On-site calibration device and calibration method for pressure relief valve

Abstract

The present invention discloses an on-site calibration device and calibration method for a pressure relief valve. The pressure relief valve is installed on a transformer and includes: a shell, an elastic member, and a film. The shell is connected to the transformer, and the shell has a chamber. One end of the elastic member is connected to the shell, and the other end of the elastic member is connected to the film. The edge of the film abuts against the inner wall of the chamber, and the film is used to divide the chamber into a first chamber and a second chamber that are independent of each other. The first chamber is connected to the oil chamber of the transformer, and the second chamber is connected to the on-site calibration device for the pressure relief valve. The on-site calibration device for the pressure relief valve is used to evacuate the second chamber to move the elastic member and the film. The present invention avoids the operation of removing the pressure relief valve from the transformer, and the operation process saves time and effort, while avoiding secondary risks.

Description

Technical Field

[0001] The present invention relates to the field of electric power, and in particular to an on-site calibration device and a calibration method for a pressure relief valve. Background Art

[0002] Transformer pressure relief valves are crucial for protecting equipment and personnel, as they prevent internal short-circuit failures in transformers, which could generate significant gas pressure impacting the transformer tank. Existing laboratory and field calibration methods for transformer pressure relief valves involve injecting gas pressure into the valve's lower port. When the pressure reaches a certain level, a spring triggers tension, causing the membrane to rise until the insulating oil is discharged through the directional drain port. However, this method requires removing the pressure relief valve from the top of the transformer. This disassembly and assembly process carries secondary risks, such as external impurities and moisture entering the transformer tank, potentially posing internal risks. Furthermore, the removal of the pressure relief valve affects the vacuum pumping of the transformer itself, making on-site verification time-consuming and labor-intensive. Summary of the Invention

[0003] In view of this, the present invention provides an on-site calibration device and a calibration method for a pressure relief valve.

[0004] Specifically, the following technical solutions are included:

[0005] A pressure relief valve on-site calibration device, wherein the pressure relief valve is installed on a transformer, and the pressure relief valve comprises: a housing, an elastic member, and a film;

[0006] The housing is connected to the transformer, and the housing has a chamber. One end of the elastic member is connected to the housing, and the other end of the elastic member is connected to the film. The edge of the film abuts against the inner wall of the chamber, and the film is used to divide the chamber into a first chamber and a second chamber that are independent of each other.

[0007] The first chamber is connected to the oil chamber of the transformer, and the second chamber is connected to an on-site verification device for a pressure relief valve. The on-site verification device for a pressure relief valve is used to evacuate the second chamber to move the elastic member and the film.

[0008] Preferably, the pressure relief valve on-site calibration device includes a pressure measuring device and a vacuum pump;

[0009] The pressure relief valve includes an oil drain pipe, the oil drain pipe is communicated with the second chamber, the pressure measuring component is arranged on the oil drain pipe, and the vacuum pump is connected to the oil drain pipe.

[0010] Preferably, the pressure measuring element is a negative pressure gauge.

[0011] Preferably, the pressure relief valve on-site verification device comprises a hose;

[0012] The oil drain pipe and the vacuum pump are connected via the hose.

[0013] Preferably, the first end of the hose is sleeved on the outlet of the oil drain pipe, and the vertical distance between the port cross section of the first end of the hose and the outlet cross section of the oil drain pipe is greater than or equal to 5 cm.

[0014] Preferably, the pressure relief valve on-site verification device includes a locking clamp;

[0015] The locking hoop is arranged on the outer wall of the hose, and is used to clamp the hose on the oil drain pipe.

[0016] Preferably, the pressure relief valve on-site verification device includes a sealing structure;

[0017] The sealing structure is arranged between the inner wall of the hose and the outer wall of the oil drain pipe.

[0018] Preferably, the sealing structure is sealant.

