EP0298069B1 - Position indicator for high voltage circuit breaker - Google Patents

Description

The invention relates to a switch position detector for high-voltage switchgear with a fixed contact which can be brought into and out of engagement with a movable contact, in particular for disconnectors and earthing switches with a fixed contact arranged on a plastic insulator, the switch position of the movable contact in at least one of its end positions by an evaluation unit connected light guide is monitored and is based on DE-B-12 29 624.

It is known that isolating switches and earthing switches have to fulfill safety tasks, namely on the one hand to create a safety distance between voltage-free system parts and live system parts, and on the other hand to earth the voltage-free system parts.

Maintenance or repair work can only be carried out safely on the system components once these tasks have been completed and secured. Switch position detectors are therefore safety-critical elements in these high-voltage switching devices.

In common switch position detectors with auxiliary switches operated by the drive, there is the possibility that, for example, the message is given in the event of a break in the drive linkage, even though the movable contact has not reached its end position. From EP-A-88 155 a switch position indicator for high-voltage disconnectors is known, in which the message is transmitted by ultrasonic pulses. Designs that work with a light beam and light guides are also known, for example, from DE-B-1 229 624.

In the version according to DE-B-12 29 624, the switching position of a high-voltage switch is monitored by light guides connected to an evaluation unit, which consist of rods made of glass or glass-like plastic. In the end positions of the contact, a prism attached to the movable contact of the high-voltage switch reflects the light transmitted by a rod into another, leading to the evaluation unit Rod. In a switch position indicator known from AT-PS 378 861, the message is given by a switching magnet arranged on the fixed contact and a magnetic switch attached to the movable contact via insulating transformers.

Such switch position detectors are, however, relatively complex and therefore uneconomical on the one hand, and on the other hand not applicable to some disconnectors and earthing switches. FR-A-2 454 662 is a temperature sensor with a bimetal tab

known, which is connected at its free end to an optical fiber. In addition to the bimetallic bracket, there is a torsion-free support rail on which an angle is attached with a reflector aligned with the end face of the light guide. At normal ambient temperature, the light emerging from the light guide is reflected back into the end of the light guide by the reflector. If there is a change in temperature, the bimetal tab is bent out and the reflected light is changed or completely interrupted. A light receiver at the other end of the light guide then triggers a false signal. The arrangement of the light guide at the free end of the relatively thin bimetal tab results in a vibration-sensitive design which is unsuitable as a switching position indicator in high-voltage switching devices.

Due to the arrangement according to the invention shown below, a switching position indicator for high-voltage switching devices is intended, which is universally applicable, has a high level of operational reliability, can be carried out economically and only gives the message when the movable contact has reached one of its end positions.

This is achieved in that from the evaluation unit to at least one of the two contacts of the high-voltage switching device only one light guide consisting of an optical fiber with a diameter of approximately 1 mm leads, the end of which can be covered by the other contact in one of its end positions and which with the covered end an optical one through light reflection Transmits signal, which is implemented in the evaluation unit and processed in logic circuits.

In cooperation with one of the two contacts, the light guide connected to the evaluation unit forms a light guide reflex light barrier, which delivers a safe switching position signal when the light exit point is covered by a contact and light is reflected back into the light guide. The light guide application also results in the known advantages of insensitivity to electromagnetic influences, in terms of weight and insulating properties.

Error reports in cases where the moving contact has not reached one of its end positions are practically impossible.

In a preferred embodiment, one end of the light guide opens into an open bore of a contact, the opening of which can be closed by the other contact.

The reflection effect can thereby be increased and the light exit point can be protected against contamination, although light guide reflex light barriers can be set so precisely that they are insensitive to contamination. The light-reflecting part of the contact can also be up to 30 mm away from the light exit point.

In a further embodiment, the light guide can pass through the plastic insulator in the longitudinal direction and have a section designed as a plug connection.

The light guide can be embedded in the plastic insulator.

Plastic insulators are preferably made of epoxy resin using the known pressure gelling process. The light guide can be introduced into the mold before the plastic insulator is cast and then cast in.

It is understood that the light guide is arranged in the shape so that the separating surface of its connector is aligned with the bottom surface of the plastic insulator.

The light guide has a high dielectric strength and is embedded in the plastic insulator, so that neither the insulation strength nor the tracking resistance of the plastic insulator are impaired.

For production reasons, the light guide can also be guided through a hole in the plastic insulator and cast in it.

This type of design will be chosen, for example, to avoid damage to the light guide from high casting temperatures.

For the same reason, the light guide can be passed through a plastic tube embedded in the plastic insulator and cast in it.

A second light guide is preferably connected to the evaluation unit, the other end of which forms a light guide reflex light barrier with part of the movable contact.

The evaluation unit is therefore suitable for additionally processing signals for the switch-off position of the high-voltage switching device.

In further embodiments, the evaluation unit is designed for at least one three-pole high-voltage switching device in order to be able to take over the switching position messages for the on and off switching positions of the three poles.

