Device comprising a high voltage apparatus including a fluid and equipment for detecting one or more physical properties of the fluid

Abstract

A device including a high voltage apparatus enclosing a fluid for providing cooling and/or electrical insulation of the apparatus, and a detector for one or more physical properties of the fluid positioned spaced apart from the housing. The device includes a pipe assembly for housing a fluid, whereby the pipe assembly is arranged between the detector equipment and the housing such that the fluid is extended without interruption in the pipe assembly. The fluid in the pipe assembly is in communication with the fluid in the housing, and the detector equipment is in direct communication with the fluid in the pipe assembly. The detector equipment is positioned below a top level of the housing and at a safe distance from the housing of the apparatus, which makes it possible to carry out inspection, testing, maintenance, and calibration of the detector equipment without taking the high voltage apparatus out of operation.

Claims

1. A device including a high voltage apparatus comprising: a housing enclosing a fluid for providing cooling and/or electrical insulation of the apparatus, a detector equipment configured to detect one or more physical properties of the fluid and positioned spaced apart from the housing at a level below a top level of the housing, and a pipe assembly for housing a fluid, the fluid in the pipe assembly is in communication with the fluid in the housing, and the detector equipment is in communication with the fluid in the pipe assembly, wherein the detector equipment is configured to detect any of light, pressure, moisture, or gas content in the fluid, the pipe assembly is arranged such that the fluid inside the pipe assembly flows between the detector equipment and the housing without interruption of obstacles in the pipe assembly, and the detector equipment is positioned at least 1 m away from the housing of the apparatus.

2. The device according to claim 1, whereby the apparatus is a high voltage transformer or an on load tap changer.

3. The device according to claim 1, whereby the detector equipment comprises one or more detectors for detecting pressure, moisture, gas, or light in the fluid.

4. The device according to claim 1, whereby the detector equipment comprises a gas or moisture sensor for measuring the content of gas or moisture in the fluid.

5. The device according to claim 1, whereby the detector equipment comprises a pressure relay or a pressure sensor for detecting a sound wave in the fluid.

6. The device according to claim 1, whereby the detector equipment comprises a sensor for detecting light in the fluid.

7. The device according to claim 1, whereby the pipe assembly comprises a pipe portion having a first end connected to the housing and a second end located at a distance from the housing, and the device comprises an oil sample valve arranged together with the detector equipment at the second end of the pipe portion.

8. The device according to claim 1, whereby the distance between the detector equipment and the housing is at least 2 m.

9. The device according to claim 1, whereby the distance between the detector equipment and the housing is less than 10 meter.

10. The device according to claim 1, whereby the detector equipment is positioned on a ground level.

11. The device according to claim 1, whereby said pipe assembly is connected to the housing at a first level and the detector equipment is positioned at a second level below the first level.

12. The device according to claim 1, whereby the pipe assembly is filled with fluid in communication with the fluid in the housing, and the detector equipment is adapted to detect the one or more physical properties while the apparatus is in operation.

13. The device according to claim 1, whereby the detector equipment is positioned said distance from the housing in a horizontal direction.

14. The device according to claim 1, whereby the apparatus is an on-load tap changer including a tap changer head positioned on top of a transformer tank, the pipe assembly is connected between the on-load tap changer head and the detector equipment, and the detector equipment is arranged at a position below the position of the tap changer head.

15. The device according to claim 1, whereby the device comprises an expansion vessel, the pipe assembly extends between the detector equipment and the expansion vessel, and the detector equipment comprises a fluid flow detector arranged to detect the fluid flow in the pipe assembly.

16. The device according to claim 1, wherein the pipe assembly positioned between the housing and the detector equipment is free of obstacles.

17. The device according to claim 16, wherein the pipe assembly is free of obstacles, the obstacles including valves.

18. The device according to claim 16, wherein the pipe assembly is free of obstacles, the obstacles including filters.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be explained more closely by the description of different embodiments of the invention and with reference to the appended figure.

(2) FIG. 1 shows schematically a device according to a first embodiment of the invention.

(3) FIG. 2 shows schematically a device according to a second embodiment of the invention including an on load tap changer.

(4) FIG. 3 shows schematically a device according to a third embodiment of the invention.

DETAILED DESCRIPTION

(5) FIG. 1 shows a device 1 according to a first embodiment of the invention. The device 1 comprises a high voltage apparatus 2 having a housing 3 enclosing a fluid for providing cooling and/or electrical insulation of the apparatus, and detector equipment 5 adapted to detect one or more physical properties of the fluid, and a pipe 6 for housing the fluid is arranged between the detector equipment 5 and the housing 3 such that the detector equipment is arranged in direct communication with the fluid in the pipe and accordingly with the fluid in the housing. In this embodiment, the high voltage apparatus 2 is disposed on the ground, and the detector equipment is disposed on or closed to the ground to allow maintenance personnel to easily reach the detector equipment. The housing 3 has a bottom portion, an upper portion and side walls connected between the bottom and upper portions. The upper portion of the housing defines a top level 20 of the housing. A first end of the pipe 6 is connected the housing 3. In this embodiment, the first end of the pipe 6 is connected to a side wall of the housing. A second end of the pipe is position at a distance from the housing. The detector equipment 5 is connected to the second end of the pipe. The detector equipment 5 is situated at a distance d away from the housing 3. In this embodiment, the detector equipment 5 is situated a distance d away from the housing in a horizontal direction. The distance d is preferably more than 1 m to provide a safe distance from the high voltage apparatus and less than 10 m to ensure that the property can be accurately measured. The detector equipment 5 is situated below the upper part of the housing. Preferably, the detector equipment 5 is positioned close to the ground so that maintenance personal easily can reach the equipment.

