DEVICE AND METHOD FOR GAS DETECTION

Description

[0001] The invention relates to a device and a method for detecting several gases in high-voltage devices filled with insulating medium, in particular high-voltage transformers.

[0002] DE 10 2013 112 823 B3 discloses a device and a method for detecting gas in high-voltage devices filled with an insulating medium. The device comprises a membrane located in the high-voltage device. At one end, the membrane is connected to a measuring chamber via a line. A thermocouple, a gas sensor, and a temperature sensor are arranged in the measuring chamber. A carrier gas is pumped through the measuring chamber and the membrane by a first pump and enriched with the gases from the insulating medium.

[0003] This well-known system is very complex. The multitude of individual components makes the system not only expensive but also maintenance-intensive. The valves for air exchange wear out particularly quickly, thus representing a weak point in the system. The flat membrane can rupture particularly quickly in the event of a sudden increase in pressure, especially when evaluating the carrier gas.

[0004] The object of the invention is to provide a device for detecting gas molecules in a high-voltage device filled with an insulating medium, which is cost-effective, easy to maintain and largely wear-free, as well as to provide a method for detecting gases in high-voltage devices filled with liquids, which ensures safe and precise operation of the device.

[0005] This object is achieved by a device according to claim 1 and by a method according to claim 5. Advantageous further developments are described in the subclaims.

[0006] According to a first aspect, the invention proposes a device (1) for detecting gas (4) in a high-voltage device (3) filled with an insulating medium (2), comprising: an inlet (5) for introducing and an outlet (6) for discharging a carrier gas (16); at least one gas sensor (12) for detecting a gas (4); a first pump (9) for conveying the carrier gas (16) in the device (1); a membrane (13) consisting of at least one semipermeable material, at least partially surrounded by the insulating medium (2), and at least partially exposed to the carrier gas (16); a second pump (10) for conveying the carrier gas (16) into the device (1) and for conveying it out of the device (1); characterized in that a separation column (19) is provided, which is arranged upstream of the gas sensor (12), and the gas sensor (12) is designed as a sensor array; a valve (20) with at least two operating states; a measuring chamber (11) in which sensors for temperature, humidity, pressure, and the at least one gas sensor (12) are arranged;wherein the membrane (13) is connected on the one hand via a first connecting line (31) to a first connection (20.1) and on the other hand via a second connecting line (32) to a second connection (20.2) of the valve (20); the first pump (9) is arranged in the first connecting line (31); a fourth connecting line (34) connects the separation column (19) to the measuring chamber (11) via a fourth connection (20.4) of the valve (20); the measuring chamber (11) is connected to an outlet (6) via a second line (8); a sample loop (21) is connected via a third connecting line (33) to a third connection (20.3) and a fourth connecting line (34) to a fifth connection (20.5) of the valve (20).

[0007] One advantage is that expanding the device to include the combination of a separation column and a sensor array is both particularly cost-effective and particularly accurate. Sensor arrays are several particularly compact semiconductor sensors arranged on a single unit. This allows a particularly compact measuring chamber to be designed. Furthermore, sensor arrays are significantly cheaper than conventional sensors used in gas-in-oil analysis. The installation of a separation column upstream of the sensor array enables pre-separation of the gases and thus improves the selectivity of the entire device. Separation columns are typically used in laboratory setups, but not in devices directly connected to high-voltage devices. Furthermore, the separation column can reduce the number of individual sensors in the sensor array. The measurements are simplified, which minimizes the computational effort required for data processing.This allows the central control unit to be constructed using the simplest means, which has a positive impact on the cost of the device. Overall, this combination results in a cost-effective, robust, low-maintenance, and less error-prone device. A further advantage is that the carrier gas, rather than the insulating medium, is circulated. This makes it possible to introduce fresh carrier gas, such as ambient air, into the device before enrichment and detection, and to discharge it from the device after detection.

