Sulfur hexafluoride density relay auxiliary check device and method

Abstract

The application provides a kind of sulfur hexafluoride density relay auxiliary checking device and method, the device includes: one end of shell body is communicated with gas tank, the other end is connected with sulfur hexafluoride density relay;Drive part drives telescopic bellows to do linear reciprocating motion relative to baffle through transmission part, and the first chamber part outside telescopic bellows when telescopic bellows is attached to baffle is configured as measurement cavity;Temperature and pressure sensing module is set in shell body, for monitoring the pressure data and temperature data of sulfur hexafluoride gas in measurement cavity;Control module is used to control drive part to work, to reduce the pressure in measurement cavity or increase the pressure in measurement cavity, and when receiving alarm node signal and lock node signal in pressure reducing process and pressure increasing process respectively, according to the pressure data and temperature data obtained, check sulfur hexafluoride density relay.The application can self-check alarm node and lock node without disassembling sulfur hexafluoride density relay.

Description

Technical Field

[0001] This application relates to the field of power equipment testing technology, and in particular to an auxiliary calibration device and method for a sulfur hexafluoride density relay. Background Technology

[0002] Sulfur hexafluoride (SF6) gas density relays are key components for protection and control in power systems, widely used in electrical equipment such as high-voltage circuit breakers. Their primary function is to monitor the gas density inside the equipment to ensure the circuit breaker operates safely and reliably under rated conditions. In power systems, circuit breaker failures can cause significant economic losses; therefore, ensuring the reliability of circuit breaker operation is of paramount importance. To ensure circuit breakers remain in good working order over the long term, relevant power industry standards clearly stipulate that various operating indicators of circuit breakers must be frequently monitored to ensure they consistently meet the specified technical requirements.

[0003] Meanwhile, the stability and reliability of the SF6 gas density relay, as a monitoring element, are equally crucial. If the SF6 gas density relay malfunctions or its monitoring data is inaccurate, it will directly lead to misjudgments of the circuit breaker's operating status, thus creating serious safety hazards. Therefore, in accordance with the requirements of power equipment maintenance regulations, the SF6 gas density relay must be calibrated regularly to ensure its measurement accuracy and operational precision, preventing relay malfunctions from affecting the normal operation of the entire protection system.

[0004] However, in practical engineering applications, SF6 gas density relays are typically installed on high-voltage, energized, or space-constrained equipment, and their installation environment is often unsuitable for frequent disassembly and calibration. Such frequent disassembly and calibration is not only complex and time-consuming, but it can also easily damage the equipment's sealing performance, increase the risk of gas leakage, reduce overall operational reliability, and result in significant maintenance costs and economic losses.

[0005] Therefore, it is necessary to provide an auxiliary calibration device and method for sulfur density relays to solve the above-mentioned problems existing in the prior art. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this application is to provide an auxiliary calibration device and method for sulfur density relays, which solves the technical problems in the prior art where frequent disassembly during relay calibration leads to complex procedures, long processing times, and easy damage to the sealing performance of the equipment.

[0007] To achieve the above and other related objectives, a first aspect of this application provides an auxiliary calibration device for a sulfur hexafluoride density relay, comprising: a housing, including a housing body and a partition, the partition being disposed inside the housing body and dividing the interior of the housing body into a first chamber and a second chamber along the length of the housing body; one end of the housing body is used to communicate with a gas tank, and the other end is used to connect to a sulfur hexafluoride density relay; an adjusting mechanism, including a drive unit, a transmission unit, and a telescopic bellows, the drive unit being connected to the transmission unit and located in the second chamber, the transmission unit being connected to the telescopic bellows and both the transmission unit and the telescopic bellows being located in the first chamber; the drive unit operates, driving the telescopic bellows relative to the... The partition moves linearly back and forth within the first chamber, and the portion of the first chamber outside the telescopic bellows when the telescopic bellows is attached to the partition forms a sealed measuring chamber. A temperature and pressure sensing module, located on the housing body, is used to monitor the pressure and temperature data of sulfur hexafluoride gas within the measuring chamber. A control module, connected to the drive unit, the temperature and pressure sensing module, and the sulfur hexafluoride density relay, is used to control the drive unit to reduce or increase the pressure within the measuring chamber. When receiving alarm and interlocking signals from the sulfur hexafluoride density relay during the depressurization and pressurization processes, respectively, the control module verifies the sulfur hexafluoride density relay based on the pressure and temperature data acquired from the temperature and pressure sensing module.

[0008] In some embodiments of the first aspect of this application, the transmission part includes an end cap and a movable member with internal threads, the end cap being connected to one end of the telescopic bellows, and the movable member being disposed on one side of the end cap and located inside the telescopic bellows.

[0009] In some embodiments of the first aspect of this application, the drive unit includes a drive shaft having an external thread adapted to the internal thread of the moving member, the drive shaft passing through the telescopic bellows and threadedly engaging with the moving member.

[0010] In some embodiments of the first aspect of this application, the adjustment mechanism further includes an end plate and two limiting blocks, the end plate being connected to the other end of the telescopic bellows, and the two limiting blocks being symmetrically arranged on opposite sides of the end plate and slidably connected to the inner wall of the housing body.

[0011] In some embodiments of the first aspect of this application, a sealing element is further included, wherein a sealing hole is provided on one side of the end plate near the partition, and the sealing element is disposed in the sealing hole.

[0012] In some embodiments of the first aspect of this application, one end of the housing body is provided with an air inlet for communicating with a gas tank; the other end of the housing body is provided with a connection port for connecting with a sulfur hexafluoride density relay.