(6) The pipe assembly is arranged such that when the pipe assembly is filled with fluid, the fluid is extended between the detector equipment and the housing without interruption by other media, e.g. valves, filters and the like, in the pipe assembly. Thus, the fluid is allowed to flows without any interruption between the housing and the detector equipment. The fluid is, for example oil, such as vegetable oil, mineral oil or synthetic or natural esters, or gas, such as SF6. The device may also include two or more detector equipment 5 connected to the pipe at spaced apart positions along the pipe. The device further comprises an expansion vessel 22 arranged above the housing. An expansion vessel must always be positioned above the oil level in the apparatus, otherwise it cannot function as an expansion vessel.

(7) The apparatus 1 is, for example, a high voltage transformer immersed in oil. In this embodiment, the detector equipment 5 includes a pressure relay P, a sensor M for measuring the content of moisture in the fluid, a sensor H for measuring the content of hydrogen in the fluid, and a sensor L for detecting light in the fluid. However, the detector equipment may include a single sensor or a combination of several sensors or relays. For example, the detector equipment may include two or more sensors of the same type arranged along the pipe to achieve redundancy and to enable measurement of the rate of change of one or more physical properties. During operation of the apparatus, the pipe 6 is filled with fluid in communication with the fluid in the apparatus 2. The detector equipment 5 is adapted to detect physical properties of the fluid in the pipe assembly 6. In this embodiment of the invention, the device also includes an oil sample valve 8 arranged together with the detector equipment 5 at a second end of the pipe assembly 6.

(8) FIG. 2 shows schematically a device 1 according to a second embodiment of the invention. The device 1 comprises a high voltage apparatus 2. In this embodiment, the high voltage apparatus 2 is an on load tap changer (OLTC). The OLTC includes a tap changer head 14. The high voltage part of the OLTC is mounted inside a transformer tank 4 and the tap changer head 14 is mounted on top of the transformer tank 4. The transformer tank 4 is filled with a fluid for providing electrical insulation and cooling of the OLTC and a transformer housed in the tank. The tap changer head 14 forms a compartment filled with fluid in communication with the fluid in the transformer tank 4. The tap changer head 14 comprises a housing 3 enclosing the fluid for providing cooling and/or electrical insulation of the OLTC. The housing 3 has a bottom portion, an upper portion and side walls connected between the bottom and upper portions. The upper portion of the housing defines a top level 20 of the housing 3. The device may further comprise a motor-drive mechanism 9 connected to shafts 10, 12 possibly using a bevel gear 11.

(9) The device further comprises a pipe assembly 6 having a first end 6a connected to the housing 3 of the tap changer head 14 and a second end 6b connected to detector equipment 5. The pipe assembly 6 may comprise a pipe and connection portions at the first and second ends 6a, 6b for connecting the pipe to the housing 3 and the detector equipment 5. The pipe is made of any material in which a fluid can be contained, such as metal or plastic. Preferably, the inside of the pipe is made of material that can reflect light. In this embodiment, the fluid is oil. As shown in FIG. 2, the pipe assembly 6 may have a vertically arranged pipe portion 6c to contain and connect the fluid from a first level at the first end 6a, e.g. on top of the apparatus 2, to a second level at the second end 6b, e.g. on a ground level. For convenience, safety and efficiency, the second level is below the first level as seen from the ground level. However, depending on the geometry of the location, the second level may be on substantially the same level. In another embodiment the second level is on a higher level in relation to the ground level on which the apparatus 2 is placed.

(10) The fluid enclosed in the housing 3,3 is used for heat dissipation and insulation of the high voltage apparatus. The fluid is contained in the housing and in the pipe assembly 6, 6 all the way towards the detector equipment 5, 5 without interruption of the fluid flow. In this way, the detector equipment 5,5 is in direct communication with the fluid as used in the high voltage apparatus. Because the fluid flows in a closed system, without openings to open air, the pressure measured by the detection equipment is the pressure of the fluid as it flows through the housing.

(11) The length of the pipe assembly is such that the distance between the housing and the detector equipment is allowed to be sufficiently long for a person to perform inspection and maintenance of the detection equipment in a safe and efficient manner when the apparatus is in operation. The distance should be at least 1 meter, and preferably at least 2 m. Suitably, the distance is less than 10 m.

