Maintenance project of SF6 gas detection alarm device (including probe) in main substation of Line 1, 2 and 3 of Xi 'an Metro Operation Branch in 2019

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Maintenance project of SF6 gas detection alarm dev

1. Project name: Maintenance project of SF6 gas detection alarm device (including probe) in main substation of Line 1, 2 and 3 of Xi 'an Metro Operation Branch in 2019

2. Project application basis

GB26860-2011 "Electric Power Safety work Regulations"

DLT 639-1997 "SF6 Electrical Equipment Operation, testing and maintenance personnel safety protection rules"

GB/T8905-2012 SF6 Guidelines for Gas Management and Detection in Electrical Equipment

DL/T 595-2016 SF6 Guidelines for Gas Supervision of Electrical Equipment

DL/T1555-2016 "SF6 Gas Leakage Online Monitoring Alarm Device Operation and maintenance Guidelines"

JBT 10893-2008 "SF6 Environmental Monitoring System for High Voltage Combined Electrical Distribution Room"

Eighteen major anti-accident measures of the State Grid Corporation

SF6 gas is widely used in medium and high pressure equipment, and its safety has been widely concerned by people. SF6 gas is heavier than air, and tends to gather in the low area after leakage, which is easy to cause hypoxia in the lower space. In addition, SF6 gas generates harmful and toxic gas after high-temperature reaction in the insulator and metal substance inside the electrical equipment. Once the leak is a great threat to the atmospheric environment and personal safety, Therefore, in the "DLT 639-1997 SF6 electrical equipment operation, test and maintenance personnel safety protection Rules" chapter 4 requirements and "JBT 10893-2008 high-voltage combination electrical distribution room SF6 environmental monitoring system", "18 major anti-accident measures of the State Grid Company" requirements. An oxygen meter and an SF6 concentration alarm meter should be installed in the SF6 distribution device area to ensure the safety of on-site workers.

SF6 Safety Regulations Excerpt:

Article 191 Power distribution rooms and SF6 gas laboratories equipped with SF6 equipment must be equipped with powerful ventilation devices. The tuyere should be set in the lower part of the room;

Article 192 In the room, when the equipment is filled with SF6 gas, the relative humidity of the surrounding environment is 80%, and the ventilation system must be turned on to avoid SF6 gas leakage in the working area. The SF6 gas content in the working area air shall not exceed 1000ppm;

Article 196 When entering the SF6 distribution unit room, the staff must first ventilate for 15min, and measure the SF6 gas content with a leak detector. Try to avoid one person entering the SF6 distribution unit room for inspection, and no one is allowed to enter the maintenance work;

Article 198 Staff entering the SF6 distribution unit room low area or cable trench to work should first test the oxygen content (not less than 18%) and SF6 gas content is qualified;

Article 199 The oxygen meter and the SF6 gas leakage alarm meter shall be installed in the low area of the SF6 power distribution unit room. These instruments should be tested regularly to ensure good condition;

Article 203 In the event of an emergency, all ventilation systems shall be opened immediately for ventilation. In case of rupture of the equipment's anti-explosion film, it should be treated with power failure and wiped clean with gasoline or acetone.

3. Project overview

This project mainly conducts maintenance and functional testing of SF6 gas detection and alarm devices in four main substations in the first and second lines, tests the functions of SF6 gas detection and alarm devices in line 3, and verifies the accuracy of the functions. It can restore SF6 concentration status, oxygen concentration, timed ventilation, SF6 concentration and oxygen abnormal automatic ventilation, forced ventilation, voice function, flute sound and sound and light alarm warning in each monitoring unit in the real-time monitoring switch (GIS) room.

Xi 'an Metro Line 1 Jinhua Main substation, Line 1 Huancheng Xiyuan main substation, Line 2 Administration Center main substation, Line 2 Exhibition Center main substation, Line 3 Bowen Road main substation, Line 3 Wuzhuang main substation SF6 gas detection and alarm device produced by a company in Jiangsu and Zhejiang Province failed for a long time after installation and use. The SF6 gas leakage concentration and oxygen concentration in the environment cannot be detected normally, the host of the SF6 monitoring device cannot display the uploaded data of each monitoring unit normally, and some functions cannot operate normally. The monitoring unit of the GIS switch room fails, affecting the personal safety of personnel and the operation of GIS electrical equipment, and there is a hidden security problem to a certain extent.

