EP3074998B1 - Earthing switch for traction power supply systems and method for earthing a part of a traction power supply system using an earthing switch - Google Patents

Description

Earthing switches are special switching devices that in the simplest case connect an electrical line to ground and thus establish a safe state. In overhead catenary systems, earthing switches are mainly used in halls and factories and automated grounding systems for tunnel rescue. A system for automated grounding is, for example, from the " Specification "Automatic Grounding Device (AEE)" of the SBB CFF FFS from 18.04.2012 on page 5 known. Another system for automated grounding is Sicat AES from the journal article " Catenary grounding - automated with Sicat AES ", published in" Electric Railways Special Edition S3 / 2013 ", known.

It is from the product description of the outdoor circuit-breaker of the FLaV 25-2000-16-1B and 2B series Page 9 of the "Operation, Installation and Maintenance Manual for Driescher Freiluft Schaltgeräte für Bahnanlagen" with order number 3-811201068.05-04 by Elektrotechnische Werke Fritz Driescher & Söhne GmbH, 85366 Moosburg It is known to use so-called pre-ignition horns for switch-disconnectors in order to improve the short-circuit breaking capacity. Fig. 11 on page 12 of the same product description shows that the pre-ignition horns are equipped with a tip that is particularly temperature-stable. Such temperature-resistant tips have a particularly low wear during operation and thus reduce maintenance and repair costs. The temperature stable tips are well known in the art and are often made of tungsten alloys and welded to the pre-ignition horns made of copper.

Earthing switch 8WL6144-1A for AC 25 kV traction current systems Siemens AG, known from "Product Information / Version 1.2.0 / No. A6Z00029955871" from 2013 on page 3 , is a grounding switch for railway power plants having a first main contact and a movable second main contact, wherein the movable second main contact for producing an air gap from the first main contact is movable away. The earthing switches themselves are differentiated according to the standard with regard to their short-circuit breaking category. The earthing switch 8WL6144-1A is a grounding switch, which is only closed by design and thus produces a grounded condition, if the catenary was previously switched off, secured against reconnection and checked for absence of voltage. These measures prevent the earthing switch from switching to a short circuit - which would damage or destroy it.

It is also known from the same product information of the SICAT 8WL6144 series of Siemens AG circuit breakers, in which arc horns made of copper are provided. In the relatively complex Magna Flash welding process burn-off elements are welded from a tungsten copper alloy. The butt welded to the arcing horns consumables must be replaced during erosion of the material in the course of maintenance. The entire arc horns are exchanged and realigned so that the planned switching arc extinction is ensured.

Earthing switches, which are used for AC and DC traction power supply and are to be connected to a live catenary, must, in contrast to the known 8WL6144-1A earthing switch, be short-circuit proof. These switches are characterized today primarily by the fact that the switching blade enters the contact at a high speed and thus takes place in connection with the pre-ignition an entry into the contact at low instantaneous value of the current. Examples are z. B. switches of the series FES 3-20-1 B Fa. Driescher.

The rapid entry or the rapid closing of the main contacts results in the known effect of the current increase, because the closing process must remain in the time range of the lower portion of the current rise, so as not to be hindered by the current forces at the inlet of the switch blade. However, compared to the switch series 8WL6144-1 from Siemens AG, these switches are comparatively more robust due to the higher requirements and therefore more expensive. Although the voltage test according to the five safety rules according to EN 50110 is standard today before the earthing switch is inserted, earthing switches of the higher category with short-circuit breaking capacity are nevertheless required (for example AEE of the Swiss Federal Railways). This is justified by the fact that in cases of emergency shutdown there would be no time for a voltage test and within a few seconds a safe state must be established. Other reasons could be incorrect operation.

It is forgotten that a grounding switch triggers the short circuit and then carries him, but this earthing switch only withstand this load when the supplying circuit breaker switches off the voltage and thus the short circuit current in the substation or the substations via its short circuit detection.

Furthermore, earthing switch from the CH 536 023 A . DE 199 49 493 A1 and disconnector from the EP 0 072 771 A1 known.

Starting from the well-known earthing switch for railway power systems of the type 8WL6144-1A, the object of the invention is to provide a suitable for a multiple short-circuit closing earthing switch in a railway power plant, which can be produced inexpensively.

This object is achieved by a traction current system according to claim 1.