[0013] To achieve the above and other related objectives, a second aspect of this application provides an auxiliary calibration method for a sulfur hexafluoride density relay, applied to the sulfur hexafluoride density relay auxiliary calibration device described above. The method includes: activating the drive unit of the adjustment mechanism to operate in a preset rotation direction; driving the telescopic bellows of the adjustment mechanism to move linearly along the direction towards the partition of the housing via the transmission unit of the adjustment mechanism until the other end of the telescopic bellows contacts the partition, thereby forming a sealed measuring chamber outside the telescopic bellows; continuing to drive the transmission unit to move the telescopic bellows linearly along the direction towards the partition to reduce the pressure inside the measuring chamber; receiving alarm node signals and interlocking node signals transmitted by the sulfur hexafluoride density relay during the pressure reduction process, and acquiring the corresponding temperature and pressure at the same time. The sensor module collects pressure and temperature data; the control drive unit stops working; the drive unit starts working in the opposite direction to the preset rotation direction, driving the telescopic bellows to move linearly away from the partition through the transmission unit to increase the pressure in the measuring chamber; the lockout node signal and alarm node signal transmitted by the sulfur hexafluoride density relay during the pressurization process are received respectively, and the pressure and temperature data collected by the temperature and pressure sensor module at the same time are acquired; the transmission unit continues to drive the telescopic bellows to continue moving linearly away from the partition until the other end of the telescopic bellows is away from the partition; the control drive unit stops working; the acquired pressure and temperature data during the depressurization and pressurization processes are processed, and the sulfur hexafluoride density relay is verified based on the data processing results.

[0014] In some embodiments of the second aspect of this application, the continuing drive transmission unit drives the telescopic bellows to move linearly along the direction toward the partition to reduce the pressure inside the measuring chamber. It receives alarm node signals and lockout node signals transmitted by the sulfur hexafluoride density relay during the pressure reduction process, and acquires pressure data and temperature data collected by the temperature and pressure sensing module at the same time. The specific process includes: the continuing drive transmission unit drives the telescopic bellows to continue moving linearly along the direction toward the partition, increasing the volume of the measuring chamber to reduce the pressure inside the measuring chamber until it drops to a preset pressure reduction alarm value, thereby triggering the alarm node action of the sulfur hexafluoride density relay; receiving the alarm node signal and lockout node signal transmitted by the sulfur hexafluoride density relay during the pressure reduction process. The sulfur density relay transmits an alarm node action signal, and upon receiving the alarm node action signal, it acquires the first alarm pressure data and the first alarm temperature data collected by the temperature and pressure sensing module at the same moment; then it continues to drive the transmission unit to drive the telescopic bellows to continue to move in a straight line along the direction towards the partition, so that the volume of the measuring chamber continues to increase, and its internal pressure continues to decrease to the preset pressure reduction lockout value, thereby triggering the lockout node action of the sulfur hexafluoride density relay; it receives the lockout node action signal transmitted by the sulfur hexafluoride density relay, and upon receiving the lockout node action signal, it acquires the first lockout pressure data and the first lockout temperature data collected by the temperature and pressure sensing module at the same moment.

[0015] In some embodiments of the second aspect of this application, the start-up drive unit operates in a direction opposite to a preset rotation direction, driving the telescopic bellows to move linearly away from the partition via a transmission unit, thereby increasing the pressure inside the measuring chamber. It receives the locking node signal and alarm node signal transmitted by the sulfur hexafluoride density relay during the pressurization process, and acquires the pressure data and temperature data collected by the temperature and pressure sensing module at the same time. The specific process includes: controlling the drive unit to operate in a direction opposite to a preset rotation direction, driving the telescopic bellows to move linearly away from the partition via a transmission unit, thereby reducing the volume of the measuring chamber and increasing its internal pressure to a preset pressurization locking value to trigger the sulfur hexafluoride... The sulfur hexafluoride density relay returns to its lockout node; it receives the lockout node return signal transmitted by the sulfur hexafluoride density relay, and at the same time, acquires the second lockout pressure data and the second lockout temperature data collected by the temperature and pressure sensing module; it continues to drive the transmission unit to drive the telescopic bellows to continue to move in a straight line away from the partition, so that the volume of the measuring chamber continues to decrease, and the internal pressure continues to rise to the preset pressure rise alarm value, thereby triggering the sulfur hexafluoride density relay alarm node return; it receives the alarm node return signal transmitted by the sulfur hexafluoride density relay, and at the same time, acquires the second alarm pressure data and the second alarm temperature data collected by the temperature and pressure sensing module.

[0016] In some embodiments of the second aspect of the present application, the specific process of performing data processing on the acquired pressure data and temperature data during the pressure reduction process and the pressure rise process, and calibrating the sulfur hexafluoride density relay according to the data processing result includes: calculating the pressure reduction alarm density value, the pressure reduction locking density value, the pressure rise locking density value, and the pressure rise alarm density value of sulfur hexafluoride gas based on the Beattie-Bridgman equation of state according to the acquired first alarm pressure data, first alarm temperature data, first locking pressure data, first locking temperature data, second locking pressure data, second locking temperature data, second alarm pressure data and second alarm temperature data respectively; calculating the corresponding pressure reduction alarm standard pressure value, pressure reduction locking standard pressure value, pressure rise locking standard pressure value and pressure rise alarm standard pressure value based on the Beattie-Bridgman equation of state according to the calculated pressure reduction alarm density value, pressure reduction locking density value, pressure rise locking density value and pressure rise alarm density value respectively; comparing the pressure reduction alarm standard pressure value and the pressure reduction locking standard pressure value in the pressure reduction process with the preset alarm value and the preset locking value of the sulfur hexafluoride density relay respectively to obtain an alarm error and a locking error; calculating an alarm switching difference according to the pressure rise alarm standard pressure value in the pressure rise process and the pressure reduction alarm standard pressure value in the pressure reduction process, and calculating a locking switching difference according to the pressure rise locking standard pressure value in the pressure rise process and the pressure reduction locking standard pressure value in the pressure reduction process; if all of the alarm error, the locking error, the alarm switching difference, and the locking switching difference are within the corresponding allowable error ranges, the sulfur hexafluoride density relay is calibrated as qualified; if any one of the alarm error, the locking error, the alarm switching difference, and the locking switching difference is not within the corresponding allowable error range, the calibration is unqualified.