[0008] The sensor array can be designed in any desired manner, for example, as a semiconductor sensor consisting of oxides of metals or transition metals such as tin dioxide (SnO2), tungsten oxide (WO3), and / or doped with precious metals such as platinum (Pt) or palladium (Pd). The sensor array can, for example, be based on the pellistor principle and / or be a Taguchi gas sensor.

[0009] The separation column can be constructed in any desired manner, for example, from metal or quartz glass. It can be lined internally with a defined stationary phase, e.g., viscous polyorganosiloxanes. The length of the separation column is preferably approximately 0.5 to 1.0 m. The separation column can be of the PoraBond Q, WP Plot Q, Hayesep N, or Hayesep Q type.

[0010] The high-voltage device can be designed in any way as required, for example as a high-voltage transformer, power transformer, on-load tap changer, circuit breaker, capacitor bushing or other oil-filled electrical equipment.

[0011] The insulating medium can be designed in any way as required, for example as insulating oil or ester liquid.

[0012] The gas to be detected can be formed in any desired manner as required and can, for example, contain at least one hydrocarbon compound and / or other gas molecules and / or other gas atoms.

[0013] The semipermeable membrane can be designed in any way as required and can, for example, consist at least partially of Teflon.

[0014] The pumps can be designed in any way as required, for example as diaphragm pumps.

[0015] It may be provided that a valve with at least two operating states is provided.

[0016] The valve can be designed in any desired manner, for example, as a Valco 6-port valve or a Valco 8-port valve. The valve can preferably be switched to at least two operating states.

[0017] It may be provided that an inlet, a first line and a filter are provided and the first line is connected to a sixth connection of the valve; the membrane is connected on the one hand via a first connecting line to a first connection and on the other hand via a second connecting line to a second connection of the valve; the first pump is arranged in the first connecting line; a measuring chamber is provided in which sensors for temperature, humidity and pressure and / or gas sensors are arranged; a fourth connecting line connects the separation column to the measuring chamber via a fourth connection of the valve; the measuring chamber is connected to an outlet via a second line.

[0018] It may be provided that a sample loop is connected via a third connecting line to a third port and a fourth connecting line to a fifth port of the valve.

[0019] The sample loop can be designed in any way as required and can, for example, be made at least partially of Teflon.

[0020] It may be provided that the sensors in the measuring chamber, the first pump, the second pump and the valve are connected to a control device; and the sensors in the measuring chamber, the first pump, the second pump and the valve are controlled based on the measurements of the sensors in the measuring chamber.

[0021] It may be provided that the inlet has a first line, a pump and a filter.

[0022] It may be provided that the membrane is at least partially spiral-shaped and / or at least partially meander-shaped and / or at least partially helical.

[0023] It may be provided that at least one temperature sensor is provided.

[0024] It may be provided that the outlet has a second line.

[0025] It may be provided that a line or connecting line for the transport of the gases to be analyzed is present, which has a pump.

[0026] It may be provided that a measuring chamber is provided in which sensors are arranged to determine temperature, ambient humidity, pressure and various gases.

[0027] It may be provided that at least one thermocouple is arranged in the measuring chamber.

[0028] It may be provided that the temperature sensor and the thermocouple are connected to a control device and the thermocouple is controlled based on the measurements of the temperature sensor.

[0029] It may be provided that during operation of the first pump, the second pump has the function of a closed valve and during operation of the second pump, the first pump has the function of a closed valve.

[0030] It may be provided that the thermocouple is designed as a Peltier element.

[0031] It may be provided that the measuring chamber is lined inside with an inert material, platinum or gold or another precious metal.

[0032] According to a second aspect, the invention proposes a method for detecting a plurality of gases in a high-voltage device filled with an insulating medium, preferably by means of a device according to one of the preceding claims, wherein: In a first step, a measuring chamber is flushed with a carrier gas by conveying the carrier gas through the separation column into the measuring chamber and out of the measuring chamber; In a second step, the carrier gas is conveyed through a membrane and enriched by gas flowing through the membrane; In a third step, a sensor in the measuring chamber measures the gas after it has passed through the separation column.