It is an advantage of the invention that the functionality of the earthing switch is widened in comparison to conventional earthing switches, because the short circuit breaking strength of the earthing switch according to the invention is considerably increased. This is achieved because the short circuit is not ignited through the main contacts, which extends the life of the main contacts while ensuring relative integrity and, associated therewith, a relative low maintenance of the main contacts. The current transfer via the Vorzündanordnung during the closing movement / switch-on ensures that the Vorzündanordnung triggers as a "victim element" the short circuit. The Vorzündanordnung can easily be repaired depending on the wear, which offers cost advantages in terms of operation and maintenance of the earthing switch.

The earthing switch is comparatively simple in design, uses the same platform concept for existing disconnectors and earthing switches and is inexpensive to manufacture. In operation, the earthing switch is particularly low maintenance because it is not damaged or destroyed during a short-circuit closing (in emergency situations).

The earthing switch according to the invention is suitable for applications in both DC and AC operation.

In a preferred embodiment of the earthing switch according to the invention, the pre-ignition arrangement is arranged above the main contacts. This is advantageous because a protection of the main contacts is ensured because the main contacts are not in the range of thermal buoyancy of the arc column occurring. This ensures via the minimum principle of the arc, that its bases always on the appropriate, provided for this purpose tips Vorzeündanordnung.

In a further preferred embodiment of the earthing switch according to the invention, the pre-ignition arrangement has a pre-ignition device for each main contact.

The Vorzündeinrichtungen do not touch, but are designed so constructive that an ignition is done safely by exceeding a critical field strength and leads to the formation of an arc. The distance between the pre-ignition devices is chosen as a function of the voltage system and the rated voltage. This embodiment of the Vorzündanordnung is advantageous because corresponding wear occurs by arcing in the region of both main contacts only at the designated Vorzündeinrichtungen.

In another preferred embodiment of the earthing switch according to the invention, the pre-ignition devices are designed as pre-ignition horns. This is advantageous because pre-ignition horns are designed and designed only for short circuit switching. This pre-ignition horns are well designed for the loads acting and especially suitable for use with earthing switches.

According to a preferred embodiment of the aforementioned embodiment, the Vorzündhörner are mounted substantially in horizontal alignment and associated with the respective main contact. This is an advantage because arcing in this way occurs only in the area of the pre-ignition horns.

In a further preferred embodiment of the earthing switch according to the invention, the pre-ignition devices are designed as arcing horns.

This is an advantage because arc horns out of use with circuit breakers, while maintaining a high breaking current capacity have long been known and tested. The use of arcing horns is particularly useful if a short-circuit withstand voltage is required for load-break switches. A high Ausschaltstrombelastbarkeit can not afford the Vorzündhörner in comparison, so that this embodiment is particularly suitable for earthing switch with a particularly high short-circuit resistance.

In another preferred embodiment of the grounding switch according to the invention, the arc horns are mounted substantially in vertical alignment and associated with the respective main contact. This is an advantage because it creates arcs only in the area of the arc horns. These arcs are driven upwards along the arc horns by the thermal buoyancy and eventually reach the ends of the arcing horns intended for wear.

In a further preferred embodiment of the earthing switch according to the invention, the earthing switch is suitable for making a short-circuit closing several times. A grounding switch according to the invention is able to switch on a short circuit once or several times, which is an advantage over known earthing switches, which are triggered by a short-circuit switch i.d.R. to be damaged. The grounding switch according to the invention is therefore particularly low maintenance and short-circuit protection.

According to the invention, the turn-on speed of the earthing switch is selected so that a short circuit with arcing at the Vorzündanordnung by means of a circuit in the power network earthing switch associated circuit breaker can be seen and turned off before touching the main contacts of the earthing switch. Instead of a circuit breaker and a so-called quick switch can be used.

This effect is achieved by virtue of the fact that circuit breakers in a traction current network can detect a short circuit, as occurs when an arc occurs at the pre-ignition arrangement. The circuit breakers would then interrupt the short circuit accordingly, so that when closing the main contacts already deleted the arc and the main contacts are de-energized. Circuit breakers and also special high-speed switches are generally capable of meeting a protection trip and power down time of typically less than 100 ms. A current load of the main contacts of the earthing switch would therefore only occur in the event of a switching failure of the power circuit breakers. If a switching failure of a circuit breaker occurs, a backup protection is activated. In the substations, this usually causes the circuit breaker to trip on the input side. Although their switching times are only 20 ms, the total current flow time can be extended by further processing or transfer times. These errors are to be set for an already unlikely event of a Kurzschlusseinschaltung by the earthing switch with an extremely low probability and play little role in everyday life.