[0017] As described above, the auxiliary calibration device and method for a sulfur hexafluoride density relay of the present application have the following beneficial effects:

[0018] By placing a partition inside the housing body and dividing the interior of the housing body into a first chamber and a second chamber along the length of the housing body, one end of the housing body is used to communicate with the gas tank, and the other end is used to connect to the sulfur hexafluoride density relay for auxiliary calibration of the sulfur hexafluoride density relay. At the same time, a transmission part and a telescopic bellows connected to each other are set in the first chamber, and a drive part connected to the transmission part is set in the second chamber. When the drive part is working, the transmission part drives the telescopic bellows to make linear reciprocating motion relative to the partition in the first chamber. When the telescopic bellows moves to fit the partition, the first chamber part outside the telescopic bellows at this time constitutes a sealed measuring chamber. Meanwhile, a temperature and pressure sensing module is also installed in the housing to monitor the pressure and temperature data of sulfur hexafluoride gas in the measuring chamber. A control module is also designed to control the operation of the drive unit to reduce or increase the pressure in the measuring chamber. When receiving alarm and lockout signals from the sulfur hexafluoride density relay during the depressurization and pressurization processes, respectively, the module verifies the quality of the sulfur hexafluoride density relay based on the pressure and temperature data transmitted by the temperature and pressure sensing module. This allows for self-verification of the alarm and lockout nodes without disassembling the sulfur hexafluoride density relay, improving equipment maintenance efficiency and ensuring the safe and stable operation of the power system. Attached Figure Description

[0019] Figure 1 The diagram shown is a structural schematic of an auxiliary calibration device for a sulfur hexafluoride density relay in one embodiment of this application.

[0020] Figure 2 The image shown is a top view of an auxiliary calibration device for a sulfur hexafluoride density relay in one embodiment of this application.

[0021] Figure 3 Displayed as Figure 2 A cross-sectional view along the AA direction.

[0022] Figure 4 The diagram shown is a scene diagram of an auxiliary calibration device for a sulfur hexafluoride density relay in one embodiment of this application.

[0023] Figure 5 The diagram shown is a flowchart illustrating an auxiliary verification method for a sulfur hexafluoride density relay in one embodiment of this application.

[0024] Figure 6 The diagram shown is a schematic of the data processing and verification process in the sulfur hexafluoride density relay auxiliary verification method in one embodiment of this application.

[0025] Component designation explanation

[0026] 1. Housing; 11. Housing body; 12. Partition; 13. Air inlet; 14. Connection port; 2. Adjustment mechanism; 21. Drive unit; 211. Drive shaft; 22. Transmission unit; 221. End cover; 222. Moving part; 23. Telescopic bellows; 24. End plate; 25. Limiting block; 3. Temperature and pressure sensing module; 4. Control module; 5. Sealing component. Detailed Implementation

[0027] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0028] In the embodiments of this application, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" do not necessarily imply that they are different.

[0029] It should be noted that, in the embodiments of this application, the words "exemplary" or "for example" indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0030] In this application embodiment, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0031] Before providing a further detailed description of the present invention, the nouns and terms used in the embodiments of the present invention are explained, and the nouns and terms used in the embodiments of the present invention are subject to the following interpretations:

[0032] <1> The Beattie-Bridgman equation of state, first proposed by J.A. Beattie and O.C. Bridgman in 1927, is an empirical equation describing the equilibrium state of real gases. This equation establishes the relationship between gas pressure, temperature and molar volume through thermal pressure, internal pressure correction terms and the assumption of molecular clustering. Its expression includes the gas constant R and empirical constants A and B determined by pVT experiments, and is applicable to a variety of gases.

[0033] To facilitate understanding of the embodiments of this application, in conjunction with Figures 1-4 Detailed description. The sulfur hexafluoride density relay auxiliary calibration device in this embodiment includes: a housing 1, an adjustment mechanism 2, a temperature and pressure sensing module 3, and a control module 4.

[0034] The housing 1 includes a housing body 11 and a partition 12. The partition 12 is disposed inside the housing body 11 and divides the interior of the housing body 11 into a first chamber and a second chamber along the length of the housing body 11. One end of the housing body 11 is used to communicate with the gas tank, and the other end is used to connect to a sulfur hexafluoride density relay. The adjustment mechanism 2 includes a drive unit 21, a transmission unit 22, and a telescopic bellows 23. The drive unit 21 is connected to the transmission unit 22 and is located in the second chamber. The transmission unit 22 is connected to the telescopic bellows 23 and both the transmission unit 22 and the telescopic bellows 23 are located in the first chamber. When the drive unit 21 operates, it drives the telescopic bellows 23 to make linear reciprocating motion relative to the partition 12 in the first chamber through the transmission unit 22, and the portion of the first chamber outside the telescopic bellows 23 when it is in contact with the partition 12 forms a sealed measuring chamber. A temperature and pressure sensing module 3 is disposed in the housing body 11 and is used to monitor the pressure and temperature data of the sulfur hexafluoride gas in the measuring chamber. The control module 4 is connected to the drive unit 21, the temperature and pressure sensing module 3, and the sulfur hexafluoride density relay. It is used to control the operation of the drive unit 21 to reduce or increase the pressure in the measuring chamber. When receiving the alarm node signal and the lockout node signal transmitted by the sulfur hexafluoride density relay during the pressure reduction and pressure increase processes, respectively, the control module 4 verifies the sulfur hexafluoride density relay based on the pressure data and temperature data transmitted by the temperature and pressure sensing module 3.

[0035] For example, the housing body 11 is cylindrical in shape, and the partition 12 is arranged along the circumference of the cylindrical housing body 11, thereby dividing its interior into a first chamber and a second chamber along the length of the housing body 11. At the same time, one end of the housing body 11 is connected to the gas tank, and the other end is connected to the sulfur hexafluoride density relay, which displays the gas tank pressure value.

[0036] A transmission unit 22 and a telescopic bellows 23 are connected to each other in the first chamber. A drive unit 21 connected to the transmission unit 22 is located in the second chamber. The transmission unit 22 converts the rotational motion of the drive unit 21 into linear motion, thereby driving the telescopic bellows 23 to move back and forth in a straight line in the first chamber along the direction toward or away from the partition 12. When it moves along the direction toward the partition 12 until it is in contact with the partition 12, the part of the first chamber outside the telescopic bellows 23 forms a sealed measuring chamber. By adjusting the pressure in the measuring chamber, the sulfur hexafluoride density relay is triggered to activate the alarm node and the lockout node during the pressure reduction and pressure increase processes. The sulfur hexafluoride density relay transmits the alarm node signal and the lockout node signal corresponding to the pressure reduction and pressure increase processes to the control module 4. The alarm node signal includes the alarm node action signal during the pressure reduction process and the alarm node return signal during the pressure increase process; the lockout node signal includes the lockout node action signal during the pressure reduction process and the lockout node return signal during the pressure increase process.