[0019] A pressure relief valve on-site calibration method, using the pressure relief valve on-site calibration device as described above, the method comprising:

[0020] S100, checking the oil level of the oil tank of the transformer, and calculating a first pressure value of the oil in the oil tank of the transformer acting on the membrane through the first chamber;

[0021] S200, connecting the pressure relief valve and the pressure relief valve on-site verification device to communicate with the second chamber and the pressure relief valve on-site verification device;

[0022] S300, starting the pressure relief valve on-site verification device to evacuate the second chamber, and recording a second pressure value applied by the pressure relief valve on-site verification device to the pressure relief valve when the elastic member starts to act;

[0023] S400 , summing the absolute value of the second pressure value and the first pressure value to obtain a third pressure value, and comparing the third pressure value with a design value of the pressure relief valve to determine whether the pressure relief valve is qualified.

[0024] Preferably, when the absolute value of the difference between the third pressure value and the design value of the pressure relief valve in step 400 is less than or equal to 5 kPa, the pressure relief valve is judged to be qualified.

[0025] The beneficial effects of the technical solution provided by the present invention include at least:

[0026] The present invention uses a pressure relief valve on-site verification device connected to the second chamber of the pressure relief valve and evacuates the second chamber. This second chamber then applies force to the membrane and elastic member, causing them to move and verifying the valve's compliance. This eliminates the need to remove the pressure relief valve from the transformer, saving time and effort while also avoiding secondary risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 This is a schematic diagram of the installation of the pressure relief valve on-site calibration device of the present invention.

[0029] The reference numerals in the figures represent respectively:

[0030] 1- Transformer; 2- Housing; 3- Elastic part; 4- Diaphragm; 5- Oil drain pipe; 6- Vacuum pump; 7- Hose; 8- Pressure measuring device; 9- Locking clamp; 10- Oil conservator.

[0031] The above drawings illustrate specific embodiments of the present invention, which will be described in more detail below. These drawings and the accompanying description are not intended to limit the scope of the present invention in any way, but rather to illustrate the concept of the present invention to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] Before further describing the embodiments of the present invention in detail, the directional nouns involved in the embodiments of the present invention, such as "upper", "lower", "side", etc., are used to represent the position of the subject matter. Figure 1 The directions shown in the figure are for reference only and do not limit the scope of protection of the present invention.

[0034] To make the technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0035] This embodiment introduces a pressure relief valve on-site calibration device, which is installed on a transformer 1. The pressure relief valve includes: a shell 2, an elastic member 3 and a film 4; the shell 2 is connected to the transformer 1, and the shell 2 has a chamber, one end of the elastic member 3 is connected to the shell 2, and the other end of the elastic member 3 is connected to the film 4, the edge of the film 4 is in contact with the inner wall of the chamber, and the film 4 is used to divide the chamber into a first chamber and a second chamber that are independent of each other; the first chamber is connected to the oil chamber of the transformer 1, and the second chamber is connected to the pressure relief valve on-site calibration device, and the pressure relief valve on-site calibration device is used to vacuum the second chamber to move the elastic member 3 and the film 4.

[0036] Further, if Figure 1 As shown, the outer edge of membrane 4 abuts against the inner wall of housing 2. Membrane 4 divides the chamber within housing 2 into an upper chamber and a lower chamber. The lower chamber is the first chamber, and the upper chamber is the second chamber. Because membrane 4 moves up and down under the action of external force, the volumes of the first and second chambers change with the movement of membrane 4. The operating principle of the pressure relief valve is as follows: housing 2 of the pressure relief valve is mounted on top of transformer 1. Inside housing 2 is an elastic member 3, to which membrane 4 is attached. The first chamber communicates with the oil chamber of transformer 1. When the pressure of the insulating oil in the first chamber increases, the oil pressure acting on membrane 4 exceeds the elastic force of elastic member 3, causing membrane 4 to rise and stretch elastic member 3. When the height of membrane 4 exceeds the height of the oil drain port on housing 2, the insulating oil in transformer 1 flows out of the oil drain port, reducing the oil pressure within transformer 1 and protecting transformer 1 from explosion.

