High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Multiple break
Reexamination Certificate
2002-06-21
2003-07-15
Enad, Elvin (Department: 2832)
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Multiple break
C218S007000
Reexamination Certificate
active
06593538
ABSTRACT:
The invention relates to an interrupter device of the hybrid type for high or medium voltage. The term “hybrid” applies to interruption which is of the combined type in which two different interruption techniques are caused to co-operate. The term “hybrid” is used in particular to designate an interrupter device that comprises both a vacuum interrupter containing a first pair of arcing contacts, and also a gas interrupter containing a second pair of arcing contacts.
BACKGROUND OF THE INVENTION
A device of this type is known from U.S. Pat. No. 3,038,980. It comprises a casing filled with a dielectric gas and having a longitudinal axis. The two interrupters are connected electrically in series and are disposed inside the casing, while the control mechanism for controlling the device is disposed outside the casing. The mechanism for actuating the contacts of the two interrupters is relatively simple in that one of the two contacts of the gas interrupter is secured to a moving contact which is adjacent to it in the vacuum interrupter. The other contact of the gas interrupter is secured to a drive rod connected to the control mechanism for controlling the device. A mechanism having a spring associated with an abutment maintains the contacts of the gas interrupter one against the other during a first portion of their stroke while the device is opening, until the contacts of the vacuum interrupter have separated by a determined distance. The object of such a sequence for separating the contacts of the two pairs is to make it possible to delay the separation of the contacts of the second pair (gas interrupter) relative to the separation of the contacts of the first pair (vacuum interrupter).
Unfortunately, such a sequence is not satisfactory if the high-voltage hybrid device associates a gas interrupter designed for a standardized high voltage higher than 72.5 kV with a vacuum interrupter designed for a standardized medium voltage lower than 52 kV. So long as the contacts of the gas interrupter have not separated while the device is interrupting a fault current, the vacuum interrupter is subjected to the entire transient recovery voltage across the terminals of the interrupter device while its contacts are separating. Unfortunately, the vacuum interrupter is designed to withstand only a recovered voltage that remains within medium voltage limits. Thus, a high-voltage hybrid interrupter device that implements the above-described sequence for separating contacts can interrupt the current only after the two contacts of the gas interrupter have separated. Such operation involves an arcing time that is relatively long, and that is longer than the time a vacuum interrupter is designed to withstand. The general structure of the device described in that U.S. Pat. No. 3,038,980 does not make it possible to modify the sequence for separating the contacts. In particular, it is not possible with such a device to obtain simultaneous or delayed separation of the contacts of the vacuum interrupter relative to the separation of the contacts of the gas interrupter.
Another device of that type is known from patent application EP 1 109 187, which enables the sequence for separating the contacts to be adjusted so as to be able to obtain simultaneous or slightly delayed separation of the contacts of the vacuum interrupter relative to the separation of the contacts of the gas interrupter. The moving contact of the vacuum interrupter is connected to a connecting rod having one end that rotates, the end or head of the connecting rod being hinged on a crank pin of a flywheel that can be coupled to or uncoupled from a toothed rod controlled in translation by the drive rod of the gas interrupter.
However, that device presents certain drawbacks from a mechanical point of view. Firstly, it is necessary to exert sufficient force on the moving contact of the vacuum interrupter so long as current is able to pass therethrough, so as to ensure mutual pressure between the contacting surfaces of the contacts of the interrupter which is greater than a given value in order to overcome the electrodynamic forces generated by the passing current. The flywheel of the device must therefore be provided with a resilient return system which enables the required force to be exerted on the moving contact of the vacuum interrupter. Secondly, the motion of the drive rod of the gas interrupter is transmitted towards the vacuum interrupter by a connecting rod having an axis that is oblique relative to the axis of translation of the moving contact of the vacuum interrupter. That results in significant transverse stresses on the vacuum interrupter, thereby limiting its mechanical endurance.
Finally, another device of this type exists which is described in patent application EP 1 117 114, and which compared to the previous device has, in particular, the advantage that the moving contact of the vacuum interrupter is always subjected to forces that are directed only along the longitudinal axis of the interrupter. In addition, resilient spring means are provided to maintain a mutual pressure between the contacts of the vacuum interrupter while the interrupter is closed. However, in that device, the separating movement of the contacts of the vacuum interrupter is under the control of the drive rod of the gas interrupter, so the contacts of the vacuum interrupter can be separated only once the contacts of the gas interrupter have been opened. It is necessary for that device to have such a sequence of deferred separation of the contacts so as to cause the current to pass through zero before the vacuum interrupter ensures interruption on its own. The device is used exclusively as a generator circuit-breaker, and consequently, the gas interrupter is present only to reduce the unbalanced fraction of the current.
Obviously, with that device, it is not possible to produce simultaneous or slightly delayed separation of the contacts of the vacuum interrupter relative to the separation of the contacts of the gas interrupter.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the invention is to remedy the drawbacks or limitations of the prior art, by providing a hybrid interrupter device for high or medium voltage that is relatively compact and longlasting, and that when operating with a single drive member, i.e. with a control mechanism connected to a single drive rod, enables the interrupter contact separation sequence to be adjusted.
To this end, the invention provides a hybrid-type interrupter device for high or medium voltage, the device comprising:
a casing filled with a dielectric gas and having a longitudinal axis;
a vacuum interrupter disposed inside the casing, and having a first pair of arcing contacts constituted by a first contact which is fixed and by a second contact which can be moved in translation in the longitudinal direction of the casing;
means provided to exert a force on the second contact such that the mutual pressure between the contacting surfaces of the first and second contacts is greater than a determined value while the vacuum interrupter is allowing current to pass;
a gas interrupter disposed inside the casing, and having a second pair of arcing contacts constituted by a third contact which is fixed and by a fourth contact which can be moved in translation in the longitudinal axial direction, and also having a blast chamber which comprises a thermal blast volume; and
a drive rod connected to the fourth contact and that can be held stationary or moved in translation by control means;
the device further comprising;
connection means electrically interconnecting the second and third contacts, and capable of being moved in translation in the longitudinal axial direction together with the second contact;
displacement means connected to the connection means and to the drive rod for displacing them so as to separate the second and fourth contacts from the first and third contacts respectively, said displacement means comprising dead-stroke link means connecting the connection means to the rod, the link means making it possible to
Dufournet Denis
Perret Michel
Alstom
Enad Elvin
Fishman M.
Sughrue & Mion, PLLC
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