[0037] A temperature and pressure sensing module 3 is installed on the housing body 11 to monitor and measure pressure and temperature data within the measuring chamber. For example, the temperature and pressure sensing module 3 is a temperature and pressure sensor that integrates pressure and temperature data measurement and has a temperature correction function. Simultaneously, a control module 4 is designed to control the start and stop of the drive unit 21. When receiving alarm and lockout signals from the sulfur hexafluoride density relay during the depressurization and pressurization processes, respectively, it receives the pressure and temperature data collected by the temperature and pressure sensing module 3. Finally, it verifies the sulfur hexafluoride density relay's compliance based on the received pressure and temperature data. For example, the control module 4 is a designed control board installed inside the housing body 11. The pressure data includes the first alarm pressure data and the first lockout pressure data during the depressurization process, and the second lockout pressure data and the second alarm pressure data during the pressurization process. The temperature data includes the first alarm temperature data and the first lockout temperature data during the depressurization process, and the second lockout temperature data and the second alarm temperature data during the pressurization process.

[0038] In some embodiments of this application, such as Figure 2 and Figure 3 As shown, the transmission unit 22 includes an end cap 221 and a movable member 222 with internal threads. The end cap 221 is connected to one end of the telescopic bellows 23, and the movable member 222 is disposed on one side of the end cap 221 and located inside the telescopic bellows 23.

[0039] Specifically, the end cap 221 and the upper opening of the telescopic bellows 23 (upper and lower refer to...) Figure 3 The upper and lower circumferential edges are connected as shown, thereby closing the upper opening of the telescopic bellows 23. When the moving member 222 is driven to move back and forth in a straight line toward or away from the partition 12, for example, in Figure 3 In the placement direction shown, when the moving part 222 is driven to make a vertical linear motion, it drives the end cover 221 to make a synchronous vertical linear motion, and the end cover 221 drives the telescopic bellows 23 to make a synchronous vertical linear motion, thereby adjusting the volume of the measuring cavity.

[0040] In some embodiments of this application, such as Figure 1 and Figure 3 As shown, the drive unit 21 includes a drive shaft 211 having an external thread adapted to the internal thread of the moving member 222. The drive shaft 211 passes through the telescopic bellows 23 and is threadedly engaged with the moving member 222.

[0041] For example, the drive unit 21 is a miniature motor, and its drive shaft 211 is a screw adapted to the internal thread of the moving member 222. A receiving hole is provided in the middle of the partition plate 12 to accommodate the drive shaft 211, allowing the drive shaft 211 to pass through the receiving hole and into the telescopic bellows 23, where it is threadedly connected to the moving member 222, thus converting the rotational motion of the motor into linear motion. When the drive shaft 211 rotates, it drives the moving member 222 and the end cap 221 to move linearly towards or away from the partition plate 12 through the threaded engagement, thereby causing the telescopic bellows 23 to extend or retract, adjusting the internal volume of the measuring cavity.

[0042] In some embodiments of this application, such as Figure 1 and Figure 3 As shown, the adjustment mechanism 2 also includes an end plate 24 and two limiting blocks 25. The end plate 24 is connected to the other end of the telescopic bellows 23, and the two limiting blocks 25 are symmetrically arranged on opposite sides of the end plate 24 and slidably connected to the inner wall of the housing body 11.

[0043] Specifically, an end plate 24 is circumferentially provided on the outer wall of the lower opening of the telescopic bellows 23, and two limiting blocks 25 are provided on opposite sides of the end plate 24. For example, a guide rail is provided on the inner wall of the housing body 11, so that the limiting blocks 25 slide in the guide rail on the inner wall of the housing body 11, thereby restricting the circumferential rotation of the telescopic bellows 23 during linear motion and ensuring that it only makes linear reciprocating motion along the length direction of the housing body 11.

[0044] In some embodiments of this application, such as Figure 3 As shown, the sulfur hexafluoride density relay auxiliary calibration device also includes a sealing element 5. A sealing hole is provided on the side of the end plate 24 near the partition plate 12, and the sealing element 5 is disposed in the sealing hole.

[0045] Specifically, when the telescopic bellows 23 moves toward the partition 12 under the action of the moving part 222 and the end cap 221, and the end plate 24 is pressed against the partition 12, the sealing element 5 is pressed between the end plate 24 and the partition 12 to enhance the sealing performance of the measuring chamber and prevent sulfur hexafluoride gas from leaking from the mating surface of the end plate 24 and the partition 12. For example, the sealing element 4 is a sealing ring.

[0046] In some embodiments of this application, such as Figure 1 and Figure 3 As shown, one end of the housing body 11 has an air inlet 13 for connecting to a gas tank. The other end of the housing body 11 has a connection port 14 for connecting to a sulfur hexafluoride density relay.

[0047] Specifically, an air inlet 13 is designed to connect with the gas tank so that sulfur hexafluoride gas can enter the measuring chamber. Furthermore, a connection port 14 is designed to connect with the sulfur hexafluoride density relay, thus connecting the measuring chamber with the pressure-sensing chamber of the sulfur hexafluoride density relay to perform a calibration operation.

[0048] like Figure 3 and Figure 4 As shown, the sulfur hexafluoride density relay auxiliary calibration device provided in this embodiment of the application is connected to the sulfur hexafluoride density relay through connection port 14 to calibrate it. Simultaneously, the sulfur hexafluoride density relay auxiliary calibration device also has a remote transmission function. Connected to the terminal equipment, it can not only record the calibration data of the alarm node signals and interlocking node signals transmitted by the sulfur hexafluoride density relay, as well as the pressure data and temperature data transmitted in real time by the temperature and pressure sensing module 3, but also transmit the data processing results obtained by the control module 4 based on the pressure and temperature data acquired during the pressure reduction and pressure increase processes, along with the original data, to the terminal equipment backend. Furthermore, it can remotely control the self-calibration time and frequency.

