We Claim:
1. A fast earthing switch (1) comprising
two contacts (2) of which at least one contact (2) is movable in relation to the other
contact between a closed position, in which the contacts (2) are connected, and an open
position, in which the contacts (2) are unconnected, said contacts (2) defining an arcing re-
gion in which an arc is generated during a current interrupting operation and in which an
arc-quenching medium is present,
a cylinder-like guiding tube (3) in which the at least one movable contact (2) forming
a piston (4) is slidably arranged for linearly moving between the closed position and the open
position, whereby
the guiding tube (3) is closed at an upper end (5) so that the piston (4) defines a first
compression chamber (9) with the upper end (5) for thereby decelerating movement of the
piston (4) when moving into the open position and/or
the guiding tube (3) is closed at a thereto opposite lower end (6) so that the piston (4)
defines a second compression chamber (10) with the lower end (6) for thereby decelerating
movement of the piston (4) when moving into the closed position, and
the piston (4) is provided as disc-like piston (8) sliding on an inner surface of the
guiding tube (3) and having a thereto orthogonal arranged piston rod (7) linearly extending
in moving direction within the guiding tube (3), and
the disc-like piston (8) comprises at least one piston bar-like element (13) extending
from the disc-like piston (8) linear in moving direction towards the upper end (5) and/or the
lower end (6) and the upper end (5) and/or the lower end (6) comprises a respective piston
bar-like opening (14) through which the piston (4) bar-like element passes when the piston
(4) reaches the open position and/or the closed position, or
the lower end (6) comprises at least one lower bar-like element (15) extending from
the lower end (6) linear towards the upper end (5) and the disc-like piston (8) comprises a
respective lower bar-like opening (16) through which the lower bar-like element (15) passes
when the piston (4) reaches the closed position.
2. The fast earthing switch (1) according to the previous claim, whereby at least one pressure
relief valve (11) is provided in the upper end (5) and/or in the lower end (6) of the guiding
tube (3).
3. The fast earthing switch (1) according to any of the previous claims, whereby the piston
rod (7) is hollow and the upper end (5) comprises a damper element (12) facing the hollow
piston rod (7) and that, when the piston (4) reaches the open position, becomes surrounded
by the hollow piston rod (7).
4. The fast earthing switch (1) according to the previous claim, whereby the piston rod (7) is
provided as a tube and the damper element (12) comprises a tube-like shape having a diam-
eter smaller than a diameter of the piston rod (7).
5. The fast earthing switch (1) according to any of the previous claims, whereby the upper
end (5) of the guiding tube (3) comprises a gas refilling valve.
6. The fast earthing switch (1) according to any of the previous claims, whereby the lower
end (6) is provided disc-like surrounding the piston rod (7).
7. The fast earthing switch (1) according to any of the previous claims, comprising an oper-
ating mechanism (17) for said movable contact (2).
8. A three-pole high voltage substation comprising for each pole a fast earthing switch (1)
according to any of the previous claims and in particular for each pole a motor for actuating
the fast earthing switch (1) of the corresponding pole.
9. Use of the fast earthing switch (1) according to any of the previous fast earthing switch
(1) claims for interrupting non-short-circuit currents and/or for guiding short circuit currents
to ground comprising.
10. Method for decelerating movement of a piston (4) in a fast earthing switch (1) comprising
two contacts (2) of which at least one contact (2) is movable in relation to the other
contact between a closed position, in which the contacts (2) are connected, and an open
position, in which the contacts (2) are unconnected, said contacts (2) defining an arcing re-
gion in which an arc is generated during a current interrupting operation and in which an
arc-quenching medium is present,
cylinder-like guiding tube (3) in which the at least one movable contact (2) forming
the piston (4) is slidably arranged for linearly moving between the closed position and the
open position, whereby
the guiding tube (3) is closed at an upper end (5) so that the piston (4) defines a first
compression chamber (9) with the upper end (5) end (6), and/or
the guiding tube (3) is closed at a thereto opposite lower end (6) so that the piston (4)
defines a second compression chamber (10) with the lower end (6) and
the piston (4) is provided as disc-like piston (8) sliding on an inner surface of the
guiding tube (3) and having a thereto orthogonal arranged piston rod (7) linearly extending
in moving direction within the guiding tube (3), and comprising the step of:
Decelerating movement of the piston (4) when moving into the open position and/or
into the closed position, whereby
the disc-like piston (8) comprises at least one piston bar-like element (13) extending
from the disc-like piston (8) linear in moving direction towards the upper end (5) and/or the
lower end (6) and the upper end (5) and/or the lower end (6) comprises a respective piston
bar-like opening (14) through which the piston (4) bar-like element passes when the piston
(4) reaches the open position and/or the closed position, or
the lower end (6) comprises at least one lower bar-like element (15) extending from
the lower end (6) linear towards the upper end (5) and the disc-like piston (8) comprises a
respective lower bar-like opening (16) through which the lower bar-like element (15) passes
when the piston (4) reaches the closed position.