Method for drying a gas chamber and arrangement comprising a protective gas-filled chamber

Abstract

The invention relates to a method for drying a chamber comprising a predominantly protective-gas atmosphere in the chamber under positive pressure, which has an operating pressure p1 and a predetermined minimum pressure p.sub.min, wherein the minimum pressure p.sub.min of the gas chamber is monitored and the operating pressure p1 is greater than the minimum pressure p.sub.min, wherein the method comprises the following steps: a) removing of a partial quantity Vi of the protective gas from the chamber, wherein the partial quantity Vi is equivalent to the pressure differential p, which is smaller or equal to the differential between p1 and p.sub.min, b) introducing a partial quantity V2 of a dry or dried protective gas into the gas chamber up to a gas pressure p2, which is greater than p.sub.min and c) repeating method steps a) and b) after a predetermined waiting time t. The invention further relates to an arrangement for carrying out the method.

Claims

1. A method for drying a gas space with a protective gas atmosphere prevailing in the gas space under a positive pressure with an operating pressure p1 and a predetermined minimum pressure p.sub.min, wherein the predetermined minimum pressure p.sub.min of the gas space is monitored and the operating pressure p1 is greater than the minimum pressure p.sub.min, wherein the method comprises the following steps: a. Removing a partial amount V1 of the protective gas from the gas space, wherein the partial amount V1 is equivalent to a pressure difference p which is less than or equal to the difference between p1 and p.sub.min, b. Introducing a partial amount V2 of a dry or dried protective gas into the gas space up to a gas pressure p2 which is greater than p.sub.min and c. Repeating method steps a) and b) after a predetermined waiting time t.

2. The method according to claim 1, characterized in that the moisture content of the partial amount V1 of the protective gas removed is measured, and the method steps a) through c) are repeated until the moisture content of the protective gas thereby removed has fallen below a predetermined level.

3. The method according to claim 1, characterized in that the partial amount V1 is of such a size that the differential pressure p amounts approximately to the difference between the operating pressure p1 and the minimum pressure p.sub.min of the gas space.

4. The method according to claim 1, characterized in that the operating pressure p1 of the gas space is greater than or equal to the rated pressure of the gas space.

5. The method according to claim 1, characterized in that the partial amount V1 removed is dried by means of at least one drying filter and then is stored in another gas space.

6. The method according to claim 1, characterized in that a container for electrical equipment or such electrical equipment per se is provided as the gas space to be monitored, which is filled with a quenching gas as the protective gas.

7. The method according to claim 6, characterized in that the partial amount V1 is stored in a storage container out of which the partial amount V2 is preferably removed.

8. The method according to claim 6, characterized in that the partial amount V2 is fed into another gas space, which is designed as a container for electrical equipment or as such electrical equipment per se.

9. An arrangement comprising a first and a second gas space (1, 2) filled with a protective gas, a line system (12) connecting the first and the second gas spaces (1, 2), at least one compressor (3) arranged in the line system (12), at least one gas drying unit (4) arranged in the line system (12), means for detecting the gas pressure inside the line system (12), valves (5.1, 5.2, 5.3, 5.4), which can be controlled in such a way that the compressor (3) can alternately convey gas from the first gas space (1) into the second gas space (2) and can convey gas from the second gas space (2) into the first gas space (1), means for controlling the compressor as a function of the pressure inside the line system (12) and means for controlling the valves (5.1, 5.2, 5.3, 5.4) as a function of the desired direction of conveyance of the gas.

10. The arrangement according to claim 9, characterized in that the first gas space (1) accommodates electrical equipment or is designed as electrical equipment.

11. The arrangement according to claim 9, characterized in that the second gas space (2) is designed as a storage container for the protective gas.

12. The arrangement according to claim 9, characterized in that the second gas space (2) accommodates electrical equipment or is designed as electrical equipment.

Description

(1) The invention will now be explained in greater detail below on the basis of one embodiment that is illustrated in the drawings.

(2) The drawings show:

(3) FIG. 1 a schematic diagram of an arrangement for drying a protective gas-filled gas space,

(4) FIG. 2 a variant of the connection of the gas line 12 to the first gas space,

(5) FIG. 3 a diagram illustrating the mode of operation of the compressor in the method according to the invention.

(6) The method according to the invention is described below with reference to an exemplary embodiment in which a first gas space 1 is designed as a container for a unit of electrical equipment and a second gas space 2 is designed as a gas storage container (gas bottle). The first gas space 1 and the second gas space 2 are connected to one another by a gas line 12. A compressor 3 and a filter 4 are connected to the gas line 12 in such a way that bidirectional operation of the compressor 3 is possible. Therefore the compressor 3 is arranged in a type of hydraulic/pneumatic bridge circuit which can be operated by means of a total of four electrically controllable valves 5.1, 5.2, 5.3 and 5.4. The valves 5.1, 5.2, 5.3 and 5.4 are connected by a control line 6 to a control unit 7 which can be operated in turn by means of an operating unit 8. The control unit 7 also communicates with pressure pickups 9.1 and 9.2 and moisture sensors 10.1 and 10.2 in the control line 6.

