The Peltier element (61) is supplied with power by a suitably rated current transformer (62).

Description

Current transformer located at high voltage potential

description

The invention relates to a current transformer located at high voltage potential according to the preamble of claim 1.

Current transformers of the type mentioned at the outset are used to detect currents in a high-voltage conductor carrying a high-voltage system.

From DE-OS 25 46 694 a measuring transmitter for high-voltage lines has become known, which has operating potential, ie. H. Has high-voltage potential, located transducer 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, for example by a transmitter, to ground potential. How the transducer is designed is not apparent from DE-OS 25 46 694.

From DE-OS 37 12 190 a current transformer of the type mentioned has become known, the transducer of which is in the form of a Rogowski coil. The Rogowski coil is wrapped around the outer circumference of the electrical conductor. The electrical signals recorded in the process are fed to a measuring unit located within the inner conductor, from which the evaluated signals are conducted outwards via an data line in the form of a glass fiber line through an isolator. The power supply for the measuring unit takes place via a further glass fiber line, which is led from earth potential through the insulator to high voltage potential. This configuration is relatively complicated, in particular because of the special power supply for the Meßwertauf participants. Another version of current transformers are inductive transducers, see e.g. B. CH-PS 514 923, which have one or more ring cores in the area of the outer casing, which surround the conductor concentrically. These current transformers are technically complex to manufacture.

From JP abstract 58-124 960 a measuring arrangement has become known which is arranged in a semi-cylindrical cutout in the inner lead. The sensor is a photo element with which the electric field inside the cutout is detected. In this configuration, it is important that the greatest concentration of the current paths is present where the sensor is arranged. This takes place in the arrangement according to the JP abstract by virtue of the fact 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 meandering shape 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.

The object of the invention is to provide a current transformer of the type mentioned, which is easy to manufacture and has a high measurement accuracy.

This object is achieved according to the invention by the characterizing features of claim 1.

Particular embodiments of the invention are specified in the subclaims.

According to the invention, the measuring device is located within the outer contour within a recess of the inner conductor which is at high voltage potential; Light signals generated by the measuring unit are guided according to claim 2 as a light beam or via light guides - specifically according to claim 3 - in a metal-encapsulated high-voltage switchgear assembly through the post insulator to ground potential. If the light signal via a light beam in a metal-encapsulated high-voltage system to earth potential, then radial bores are provided in the inner conductor and in the outer conductor, which are permeable to the light beam. That at least the Außenlei ter must be seen with a transparent seal in the radial bore ver goes without saying. It is also obvious that the radial bores must continue to be aligned with one another.

As mentioned at the outset, DE-OS 37 12 190 discloses a measuring arrangement located at high voltage potential, the measuring signals of which 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 differently.

The embodiment according to the invention makes it possible to form a current converter unit which can be retrofitted in existing systems. Due to the fact that the cylinder covering the coil has an outer diameter that is equal to the outer diameter of the inner conductor, the dielectric breakdown strength does not change in the case of metal-encapsulated high-voltage systems between the inner conductor in the region of the coil and the outer conductor.

If the inner conductor or the inner conductors (in the case of a multiphase arrangement) are held within the metal encapsulation by means of a disk-shaped support insulator, then the light guides according to claim 3 will preferably be laid out in a spiral or meandering shape inside the support insulator. This results in a favorable arrangement with regard to the creepage distances along the light guides.

It is known from DE-OS 32 07 306 how light conductors of high and low voltage potential can be conducted. However, the known insulator is not a disk-shaped support insulator located within a gas-insulated, metal-encapsulated system, but rather one Porcelain insulator with plates to extend the creepage distances. In addition, the light guides are on the outer surface and they run helically, but not spiral.

In a particularly advantageous embodiment of the invention, according to claim 4, a capacitor arrangement can also be provided within the outer surface of the conductor for the voltage supply of the transmission circuit arrangement, which is formed in that the conductor has a circumferential depression in which the Well an electrode is arranged isolated. The outside diameter of the electrode corresponds to the outside diameter of the conductor.

The from _; The transducer current consumed is an analog signal per se, and accordingly the transmission 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 which is used directly as a light beam or by means of the light guide to an evaluation unit located at earth potential or outside the encapsulation.

The measured values can additionally be transmitted in analog form with a further light beam path or light guide path into the outside space to the evaluation unit in order to be able to record the phase angle precisely.

The transmission circuit arrangement is at a high potential within the current-carrying inner conductor.

For technical reasons, for example with high load currents or with solar radiation, the temperature of the inner conductor can reach temperatures above 80 ° C. Temperature increases of up to 130 ° C. cannot be ruled out. However, the reliable functioning of the transmission circuit arrangement and the associated optoelectronics is only guaranteed up to limit values of the operating temperature; the limit values are 75 ° C, in special cases also 125 ° C. According to the features of claim 8, a Pelier element can be used for cooling, the basic principle of which is generally known and is described, for example, in Meyers Lexicon of Technology and the Exact Natural Sciences, Volume 3, Bibliographical Institute, Mannheim / Vienna / Zurich, 1970 is explained.

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 two exemplary embodiments of the invention are shown.

Show it:

Figure 1,. 1 shows a schematic representation of a current transformer within a high-voltage switchgear assembly, with light guides,

Figure 2 shows the current transformer of Figure 1 with direct light, and

3 shows a current transformer according to FIG. 1 with cooling.