From November 27, 2019 to December 4, 2019, Weavers detection technology installation service personnel replaced the entire set of SF6 detection and alarm devices at the Jinhua Main transformer station of Metro Line 1, the Huancheng Xiyuan Main Transformer Station of Metro Line 1, the main transformer station of Administrative Center of Metro Line 2, and the main transformer station of Convention and Exhibition Center of Metro Line 2. The maintenance project includes the removal of the original set of old SF6 detection and alarm devices at the above 4 stations, the replacement of the 4 stations with 4 newly purchased SF6 monitoring hosts, 28 SF6 and oxygen monitoring units, 4 temperature and humidity monitoring units, and the laying and installation of related communication transmission cables and power cables. At the same time, the SF6 gas detection and alarm devices of each station were powered on for functional testing. Standard 1000PPm SF6 gas and standard 18% oxygen were used to test SF6 and oxygen monitoring units at each station. After testing, all functions comply with DL/T1555-2016 "SF6 Gas Leakage Online Monitoring Alarm Device Operation and Maintenance Guidelines", Line 3 Bowen Road main substation (replace the host of SF6 monitoring system) and verify each monitoring unit.

4. Maintenance of SF6 gas detection and alarm device for Line 1 and 2:

The SF6 gas detection and alarm devices of Jinhua Main substation, Xiyuan main substation, Administration Center main substation and Convention Center main transformer station have achieved the following functions after maintenance and replacement:

1. SF6 gas detection alarm device monitors the functions of the host with flexible touch operation and clear interface display;

2. SF6 gas detection and alarm device monitoring to realize the SF6 gas detection and alarm device monitoring host interface information normal display; It can dynamically display the SF6 concentration content status of each monitoring unit in each switch (GIS) room in real time. When the SF6 gas concentration exceeds 1000PPm (the national standard value is 1000PPm, the alarm threshold can be set by the user), the monitoring system can automatically issue an audible and visual alarm and start the GIS fan at the same time. When the SF6 monitoring host is set to the alarm threshold of 1000PPm, when the SF6 gas detection reaches the set threshold, the SF6 concentration status display bar displays the monitored concentration value with red warning font; Below 1000PPm, the SF6 concentration value monitored is displayed in green font;

3. When the oxygen content is below 18.0% (national standard value 18.0%, the user can set it by himself), the oxygen content of the monitoring unit is displayed in red font (such as 17.5%), the monitoring system can automatically issue a sound and light alarm and start the GIS fan at the same time, and the actual value is displayed in green (such as 20.5%);

4. SF6 gas detection and alarm device monitoring and measuring host can normally display the temperature and humidity monitored by GIS switch room;

5. SF6 gas detection and alarm device has timed ventilation function, and can set up 8 periods of ventilation function within 24 hours a day;

6. Manual start and automatic start fan function is normal;

7. The oxygen curve display at the three monitoring points on the host interface is normal.

8. Check that the voice prompt function is normal.

9. The infrared sensing function of human body is normal;

10. The historical data query function is normal.

Fifth, Line 3 Bowen Road transformer main transformer station SF6 gas detection alarm device detection/maintenance report

1. Remove the host of the original SF6 gas detection and alarm device and replace it with the host of the SF6 concentration online monitoring system produced by Wever Detection, and upgrade the monitoring host system and modify the source code program. Because the original SF6 monitoring probe has not been replaced, the host program needs to be modified to ensure the normal data communication of the original monitoring probe;

2. After testing, there are 8 probes in the switch room, 5 of which cannot communicate normally, so the SF6 and oxygen monitoring probes replaced by the main transformer station of Jinhua are moved to 5. However, due to the large error of the monitoring probe, it can not effectively monitor the state of SF6 and oxygen in the environment and ensure safety.

3, the newly replaced Weavers SF6 monitoring host can dynamically display the SF6 concentration status of each monitoring unit in the substation (GIS room) environment (“ Normal ” Display status, because the previous monitoring probe is qualitative detection) and oxygen content, the system can set the concentration of more than 1000ppm (national standard value, the user can customize the alarm threshold), oxygen less than 18.0% (national standard value, the user can customize the alarm threshold), oxygen value red font prompt, otherwise the normal color display the actual value;

4, the detection of SF6 gas detection alarm device can be timed ventilation function, and meet the ventilation function of 8 periods within 24 hours;

5, SF6 gas detection alarm device monitoring information can be displayed normally; At present, the accuracy of SF6 gas monitoring, oxygen monitoring and temperature and humidity monitoring cannot be verified, because the monitoring probe has not been replaced, and the original monitoring probe error is too large.