(12) The detector equipment comprises at least one detector, preferably more than one detector, for control, detection or measurement of one or more physical properties of the fluid. Examples of suitable detectors that can be used in the detector equipment are detectors adapted for measuring pressure and detecting a sound wave in the fluid. Other examples are detectors adapted for detecting a moisture and gas content in the fluid, such as hydrogen and water content. A further example may be a detector adapted for detecting light in the fluid. In this embodiment, the detector equipment includes a pressure sensor or pressure relay 7.

(13) The device 1 may further comprise an expansion vessel 13, such as an oil conservator, and a fluid flow detector 15 for measuring the flow of the fluid. The fluid flow detector 15 is, for example, an oil flow relay or a flow sensor. In this embodiment, the expansion vessel 13 and the fluid flow detector 15 are connected to the OLTC head by means of a separate pipe 17. In FIG. 2, the pressure relief device 14 and the oil flow relay 15 are positioned on top of the apparatus 2.

(14) The detector equipment 5 may also include other measurement utilities, such as an oil sample valve 8, as shown in FIG. 2. The pipe assembly 6 comprises a pipe portion having a first end 6a connected to the housing 3 and a second end 6b located at a distance from the housing, and the device comprises an oil sample valve 8 arranged at the second end 6b of the pipe together with the detector equipment 5.

(15) FIG. 3 shows schematically a device according to a third embodiment of the invention. In this embodiment the device comprises a pipe assembly 19 having a first end 6a connected to the housing 3 of the tap changer head 14 and a second end 6b connected to the expansion vessel 13. The pipe assembly 19 includes a first pipe portion 20 extending between the housing 3 of the apparatus and the detector equipment 5, and a second pipe portion 21 extending between the detector equipment 5 and the expansion vessel 13. The detector equipment 5 further comprises a fluid flow detector 15 arranged to detect the fluid flow in the pipe assembly 19. In this embodiment, the flow detector is arranged to detect the flow in the second pipe portion 20. This embodiment differs from the previous embodiment in that the expansion vessel 13 and the fluid flow detector 15 are connected to the same piping assembly 19 as the detector equipment 5. The fluid flow sensor 15 is positioned at a level below the tap changer head 14. This embodiment makes it easier for a service technician to reach the flow sensor 15 during service and calibration of the sensor and makes it possible to provide service and calibration of the sensor while the high voltage apparatus is in operation. Further, this embodiment will minimize the number of pipes that need to be connected to the apparatus and improves the efficiency of the device.

(16) In one embodiment, other measurement utilities, for example, the oil flow relay 15 can also be combined with the detector equipment. These other measurement utilities may be positioned in the proximity of the detector equipment, i.e. at a distance from the apparatus, or these measurement utilities may be comprised in the detector equipment.

(17) The device according to the invention can be used for detecting one or more physical properties of a fluid enclosed in a housing of a high voltage apparatus, while the apparatus is in operation. A possible delay in reaction time of a circuit breaker adapted for taking the apparatus out of operation is not critical.

(18) For example, a pressure wave will be spread with a speed of sound within the media where the sound is generated. When the sound wave reached a material with another density or shape, the sound wave will bounce and thereby damp the sound impulse. However, if the media is extended without interruption, for example in a pipe, the sound wave will hit the pipe inlet at the first end 6a and follow this media (the fluid) towards the second end 6b of the pipe 6 at the detector equipment 5. The pressure or sound wave can thus be detected at a distance from the apparatus 2. The loss of detection time is dependent on the distance and the speed of the sound in the media, which speed is 1320 m/s in mineral oil. If the detector equipment 5 with a sensor for detecting wave sounds is located at a distance of 5 meters, the delay in detection time is about 4 milliseconds. This can be compared to a reaction time for breaking open an AC trip circuit in a pressure relay that is in the range of 2 to 12 milliseconds and a reaction time of the circuit breaker for taking the apparatus 2 out of operation that is in the range of about 100 milliseconds.

(19) Another example regards detecting gas or moisture content in the fluid. Gas and moisture diffuse in the fluid and follow the fluid contained in the pipe assembly. Gas and moisture can thus be detected at a distance from the apparatus. The loss in detection time depends on the diffusion speed in the media with its viscosity at the actual temperature and the distance. If sensors are placed on the ground level, it can be estimated that a distance up to 5 meter will cause a delay in the range of days. These types of measurements are normally today performed manually once every 2 to 5 years. Therefore, a delay of some days or even weeks is not a critical delay. With regard to temperature, the device 1 allows a control of the temperature at the measurement point, i.e. at the detector equipment.

(20) The sensors used for measuring a physical property value may be connected to a protection system arranged to be connected to the circuit breaker or a logger or a monitoring system. The sensors may in the simplest case be adapted to allow values of the physical property to be within a predetermined range of reference values having an upper and a lower limit. If the detected value falls outside the predetermined range, an alarm signal can be initiated, and other types of algorithms taking history into consideration can also be used.