[0033] It may be provided that In the first and third steps, the valve is in a first operating state for purging the measuring chamber and measuring the gases; in the third step, the valve is in a second operating state for enriching the carrier gas.

[0034] It may be provided that the carrier gas is transported through a valve, a sample loop, the fourth connecting line and the separation column into the measuring chamber, where the gases collected in the membrane are detected by the sensors.

[0035] It may be provided that During purging, the carrier gas is sucked in through a first line, transported through the valve and over the separation column into the measuring chamber and discharged through the outlet.

[0036] It may be provided that the measuring chamber is rinsed using the second pump.

[0037] It may be provided that the carrier gas is transported by means of a first pump.

[0038] It may be provided that the quantity and / or type of gas in the measuring chamber can be determined before and / or after the carrier gas has been removed.

[0039] It may be provided that the quantity and / or type of gas in the measuring chamber can be determined before and / or after the carrier gas has been transported.

[0040] The invention and its advantages are described in more detail below with reference to the accompanying drawings. They show: Fig. 1 shows a first embodiment of a device for detecting gas; Fig. 2 shows a first operating state of the first embodiment of a device for detecting gas; Fig. 3 shows a second operating state of the first embodiment of a device for detecting gas; Fig. 4 shows a second embodiment of a device for detecting gas; Fig. 5 shows a first operating state of the second embodiment of a device for detecting gas; Fig. 6 shows a second operating state of the second embodiment of a device for detecting gas; Fig. 7 shows a method for detecting gas.

[0041] Identical reference numerals are used for identical or equivalently functioning elements of the invention. Furthermore, for the sake of clarity, only those reference numerals are shown in the individual figures that are necessary for the description of the respective figure. The illustrated embodiments merely represent examples of how the device according to the invention can be designed and thus do not represent a conclusive limitation of the invention.

[0042] Figure 1 shows a first embodiment of a device 1 for detecting gas molecules, ions, or gases 4 in a high-voltage device 3, which is filled with a liquid or an insulating medium 2. The high-voltage device 3 can be designed as a high-voltage transformer, power transformer, on-load tap changer, circuit breaker, or capacitor bushing.

[0043] The device 1 has a membrane or capillary 13 made of at least one semipermeable material and having a tubular or hose-like structure. The tubular membrane 13 can be shaped as desired, for example, spiral and / or helical and / or meandering. This advantageous design of the membrane 13 makes it suitable for particularly high pressures. The membrane 13 is located in the high-voltage device 3 or at least in a part of the high-voltage device to which the insulating medium 2 is accessible. Thus, the membrane 13 can be arranged in a Buchholz relay, a cooling line, etc. Due to the tubular design and the one-way gas-permeable (semipermeable) material, molecules of the gas 4 can enter a circuit of the device 1.

[0044] The membrane 13 is connected at one end, which forms its inlet, to a first connection 20.1 of a valve 20 via a first connecting line 31, and at another end, which forms its outlet, to the second connection 20.2 of the valve 20 via a second connecting line 32. A first pump 9 is arranged in the second line 32.

[0045] The device further comprises a sample loop 21. A sample loop is a gas-tight capillary with a defined volume. This is usually made of fused silica. However, it can also be made of a suitable plastic. The sample loop 21 is connected to the third and fourth ports 20.3, 20.4 of the valve 20 via a third and a fourth connecting line 33, 34. The device 1 further comprises a first line 7, which has an inlet 5 on one side and is connected to a fifth port 20.5 of the valve 20 on the other side. A filter 15 and a second pump 10 are arranged in the first line 7.

[0046] A separation column 19 is arranged between the sixth connection 20.6 and the measuring chamber 11 via a fifth connecting line 35. The measuring chamber 11 is also connected to an outlet 6 via a second line 8.

[0047] The measuring chamber 11 has a thermocouple 14, e.g., a Peltier element, which is used to control the temperature of the measuring chamber 11. In addition, at least one gas sensor 12 and one temperature sensor 18 are arranged in the measuring chamber 11.