The evaluation unit preferably contains at least one microprocessor and optical transmit and receive diodes for converting the optical signals into electrical signals and interfaces.

The evaluation unit is thus not only suitable for processing the signals coming from the fiber optic reflection light barrier and for example the fiber optic cable to a control and monitoring unit, the position report, fault message etc. but also additional functions, e.g. Interlocks to take over.

However, electrical auxiliary switches or limit switches can also be connected to the evaluation unit, as a result of which the evaluation unit can process, for example, all messages from the electrical equipment of an encapsulated switch cell.

Optical fibers, surrounded by a size, are particularly suitable for casting or embedding in plastic insulators.

Exemplary embodiments of the subject matter of the invention are explained in more detail below with reference to the accompanying drawing.

• Fig.1 den Aufriß eines Hochspannungstrennschalters mit Schaltstellungsmeldern für die Ein- und Ausschaltstellung,
• Fig. 2 das Detail einer Ausführungsform der Schaltstellungsmeldung am Hochspannungstrennschalter gemäß Fig. 1,
• Fig. 3 das Detail einer anderen Ausführungsform der Schaltstellungsmeldung am Hochspannungstrennschalter gemäß Fig. 1,
• Fig. 4 eine Schaltstellungsmeldung an einem Hochspannungserdungsschalter fur Freiluft und
• Fig. 5 das Blockschaltbild einer Ausführung der Auswerteeinheit.

Show it

• 1 shows the elevation of a high-voltage disconnector with switch position indicators for the on and off position,
• 2 shows the detail of an embodiment of the switching position message on the high-voltage isolating switch according to FIG. 1,
• Fig. 3 shows the detail another embodiment of the switching position message on the high-voltage disconnector according to FIG. 1,
• Fig. 4 shows a switching position message on a high-voltage earthing switch for outdoor and
• 5 shows the block diagram of an embodiment of the evaluation unit.

1 shows the pole of an interior high-voltage disconnector 1, for example for an operating voltage of 36 kV, in the off position. It consists of two plastic insulators 2, 3 mounted on a frame 16 and a contact track which has a fixed contact 4 with a connecting lug, a contact knife 18 and a rotary contact 5 with a connecting lug. The busbars 6, 7 are electrically conductively connected to the connecting lugs.

The movable contact, which can be brought into and out of engagement with the fixed contact 4 by pivoting, is formed by the rotary contact 5 and the contact knife 18, which consists of two parallel knives which are connected to one another by spacer bolts and at the other end by the spring force a helical tension spring are pressed laterally on the rotary contact 5. The switch-on position of the contact knife 18 is indicated by dashed lines.

A light guide 8, 9, which has a section 10, 11 designed as a plug connection, leads through each of the two plastic insulators 2, 3. The separating surface of the plug connections is aligned with the bottom surface of the plastic insulators 2, 3. After the sections 10, 11, the light guides 8, 9 are led out of the frame 16 and via the conductor sections 12, 13 to an evaluation unit 17, which is, for example, in the control part of an encapsulated one Switch cell is connected. The light guides 8, 9 are embedded in the plastic insulators 2, 3 and were cast in during the production of the plastic insulators 2, 3.

The free ends of the light guides 8, 9 open into open bores 14, 15 on the one hand of the fixed contact 4 and on the other hand of the rotary contact 5. These bores 14, 15 each run obliquely through the fixed contact 4 or rotary contact 5 from a predetermined position of a side surface to the base surface, where they are aligned with the free ends of the light guides 8, 9. In the illustrated switch-off position of the high-voltage circuit breaker 1, a knife end of the contact knife 18 closes the open bore 15 on the rotary contact 5, in the switch-on position indicated by dashed lines, on the other hand, a free knife end of the contact knife 18 closes the open bore 14 on the fixed contact 4. One from the evaluation unit 17 through the light guides 8 , 9 transmitted light beam, as long as the open bore 14, 15 is closed, is reflected back from the preferably silver-plated contact surfaces of the contact knife 18 into the light guide 8, 9. The resulting light signal of this light guide reflex light barrier is preferably processed in the evaluation unit 17 to form a digital switch position signal.

2 shows a detail of the fixed contact 4 screwed onto the plastic insulator 2 on an enlarged scale and partly in section. The light guide end 19 with the light exit point of the light guide 8 embedded in the plastic insulator 2 protrudes somewhat into the open bore 14 of the fixed contact 4, as a result of which this can be screwed more precisely into the correct position aligned with the light guide 8.

Fig. 3 shows another embodiment of the switching position message on the fixed contact 4 of the high-voltage disconnector 1, which is shown in side view on an enlarged scale. The contact knife 18, drawn in section, is in engagement with the fixed contact 4. The light guide 8 consists of an optical fiber with a diameter of about 1 mm and is guided through a plastic tube embedded in the plastic insulator 2 and potted in it.

The light exit point 20 of the end of the light guide 8, which protrudes somewhat from the plastic insulator 2, is covered by part of the contact knife 18, whereby a light guide reflex light barrier is formed, the light signal of which in turn is processed in the evaluation unit 17 to form a switch position signal.