In the DC voltage range, switch-off times for high short-circuit currents of, for example, more than 20 kA are in the range of 20 to 30 ms. Frequently, even currents are switched off within less than 20 ms.

Even in the AC voltage range today is spoken in an emergency shutdown for high short-circuit currents over shutdown times in the range of 20 to 60 ms with a mean turn-off of 40 ms.

The turn-off time of a power circuit-breaker depends not only on the current amplitude but also on the direction of current flow, the current increase and the measured loop impedance. These additional measurement processing algorithms will be but effective only for lower amplitudes. Otherwise, the short circuit with high amplitudes would cause greater damage. The aim of the impedance measurements is reliable short-circuit detection in the entire associated switching group, even for lower short-circuit currents and the distinctiveness of high operating currents. These impedance stages generally entail between 20 and 30 ms delay time, so that the short-circuit current flow duration up to max. 100 ms (20 ms to 60 ms + 30 ms).

From this simple rough calculation results the aforementioned estimate of less than 100 ms shutdown time of a circuit breaker.

The earthing switch is therefore designed so that its closing speed is relatively slow enough that a corresponding arc is already safely shut down by a circuit breaker before the main contacts close. Closing the main contacts is achieved after about 200 to 250 ms. It is therefore essential to combine the properties of the earthing switch according to the invention with the properties of conventional circuit breakers. Thus, a simpler and more cost-effective solution for applications of a grounding switch with Kurzschlusseinschaltung is possible with the grounding switch according to the invention by a simple design solution over previous earthing switches. Another advantage of this design is to be relatively simple in design from the drive, because in particular no snap-action function of the earthing switch based on spring drives is required to accelerate the closing process of the main contacts and thus reduce the burden of an occurring arc.

In a further preferred embodiment of the earthing switch according to the invention, the pre-ignition arrangement has detachably attachable burn-off elements.

This is an advantage because the Abbrandelemente can be attached to a Vorzündanordnung and easily replaced without the corresponding arc horns of Vorzündanordnung must be replaced. As a result, both in the production of Abbrandelemente and in the maintenance of Vorzündanordnung costs, since now only the Abbrandelemente must be replaced.

Another advantage is that when replacing the Abbrandelemente no readjustment of the entire Vorzündanordnung must be done, which saves time and costs in maintenance. Furthermore, the technical availability of the catenary system is increased.

In a preferred embodiment of the aforementioned embodiment, the Abbrandelemente on an internal thread and can be attached to the Vorzündanordnung in the manner of a screw connection. Such a screw connection is advantageous in that on the one hand a long-term secure locking of the Abbrandelements is ensured by the screw on the Vorzündanordnung and on the other hand, the Abbrandelement can be easily replaced.

In another preferred embodiment of the earthing switch according to the invention, the length of the erosion elements is dimensioned according to an expected short-circuit closing frequency of the grounding switch. This is an advantage because depending on customer or project requirements with respect to the switching frequency of Vorzündanordnung a Abbrandelement suitable length can be selected to comply, for example, a predetermined maintenance interval even with heavy use of the Abbrandelemente without additional maintenance.

In another preferred embodiment of the grounding switch according to the invention, the burn-off elements comprise as material a dispersion-hardened copper material. This is an advantage because it can optimize the switching off of operating currents. The Abbrandelemnte from dispersion strengthened copper material have over pure copper to a higher temperature and thus arc resistance, which leads to a longer usability of the Vorzündanordnung without maintenance costs. Another advantage is that the Abbrandelemente of dispersion strengthened copper material compared to known tips made of tungsten are also priced significantly cheaper in purchasing.

The preparation of this material is powder metallurgically by reaction times; For example, CEP DISCOP high-performance copper materials from Compound Extrusion Products GmbH in Freiberg are known (application brochure 09/09). The use of this refractory material is advantageous because it reduces the frequency of maintenance of the consumable elements.