[0037] Further, if Figure 1 As shown, it can be understood that the design value of the pressure relief valve refers to the oil pressure exerted by the insulating oil on the diaphragm 4 when the diaphragm 4 rises, driving the elastic member 3 to operate. At this time, the height of the diaphragm 4 is lower than the height of the oil drain port on the housing 2, and the oil drain port is always connected to the second chamber. Typically, when calibrating the pressure relief valve, the pressure relief valve must be removed from the transformer 1. Then, a force is applied to the diaphragm 4 through the first chamber to create a large pressure differential between the upper and lower sides of the diaphragm 4, driving the elastic member 3 to operate. In this embodiment, however, a pressure relief valve on-site calibration device is connected to the oil drain port, connecting the pressure relief valve on-site calibration device to the second chamber. The pressure relief valve on-site calibration device is used to evacuate the second chamber to apply a force to the diaphragm 4, creating a large pressure differential between the upper and lower sides of the diaphragm 4, driving the elastic member 3 to operate. The pressure relief valve on-site calibration device of this embodiment avoids the need to remove the pressure relief valve from the transformer 1, saving time and effort while also avoiding secondary risks.

[0038] Preferably, the pressure relief valve on-site calibration device includes a pressure measuring device 8 and a vacuum pump 6; the pressure relief valve includes an oil drain pipe 5, the oil drain pipe 5 is connected to the second chamber, the pressure measuring device 8 is arranged on the oil drain pipe 5, and the vacuum pump 6 is connected to the oil drain pipe 5.

[0039] Further, if Figure 1 As shown, the oil drain pipe 5 is connected to the oil drain port on the housing 2 so that the insulating oil in the transformer 1 can be smoothly discharged through the oil drain pipe 5 .

[0040] Preferably, the pressure measuring element 8 is a negative pressure gauge, so that the pressure exerted by the vacuum pump 6 on the film 4 through the second chamber can be visually observed.

[0041] Preferably, the pressure relief valve on-site verification device includes a hose 7 ; the oil drain pipe 5 and the vacuum pump 6 are connected via the hose 7 .

[0042] Furthermore, in this embodiment, the hose 7 is a high-strength cross-linked polyethylene hose, which is convenient for connection with the oil drain pipe 5 and the vacuum pump 6 .

[0043] Preferably, the first end of the hose 7 is sleeved on the outlet of the oil drain pipe 5, and the vertical distance between the port cross section of the first end of the hose 7 and the outlet cross section of the oil drain pipe 5 is greater than or equal to 5 cm.

[0044] Further, if Figure 1 As shown, the inlet of the oil drain pipe 5 is connected to the oil drain port on the housing 2, the first end of the hose 7 is connected to the outlet of the oil drain pipe 5, and the second end of the hose 7 is connected to the vacuum pump 6. To ensure a secure connection between the hose 7 and the oil drain pipe 5, the vertical distance between the port cross-section of the first end of the hose 7 and the outlet cross-section of the oil drain pipe 5 is greater than or equal to 5 cm. It is understood that the overlap length of the connection between the hose 7 and the oil drain pipe 5 is greater than or equal to 5 cm.

[0045] Preferably, the pressure relief valve on-site verification device includes a locking clamp 9 ; the locking clamp 9 is arranged on the outer wall of the hose 7 , and the locking clamp 9 is used to clamp the hose 7 on the oil drain pipe 5 .

[0046] Furthermore, the locking hoop 9 is arranged within the overlapping length range of the connection between the hose 7 and the oil drain pipe 5 , and the locking hoop 9 is sleeved on the outside of the hose 7 to clamp the hose 7 on the oil drain pipe 5 .

[0047] Preferably, the pressure relief valve on-site verification device includes a sealing structure; the sealing structure is arranged between the inner wall of the hose 7 and the outer wall of the oil drain pipe 5.