4 shows an embodiment of the switching position message on a high-voltage earthing switch for outdoor use.
The evaluation unit 17 is arranged in the drive box of the high-voltage earthing switch, which is fixedly mounted on an earthed post and consists of the frame 33, porcelain insulator 32, fixed contact 34 with connecting bolts 36 and switch blade 35. The switch blade 35 in the switched-on position has a U-shaped cross section and is mounted on the frame 33 so that it can be pivoted by 90 °. The switch-off position of the switching knife 35 is indicated by dashed lines. From the evaluation unit 17, the light guide 38 leads through the interior of the switch blade 35 in an arc into an open bore at the end of the switch blade, so that the light exit point points to the fixed contact 34 and forms a light guide reflex light barrier with a contact surface thereof. It is understood that the light guide 38 is attached to the switch blade 35 either by means of clamps or gluing. In this case, it is possible to dispense with a section of the light guide 38 designed as a plug connection for easier assembly.

5 shows the block diagram of an embodiment of the evaluation unit 17. The dot-dash line indicates the electromagnetically sealed housing in which the electronics of the evaluation unit 17 are accommodated. In the simplest case, the electronics can consist of optical transmit and receive diodes 21 for converting the optical signals into electrical signals and electronic logic circuits. In the illustrated embodiment, however, the evaluation unit 17 consists of the microprocessor 22 with supply unit 23, the optical transmit and receive diodes 21, which lead to the switch position messages for the switch-on positions E1, E2 and switch-off positions A1, A2 of two three-pole high-voltage isolating switches via optical fibers, and the optical ones Transmitting and receiving diodes 24, which are connected via bidirectional optical fibers to a central control and monitoring unit of the high-voltage switchgear. In addition, an electrical auxiliary switch A3, for example a dividing car lock, is connected to the microprocessor 22 via an interface 25.

There may also be further transmit and receive diodes and interfaces for the connection of the switching position messages or interlocks of electrical equipment, so that the evaluation unit 17 can process all messages of the electrical equipment and interlocks of an encapsulated control cell or the control panel of a compressed gas-insulated switchgear. The electronic circuits of the evaluation unit 17 are protected against interference from the high-voltage switchgear by electromagnetic shielding and filter circuits.

Switching position detectors of the previous version can be used universally, for example also in switching devices of compressed gas-insulated high-voltage switchgear, if the light guide is guided tightly through the pressure enclosure and plastic insulators.

Claims (10)

1. Switch position indicator for high-voltage switching devices (1) having a fixed contact (4; 34) which can be brought into and out of engagement with a moving contact (18; 35), in particular for disconnectors (1) and earthing switches with a fixed contact (4; 34) arranged on a plastic insulator (2; 32), the switch position of the moving contact (18; 35) being monitored in at least one of its end positions by optical guides (8...13; 38) connected to an evaluation unit (17), characterised in that there leads from the evaluation unit (17) to at least one of the two contacts (4, 5; 18; 34, 35) only one optical guide (8...13; 38), comprising an optical fibre of a diameter of about 1 mm, the end (19; 39) of which can be covered by the other contact (18; 35) in one of its end positions and which, with the end (19; 39) covered, transmits by light reflection an optical signal which is converted in the evaluation unit (17) and processed in logic circuits.
2. Switch position indicator according to Claim 1, characterised in that one end (19; 39) of the optical guide (8...13; 38) opens out into an open bore (14, 15) of a contact (4, 5; 34), the opening of which can be closed by the other contact (18; 35).
3. Switch position indicator according to Claim 1 or 2, characterised in that the optical guide (8...13) leads in the longitudinal direction through the plastic insulator (2, 3) and has part of it (10, 11) designed as a plug connection.
4. Switch position indicator according to one of Claims 1 to 3, characterised in that the optical guide (8...13) is embedded in the plastic insulator (2, 3).
5. Switch position indicator according to one of Claims 1 to 3, characterised in that the optical guide (8...13) is led through a bore, provided in the plastic insulator (2, 3), and is cast in the said bore.
6. Switch position indicator according to one of Claims 1 to 3, characterised in that the optical guide (8...13) is led through a plastic tube, embedded in the plastic insulator (2, 3), and is cast in the said tube.
7. Switch position indicator according to one of Claism 1 to 6, characterised in that there is connected to the evaluation unit (17) a second optical guide (9, 11, 13), the other end of which forms with part of the moving contact (18) an optical-guide reflected light barrier.
8. Switch position indicator according to one of Claims 1 to 7, characterised in that the evaluation unit (17) is designed for at least one three-pole high-voltage switching device.
9. Switch position indicator according to one of Claims 1 to 8, characterised in that the evaluation device (17) includes at least one microprocessor (22) with feed unit (23) and optical transmitting and receiving diodes (21) for converting the optical signals into electric signals and also interfaces (25).
10. Switch position indicator according to one of Claims 1 to 9, characterised in that electric auxiliary or limit switches are connected to the evaluation unit (17).

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