[0049] The sulfur hexafluoride density relay auxiliary calibration device provided in this application verifies whether the alarm and lockout nodes of the meter have drifted by monitoring the internal alarm and lockout node signals of the SF6 density relay without disassembling the SF6 density relay. It supports self-calibration of the SF6 density relay's alarm and lockout nodes, thus solving the problem that traditional density relays lack self-calibration functionality. Furthermore, it is compatible with almost all SF6 density relays on the market, even those without remote transmission capabilities. In addition, the sulfur hexafluoride density relay auxiliary calibration device provided in this application has a simple structure and manufacturing process, low production cost, and good conditions for mass production.

[0050] Figure 5 This is a schematic flowchart of the auxiliary verification method for sulfur hexafluoride density relays provided in the embodiments of this application. Figures 1-5As shown, the auxiliary calibration method for sulfur hexafluoride density relays is applied to the sulfur hexafluoride density relay auxiliary calibration device described above. The method includes the following steps:

[0051] Step S11: Start the drive unit 21 of the adjustment mechanism 2 to work in the preset rotation direction. The transmission unit 22 of the adjustment mechanism 2 drives the telescopic bellows 23 of the adjustment mechanism 2 to move in a straight line along the direction toward the partition 12 of the housing 1 until the other end of the telescopic bellows 23 is attached to the partition 12, so as to form the first chamber part outside the telescopic bellows 23 into a sealed measuring chamber.

[0052] Before step S11, the sulfur hexafluoride density relay auxiliary calibration device is connected to the gas tank to be measured through the air inlet 13, and the sulfur hexafluoride density relay auxiliary calibration device is connected to the sulfur hexafluoride density relay through the connection port 14. When turned on, the internal air path of the sulfur hexafluoride density relay auxiliary calibration device is unobstructed, and the sulfur hexafluoride density relay displays the gas tank pressure value. Simultaneously, the control module 4 is connected to the terminal device to transmit data.

[0053] Specifically, when the self-calibration function is activated, the drive shaft 211 of the drive unit 21 rotates in a preset rotation direction. The rotational motion of the drive shaft 211 is converted into linear motion through the internal thread engagement of the moving part 222, which drives the end cover 221, the telescopic bellows 23, and the end plate 24 to make a downward linear motion in the direction toward the partition 12. Figure 3 (as shown in the lifting direction) until the end plate 24 is in contact with the partition 12. At this time, the sealing ring is pressed between the end plate 24 and the partition 12, thereby forming the first chamber part outside the telescopic bellows 23 into a sealed measuring chamber. At this time, the gas path between the sulfur hexafluoride density relay auxiliary calibration device and the gas tank is disconnected.

[0054] Step S12: Continue to drive the transmission unit 22 to drive the telescopic bellows 23 to move in a straight line towards the partition 12 to reduce the pressure in the measuring chamber. Receive the alarm node signal and the lockout node signal transmitted by the sulfur hexafluoride density relay during the pressure reduction process, and acquire the pressure data and temperature data collected by the temperature and pressure sensing module 3 at the same time.

[0055] In some embodiments of this application, the continuing drive transmission unit 22 drives the telescopic bellows 23 to move linearly along the direction toward the partition 12 to reduce the pressure inside the measuring chamber. It receives alarm node signals and lockout node signals transmitted by the sulfur hexafluoride density relay during the pressure reduction process, and acquires pressure data and temperature data collected by the temperature and pressure sensing module 3 at the same time. The specific process includes: the continuing drive transmission unit 22 drives the telescopic bellows 23 to continue moving linearly along the direction toward the partition 12, increasing the volume of the measuring chamber to reduce the pressure inside the measuring chamber until it drops to a preset pressure reduction alarm value, thereby triggering the alarm node action of the sulfur hexafluoride density relay; receiving the alarm node signal and lockout node signal transmitted by the sulfur hexafluoride density relay during the pressure reduction process. The sulfur density relay transmits an alarm node action signal, and upon receiving the alarm node action signal, it acquires the first alarm pressure data and the first alarm temperature data collected by the temperature and pressure sensing module 3 at the same time; then it continues to drive the transmission unit 22 to drive the telescopic bellows 23 to continue to move in a straight line along the direction towards the partition 12, so that the volume of the measuring cavity continues to increase, and the internal pressure continues to decrease to the preset pressure reduction lockout value, thereby triggering the lockout node action of the sulfur hexafluoride density relay; it receives the lockout node action signal transmitted by the sulfur hexafluoride density relay, and upon receiving the lockout node action signal, it acquires the first lockout pressure data and the first lockout temperature data collected by the temperature and pressure sensing module 3 at the same time.

[0056] Specifically, during the pressure reduction process, the drive shaft 211 of the drive unit 21 continues to rotate, driving the moving part 222 to move the end cover 221 and the telescopic bellows 23 in a downward linear motion, thereby increasing the internal volume of the measuring chamber and reducing the internal pressure of the measuring chamber. The pressure drops sequentially to the preset pressure reduction alarm value and pressure reduction lockout value, thereby triggering the alarm node action and the lockout node action in succession. As a result, when the control module 4 receives the alarm node action signal and the lockout node action signal respectively, it acquires the first alarm pressure data, the first alarm temperature data, the first lockout pressure data, and the first lockout temperature data of the sulfur hexafluoride gas in the measuring chamber at the same time.

[0057] It should be noted that the volume of the measuring cavity when the telescopic bellows 23 and the partition 12 are just sealed is... Its corresponding pressure is When the telescopic bellows 23 is compressed to the preset pressure drop alarm value, the volume of the measuring chamber is... Its corresponding pressure is When the telescopic bellows 23 is further compressed until it is locked, the volume of the measuring cavity is Its corresponding pressure is When the ambient temperature is constant, the following formula is given according to the ideal gas equation:

[0058] ;Formula (1)

[0059] Therefore, according to formula (1), the internal pressure of the measuring cavity is changed by the expansion and contraction bellows 23, thereby measuring the pressure values ​​of the alarm and locking nodes.

[0060] Step S13: Control drive unit 21 to stop working.

[0061] Step S14: Start the drive unit 21 to work in the opposite direction to the preset rotation direction. Drive the telescopic bellows 23 to move in a straight line away from the partition 12 through the transmission unit 22 to increase the pressure in the measuring chamber. Receive the lockout node signal and alarm node signal transmitted by the sulfur hexafluoride density relay during the pressurization process, and acquire the pressure data and temperature data collected by the temperature and pressure sensing module at the same time.