[0048] Preferably, the sealing structure is a sealant.

[0049] Furthermore, in order to ensure the airtightness of the connection between the hose 7 and the oil drain pipe 5 , a sealant is provided at the connection between the hose 7 and the oil drain pipe 5 , and the sealant is provided between the inner wall of the hose 7 and the outer wall of the oil drain pipe 5 .

[0050] Furthermore, in this embodiment, the elastic member 3 is a spring.

[0051] This embodiment also introduces a pressure relief valve on-site calibration method, using the pressure relief valve on-site calibration device described above, the method comprising:

[0052] S100, checking the oil level of the oil conservator 10 of the transformer 1, and calculating a first pressure value of the oil in the oil conservator 10 of the transformer 1 acting on the membrane 4 through the first chamber;

[0053] S200, connecting the pressure relief valve and the pressure relief valve on-site verification device to communicate with the second chamber and the pressure relief valve on-site verification device;

[0054] S300, starting the pressure relief valve on-site verification device to evacuate the second chamber, and recording a second pressure value applied by the pressure relief valve on-site verification device to the pressure relief valve when the elastic member 3 starts to act;

[0055] S400 , summing the absolute value of the second pressure value and the first pressure value to obtain a third pressure value, and comparing the third pressure value with a design value of the pressure relief valve to determine whether the pressure relief valve is qualified.

[0056] Furthermore, an analysis of the forces acting on membrane 4 during the operation of elastic member 3 in this embodiment reveals that membrane 4 is subject to the upward pressure of the insulating oil from the first chamber, the suction pressure from the vacuum pump 6 from the second chamber, and the elastic force exerted on membrane 4 by elastic member 3. The sum of the pressure from the insulating oil in the first chamber and the suction pressure from the vacuum pump 6 from the second chamber balances the elastic force exerted on membrane 4 by elastic member 3. The pressure of the insulating oil in the first chamber represents a first pressure value. The oil level in oil conservator 10 can be used to calculate the oil volume in transformer 1. The first pressure value is calculated by combining the density of the insulating oil and the height difference between the insulating oil level in oil conservator 10 and the lower surface of membrane 4. The suction pressure from the vacuum pump 6 in the second chamber represents a second pressure value. This second pressure value is negative and can be directly read by pressure measuring device 8. The absolute value of the second pressure value is taken and added to the first pressure value to obtain the third pressure value.

[0057] Preferably, when the absolute value of the difference between the third pressure value and the design value of the pressure relief valve in step 400 is less than or equal to 5 kPa, the pressure relief valve is judged to be qualified.

[0058] The on-site calibration method for the pressure relief valve specifically includes the following steps:

[0059] Step 1: Check the oil level of the oil conservator 10 on the transformer 1, calculate the oil volume in the oil conservator 10 of the transformer 1 based on the oil level, and then calculate the pressure of the insulating oil from the first chamber on the membrane 4 based on the oil volume, the density of the insulating oil, and the vertical height between the insulating oil level in the oil conservator 10 and the lower surface of the membrane 4, i.e., the first pressure value;

[0060] Step 2: Install a negative pressure gauge on the oil drain pipe 5;

[0061] Step 3: Install the vacuum pump 6, which is connected to one end of the hose 7. The other end of the hose 7 wraps around the outlet of the oil drain pipe 5, and the length of the hose 7 wrapped around the oil drain pipe 5 is more than 5 cm.

[0062] Step 4: Use the locking clamp 9 to clamp the hose 7 and the oil drain pipe 5, and use sealant to block the gap between the hose 7 and the oil drain pipe 5;

[0063] Step 5: Turn on the vacuum pump 6 to evacuate the second chamber in the housing 2, and always pay attention to the data on the negative pressure gauge.