[0048] The gas sensor 12 is designed as a sensor array. This sensor array consists of several semiconductor sensors. The semiconductor sensors are made of oxides of metals or transition metals such as tin dioxide (SnO2) and tungsten oxide (WO3) and are doped with precious metals such as platinum (Pt) or palladium (Pd) to improve selectivity. The sensor array is constructed based on the pellistor principle, but this is not the only design. Classic semiconductor sensors are Taguchi gas sensors.

[0049] The measuring chamber 11 is lined or coated on the inside with an inert material, such as gold. This coating offers the advantage that the gases 4 do not precipitate or condense inside and accumulate in a non-reproducible manner, thereby forming at least one polar physical bond and thus being missing from the overall gas balance, which would result in incorrect values ​​compared to a laboratory analysis.

[0050] The separation column 19 can be made of either metal or quartz glass. It is lined internally with a defined stationary phase, e.g., viscous polyorganosiloxanes. The length of the separation column is approximately 0.5 - 1.0 m. Common column types are PoraBond Q, WP Plot Q, Hayesep N, or Hayesep Q.

[0051] The valve 20 has different operating states / positions. In these states, the individual connections are internally wired or connected in such a way that different circuits or connections between individual components are created in the device 1.

[0052] In a first operating state, as in Figure 2As shown, for example, a circuit for enriching the carrier gas 16 is created. Here, the first and fourth connections 20.1, 20.4 and the second connection are internally connected to the third connections 20.2 and 20.3. The first pump 9 transports the carrier gas 16 through the second connecting line 32, the capillary 13 and the sample loop 21. Since the pressure inside the high-voltage device 3 is always higher than the ambient pressure and thus also the pressure in the device 1, the gases 4 dissolved in the insulating medium 2 enter the circuit of the device 1 through the semipermeable membrane 13. The carrier gas 16 is enriched by repeated transport or circulation. The valve 20 is also connected to the central control device 17. Air from the environment can be used as the carrier gas 16.

[0053] In Figure 3A second operating state of the valve 20 is shown. Here, the fifth and third connections 20.5, 20.3 as well as the fourth and sixth connections 20.4, 20.6 of the valve 20 are internally connected to one another. Fresh carrier gas 16 (e.g., ambient air) is conveyed into the device 1 via the inlet 5 of the first line 7 by means of the second pump 10. The carrier gas 16 located in the sample loop 21 is first introduced into the separation column 19 and then into the measuring chamber 12. The carrier gas 16 and the sucked-in air are then conveyed through the second line 8 to the outlet 6. The gas sensor 12, the temperature sensor 18, and the thermocouple 14 in the measuring chamber 11, as well as the first and second pumps 9, 10, are connected to a central control device 17. The thermocouple 14 is controlled based on the measurements of the temperature sensor 18.

[0054] The valve 20 can preferably be designed as a Valco 6-port valve or a Valco 8-port valve. This valve can assume two internal operating states. When using a Velco 6-port valve, the individual parts of the device 1 are connected to the valve 20 in a specific manner. This is shown in Figure 4 shown. It is only ever possible to connect two adjacent valve ports internally. This makes the valve particularly economical and easy to operate. The diaphragm 13 is connected at one end, which forms its inlet, via a first connecting line 31 to a first port 20.1 of a valve 20, and at another end, which forms its outlet, via a second connecting line 32 to the second port 20.2 of the valve 20. A first pump 9 is arranged in the second line 32.

[0055] The device further comprises a sample loop 21. The sample loop 21 is connected to the third and fifth ports 20.3, 20.5 of the valve 20 via a third and a fourth connecting line 33, 34. The device 1 further comprises a first line 7, which has an inlet 5 on one side and is connected to the valve 20 via a sixth port 20.6 on the other side. A filter 15 and a second pump 10 are arranged in the first line 7.

[0056] A separation column 19 is arranged between the fourth connection 20.4 and the measuring chamber 11 via a fifth connecting line 35. The measuring chamber 11 is also connected to an outlet 6 via a second line 8.

