High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Magnetic blowout
Reexamination Certificate
1999-11-09
2001-08-07
Scott, J. R. (Department: 2832)
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Magnetic blowout
C218S048000, C218S055000, C218S146000, C335S195000, C361S604000
Reexamination Certificate
active
06271493
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a high voltage disconnector comprising a fixed contact and a movable contact to produce an electrical connection between a first conductor and a second conductor, wherein the movable contact can be fixed to the first conductor and the fixed contact can be fixed to the second conductor and wherein the movable contact and the fixed contact form, when they are in contact with one another, a connector electrically connecting the first and second conductors, which connector is at an angle with respect to the first and/or second conductor, such that, when the contacts are in contact with one another during operation, a Lorentz force prevails which pulls the fixed and movable contacts apart and is transverse to the first or second conductor.
DESCRIPTION OF THE RELATED ART
A high voltage disconnector of this type is, for example, disclosed in European Patent Application EP-A 0 221 603. This publication discloses a three-phase insulating disconnector for use in a high voltage switching installation. The high voltage switching installation disclosed in this publication is made up of a number of sealed compartments which are to be filled with insulating SF
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gas, as a result of which only relatively little space is needed, even with high voltage. The high voltage installation is provided, for each phase, with a connection to the feed side, a high voltage switch and at least one connection to the side to be fed.
For switching in the known high voltage switching installation use is made, in a number of locations, of a movable blade contact and a fixed brush contact. The fixed brush contact has two contact parts delimiting a slot. The blade contact can be inserted in the slot by turning, which slot has dimensions such that the blade then makes contact on either side with a contact component of the fixed brush contact.
The known high voltage installation has a number of disadvantages which manifest themselves in particular on scaling up for use with higher voltage and/or current.
In the known high voltage installation there are a number of (right angle) connections formed by the movable blade contact of a disconnector and the fixed brush contact interacting therewith, the disconnector bearing on one side only against a wall of a compartment. With the greater distances between supporting insulator and connection of the movable blade contact to the fixed brush contact, such as are needed for operation at higher voltages and/or currents, it can be that movements between the movable and fixed contacts are possible. With the known installation, in which the movable contact is constructed as a blade and the fixed contact is constructed as a slot in which the blade can be accommodated, this leads to blade and slot being able to move apart, as a result of which a connection is produced that is not reliable in operation.
This is exacerbated in the case of high currents which flow in conductors at right angles to one another. A right-angle connection of this type can be formed, for example, by a connection with a fixed contact and a movable contact of the disconnector at right angles to the fixed contact. The high currents give rise to a magnetic field around the conductor, as a result of which an electromagnetic force is exerted on the current-carrying conductor at right angles thereto. These forces on the conductors at right angles to one another lead to the conducting parts trying to bend apart at an angle. In the case of the known installation, in which the movable contact is formed by a blade and the fixed contact by a slot, this leads to blade and slot being pulled apart, which can lead to breaking of the connection. Because this occurs in the operational state, in which high currents usually flow, blade and slot (or even the entire installation) will be damaged.
SUMMARY OF THE INVENTION
The aim of the present invention is to provide a connection by means of a movable contact and a fixed contact which does not have the abovementioned disadvantages.
The aim is achieved with the present invention by means of a high voltage disconnector of the type wherein the movable contact and the fixed contact are provided with locking means which engage in one another when the two contacts are in contact with one another and act in a direction parallel to the Lorentz force which is pulling the fixed and movable contacts apart and is transverse to the first or second conductor, respectively.
The high voltage disconnector according to the present invention has the advantage that in the direction of the connection the movable contact and the fixed contact are locked and are no longer able to move apart. As a result the movable contact and the fixed contact are prevented from moving apart as a consequence of freedom of movement and/or electromagnetic forces on the conducting components. A high voltage installation having high reliability in operation can therefore be constructed using the high voltage disconnector according to the present invention. The connector forms an angle with the first or second conductor that is greater than 30°, for example greater than approximately 60°, for example approximately 90°. The highest Lorentz forces arise in the case of an angle of 90°.
In a preferred embodiment of the present invention the locking means comprise at least one groove in or rib on the movable contact and at least one rib on or, respectively, groove in the fixed contact. Because the rib on the one contact drops into the groove in the other contact a locking connection is produced which cannot be broken in the direction parallel to the connection. It is not important for the effectiveness of the high voltage disconnector whether the at least one groove is in the movable contact or in the fixed contact.
Preferably, the at least one groove in or at least one rib on the fixed contact and the at least one rib on or, respectively, at least one groove in the movable contact extend in the direction of the relative movement of the fixed and movable contacts with respect to one another when said contacts are in contact with one another. By this means as great as possible a contact area is formed between the groove and the rib, as a result of which higher forces can be resisted in the direction parallel to the connector.
As an alternative the movable contact or the fixed contact comprises a plate-shaped part and the fixed or, respectively, movable contact comprises a receiving part delimiting a slot. The plate-shaped part can be accommodated in the slot so as to make contact with the receiving part by means of its opposing plate sides, the plate-shaped part being provided with at least one rib or groove on both plate sides and the receiving part being provided with at least one groove or, respectively, rib on each side of the slot. It is not necessary for the rib to extend over the entire width of the plate-shaped part or of the receiving part, in contrast to the groove, which must be made over the entire width. Consequently, the construction of the fixed contact can be simpler and therefore the production can be more economical. In this context consideration can be given, for example, to mounting two side pieces with a rib on the fixed or movable contact. The groove can be made simply and economically by milling the movable or fixed contact.
In a further embodiment the movable contact is equipped to make contact with the fixed contact by means of a turning movement, the axis of rotation being parallel to the first conductor. This makes it possible to operate the disconnector easily by means of a rotary drive. Preferably, the at least one groove and rib are then formed as part of an arc of a circle, by which means the electrical connection can be produced smoothly.
In a further embodiment the high voltage disconnector further comprises a fixed earthing contact that can be fixed to an earth conductor to produce an electrical connection between the earth conductor and the first conductor, the fixed earthing contact being constructed in a manner essentially corres
Elin Holec High Voltage B.V.
Scott J. R.
Young & Thompson
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