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

A circumferential depression 4 is introduced within the inner conductor 11 and is covered by a cover cylinder 42 projecting from an edge 41 of the depression toward the outer surface except for a gap 43. In the by the cylinder 42nd and the bottom of the interior 40 located in the recess 40 accommodates a coil 45 which is designed, for example, as a Rogowski coil and whose measurement signals are fed via conductors 46, 47 to a circuit arrangement 25 which is arranged in the interior of the inner conductor 11. In this, the analog measurement signals led through the conductors 23 and 24 to the circuit arrangement 25 are converted into digital signals. Accordingly, the circuit arrangement 25 is an analog / digital converter. A light transmitter 26 is located on the analog / digital converter 25; Analog-digital converter and light transmitter together form the transmission circuit arrangement, the light transmitter, after conversion into light signals, transmits the digital signals to a light guide arrangement or light guide 27 which, as shown schematically in the figure, spirally or meandering through the post insulator 16 to the outside. The individual cross sections of the light guide arrangement 27 can be seen in the figure. The light guide arrangement 27 is connected to an evaluation circuit 28 in which the light signals are evaluated. The inner conductor 11 has a circumferential further depression 30, on the bottom of which insulating webs 31 and 32 are arranged, by means of which an electrode 33 is supported in an insulated manner with respect to the inner conductor 11. A capacitor or capacitance 34 is thus formed between the electrode 33 and the bottom of the depression 30; with the located between the electrode 33 and the metal enclosure 12, the capacitor capacity of 35 ^'34 forms a capacitive voltage divider.

The converter 25 is supplied with voltage by means of this capacitor arrangement 34/35 via conductor 36/37.

There is of course the possibility that the voltage supply for the converter 25 and the light transmitter 26 is provided by the measuring transducer itself and not by means of an additional supply capacity.

An additional light guide is not shown, which is assigned to the inductive transducer 45 and which in analog form of the evaluation circuit generates the signals generated by the transducer. tion feeds. These additional light guide arrangements would also be passed through the post insulator 26 in a spiral or meandering fashion; With these analog signals which are in the same phase with the variable to be measured, the phase angle can be detected precisely.

The invention can be used in gas- or liquid-insulated high-voltage switchgear and overall it has a comparatively small space requirement and can also be produced with little effort. In a modified form, it can also be used with open-air systems.

Figure 1 shows only a single conductor within the metal encapsulation; the high-voltage system can of course also be a multi-phase encapsulated system. Then the electrode 33 can only be formed over a part of the circumference, so that the voltage supply for each individual inner conductor takes place separately.

Due to the design of the arrangement according to FIG. 1, the same dielectric as in the outer encapsulation 10 is located in the interior of the transducer or the supply capacitance, so that the measurement signals are temperature-dependent to a first approximation.

As can be seen, 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 magnetic shielding of the coil in the event of short-circuit currents. The cylinder 42 serves only as a shield for the coil 45, insofar as measurement errors caused by capacitive interference are avoided. The coil 45 is expediently designed as a Rogowski coil.

The fact that the supply of the converter 25 is designed as a voltage supply has the reason that voltage is always present or the voltage leads the current. This has the advantage that the supply of the converter 25 and the associated light transmitter 26 is ensured.

The measurement signals can also be transmitted to earth potential via a direct light beam. For this purpose, the inner conductor 11 and the outer conductor 10 each have a radial bore 50 and 51, the radial bore 51 of the outer conductor 10 being closed with a window 52 made of a suitable transparent material. The evaluation unit 28 is then assigned to the window 52 in such a way that scattered light cannot impair the reception of the evaluation unit, see FIG. 2.

The cooling of the electronic components of the transmission switching arrangement takes place according to FIG. 3.

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. 3.

Claims

3 patent claims

1. A high-voltage potential measuring transducer for a high-voltage system, with a conductor having a hollow cylindrical cross-section and carrying high-voltage potential, with a transmission circuit provided within the conductor that converts the electrical measuring signals of the measuring transducer into light signals, the light signals being a ground potential located evaluation circuit can be fed, characterized. that the conductor (11) has a circumferential depression (40) which is covered by a cylinder (42) which adjoins an edge of the depression (40) in an electrically conductive manner and ends at a distance from the other edge, the wall thickness of which is thin and the outer circumference of the conductor (11) corresponds to it, and that in the interior (44) between the bottom of the depression (40) and the inner wall of the cylinder (42) a coil (45) is arranged, the singals of which Transmission circuit (25, 26) can be fed.

2. Transducer according to claim 1, characterized in that the light signals are transmitted directly or by means of light guides to Erdpoten¬ tial.

3. Transducer according to claim 2, for a metal-encapsulated, gas-insulated high-voltage system whose at least one Innenlei ter is or are surrounded by an outer conductor, which is supported by means of a support insulator against the inner conductor or conductors, characterized in that the light conductors ( 27) are laid in a spiral or meandering shape through the post insulator (16) towards the outside in the direction of the outer encapsulation (10) to earth potential.

4. Transducer according to one of the preceding claims, characterized in that on the outer circumference of the conductor (11), a further recess (30) is introduced, in which an electrode (33) is provided insulated from the conductor, the length of which in the longitudinal direction of the conductor is smaller is the length of the recess (30) and its outer diameter is the same lo

Outside diameter of the conductor, and that the capacitance (34) located between the electrode (33) and the conductor (11) generates the signals which serve to supply voltage to the transmission circuit (25, 26).

5. Transducer according to one of the preceding claims, characterized in that at the bottom of the recess (30) webs (31, 32) made of insulating material are attached, on which the electrode (33) is applied.

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

7. Transducer according to one of claims 4 and 5, characterized ge indicates that at the bottom of the recess (30) webs (31, 32) made of insulating material are attached, on which the electrode (33) is applied.

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