[0057] In a first operating state, as in Figure 5As shown, for example, a circuit for enriching the carrier gas 16 is created. Here, the first and fifth connections 20.1, 20.5 and the second connection are internally connected to the third connection 20.2, 20.3. The fifth and fourth connections 20.4, 20.5 are also connected to each other. This is irrelevant for the enrichment. The first pump 9 transports the carrier gas 16 through the second connecting line 32, the capillary 13, and the sample loop 21. Since the pressure inside the high-voltage device 3 is always higher than the ambient pressure and thus also the pressure in the device 1, the gases 4 dissolved in the insulating medium 2 enter the circuit of the device 1 through the semipermeable membrane 13. The carrier gas 16 is enriched by repeated transport or circulation. The valve 20 is also connected to the central control device 17. Ambient air can be used as carrier gas 16.

[0058] In Figure 6 a second operating state of the valve 20 is shown. Here, the third and fourth connections 20.3, 20.4 as well as the fifth and sixth connections 20.5, 20.6 of the valve 20 are internally connected to one another. Fresh carrier gas 16 (e.g. ambient air) is conveyed into the device 1 via the inlet 5 of the first line 7 by means of the second pump 10. The carrier gas 16 located in the sample loop is first introduced into the separation column 19 and then into the measuring chamber 12. The carrier gas 16 or the sucked-in air is then conveyed through the second line 8 to the outlet 6.

[0059] Figure 7 shows a flow chart for a method for detecting gases in a high-voltage device 3 filled with a liquid 2, by means of the device 1 with the following steps: Step 100: First, the device 1 is purged. The valve 20 is in the second operating state. The first pump 9 is switched off, whereas the second pump 10 is switched on. The carrier gas 16, e.g. ambient air, is sucked in via the inlet 5, i.e. the filter 15 and the first line 7. The carrier gas 16 passes through the filter 15, the valve 20, the sample loop 21, the separation column 19 and the measuring chamber 11 until it reaches the outlet 6. The device 1 is thus purged. Step 101: After a predetermined time or based on the measurements of the gas sensors 12 in the measuring chamber 11, the purging is terminated. The parameters finally determined in the measuring chamber 11 serve as the starting point or zero point for the further measurements. Step 102: In the enrichment phase of the embodiment of the Figure 3 and 6the valve 20 is switched to the first operating state and the first pump 9 is switched on, whereby the carrier gas 16 is transported or circulated in the device 1. The second pump 10 is switched off. The carrier gas 16 is moved in a circuit between the sample loop 21 and the membrane 13. Since the pressure inside the high-voltage device 3 is greater than the pressure in the device 1, gases 4 from the insulating medium 2 pass through the membrane 13, which is permeable to gas molecules in one direction, into the device 1. This results in an enrichment of the carrier gas 16. The duration of the enrichment can be varied. Step 103: After the enrichment phase, the valve 20 is switched to the second operating state. The enriched gas in the sample loop 21 is transported with the carrier gas 16 through the separation column 19 into the measuring chamber 11 and the quantity and type of the gases 4 in the measuring chamber 11 are determined via the gas sensor 12.After the determination of the gases 4, the device 1 is purged by further drawing in fresh ambient air.

[0060] The described process can be performed either continuously or several times per day. Discontinuous operation of the device 1 can lead to an increase in the lifetime of the gas sensors 12 used in the measuring chamber 11. List of reference symbols

[0061] 1Device 2Insulating medium 3High-voltage device 4Gas 5Inlet 6Outlet 7First line 8Second line 9First pump 10Second pump 11Measuring chamber 12Gas sensor 13Membrane 14Thermocouple 15Filter 16Carrier gas 17Control device 18Temperature sensor 19Separation column 20Distributor / valve / changeover valve 20.1First connection 20.2Second connection 20.3Third connection 20.4Fourth connection 20.5Fifth connection 20.6Sixth connection 21Sample loop 31First connecting line 32Second connecting line 33Third connecting line 34Fourth connecting line 35Fifth connecting line