[0062] In some embodiments of this application, the start-up drive unit 21 operates in the opposite direction to the preset rotation direction, driving the telescopic bellows 23 to move linearly away from the partition 12 via the transmission unit 22, thereby increasing the pressure inside the measuring chamber. It receives the lockout node signal and alarm node signal transmitted by the sulfur hexafluoride density relay during the pressurization process, and acquires the pressure data and temperature data collected by the temperature and pressure sensing module 3 at the same time. Specifically, the process includes: controlling the drive unit 21 to operate in the opposite direction to the preset rotation direction, driving the telescopic bellows 23 to move linearly away from the partition 12 via the transmission unit 22, thereby reducing the volume of the measuring chamber and increasing its internal pressure to the preset pressurization lockout value to trigger... The sulfur hexafluoride density relay returns to the lockout node; it receives the lockout node return signal transmitted by the sulfur hexafluoride density relay, and at the same time as receiving the lockout node return signal, it acquires the second lockout pressure data and the second lockout temperature data collected by the temperature and pressure sensing module 3; it continues to drive the transmission unit 22 to drive the telescopic bellows 23 to continue to move in a straight line in the direction away from the partition 12, so that the volume of the measuring cavity continues to decrease, and the internal pressure continues to rise to the preset pressure rise alarm value, thereby triggering the sulfur hexafluoride density relay alarm node return; it receives the alarm node return signal transmitted by the sulfur hexafluoride density relay, and at the same time as receiving the alarm node return signal, it acquires the second alarm pressure data and the second alarm temperature data collected by the temperature and pressure sensing module 3.

[0063] Specifically, during the pressurization process, the drive shaft 211 rotates in the opposite direction to the preset rotation direction. The moving part 222 drives the end cover 221 and the telescopic bellows 23 to move slowly upward in a straight line away from the partition 12, thereby reducing the internal volume of the measuring chamber and causing the internal pressure of the measuring chamber to rise. The pressure rises sequentially to the preset pressurization lockout value and pressurization alarm value, thereby triggering the lockout node return and alarm node return in succession. Thus, when the control module 4 receives the lockout node return signal and the alarm node return signal respectively, it acquires the second lockout pressure data, the second lockout temperature data, the second alarm pressure data, and the second alarm temperature data of the sulfur hexafluoride gas in the measuring chamber at the same time.

[0064] Step S15: Continue to drive the transmission unit 22 to drive the telescopic bellows 23 to continue to move in a straight line in the direction away from the partition 12 until the other end of the telescopic bellows 23 is away from the partition 12.

[0065] Specifically, the system stops working when the end plate 24 located at the other end of the telescopic bellows 23 disengages from the sealing ring.

[0066] Step S16: Control drive unit 21 to stop working.

[0067] Step S17: Process the pressure and temperature data obtained during the pressure reduction and pressure increase processes, and verify the sulfur hexafluoride density relay based on the data processing results.

[0068] In some embodiments of this application, such as Figure 6As shown, the process of processing the pressure and temperature data acquired during the pressure reduction and pressure increase processes, and verifying the sulfur hexafluoride density relay based on the data processing results, specifically includes: calculating the pressure reduction alarm density value, pressure reduction lockout density value, pressure increase lockout density value, and pressure increase alarm density value of sulfur hexafluoride gas based on the acquired first alarm pressure data, first alarm temperature data, first lockout pressure data, first lockout temperature data, second lockout pressure data, second lockout temperature data, second alarm pressure data, and second alarm temperature data, respectively; and calculating the corresponding pressure reduction alarm standard pressure value and pressure reduction lockout value based on the calculated pressure reduction alarm density value, pressure reduction lockout density value, pressure increase lockout density value, and pressure increase alarm density value, respectively, using the Betty-Bridgeman equation of state. The standard pressure value, the pressure increase lockout standard pressure value, and the pressure increase alarm standard pressure value are calculated. The pressure decrease alarm standard pressure value and the pressure decrease lockout standard pressure value during the pressure decrease process are compared with the preset alarm value and preset lockout value of the sulfur hexafluoride density relay to obtain the alarm error and lockout error. The alarm switching difference is calculated based on the pressure increase alarm standard pressure value and the pressure decrease alarm standard pressure value during the pressure decrease process, and the lockout switching difference is calculated based on the pressure increase lockout standard pressure value and the pressure decrease lockout standard pressure value during the pressure decrease process. If the alarm error, lockout error, alarm switching difference, and lockout switching difference are all within their respective allowable error ranges, the sulfur hexafluoride density relay is verified as qualified. If any one of these values ​​is not within its corresponding allowable error range, the verification is unqualified.

[0069] Specifically, the specific formula for the Betty-Bridgeman equation of state is as follows:

[0070] ;Formula (2)

[0071] in, ; ; ; Pressure is expressed in units of 1 / 2 t. ; Density, its unit is ; Temperature, its unit is .

[0072] During the pressure reduction process, the control module 4 first acquires the first alarm pressure data and the first alarm temperature data when the alarm node is activated, and calculates the pressure reduction alarm density value when the alarm node is activated according to formula (2). Then, the control module 4 acquires the first locking pressure data and the first locking temperature data when the locking node is activated. Similarly, it calculates the pressure reduction locking density value when the locking node is activated according to formula (2). .

[0073] During the pressure rise process, the control module 4 first obtains the second blocking pressure data and the second blocking temperature data when the blocking node returns, and calculates the pressure rise blocking density value when the blocking node returns according to formula (2) ; then, the control module 4 obtains the second alarm pressure data and the second alarm temperature data when the alarm node returns, and substitutes them into formula (2) to calculate the pressure rise alarm density value when the alarm node returns .

[0074] Then, the pressure reduction alarm density value , the pressure reduction blocking density value , the pressure rise blocking density value and the pressure rise alarm density value are respectively substituted into formula (2) for conversion to obtain the corresponding standard pressure value at 20°C, which are respectively the pressure reduction alarm standard pressure value, the pressure reduction blocking standard pressure value, the pressure rise blocking standard pressure value and the pressure rise alarm standard pressure value. It should be understood that the standard pressure value at 20°C ( [[ID=21) refers to the equivalent pressure value of sulfur hexafluoride gas at 20°C, which is calculated according to the measured pressure value and measured temperature value of the sulfur hexafluoride gas, under the condition that the density of the sulfur hexafluoride gas remains unchanged, by using the preset sulfur hexafluoride gas state equation (formula (2)).

