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Analysis of typical cases in the electrical industry


1. The grounding protection wire burns people

1. The accident

At 3 o'clock in the afternoon on April 6, 1994, after a factory 671 substation operation attendant took over, the person in charge of the 312 oil switch overhaul filed an application to end the overhaul, and the shift leader temporarily proposed to try the 3121 isolation above the 312 oil switch. Knife switch, check the fit of the knife switch. Therefore, without disassembling the grounding protection wire between the 312 oil switch and the 3121 isolation switch, the shift leader arbitrarily removed the "grounded" warning sign and padlock on the operating handle of the 3121 isolation switch, and closed the switch. operating. Suddenly, there was a loud bang, and the strong arc light rushed towards the person in charge of overhaul and the trainee on duty squatting in front of the 312 oil switch. Two people were severely burned by the arc light.

2. Reason analysis

Originally, the 3121 isolation knife gate was about 2 meters higher than the head, and it was blocked by a metal cabinet. Its arc should not burn people, but why did it burn people? It turns out that the arc light that burns people is not the arc light of the 3121 isolation knife gate. , But the arc generated when the two grounding wires burn out. The two grounding wires are bare copper stranded wires. When the operator clamped and connected to the equipment with a caliper, one strand of the wire was in poor contact, and the other stranded wire also broke several copper wires. Therefore, when operating in violation of regulations, the strong current caused a short circuit, which not only burned the 3121 isolation switch, but also vibrated and fell off at the poor contact of one of the grounding wires, causing a strong arc to occur, and the copper wire of the other stranded wire was disconnected. Strong arc light, the instant arc light of the two grounding wires was particularly strong, causing serious burns to 2 people nearby. The cause of this accident was to temporarily increase the work content and operate without authorization, which violated the basic operating procedures.

3. Lessons from the accident and preventive measures

1). Important operations are generally not carried out during the shift and within a quarter of an hour before and after the shift.

2). Replace the warning sign "grounded" with a clearer statement: "grounded, closing is strictly prohibited". Strictly abide by the rules and regulations, and absolutely prohibit closing with a ground wire.

3). The function of the grounding protection line is to play the role of grounding short-circuit in the event of an electric shock, so as to protect people from harm. Therefore, the quality of the grounding wire must be good, the capacity must be sufficient, and the connection must be firm.

Two, accidents caused by wrong closing of the knife and brake

1. The accident

On the morning of January 31, 1996, in the process of overhauling No. 508 oil switch in the high-voltage power distribution room of a thermal power plant, when electrician Qu squatted, his buttocks accidentally touched the transmission force of the isolated knife switch numbered 5081 on the No. 508 oil switch. Turning the arm lever caused the 5081 isolation knife switch to contact with its moving and static contacts, and the knife switch was misclosed, causing the factory's power system 502 and 500 oil switches to trip due to the action of the "overcurrent protection" device. The 6kV high-voltage two-stage bus and part The 380V busbars all lost power, the No. 2 and No. 3 boilers stopped working for more than 40 minutes, and the No. 1 generator stopped working for one hour.

2. Reason analysis

When the oil switch is overhauled, the circuit breaker must be disconnected, and the isolating knife switch on the oil switch must be opened, and the grounding protection short-circuit line must be reliably connected to the part between the oil switch and the isolating knife switch. Insert the latch on the force-transmitting arm lever and lock it (to prevent it from being moved by mistake).

The cause of this accident was that the staff violated the regulations and did not install the bolt, let alone lock it, so he bent a certain hip

The part inadvertently encountered the force transmission lever of the 5081 isolation knife, causing the 5081 isolation knife to move and static contact contact, and the static contact was connected to the bus bar to be electrified, so a strong current passed through the isolation knife to move and static The contacts then flow through the grounding protection short-circuit line and enter the ground to form a short-circuit discharge, which causes the 502 and 500 oil switches of the electrical series to trip due to the action of the "overcurrent protection" device.

Fortunately, due to the good quality of the grounding protection short-circuit wire, no personal injury was caused after the accidental closing of the switch, but the economic loss caused was huge.

3. "Incidental error" with load broach

1. The accident

At 8:40 am on June 17, 1995, He Mou, the air compressor duty officer of a certain plant in Sichuan, received the instruction from the dispatcher of the branch plant: start 4# unit; shut down one of 1# unit or 5# unit. He went to the electrical duty room and negotiated with the electrical duty officer Wang (deputy monitor) and Wu: After starting the 4# unit, one of the 1# or 5# units should be shut down. Wang followed He to carry out the operation, and Wu stayed behind the board. At 9 o'clock, the 4# unit was started on site, and then the 5# unit was shut down on site. At this time, the power distribution room made the sound of the oil switch tripping.