Claims

1. Device (1) for detecting gas (4) in a high-voltage apparatus (3) filled with an insulating medium (2), comprising: - an inlet (5) for introducing and an outlet (6) for discharging a carrier gas (16); - at least one gas sensor (12) for detecting a gas (4); - a first pump (9) for conveying the carrier gas (16) in the device (1); - a membrane (13) which consists of at least one semi-permeable material, is at least partially surrounded by the insulating medium (2) and is at least partially flowed against by the carrier gas (16); - a second pump (10) for conveying the carrier gas (16) into the device (1) and for conveying it out of the device (1); characterized in that - a separating column (19) is provided which is arranged in front of the gas sensor (12) and the gas sensor (12) is designed as a sensor array; - a valve (20) with at least two operating states; - a measuring chamber (11) in which sensors for temperature, humidity, pressure and the at least one gas sensor (12) are arranged; wherein - the diaphragm (13) is connected on the one hand to a first connection (20.1) via a first connecting line (31) and on the other hand to a second connection (20.2) of the valve (20) via a second connecting line (32); - the first pump (9) is arranged in the first connecting line (31); - a fourth connecting line (34) connects the separating column (19) to the measuring chamber (11) via a fourth connection (20.4) of the valve (20); - the measuring chamber (11) is connected to an outlet (6) via a second line (8); - a sample loop (21) is connected via a third connecting line (33) to a third connection (20.3) and a fourth connecting line (34) to a fifth connection (20.5) of the valve (20) .

2. Device according to claim 1, wherein - the diaphragm (13) is at least partially tubular and / or at least partially hose-like.

3. The device according to any one of claims 1 to 2, wherein - an inlet (5), a first line (7) and a filter (15) are provided and the first line (7) is connected to a sixth connection (20.6) of the valve (20).

4. The device according to any one of claims 1 to 3, wherein - the sensors in the measuring chamber (11), the first pump (9), the second pump (10) and the valve (20) are connected to a control device (17); and - the sensors in the measuring chamber (11), the first pump (9), the second pump (10) and the valve (20) are controlled on the basis of the measurements of the sensor in the measuring chamber (11).

5. Method for detecting gas (4) in a high-voltage device (3) filled with an insulating medium (2) by means of a device (1) according to one of the preceding claims, wherein: - in a first step, a measuring chamber (11) is purged with a carrier gas (16) by conveying the carrier gas (16) through the separation column (19) into the measuring chamber (11) and out of the measuring chamber (11); - in a second step, the carrier gas (16) is conveyed through a membrane (13) and is enriched by gas (4) flowing through the membrane (13); - in a third step, a sensor (12) in the measuring chamber (11) measures the gas (4) after it has passed through the separation column (19).

6. The method according to claim 5, wherein - in the first and third steps, the valve (20) is in a first operating state for purging the measuring chamber (11) and for measuring the gases (4); - in the third step, the valve (20) is in a second operating state for enriching the carrier gas (16).

7. Method according to claim 5 or 6, wherein - the carrier gas (16) is transported through a valve (20), a sample loop (21), the fourth connecting line (34) and the separation column (19) into the measuring chamber (11), where the gases (4) collected in the membrane (13) are detected by the sensors (12).

8. The method according to any one of claims 5 to 7, wherein - during purging, the carrier gas (16) is drawn in through a first line (7), conveyed through the valve (20) and via the separating column (19) into the measuring chamber (11) and discharged through the outlet (6).

9. The method according to any one of claims 5 to 8, wherein - wherein the measuring chamber (11) is flushed by means of the second pump (10).

10. The method according to any one of claims 5 to 9, wherein - the carrier gas (16) is conveyed by means of a first pump (9).

11. The method according to any one of claims 5 to 10, wherein - the quantity and / or type of gas (4) in the measuring chamber (11) is determined before and / or after the carrier gas (16) has been conveyed out.