The use of dispersion-strengthened copper material is further advantageous in that it is characterized by high wear resistance and high temperature resistance. Examples of a heat-resistant copper material are dispersion-hardened copper materials which, in particular, have a substantially reduced hardness at 20 ° C. after cooling only when the dispersion-hardened copper material was previously heated to above 800 ° C. for 1 hour. Such a dispersion-hardened copper material with a particularly high heat resistance is known, for example, from the alloys CEP DISCOP C3 / 11 and C3 / 80 from Compound Extrusion Products GmbH in Freiburg (application brochure 09/09).

The dispersion-hardened copper material is suitable for machining. This is an advantage because such dispersion strengthened copper materials are excellent are machinable and can be formed by short and uniform chip formation. Known tungsten copper materials, by comparison, can not be machined due to their hardness. The machinability of the dispersion-strengthened copper materials allows, for example, in the manufacturing process, the formation of a cavity and possibly an internal thread in order to attach the Abbrandelement later detachable can.

Furthermore, the subject of the present invention is a method for grounding a part of a traction current system by means of a grounding switch according to one of the preceding claims, comprising the steps according to claim 12. The same advantages arise analogously to the method according to the invention as described above for the earthing switch according to the invention.

Figur 1

eine erstes Ausführungsbeispiel des erfindungsgemäßen Erdungsschalters zu verschiedenen Zeitpunkten des Einschaltvorgangs und

Figur 2

ein Beispiel für eine Bahnstromanlage mit Leistungs- und Erdungsschaltern.

Embodiments of the invention are shown schematically in the figures, in which shows

FIG. 1

a first embodiment of the grounding switch according to the invention at different times of the switch-on and

FIG. 2

an example of a traction current system with circuit breakers and earthing switches.

In the FIG. 1 a grounding switch 1 for traction power systems with a first main contact 3 and a movable second main contact 4 is shown. The main contact 3 is at a Rod 9 spaced from a base plate 8 of the earthing switch 1. Above the first main contact 3, a Vorzündhorn 5 is arranged, which points in a substantially horizontal orientation to the second main contact 4 out. The movable second main contact 4 is arranged on a second rod 11 with an insulator element 7 and can be moved away from the first main contact 3 to produce an air gap by tilting it over a tilting joint 10. The tilting movement is carried out via a drive, not shown, which acts on a lever 11 to the second rod 11. Above the second main contact 4, a Vorzündhorn 5 is arranged, which points in a substantially horizontal orientation to the first main contact 3 out. The two pre-ignition horns 5, 6 together form the pre-ignition arrangement 5, 6 of the grounding switch 1.

In FIG. 1a is the earthing switch 1 is open, so that an air gap between the main contacts 3,4 and the Vorzündhörnern 5.6 is formed. The earthing switch 1 is turned off in this state.

In FIG. 1b the earthing switch 1 is shown at a time during the closing process, so that the air gap between the main contacts 3,4 and the Vorzündhörnern 5.6 is already significantly shortened. The main contacts 3,4 are still separated, but the pre-ignition horns 5,6 are already so close that an arc is formed between them in the event of a short circuit. The illustrated state with arcing is typically 100 ms after the beginning of the closing process.

An existing arc typically causes an associated circuit breaker (not shown) to detect the short circuit and quickly shut down. In this way, an existing arc between the pre-ignition 5.6 is already deleted before the earthing switch 1 in Figure 1c shown closed state of the main contacts 3,4 reached. An induced by the arc wear is So to expect only in the field of Vorzündhörner 5.6, so that after a multiple stress by Kurzschlusseinschaltungen the earthing switch 1, only the Vorzündhörner must be replaced, which can be comparatively inexpensive and fast.

The FIG. 2 shows a traction power plant 20 with a first catenary 21, which is associated with a first track, and a second catenary 22, which is associated with a second track. The railway line is thus passable on both sides. The two catenaries 20,21 are each fed in sections by a substation 34, each having power or quick switch 36 for feeding a feed section of a catenary. Between power or quick switch 36 and catenary 21,22 each disconnector 37 are connected; For example, 8WL8134-4 circuit breakers from Siemens AG are used. The feed sections are defined by separating points 41, wherein signs "working limit" characterize these areas. There are further earthing switch 39 according to the FIG. 1 provided for grounding the catenaries 20,21.

One of the substations 35 has a data processing center 15 and is set up to exchange measurement data on the state of the electric traction current network and of the feed sections with the other substations 4 via communication lines 33.