Wu in the electrical duty room judged that the 5# unit had been out of service, so he went to the high-voltage power distribution room alone to open the isolation switch above the 5# oil switch. However, she erroneously opened the isolation switch of the running unit #1. There was a loud "bang" and the arc short circuit at the isolation switch caused the 314 line to be powered off.

2. Reason analysis

The cause of this misoperation accident is the violation of the "guardianship system." Mr. Wu in the electrical duty room left his supervisory position without approval. In violation of the “one person operation and one person guardianship” regulations, he went to the high-voltage power distribution room alone to operate, and did not see the power cabinet number clearly and did not check the power. The on-site indication signal of the cabinet was not checked in accordance with the regulations, and the isolation switch of the running 1# unit was opened by mistake, which was the direct cause of the accident.

The indirect reason was that the deputy monitor Wang had an omission in his organization.

1) It was agreed to "stop operation of 1# or 5# group after starting 4# unit", but there is no decision. It should be clear whether it is 1# or 5#, so that all the people present have a good idea.

2) Wang, the person in charge, left the supervisory position and went to the scene without clearly explaining Wu's job responsibilities. He did not notify Wu in time after operating on-site, and he was responsible for leadership.

3) The occurrence of accidents is the inevitable result of poor management, lax labor discipline, lax implementation of safety operating procedures, and poor quality of duty personnel.

Four, overhaul the electric welding machine, electrocuted death

1. The accident

On May 17, 2002, Diao, an employee in the maintenance team of a power plant, led Zhang to overhaul a 380 V DC welding machine. After the electric welding machine is repaired, the power-on test is good, and the electric welding machine switch is turned off. Diao arranged for Zhang, a member of the working group, to dismantle the secondary wire of the electric welding machine and remove the primary wire of the electric welding machine by himself. At about 17:15, Diao squatted to remove the middle joint of the power cord of the electric welding machine. After removing one phase, he accidentally got an electric shock during the removal of the second phase, and died after the rescue failed.

2 Reason analysis

(1) Diao has been engaged in work for more than 10 years, has been engaged in electrical work and obtained a senior maintenance electrician qualification certificate; in this operation, Diao had little safety awareness and did not conduct safety risk analysis before work, and removed the middle joint of the electric welding machine power cord. When the welding machine is not checked to confirm whether the power supply has been disconnected, and the power line is live without insulation protection, it may cause electric shock. Diao's low-level illegal operations were the direct cause of the accident.

(2) Although Zhang, a member of the working group, is a member of the working class, he did not effectively supervise and remind safety at work.

One of the reasons for this accident was to stop Diao's violation of regulations.

(3) The company formulated and issued the "Regulations on the Use of Electric and Pneumatic Tools" in 2001, including the wiring of electrical equipment and the use of 15 types of equipment. After the "Regulations" was issued, studies were organized and examinations were conducted. However, Diao did not implement the rules and regulations at work, was negligent, and violated the rules based on experience and qualifications.

(4) The company’s leaders have insufficient understanding of the safety production policy of “safety first, prevention first”, and have the idea of lightening safety and focusing on operation, and are directly responsible for management.

3. Preventive measures

(1) Take effective measures to strengthen the supervision and implementation of the implementation of the rules and regulations of the on-site staff to prevent the occurrence of violations. Members of the work class must supervise each other and strictly implement the "Safety Regulations" and corporate rules and regulations.

(2) All work must implement the safety risk analysis system, and fill in the safety analysis card, and the safety analysis card should be kept for 3 months.

(3) Improve the equipment power outage system and formulate equipment power outage inspection cards.

(4) Strengthen the technical training and safety knowledge training of employees, improve the professional quality and safety awareness of employees, and enable employees to realize the dangers of operational violations from an ideological perspective.

(5) Improve the "five-simultaneous safety production system" for workshops and teams, establish personal safety production files, and conduct training or transfer for personnel who do not have the safety qualities required by their positions; when arranging jobs, they must be aware of the safety thinking status of employees in a timely manner , In order to make careful and proper arrangements for everyone's work, and strictly implement the work ticket system to ensure the safety and control of the staff.

(6) Leaders at all levels must really raise their awareness of the safety production situation of electric multi-business enterprises, increase the safety capital investment in electric multi-business enterprises, strengthen the technical and safety knowledge training for the personnel of multi-business enterprises, adjust the personnel structure, and improve Employee labor protection, strengthen on-site safety management, ensure the safety of personnel and equipment, and effectively change the passive safety production situation of power multi-business enterprises.

Five, the thread is not cleaned thoroughly, the accident occurs and hurts people's lives

On June 23, 2002, a chemical company in Yinan, Shandong Province suffered an electric shock outside the west wall of the original Beidamen Communication Office, killing one person.