(7) The method according to the invention will now be explained below with reference to the arrangement according to FIG. 1.

(8) As already mentioned, the first gas space 1 is designed as a unit of electrical equipment with SF.sub.6 filling as the protective gas.

(9) In the example described here, the first gas space 1 has a gas volume of approximately 150 liters and a rated excess pressure of 6 bar. The operating pressure p1 inside the first gas space 1 may amount to 0.3 to 0.5 bar above the rated excess pressure, for example. Assuming that the minimum pressure p.sub.min amounts to approximately the rated excess pressure of 6 bar, then 0.3 bar to 0.5 bar would be available as a pressure difference for the purpose of breathing of the first gas space 1. Basically, the minimum pressure p.sub.min may be lower than the rated excess pressure, although that is not assumed here for the sake of simplicity.

(10) In a first method step, a partial volume of protective gas V1 is removed from the first gas space 1 and sent to the second gas space 2 through the filter 4 by way of the compressor 3. In doing so, the partial amount V1 thereby removed is dried by means of the filter 4, and this partial amount V1 is fed into the second gas space 2. During the process, the valve 5.1 is closed, the valve 5.4 is open, valve 5.2 is open and valve 5.3 is closed. All valves 5.1, 5.2, 5.3 and 5.4 are closed when currentless. In other words, valves 5.1, 5.2, 5.3 and 5.4 are designed as solenoid valves, for example, which open when current flows through them accordingly.

(11) When the partial amount V1 is removed from the first gas space 1, the compressor 3 is operated until the p available for removal of the protective gas has been consumed. The pressure prevailing in the first gas space 2 is detected by means of the pressure pickup 9.1. If the pressure difference available for removal of protective gas has been used up, then reversal of the valve 5.1, 5.2, 5.3 and 5.4 is induced by the control unit 7. The valves 5.1 and 5.3 are opened, but valves 5.2 and 5.4 are closed. The compressor 3 conveys a partial amount V2 of the protective gas out of the second gas space 2, through the filter 4 and into the first gas space 1 until a pressure p2 has been reached inside the first gas space 1. The partial amount V1 of protective gas thus removed and the partial amount V2 replacing it are conveyed through the filter 4. The pressure p2 is greater than the predetermined minimum pressure p.sub.min. If the minimum pressure p.sub.min should correspond to the rated pressure, then the pressure p2 is greater than the rated pressure of the first gas space 1.

(12) The compressor is operated until a pressure difference allowing the removal of a sufficiently large partial amount V1+n out of the first gas space 1. Then a waiting time is observed until a corresponding moisture equilibrium has been established in the first gas space 1. The vapor pressure gradient between water and protective gas is increased because of the supply of a partial amount V2 of dried protective gas. After a while, an equilibrium is established again. Then a partial amount V1+n of protective gas is again removed from the first gas space 1 and a partial amount V2 of the dried protective gas from the second gas space 2 is introduced into the first gas space 1. These method steps are repeated until the pressure dew point inside the first gas space 1 has been reduced to a predetermined temperature. The pressure dew point is determined by means of the moisture measurement using moisture sensors 10.1 and 10.2. The pressure dew point is a measure of the moisture in the gas phase prevailing in the gas space 1.

(13) FIG. 2 shows an enlarged detail of one variant of a connection of the gas line to the first gas space 1, which is designed as a ring line with two non-return valves 13. The non-return valves 13 permit unidirectional transport of the gas (circulation), wherein the ring line is provided to enlarge the gas volume/dead volume of the first gas space.

(14) FIG. 3 shows the number of operating cycles of the compressor 3 over time, the first bar showing the drying cycle from the first gas space 1 to the second gas space 2 and the second bar showing the drying cycle from the second gas space 2 to the first gas space 1, and the distance between the second and third bars on the time axis illustrating the predetermined waiting time t.

LIST OF REFERENCE NUMERALS

(15) 1 First gas space

(16) 2 Second gas space

(17) 3 Compressor

(18) 4 Filter

(19) 5.1, 5.2, 5.3, 5.4 Valves

(20) 6 Control line

(21) 7 Control unit

(22) 8 Operating unit

(23) 9.1, 9.2 Pressure pickup

(24) 10.1, 10.2 Moisture sensors

(25) 12 Gas line

(26) 13 Non-return valves