6, the voice prompt function is normal;

7, the human body infrared sensing function is normal;

8. Historical data query function is normal;

9, the date and time setting function is normal;

10, sound and light alarm function is normal.

6. Detection/maintenance report of SF6 gas detection alarm device in Wuzhuang main Substation of Line 3

(1) On-site functional testing of SF6 gas detection and alarm device is as follows:

1, SF6 gas detection and alarm device monitoring the appearance of the host surface without obvious damage, no obvious software and hardware defects that lead to unavailability;

2, SF6 monitoring host manual start fan function is normal, manual stop fan function is normal;

3. The SF6 monitoring host cannot enter the function Settings and needs to enter with a password. Currently, it has no permission to set functional operations;

4, the detection of SF6 monitoring host has no timing ventilation function, that is, it cannot set time ventilation within 24 hours throughout the day;

5, the detection of human infrared sensing function is normal;

6. Check that the voice prompt function is normal;

7. There is an alarm indicator on the SF6 monitoring host, but it cannot test whether the audible and visual alarm function is normal and reliable;

8. SF6 monitor host display interface touch function is normal, touch fan start and stop function can respond normally, touch parameter setting response is normal;

9. SF6 monitoring host date and time setting function is normal;

10, SF6 monitoring host shows that the probe function is normal, 1# is the temperature and humidity monitoring probe, 2#-7# is the oxygen and SF6 probe.

(2) Verify the accuracy of each SF6 and oxygen monitoring probe and temperature and humidity monitoring probe

1, the 2# SF6 and oxygen monitoring probe uses 1000PPM SF6 standard gas (belonging to 0.1% SF6 and 99.9% N2 mixed standard gas) for SF6 sensor probe test, its oxygen value does not fall but rises to 21.97%, SF6 from beginning to end shows normal (because the SF6 display interface of the system is normal, No measured concentration content value is shown, according to “ Normal ” To display the state of its corresponding number probe);

2. The SF6 sensor probe was tested by the same method for the 3# SF6 and oxygen monitoring probe, and its oxygen value did not decrease and change in response, continuously displaying 21.97%, and SF6 showed normal from beginning to end;

3. SF6 sensor probe test was carried out on SF6 and oxygen monitoring probes of 4#, 5#, 6# and 7# in turn, and the oxygen value of each probe did not decrease, and all increased to 21.97% in different degrees and no longer changed;

3, and then the standard 18% oxygen (18%O2: 82%N2 mixed gas) The SF6 and oxygen monitoring probes of 2#, 3#, 4#, 5#, 6#, 7# were tested by oxygen concentration sensor probes. The oxygen value of each probe did not decrease, and it did not change after rising to 21.97% in different degrees, and SF6 was displayed as normal from beginning to end.

4. The 1# temperature and humidity monitoring probe is tested by proper heating and humidification, the temperature rises from 7.91 ° C to 9.45 ° C, and the humidity rises from 45.78% to 85.56%, indicating that the 1# temperature and humidity monitoring probe plays a detection role, but its accuracy is not a standard sample to determine whether it is accurate;

5. During the whole test process, SF6 gas detection device has no audible and visual alarm, nor has the fan started.

(3) Conclusion

1. Each SF6 monitoring probe adopts 1000ppm standard SF6 gas (1:1000 SF6: N2 mixed gas) test, the oxygen content of each probe should decrease (taking into account the oxygen residual of the test tool, generally falling to at least 10%), the actual test results show that the oxygen content remains unchanged (current 21.97%), but some probes with low oxygen appear to rise, so it is judged that each SF6 monitoring probe is invalid. SF6 concentration in the environment cannot be detected online in real time. When SF6 gas is passed into SF6, the SF6 detection value changes, the status bar is always displayed as normal, and the interface, sound and light alarm, and automatic ventilation are not triggered from the beginning, so it is inferred that the SF6 concentration detection probe is invalid.

2, the oxygen monitoring probe using standard 18% oxygen (18%O2:82%N2 mixed gas) test, the monitoring probe oxygen content remained unchanged or even some probes increased, and the 18% standard oxygen value deviation is too large; Therefore, it is concluded that all oxygen monitoring probes are ineffective for oxygen detection.