1. The accident

It rained overnight on June 22, 2002, and at 5 o'clock on the 23rd, the company's compound fertilizer workshop was shut down according to the scheduled plan for equipment cleaning and renovation. At 8 o'clock, after Wang and Han took over, they were responsible for cleaning up the remaining materials in the finished sieving bin according to the arrangement of the shift. At about 8:20, Wang left the workshop. At about 8:30, Han came out and went to the north of the workshop to look for tools. He found a person lying outside the west wall of the original north gate communication room in the northeast corner of the workshop, with his head facing southeast and west, and his feet placed in a north-south place. On the iron ladder, it is more than 2m away from the west wall of the communication room. At this time, Han hurried to the workshop office to report. The company and workshop leaders ran to the scene together. At that time, they found that there was a wire coming down from the west window of the communication room. The workshop director Yu hurriedly called to pull the switch, and the deputy manager Du hurried to use it. Contact with the phone and ran to find the vehicle. After pulling down the main power switch of the compound fertilizer workshop, the workshop employee Li held the rod tube not far from Wang to pull Wang, but was knocked down by electricity (it was immediately picked up by the maintenance worker Yin. ) At that time, workshop director Yu found out that it was not the electricity in the compound fertilizer workshop, so he hurried to the company's power distribution room, and with the cooperation of the electrician monitor Zhang, he quickly pulled down the company's east road power supply main switch. At this time, Du and Wen Xun, who had contacted the vehicle and ran to the scene, immediately turned Wang over, and Li, the electrician, performed artificial respiration to rescue him. Everyone carried Wang to the scene. The car that had arrived at the scene was immediately rushed to the county hospital for rescue. On the way to the hospital, two electricians gave Wang Mou artificial respiration together. The time to reach the hospital was about 8:40, and Wang died after being rescued.

2. Analysis of the cause of the accident

After the accident, through the organization of personnel to conduct on-site investigation and analysis, it is believed that the leakage wire was the lighting wire that led from the old factory to the original North Gate Communication Office and the original woven bag factory office many years ago. The appearance of the wire and the end of the wire are very old. The father

The company has never used this line after the company acquired the original Yinan Fertilizer Plant in August 2001. The original company’s electrician did not know when the line was renovated and withdrawn. The line ends were not cleaned up, and they were plated on the windows of the original North Gate’s communication room (because the company is located here). It is planned to build a shed. For four or five consecutive days before the 21st of this month, the construction personnel have repeatedly measured, digging the foundation, burying, and pouring concrete. More than 10 people have erected frames and welded steel beams here. Construction and rest were performed around this window, and the tied rod pipes also extended to the south side of the window, and there was never any cable landing here). From 10 pm on June 22nd to 5 am on the 23rd, the heavy rain continued unabated and accompanied by Strong winds of level 4 to 5 scraped the power cord of the pan to the ground. The deceased Wang went to the place of the accident to look for tools (an iron rod with a diameter of 30mm and a length of about 1.4m was erected on the west wall of the communication room) when he stepped on a flat iron ladder and fell accidentally (the ladder is about 25cm from the ground) , One of which was carried on an iron stand), his face touched the bare power cord, and an electric shock occurred (the left side of the corpse’s face had a 3×5cm2 burn scar). The second electric shock occurred during the rescue process. The reason was that Wang's body, iron ladder, and iron rod formed a live circuit.

3. Preventive measures

The lessons of this accident are profound. It brought great harm and pain to the deceased and his family, and had a certain impact on the enterprise and society. The company held many meetings, inferred from one another, and adopted the following preventive measures:

1) In accordance with the principle of "Four Don't Let Go", the company leaders organized a meeting of all employees to educate employees on safety production knowledge with accident cases that occurred around them, so as to enhance their safety awareness.

2) The company formed an inspection team, led by the leader, to conduct a comprehensive safety production inspection of the company's production and living areas, and promptly rectified problems when found.

3) The county power supply bureau and the company's electrical repair personnel carried out a thorough and standardized rectification of the company's high-voltage and low-voltage lines.

4) The company has formulated and implemented a specific safety production education plan. Every day, the workshop is responsible for the use of pre-shift and after-shift training for employees on safety production knowledge for 30 minutes.

5) Deal with the persons responsible for the accident.

