FIELD OF INVENTION
The invention to the area of SF6 Gas Monitoring Systems used in high voltage
SF6 Circuit Breakers and other SF6 filled equipment. More particularly, the
invention relates to an improved SF-6 gas monitoring system.
BACKGROUND OF INVENTION
The SF6 gas monitoring is an important functions in SF6 gas filled substation
equipment for examples, Circuit Breakers, Gas Insulated Substation Modules, CT
& PT etc. SF6 gas monitoring system consists of a pressure gauge, a density
monitor, a filling valve, and an outlet connection connectable to the gas filled
equipment. For safe and successful operation of these types of equipments, it is
essential to maintain a minimum gas density in the equipment. SF6 gas
monitoring system monitors the density of the gas in the equipment.
Prior art monitoring systems (refer figure-3) comprises a Density Monitor (1), a
Manometer (2), a Gas inlet Valve (3), an External Pipe (4), a Sealing Ring (5),
and a valve device (6) such systems pose a multiple technical problems in case
of replacement of some of the constituents components for example, the density
monitor and manometer from SF6 gas filled equipment. During this replacement
process generally the original position of the seal (5) gets disturbed resulting in
leakage of SF6 Gas. Occasionally in course of transportation of the equipment
the piping (4) with brazed joints gets damaged due to transport vibrations and
results in the problem of SF6 gas leakage at site.
The major technical problems of prior art monitoring systems can be summarized
as under:

1. Replacement of Manometer (2) and density monitor (1) without removing
SF6 gas from breaker is extremely difficult due to inevitable displacement
of the sealing ring (5), particularly due to the reason that an internal
pressure in the system still prevails.
2. Leakage of SF6 gas due to pipe (4) damages in transit.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention is to propose an improved SF6
gas monitoring system which eliminates the disadvantages of prior art.
Another object of the invention is to propose an improved SF6 gas monitoring
system which allows an easy replacement of its constituent components in
particular the manometer and the density monitor from the gas-filled SF-6
equipment.
A further object of the invention is to propose an improved SF-6 gas monitoring
system which eliminates the damage of the external piping of the equipment in-
transit.
SUMMARY OF INVENTION
Accordingly, there is provided an improved SF6 gas monitoring system,
comprising monitoring devices (4,6) connected to a filling-point duct; a cartridge-
type valve device (5) disposed adjacent to the monitoring devices (4, 6) enabling
connection and/or termination of the connection of the devices from the valve
device, the cartridge type valve device (5) comprising a first plug (7), a valve

seat (8), a biasing means (9), a washer (11), a second plug (12), a pin (14), and
a plurality of seals (13,15 to 19), one of said plurality of seals (17) is disposed in
such a way that a radial including a facial sealing between the pin (14), the
second plug (12), and the washer (11) can be achieved, and in that while
replacement of the measuring deices (4,6), the pin (14) on release from its
position is enabled to generate a biasing force via the spring (9) which allows the
ball (10) to isolate the connection between the equipment and the monitoring
system.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - is a front view of a SF6 monitoring system according to the invention
Figure 2 - is a sectional view of a Cartridge type valve device of the monitoring
system of Figure 1.
Figure 3 - is a Prior art of a SF-6 gas monitoring system.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
As shown in figure-1, the inventive SF-6 gas monitoring system is provided with
a Non Return valve device (1) which facilitates filling of SF6 gas through it and
allows the-gas flow through an internal duct to SF6 Gas Outlet (2) from where
the gas enters into the SF6 gas equipment directly. The Manometer (4) and
Density Monitor (6) are connected to a filling point duct through the cartridge
type valve device (5) which allows the connection and disconnection of the
monitoring devices namely a pressure gauge (4) and the density monitor (6).

As shown in Figure-2, the cartridge valve device consists of a first plug (7), a
Valve Seat (8), Spring (9), a Ball (10), a Washer (11), a second Plug (14), and a
plurality of seals (13,15,16,17,18 and 19). All these components are assembled
in a block. The seal (17) is arranged to provide both radial and facial sealing
between the pin (14), the second plug (12), and the washer (11). The Pin (14),
Valve seat (8), Spring (9) and ball (10) are assembled in such a way that during
normal operation of the system, the pin (14) pushes the ball (10) against the
spring (9) which allows the SF6 gas flow from the equipment to the manometer
(4), which the density monitor (10) ensures a continuous monitoring.
For replacement of the Manometer/Density Monitor from the system, the
cartridge type valve device (5) is kept in a close location by loosening the pin
(14) which in turn releases the ball (10) which seals the path by the tension
offered by the spring (9), thus isolating their connecting to the main equipment.
With this gas supply to manometer (4) and density monitor (6) blocked without
removing the supply of gas to the equipment and replacement of the connecting
parts for example, the manometer and density monitor can be carried out easily.
Such an innovative configuration enables an easy replacement of the manometer
and density monitor and eliminates transit damages of the equipment which
finally results in cost reduction and efficiency of the equipment.

WE CLAIM
1. An improved SF6 gas monitoring system, comprising:
- monitoring devices (4,6) connected to a filling-point duct;
- a cartridge-type valve device (5) disposed adjacent to the monitoring
devices (4, 6) enabling connection and/or termination of the connection of
the devices from the valve device, the valve device (5) comprising a first
plug (7), a valve seat (8), a biasing means (9), a washer (11), a second
plug (12), a pin (14), and a plurality of seals (13,15 to 19),
characterized in that one of said plurality of seals (17) is disposed in such
a way that a radial including a facial sealing between the pin (14), the
second plug (12), and the washer (11) can be achieved, and in that while
replacement of the measuring deices (4,6), the pin (14) on release from
its position is enabled to generate a biasing force via the spring (9) which
allows the ball (10) to isolate the connection between the equipment and
the system.
2. The system as claimed in claim 1, wherein the pin (14), the valve seat (8),
the spring (9), and the ball (10) are disposed to allow during normal
operation of the system the pin (14) is allowed to push the ball (10)
against the spring (9) which enables establishment of the connection
between the equipment and the system, and wherein upon establishment
of the connection, the SF6 gas is allowed to flow from the equipment to
the measuring devices (4,6) to commence monitoring.
3. An improved SF6 gas monitoring system as substantially described and
illustrated herein with reference to the accompanying drawings.

The invention relates to an improved SF6 gas monitoring system, comprising
monitoring devices (4,6) connected to a filling-point duct; a cartridge-type valve
device (5) disposed adjacent to the monitoring devices (4, 6) enabling
connection and/or termination of the connection of the devices from the valve
device, the valve device (5) comprising a first plug (7), a valve seat (8), a biasing
means (9), a washer (11), a second plug (12), a pin (14), and a plurality of seals
(13,15 to 19), one of said plurality of seals (17) is disposed in such a way that a
radial including a facial sealing between the pin (14), the second plug (12), and
the washer (11) can be achieved, and in that while replacement of the
measuring deices (4,6), the pin (14) on release from its position is enabled to
generate a biasing force via the spring (9) which allows the ball (10) to isolate
the connection between the equipment and the system.