Truck-mounted breakers intended for high-voltage lines and a...

Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electrical power distribution systems and devices

Reexamination Certificate

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C200S04800A, C200S050270

Reexamination Certificate

active

06172866

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
According to a first aspect, the present invention relates to truck-mounted breakers intended for high-voltage lines. According to a second aspect, the invention relates to a method of supporting electrical counterpart contact units in a breaker. By high-voltage line is normally meant a line for voltages above 72.5 Kv, and shall be interpreted as such in this Application.
2. Discussion of the Background
A truck-mounted breaker, so-called truck breakers of the kind with which the invention is concerned, connects and disconnects part of the electric circuit, by moving the electric contact devices carried by the truck breaker into and out of engagement with corresponding, stationarily mounted counterpart contact devices, wherewith the contact devices are preferably moved linearly on a pair of stand-mounted rails. This results in an insulation gap (air gap) on each side of the breaker, which corresponds to opening a disconnector on each side of the breaker. The counterpart contact units of the counterpart contact device are normally mounted in a top and a bottom row, of which the bottom row is normally supported by insulators that are mounted directly on the stand, and which also support the linearly movable contact device, therewith guaranteeing a good fit between the bottom contact units and the counter-contact units. The countercontact units in the upper row are normally held up by insulators depending from a portal. A portal is anchored on a plinth that is separate from a concrete plinth of the stand that supports the linearly displaceable contact device. Consequently, there is a risk that these upper countercontact units will not be retained in a correct position for receiving corresponding electrical contact units on the displaceable contact device. This is because the position of the portal relative to the position of the stand carrying the electrical contact device being disturbed by the thawing of frozen ground, earthquakes or other soil or earth disturbances. Such misalignment may make it impossible to mutually connect the upper contact units with the counter-contact units.
Truck breakers for low and intermediate voltage problems are not confronted with this problem, since in these cases the counter-contacts can be mounted on horizontal beams, one for each vertically distributed group of counter-contact units, as disclosed in DE 1 415 613, for instance. This is made possible by virtue of the short insulation paths that are required in such cases, so as to enable each counter-contact to be attached to the stand with a short insulation element. However, it is not possible to scale-up such a construction for high-voltages, since the pin insulators then become longer and result in an unacceptably high building structure if requisite safety distances are to be maintained.
SUMMARY OF THE INVENTION
Against this background, the present invention endeavours to eliminate the risk of relative misalignment between the upper electrical contact units and electrical counter-contact units respectively.
This object has been achieved in accordance with the invention with a truck breaker intended for high voltage lines including a contact device that is moveable linearly with truck movement and a stationarily mounted counter contact device. and also with a method including the particular step of mounting the counter contact units on upwardly extending insulating pillars that rest on a stand-point located at a level which lies beneath the lowermost counter contact unit.
Because all counter contact units, including the counter contact units in the upper row, are supported in this way by the stand that also carries the linearly movable contact device there is achieved relative positional fixation also with respect to the upper counter contact units, so as to ensure that the positions of the counter contact units in relation to corresponding contact units on the linearly displaceable contact device will be correctly maintained. As a result of the particular arrangement of the supportive devices, this can be achieved with a relatively compact stand.
In a preferred embodiment of the invention, the upper counter contact units are each supported by a respective insulator pillar. According to this preferred embodiment, each upper counter contact unit is supported by an insulator pillar section mounted respectively on top of and underneath the insulator pillar section of the counter contact unit, such that as to constitute an extension thereof. This constitutes a very simple design. In an alternative preferred embodiment, each insulator pillar of the counter contact units is disposed parallel with the insulator pillar of the lower counter contacts and is longer than said counter contacts. This construction reduces the risk of sparking caused by leakage currents.
In still another preferred embodiment, the counter contact units are mounted on high-voltage cable connectors, in which case no additional insulator pillars are required.
The afore-described embodiments and other advantageous embodiments of the invention will be apparent from the dependent claims.


REFERENCES:
patent: 1929293 (1933-10-01), Saint-Germain
patent: 2128149 (1938-08-01), Linde
patent: 3941659 (1976-03-01), May et al.
patent: 3958156 (1976-05-01), Tjebben
patent: 1 415 613 (1969-05-01), None

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