6. Vicious misoperation accident of power transmission

1. The accident

On May 18, the 110kV Yuanling Substation carried out the #2 main transformer body, 102 switch, CT, 502 switch, CT, and 10kV Ⅱ, Ⅲ section B bus equipment pre-test and protection regular inspection work as planned. At 18:02, the 2# main transformer body, 102 switch, CT, 502 switch, CT and 10kV Ⅱ, Ⅲ section B bus equipment power failure pre-test and protection regular inspection work ended. At 18:15, the dispatch command "change the 2# main transformer from the overhaul state to the running state, and the 10kV Ⅱ, Ⅲ section B bus from the overhaul state to the running state". In order to shorten the power recovery operation time, Mo Mou, the head of the inspection center station, arranged for the power recovery operation to be carried out in two groups at the same time. One group was responsible for the operation of "10kV Ⅱ, Ⅲ section B bus from the maintenance state to the running state", and the other was responsible The operation of "2# main transformer changed from overhaul status to running status". At 18:17, inspectors Diao and Liang were responsible for the operation of the 10kV Ⅱ and Ⅲ section B bus from the overhaul state to the running state (the operation of the 10kV#2 low 502 switch is in charge of the group);

At 18:20, the inspectors Zhong (guardian) and Lu (operator) are responsible for the operation of the 2# main transformer from the overhaul state to the running state (open the 10kV#2 low main transformer side 502T0 grounding switch The operation is the responsibility of this group).

At 18:41, when Zhong and Lu entered the 10-kV high-voltage chamber to prepare to open the 502T0 grounding switch on the low side of the 2# main transformer, the stationmaster Mo asked them to push the grounding vehicle away from the high-voltage chamber channel. After completing the work assigned by the station master, when returning to the operating site, he did not seriously confirm whether the operation has been performed and check the equipment status, so he opened the 2# main transformer low side 502T0 grounding switch and checked that it was opened. Tick "√" on the operation item and record the execution time. Then continue to operate down, at 19:02, when the operation reaches the 2# main transformer high 102 switch, the switch will flash green, accompanied by an audio signal, and the light card "dropped card has not been restored" lights up. The inspection of the main transformer protection screen found that the 2# main transformer differential protection action was lost, and the high 102 switch tripped; the inspection of the main transformer body, GIS switch and other equipment found no abnormalities; at 19:31, the transformer During the inspection of the low 502 switch, it was found that the low side 502T0 grounding switch of the 2# main transformer was in the closing position.

With the approval of the local government, the #2 main transformer will be transferred to the overhaul state, and the 2# main transformer will be subjected to winding deformation test, oil chromatographic analysis, winding insulation test and other tests. The test results meet the requirements, and the 2# main transformer will be restored at 23:00 run.

2. Analysis of the cause of the accident and exposure issues

1) The operator has a weak safety awareness, and the 502T0 grounding switch on the low side of the #2 main transformer has not been opened, and the operation has been marked "√" without inspection.

Mark and record the virtual execution time and leave the operating location. In the follow-up operation of the operation task, the actual operation omission was the main cause of the accident.

2) During the operation, the head of the patrol inspection center violated the "Two Invoices" implementation rules of the original Guangdong Electric Power Industry Bureau, arranging the operators to perform work that has nothing to do with the operation task, causing the operation to be interrupted and causing the operators to be mentally dispersed. There is an operation omission.

3) Due to the tight operation time, the two groups of operators are separated to perform logical switching operations at the same time. Only the safety measures that will not endanger the 10 kV bus operators in the second and third section of the #2 main transformer are considered when the power is restored. (The switch for lowering the 502 trolley is not pushed into the switch cabinet, so that there is an obvious disconnection point between the two operation interfaces), but the blocking function between the 502 switch and the 502T0 grounding switch is ignored, resulting in the blocking device not playing its role. Some blocking effect.

3. Preventive measures

1) Conscientiously implement the "Notice on Effectively Preventing Electrical Misoperation Accidents" (China Southern Power Grid Safety Supervisor [2004] No. 16), earnestly strengthen leadership, improve work style, and follow the "strict, detailed and practical" It is required to do a good job of "preventing mistakes"; raise awareness, ensure investment, and effectively strengthen the safety production quality education and skill training of all personnel; earnestly implement the relevant content of the "25 key requirements for preventing major accidents in power production", and comprehensively strengthen "Error prevention" work and device management; take "error prevention" work as the current focus of safety supervision, and strengthen safety inspection and guidance on the front line of production.

2) The relevant regulations of the "Electrical Industry Safety Work Regulations" and the "Two Invoices" must be strictly implemented.

3) It is forbidden to do other irrelevant work items while operating, not to interfere with the normal work of the operator, and properly handle various work items during the operation.

4) When formulating a power outage plan, it should be considered that the staff on duty have ample operating time; when grouping and simultaneous operations are required due to the tight operating time, it must be performed in the same substation at the same time with no logical relationship between the switching operations, and Fully consider the reasonable arrangement of personnel operations and do a good job in overall planning and coordination.

5) Corresponding preventive measures must be implemented before operation, and the control and analysis of dangerous points must be strengthened. In the operation task, any operation that can operate the knife switch without electricity should be operated without electricity. On the one hand, it can reduce the accidents during the operation due to the quality of the knife switch, and on the other hand, make the chain of the knife switch and the ground knife play a role. , To improve the effectiveness of the "five prevention devices".

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