[0075] Finally, the alarm error and blocking error in the pressure reduction process are calculated, as well as the alarm switching difference and blocking switching difference between pressure rise and pressure reduction. The calculated alarm error, blocking error, alarm switching difference and blocking switching difference are respectively compared with the corresponding allowable error ranges. If all of them are within the corresponding allowable error ranges, the sulfur hexafluoride density relay is verified to be qualified; if any one of the alarm error, blocking error, alarm switching difference and blocking switching difference is not within the corresponding allowable error range, the verification is unqualified, so that the verification of the sulfur hexafluoride density relay can be realized without replacing the sulfur hexafluoride density relay. Of course, the processed standard pressure value at 20°C can also be transmitted to the background for verification through the control module 4.

[0076] It should be noted that the preset pressure reduction alarm value, preset pressure reduction blocking value, preset pressure rise blocking value, preset pressure rise alarm value, preset alarm value, preset blocking value, preset rotation direction and each allowable error range in the embodiments of the present application shall be determined according to actual conditions, and the present application does not make specific limitations on this.

[0077] In summary, addressing the technical problems of frequent disassembly during relay calibration in existing technologies, which leads to complex processes, long processing times, and potential damage to the sealing performance of the equipment, this application provides an auxiliary calibration device and method for sulfur hexafluoride (SF6) density relays. This method involves placing a partition inside the housing body, dividing the interior of the housing body into a first chamber and a second chamber along its length. One end of the housing body is connected to a gas tank, and the other end is connected to the SF6 density relay for auxiliary calibration. A transmission unit and a telescopic bellows are connected to the first chamber, and a drive unit connected to the transmission unit is located in the second chamber. When the drive unit operates, the transmission unit drives the telescopic bellows to reciprocate linearly relative to the partition within the first chamber. When the telescopic bellows moves to contact the partition, the portion of the first chamber outside the bellows forms a sealed measuring chamber. Additionally, a temperature and pressure sensing module is installed within the housing body. This device monitors the pressure and temperature data of sulfur hexafluoride (SF6) gas within a measuring chamber. A control module is also designed to control the drive unit, adjusting the pressure within the measuring chamber to either decrease or increase it. Upon receiving alarm and interlock signals from the SF6 density relay during the depressurization and pressurization processes, the module verifies the relay's compliance based on the pressure and temperature data acquired from the temperature and pressure sensing module. This allows for self-verification of the alarm and interlock signals without disassembling the relay, improving equipment maintenance efficiency and ensuring the safe and stable operation of the power system. This application monitors the density of SF6 gas in a sealed container, displaying the gas density on-site and triggering an alarm when the density reaches a set value. It is suitable for high-voltage system detection. SF6 gas density relays are widely used in power, metallurgy, petrochemical, coal mining, electrified railways, and public utilities industries, and have been applied in numerous national key projects. Therefore, this application effectively overcomes the shortcomings of existing technologies and possesses high industrial application value.

[0078] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. An auxiliary calibration device for a sulfur hexafluoride density relay, characterized in that, include: The housing includes a housing body and a partition, the partition being disposed inside the housing body and dividing the interior of the housing body into a first chamber and a second chamber along the length of the housing body; one end of the housing body is used to communicate with a gas tank, and the other end is used to connect to a sulfur hexafluoride density relay; The adjustment mechanism includes a drive unit, a transmission unit, and a telescopic bellows. The drive unit is connected to the transmission unit and is located in the second chamber. The transmission unit is connected to the telescopic bellows and both the transmission unit and the telescopic bellows are located in the first chamber. When the drive unit operates, it drives the telescopic bellows to make a linear reciprocating motion relative to the partition within the first chamber through the transmission unit, and forms a sealed measuring chamber by the portion of the first chamber outside the telescopic bellows when the telescopic bellows is in contact with the partition. A temperature and pressure sensing module is installed in the housing body and is used to monitor the pressure and temperature data of sulfur hexafluoride gas in the measuring chamber. The control module, connected to the drive unit, the temperature and pressure sensing module, and the sulfur hexafluoride density relay, is used to control the operation of the drive unit to reduce or increase the pressure inside the measuring chamber. When receiving alarm node signals and lockout node signals transmitted by the sulfur hexafluoride density relay during the pressure reduction and pressure increase processes, respectively, the control module verifies the sulfur hexafluoride density relay based on the pressure data and temperature data transmitted by the temperature and pressure sensing module.

2. The auxiliary calibration device for the sulfur hexafluoride density relay according to claim 1, characterized in that, The transmission part includes an end cap and a movable member with internal threads. The end cap is connected to one end of the telescopic bellows, and the movable member is disposed on one side of the end cap and located inside the telescopic bellows.

3. The auxiliary calibration device for the sulfur hexafluoride density relay according to claim 2, characterized in that, The drive unit includes a drive shaft having an external thread adapted to the internal thread of the moving part, the drive shaft passing through the telescopic bellows and threadedly engaging with the moving part.

4. The auxiliary calibration device for the sulfur hexafluoride density relay according to claim 1, characterized in that, The adjustment mechanism also includes an end plate and two limiting blocks. The end plate is connected to the other end of the telescopic bellows, and the two limiting blocks are symmetrically arranged on opposite sides of the end plate and slidably connected to the inner wall of the housing body.

5. The auxiliary calibration device for the sulfur hexafluoride density relay according to claim 4, characterized in that, It also includes a sealing element, wherein a sealing hole is provided on one side of the end plate near the partition, and the sealing element is disposed in the sealing hole.

6. The auxiliary calibration device for the sulfur hexafluoride density relay according to claim 1, characterized in that, One end of the housing body has an air inlet for connecting to a gas tank; the other end of the housing body has a connection port for connecting to a sulfur hexafluoride density relay.