[0064] Step 6: When you hear the sound of the spring in the pressure relief valve moving, record the data on the negative pressure gauge;

[0065] Step 7: Obtain a second pressure value according to the reading of the negative pressure gauge in step 6. The second pressure value is a negative value. The third pressure value is obtained by summing the absolute values ​​of the first pressure value and the second pressure value in step 1. The third pressure value is used as the actual action value of the pressure relief valve.

[0066] Step 8: Compare the third pressure value in step 8 with the design value of the pressure relief valve. If the error between the third pressure value and the design value of the pressure relief valve is within ±5kPa, the pressure relief valve is considered qualified.

[0067] In the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The term "plurality" refers to two or more than two, unless otherwise clearly defined.

[0068] Other embodiments of the present invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as illustrative only.

[0069] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A pressure relief valve on-site calibration device, wherein the pressure relief valve is installed on a transformer, characterized in that: The pressure relief valve comprises: a housing, an elastic member and a film; The housing is connected to the transformer, and the housing has a chamber. One end of the elastic member is connected to the housing, and the other end of the elastic member is connected to the film. The edge of the film abuts against the inner wall of the chamber, and the film is used to divide the chamber into a first chamber and a second chamber that are independent of each other. The first chamber is in communication with the oil chamber of the transformer, and the second chamber is in communication with a pressure relief valve on-site verification device, wherein the pressure relief valve on-site verification device is used to evacuate the second chamber to move the elastic member and the film; The pressure relief valve on-site calibration device includes a pressure measuring device and a vacuum pump; The pressure relief valve includes an oil drain pipe, the oil drain pipe is communicated with the second chamber, the pressure measuring component is arranged on the oil drain pipe, and the vacuum pump is connected to the oil drain pipe.

2. A pressure relief valve on-site calibration device according to claim 1, characterized in that: The pressure measuring component is a negative pressure gauge.

3. The pressure relief valve on-site calibration device according to claim 1, characterized in that: The pressure relief valve on-site verification device includes a hose; The oil drain pipe and the vacuum pump are connected via the hose.

4. The pressure relief valve on-site calibration device according to claim 3, characterized in that: The first end of the hose is sleeved on the outlet of the oil drain pipe, and the vertical distance between the port cross section of the first end of the hose and the outlet cross section of the oil drain pipe is greater than or equal to 5 cm.

5. The pressure relief valve on-site calibration device according to claim 4, characterized in that: The pressure relief valve on-site verification device includes a locking clamp; The locking hoop is arranged on the outer wall of the hose, and is used to clamp the hose on the oil drain pipe.

6. The pressure relief valve on-site calibration device according to claim 4, characterized in that: The pressure relief valve on-site verification device includes a sealing structure; The sealing structure is arranged between the inner wall of the hose and the outer wall of the oil drain pipe.

7. The pressure relief valve on-site calibration device according to claim 6, characterized in that: The sealing structure is a sealant.

8. A method for on-site calibration of a pressure relief valve, using a device for on-site calibration of a pressure relief valve according to any one of claims 1 to 7, characterized in that: The method comprises: S100, checking the oil level of the oil tank of the transformer, and calculating a first pressure value of the oil in the oil tank of the transformer acting on the membrane through the first chamber; S200, connecting the pressure relief valve and the pressure relief valve on-site verification device to communicate with the second chamber and the pressure relief valve on-site verification device; S300, starting the pressure relief valve on-site verification device to evacuate the second chamber, and recording a second pressure value applied by the pressure relief valve on-site verification device to the pressure relief valve when the elastic member starts to act; S400 , summing the absolute value of the second pressure value and the first pressure value to obtain a third pressure value, and comparing the third pressure value with a design value of the pressure relief valve to determine whether the pressure relief valve is qualified.

9. A pressure relief valve on-site calibration method according to claim 8, characterized in that: When the absolute value of the difference between the third pressure value and the design value of the pressure relief valve in step 400 is less than or equal to 5 kPa, the pressure relief valve is judged to be qualified.

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