EP3035353A1

EP3035353A1 - Circuit breaker pole for subsea application

Info

Publication number: EP3035353A1
Application number: EP14004278.9A
Authority: EP
Inventors: Maik Hyrenbach
Original assignee: ABB Technology AG
Current assignee: ABB Technology AG
Priority date: 2014-12-18
Filing date: 2014-12-18
Publication date: 2016-06-22

Abstract

The invention relates to a circuit breaker pole for subsea application wherein the pole contains a vacuum interrupter and a drive mechanism, according to the preamble of claim 1. In order to prevent the aforesaid disadvantages, the hollow cylinder of insulating material, or the hollow cylinders of insulating material is or are made of pressure proof ceramics or porcelain, which is or are at the end surfaces metalized to allow soldering, in such, that the complete pole is assembled by soldering.

Description

The invention relates to a circuit breaker pole for subsea application wherein the pole contains a vacuum interrupter and a drive mechanism, according to the preamble of claim 1.
Circuit breaker poles for subsea application, means high pressure of about 300 bar outside and about one bar inside the pole.
Known or proposed solutions are using housings of insulation material with embedded or bolted metallic bushings for the electrical connection. In these housings the vacuum interrupter, the drive mechanism and the other components are assembled or (in case of the vacuum interrupter) assembled or embedded. Openings or complete sections are bolted. The connection is sealed using seals made of elastic material, as elastomers EPDM or NBR.
As the installation will be used in insulating oil under a high pressure of about 300 bar or more, the seal is highly stressed. Not only the risk that the seal will be malfunctioned or being destroyed by the high pressure, but also chemical processes may have a negative impact on the function. Due to incompatibilities with oil, which is normally filled in containers, in which the poles are arranged, or with substances in the oil or produced by the oil over lifetime, the seal might dwell, which can lead to mechanical destruction, or it might react with the substances, which will influence the mechanical behavior. A leak of the seal will allow oil to enter the pole and this will lead to a malfunction of the switch. Due to the high pressure it will be unable to open.
As a second aspect seals made of elastomers are known to show the effect of permeation.Especially for gases, they are never completely sealing, as depending on time and difference in concentration and pressure, gas is permeating through the seal from one side to the other side.
This can lead to a pressure rise in the pole with the same effect as mentioned above. The gases can be for example water vapor which might be dissolved the oil or other gases produced by decomposition products of the oil.
So it is the object of the invention, to avoid all these risks and disadvantages.
In the design of vacuum interrupters it is well known, that ceramics and metals can be soldered gastight. This is state of the art in the production with a long term experience. Due to the high requirement on the vacuum inside the vacuum interrupter over lifetime, it is well known, that the leakage rates are much less then for every known seal connection.
Due to the use of metal and ceramics, the permeation is below measurable limit. When using the production process of a vacuum interrupter for building a housing of the complete pole by soldering ceramics and metal parts, an insulating housing with metal inserts for current carrying and for operating and control signals for the drive mechanism can be produced without any seal. The risk of leakage and permeation is completely avoided. Chemical incompatibility must be checked with the ceramics and the soldering areas, but most likely will have no effect.
The reliability of the pole can be improved significant.
Core of the invention therefore is, that the hollow cylinder of insulating material, or the hollow cylinders of insulating material is or are made of pressure proof ceramics or porcelain, which is or are at the end surfaces metalized to allow soldering, in such, that the complete pole is assembled by soldering.
By that the structure itself is presssuretight, and leakage risk is excluded because no sealed flanges are used.
In a further embodiment all externally connectable electrical connectors to the vacuum interrupter and the drive mechanism are embodied as conductive rings, which are soldered between at least two hollow cylinders of insulating material, or between one conductive part of the pole and one hollow insulating cylinder.
So alternating serially arranged insulating and conductive cylinders can build up a structure, where the external terminals can be embodied by simple conductive rings, solded between two serially arranged insulating cylinders, or between one insulating cylinder and one conductive cylinder or a metallic end cap.
In a futhermore advantageous embodiment the several hollow insulating cylinders are arranged in series as such, that the conductive rings in the pole are located close to the place, where the terminals of the vacuum interrupter inside the pole is placed, so that the terminals of a fixed contact and the terminal of a moving contact of the vacuum interrupter can be directly connected to the conductive rings.
In a futhermore advantageous embodiment the connectors for the drive mechanism are embodied as a cylindrical multilayered structure of alternating layers of conductive and insulating rings.
So the pole housing consists of three different elements:

1. Hollow cylinder or cylinders made of pressure proof ceramics or porcelain, which is or are at the end surfaces metalized to allow soldering.
2. End caps allowing high pressure withstand and closing the cylinder. These can be hemispheric metal or porcelain or ceramic elements. Other pressure resistant shapes are possible.
3. Metal hollow cylinders made of copper, or other metal which can be soldered with the porcelain and is able to carry the required current.

The cylinders might have contact areas for the external and/or internal connection with the current path. This can be connection lugs. Other means as threads for direct connection, especially at the primary contact are possible.
By the combination of these elements of different length, a housing can be prepared. In best case segments or at least two parts are produced, before the active parts are inserted, as drive mechanism and the vacuum interrupter. In the last step the compartment is closed by a final soldering process. This can be done for example by inductive heating of the last connection, which avoids damage of already soldered connections or of components inside the housing. Doing this e.g. under SF6 gas atmosphere, this can increase the dielectric withstand level inside the pole. By this the length of the push-rod for the VI can be optimized. For the low voltage connections for the drive operation and control, alternative solutions, as embedded contacts in the porcelain or in the end cap ca be considered.
The connection of the moving contact can be done in several ways: using a flexible copper between the moving contact and the primary conductor for the moving contact or it can be a contact spring or multicontacts between two conductive tubes, one connected with the moving contact, the other with the primary conductor for the moving contact or even being part of it. Using the concept further on, an alternative solution can be to build the first half of the pole directly of a pressure proof vacuum interrupter, not requiring an additional housing. The second half would then covering drive mechanism.
Figure 1 shows a structure of alternating conductive and insulating cylinders and rings.
Both end caps can be made of steel or porcelain. The contact rings are soldered between two parts each. In the right part of figure 1, there is arranged a multilayered arrangement of alternating conductive and insulating rings, in order to result a multicontacting for signal wires for the drive.
Inside the displayed pole, a vacuum interrupter and an drive mechanism is arrangend pressure tight by the enclosure, resulted by the pole.
Figure 2 shows the inner locations of the vacuum interrupter and the drive mechanism. Like it is shown, the terminals of the vacuum interrupter are locatd as such, that they are near to the conductive rings, soldered in the pole, in order to contact the terminals of the vacuum interrupter 30 with the external connections via the soldered conductive rings.
According to the location of the drive 31, the aforesaid multilayered insulating and conductive rings are connected to the signal wires of the drive.
Figure 3 shows how the pole concerning to the invention will be assembled until before the vacuum interrupter and the drive will be arranged inside the pole, and the remaing only soldering line between the two parts of the pole will be closed by soldering finally.

Claims

Circuit breaker pole for subsea application wherein the pole is made of a of at least one hollow cylinder of insulating material, which contains a vacuum interrupter and a drive mechanism, with electrical connections
characterized in
that the hollow cylinder of insulating material, or the hollow cylinders of insulating material is or are made of pressure proof ceramics or porcelain, which is or are at the end surfaces metalized to allow soldering, in such, that the complete pole is assembled by soldering.
Circuit breaker pole according to claim 1,
characterized in
that all externally connectable electrical connectors to the vacuum interrupter and the drive mechanism are embodied as conductive rings, which are soldered between at least two hollow cylinders of insulating material, or between one conductive part of the pole and one hollow insulating cylinder.
Circuit breaker pole according to claim 2,
characterized in
that the several hollow insulating cylinders are arranged in series as such, that the conductive rings in the pole are located close to the place, where the terminals of the vacuum interrupter inside the pole is placed, so that the terminals of a fixed contact and the terminal of a moving contact of the vacuum interrupter can be directly connected to the conductive rings.
Circuit breaker pole according to one of claim 1 to 3,
characterized in
that the connectors for the drive mechanism are embodied as a cylindrical multilayered structure of alternating layers of conductive and insulating rings.