Electricity: circuit makers and breakers – Liquid contact – Time delay
Patent
1991-01-09
1992-10-06
Scott, J. R.
Electricity: circuit makers and breakers
Liquid contact
Time delay
200148B, H01H 3354
Patent
active
051533987
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a metal-clad, compressed-gas insulated, high-voltage switching station with an insulated grounding switch whose housing is flange-mounted to the casing of the high-voltage switching station by way of flanges and fixing agents which connect these flanges, whereby one insulating ring is mounted gastight between both flanges. On the inside of this insulating ring, an annular electric conductor, which is provided with a terminal lug, is embedded such that the terminal lug which runs outside passes radially through the insulating ring, and the annular part of the conductor surrounds the contact pin of the grounding switch with clearance, whereby the conductor bears a sliding contact by way of which it is electrically connected to the contact pin.
This type of an insulated grounding switch for a metal-clad, compressed-gas insulated, high-voltage switching station is known from the teachings of U.S. Pat. No. 3,778,374. The conductor, with the terminal lug running to the outside, which is embedded in the insulating ring can be either grounded via this grounding switch or a voltage can be applied to it which is then transferred to the contact pin of the grounding switch in order to implement testing. In the known grounding switch, the annular part of the conductor is embedded on the inside of the insulating ring. This insulating ring reposes between the flange of the housing of the grounding switch and the flange of the casing of the high voltage switching station and is penetrated by the fixing agents which serve to fasten the grounding switch to the high voltage switching station. In this manner, the insulating ring is pressurized by the compression forces required for fastening it and is thereby mechanically stressed by high compressive forces.
Consequently, the tightening torques for the fixing agents must be stipulated precisely and with a narrow tolerance range in order to avoid overloading the insulating material. Furthermore, the fixing agents must be provided with an insulation since they are located in the immediate vicinity of the embedded conductor and are connected to the grounded casing. The entire outer surface area of the insulating ring is furthermore exposed. In the case of outdoor use, this can create problems since then the insulating property of the insulating ring can be impaired by deposits.
SUMMARY OF THE INVENTION
The invention is based on the task of improving the insulation of the grounding switch in the case of a metal-clad, compressed-gas insulated, high-voltage switching station of the initially described type.
In order to solve this task in the case of a metal-clad, compressed-gas insulated, high-voltage switching station with an insulated grounding switch according to the invention, the insulating ring reposes within a metallic ring of at least the same height and with this metallic ring is mounted gastight between both flanges. The metallic ring has a radially directed opening through which the terminal lug, which is provided with an insulating enclosure, extends, and the fixing agents penetrate only the outer metallic ring.
For the insulating ring, the outer metallic ring acts as a prop ring, which encloses the insulating ring on the entire outer surface area. Only at one spot on the periphery does it have an opening, which, however, does not extend through its entire height and which is penetrated but not interrupted by the insulated andgastightly projecting terminal lug. Thus, there is always a metallic connection between the housing of the grounding switch and the casing regardless of whether the grounding switch is being used for grounding or for test purposes. The fixing agents are only run through metallic parts and do not require a separate insulation. Moreover, in this manner, a precise insulating clearance is guaranteed between the mounting flanges as well as a defined packed sealing gap between the flange and the ring, respectively.
The forces required for fastening are absorbed only by the metal parts. The insulati
REFERENCES:
patent: 3778574 (1973-12-01), Clark
patent: 3876846 (1975-04-01), Graybill
patent: 3987260 (1976-10-01), Wilson
patent: 4486634 (1984-12-01), Nakano et al.
Funk Karl-Heinz
Haarhuis Jurgen
Lorenz Dieter
Scott J. R.
Siemens Aktiengesellschaft
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