All substations 34, 35 are connected via communication lines 33 to a communications network 32 which is connected to a higher-level control center, such as a Supervisory Control and Data Acquisition (SCADA) system 31.

The power or quick switches 36 must detect a short circuit on the basis of their own assigned protection and switch off the voltage. An entrainment circuit of one or more earthing switches 39 to one or more power circuit breakers 36 is not existent and necessary. Switches for which the short-circuit switching function is required must be designed differently.

Characteristic of this switch is a kind of snap-action or quick-switching function to achieve a rapid contact movement. Constructive solutions show o.g. Switch type FES 3-20-1 B from the company Driescher. If a circuit breaker without such design requirements is used for short circuit on demand, the contact is typically thermally overloaded and destroyed. This is due to the fact that the drive of the switch as a crawl drive moves the movable switching contact too slowly and thus the resulting arc is too long and is often prevented in addition by the effective current forces at the entry. Through type tests, the function of the short-circuit withstand voltage is usually proven for the product. The current flow time in these cases is between 250 ms for DC traction current systems and 1000 ms for AC traction systems. However, these times do not correspond to the real practice conditions but contain security surcharges. As already stated, the connection of a live overhead line by interlocks is avoided and occurs only in emergencies or exceptional situations. It can be deduced that the frequency of such circuits is very low. A repeated or repeated function of more than two "faulty circuits" without maintenance is not given or necessary.

The earthing switch 39 according to the invention offers a comparatively simply constructed solution which is inexpensive to manufacture and requires little maintenance.

Claims (12)

1. Traction power supply system (20) with contact lines (21, 22), with substations (34) for supplying power to the contact lines (21, 22), wherein the substations (34) each have circuit breakers (36) or high-speed circuit breakers for supplying power to feed sections of the contact lines, and with at least one earthing switch (1, 39) for earthing one of the contact lines (21, 22), which has a first main contact (3) and a moveable second main contact (4), wherein the moveable second main contact (4) can be moved away from the first main contact (3) in order to produce an air gap and the earthing switch (1, 39) has a pre-ignition arrangement, which is suitable for a short-circuit activation of the earthing switch, wherein the activation speed of the earthing switch is chosen such that a closing of the main contacts (3,4) is achieved after 200 to 250 ms.
2. Traction power supply system (20) according to claim 1,
   characterised in that
   the pre-ignition arrangement is arranged above the main contacts.
3. Traction power supply system (20) according to claim 1 or 2,
   characterised in that
   the pre-ignition arrangement has one pre-ignition device for each main contact.
4. Traction power supply system (20) according to claim 3,
   characterised in that
   the pre-ignition devices (5,6) are embodied as pre-ignition horns (5,6).
5. Traction power supply system (20) according to claim 4,
   characterised in that
   the pre-ignition horns (5,6) are substantially attached in a horizontal orientation and allocated to the respective main contact (3,4).
6. Traction power supply system (20) according to claim 3,
   characterised in that
   the pre-ignition devices are embodied as arcing horns.
7. Traction power supply system (20) according to claim 6,
   characterised in that
   the arcing horns are substantially attached in a vertical orientation and allocated to the respective main contact (3,4).
8. Traction power supply system (20) according to one of the preceding claims,
   characterised in that
   the pre-ignition arrangement has contact erosion elements which can be attached in a removable manner.
9. Traction power supply system (20) according to claim 8,
   characterised in that
   the contact erosion elements may have an internal thread and can be attached to the pre-ignition arrangement in the manner of a screw connection.
10. Traction power supply system (20) according to claim 8 or 9,
    characterised in that
    the length of the contact erosion elements is dimensioned according to an anticipated short-circuit activation frequency.
11. Traction power supply system (20) according to one of claims 8 to 10,
    characterised in that
    the contact erosion elements comprise a dispersion-strengthened copper material as their material.
12. Method for earthing a part of a traction power supply system according to one of the aforementioned claims, comprising the steps:

    - with voltage applied to the part of the traction power supply system, when the earthing switch (1) is closed, an arc is ignited which forms a short-circuit via the pre-ignition arrangement and

    - the short-circuit is deactivated by at least one circuit breaker present in the traction power supply system, so that the main contacts (3,4) of the earthing switch (1) are power-free before contact is made.

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