7. An auxiliary calibration method for a sulfur hexafluoride density relay, characterized in that, The method, applied to the auxiliary calibration device for the sulfur hexafluoride density relay as described in any one of claims 1 to 6, comprises: The drive unit of the adjustment mechanism operates in a preset rotation direction. The transmission unit of the adjustment mechanism drives the telescopic bellows of the adjustment mechanism to move in a straight line along the direction towards the partition of the housing until the other end of the telescopic bellows is attached to the partition, so as to form a sealed measuring chamber in the first chamber part outside the telescopic bellows. The drive unit continues to drive the telescopic bellows to move in a straight line towards the partition to reduce the pressure in the measuring chamber. It receives the alarm node signal and the lockout node signal transmitted by the sulfur hexafluoride density relay during the pressure reduction process, and obtains the pressure data and temperature data collected by the temperature and pressure sensing module at the same time. The control drive unit has stopped working; The start-up drive unit operates in the opposite direction to the preset rotation direction. Through the transmission unit, it drives the telescopic bellows to move in a straight line away from the partition to increase the pressure in the measuring chamber. It receives the lockout node signal and alarm node signal transmitted by the sulfur hexafluoride density relay during the pressurization process, and acquires the pressure data and temperature data collected by the temperature and pressure sensing module at the same time. Continue driving the transmission unit to move the telescopic bellows in a straight line away from the partition until the other end of the telescopic bellows is away from the partition. The control drive unit has stopped working; The pressure and temperature data obtained during the pressure reduction and pressure increase processes are processed, and the sulfur hexafluoride density relay is verified based on the data processing results.

8. The auxiliary calibration method for sulfur hexafluoride density relays according to claim 7, characterized in that, The continuing drive transmission unit drives the telescopic bellows to move linearly along the direction towards the partition to reduce the pressure inside the measuring chamber. It receives alarm and interlock signals from the sulfur hexafluoride density relay during the pressure reduction process and acquires pressure and temperature data collected by the temperature and pressure sensing module at the same time. The specific process includes: The drive unit continues to drive the telescopic bellows to continue to move in a straight line towards the partition, which increases the volume of the measuring chamber to reduce the pressure inside the measuring chamber until it drops to the preset pressure reduction alarm value, thereby triggering the alarm node of the sulfur hexafluoride density relay. Receive the alarm node action signal transmitted by the sulfur hexafluoride density relay, and when the alarm node action signal is received, acquire the first alarm pressure data and the first alarm temperature data collected by the temperature and pressure sensing module at the same time. The drive unit continues to drive the telescopic bellows to continue to move in a straight line towards the partition, so that the volume of the measuring chamber continues to increase and the internal pressure continues to decrease to the preset pressure reduction lockout value, thereby triggering the locking node action of the sulfur hexafluoride density relay. It receives the locking node action signal transmitted by the sulfur hexafluoride density relay, and at the same time as receiving the locking node action signal, it acquires the first locking pressure data and the first locking temperature data collected by the temperature and pressure sensing module.

9. The auxiliary verification method for sulfur hexafluoride density relays according to claim 8, characterized in that, The start-up drive unit operates in the opposite direction to the preset rotation direction. Through the transmission unit, it drives the telescopic bellows to move linearly away from the partition, increasing the pressure inside the measuring chamber. It receives the interlocking and alarm signals transmitted by the sulfur hexafluoride density relay during the pressurization process, and acquires the pressure and temperature data collected by the temperature and pressure sensing module at the same time. The specific process includes: The control drive unit operates in the opposite direction to the preset rotation direction. Through the transmission unit, it drives the telescopic bellows to move in a straight line away from the partition, which reduces the volume of the measuring chamber and increases the internal pressure to the preset pressure increase lockout value, thereby triggering the sulfur hexafluoride density relay lockout node to return. Receive the lockout node return signal transmitted by the sulfur hexafluoride density relay, and when the lockout node return signal is received, acquire the second lockout pressure data and the second lockout temperature data collected by the temperature and pressure sensing module at the same time. The drive unit continues to drive the telescopic bellows to continue to move in a straight line away from the partition, so that the volume of the measuring chamber continues to decrease and the internal pressure continues to rise to the preset pressure alarm value, thereby triggering the sulfur hexafluoride density relay alarm node to return. Receive the alarm node return signal transmitted by the sulfur hexafluoride density relay, and when the alarm node return signal is received, acquire the second alarm pressure data and the second alarm temperature data collected by the temperature and pressure sensing module at the same time.

10. The auxiliary verification method for sulfur hexafluoride density relay according to claim 9, characterized in that, The process of processing the pressure and temperature data acquired during the depressurization and pressurization processes, and then verifying the sulfur hexafluoride density relay based on the data processing results, specifically includes: Based on the Bertie-Bridgeman equation of state, the pressure reduction alarm density value, pressure reduction lockout density value, pressure increase lockout density value, and pressure increase alarm density value of sulfur hexafluoride gas are calculated according to the first alarm pressure data, first alarm temperature data, first lockout pressure data, first lockout temperature data, second lockout pressure data, second lockout temperature data, second alarm pressure data, and second alarm temperature data, respectively. Based on the calculated pressure reduction alarm density value, pressure reduction lockout density value, pressure increase lockout density value, and pressure increase alarm density value, the corresponding pressure reduction alarm standard pressure value, pressure reduction lockout standard pressure value, pressure increase lockout standard pressure value, and pressure increase alarm standard pressure value are calculated according to the Betty-Bridgeman state equation. The standard pressure values ​​for pressure reduction alarm and pressure reduction lockout during the pressure reduction process are compared with the preset alarm and preset lockout values ​​of the sulfur hexafluoride density relay to obtain the alarm error and lockout error. The alarm switching difference is calculated based on the standard pressure values ​​of the pressure increase alarm during the pressure increase process and the standard pressure values ​​of the pressure decrease alarm during the pressure decrease process. The interlocking switching difference is calculated based on the standard pressure values ​​of the pressure increase interlocking during the pressure increase process and the standard pressure values ​​of the pressure decrease interlocking during the pressure decrease process. If the alarm error, interlocking error, alarm switching difference, and interlocking switching difference are all within their respective allowable error ranges, the sulfur hexafluoride density relay is qualified; if any one of these factors is not within its corresponding allowable error range, the verification is unqualified.

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