Personal protection against electric shock and arc damage

[Abstract] analysis through a case of personal electric shock and arc injuries, described the dangers of electric shock and arc harm, analyzed the risks and causes of electric shock and arc damage, how to effectively prevent electric shock and arc have been hurt Discussed and combined with the actual proposed specific experience and practices.

〔Key words〕 electric shock; electric arc; person; discussion

Personal electric shock and arc injury accidents have been typical accidents in electric power safety production, accounting for more than 50% of accident statistics in recent years , and the degree of harm caused by personal electric shock and electric arc injuries is large, and it is not negligible for electric power production operation safety management. .

1 accident case analysis

When 2007-04-20, a power supply bureau substation maintenance personnel to work in eliminating defects 220kV substation, a maintenance staff without expanding the scope of work, misuse Gordon energized equipment, resulting in insufficient safety distance and charged body, thus the arc burns accident occurred .

2008-12-19, a Power Supply Company in the course of the inspection personnel â…¡ of bus No. 10 kV capacitor switching group 512 is pushed into the trolley in the operating position, by switching the switchgear cell and a short-circuit discharge knocking, resulting in One operator was burned by the arc.

2012-02-27, an engineering company to undertake a survey of employees in 10 kV current transformer replacement work site without permission, 10 kV open switchgear door, electrocution accident. The following are the reasons for the above-mentioned several accidents.

(1) Failing to properly perform the work ticket or operating ticket system and failing to implement safety measures as required are the main causes of personal electric shock and arc injury.

(2) The person in charge of the work or the guardian is not in the custody and the entire work loses the security guardianship.

(3) Work team members did not fulfill their safety responsibilities, violated work procedures, and did not stop or oppose violations.

(4) The switching operation does not take into account the management requirements of the operator's safety protection. It is necessary to study various safety protection equipment for on-site operation personnel of high-voltage equipment and further improve the level of labor protection and safety protection.

2 Risk Analysis

2.1 Risk analysis of electric shock or arc injury

According to the risk analysis, the following factors are the main causes of work-related electrical or arc injuries:

(1) Risk assessment before work;

(2) The implementation of "two votes, three systems";

(3) The management and use of tools and protective equipment;

(4) Standard implementation of safety measures;

(5) Power management and use;

(6) Improper use of construction machinery;

(7) Management and implementation of special operations;

(8) Personnel Qualification Assessment, Staff Training;

(9) Operational arrangements for operational personnel;

(10) The specification of the operation.

2.2 common violations or hidden dangers

(1) The safety distance between a person and a charged device during work is insufficient, causing arc discharge to the human body.

(2) Unauthorized enlargement of the scope of work and misappropriation of electrified equipment, resulting in arc burns due to insufficient safety distance from live objects.

(3) Licensing is not implemented, security is unclear, and there are still live situations in the workplace such as live parts.

(4) In the workplace, improper use of tools or working in an activity space where there is insufficient safety distance but no corresponding measures may result in personal electric shocks and arc injuries.

(5) Unsupervised operation during operation, excessive movement during operation or near live equipment was not detected in time, resulting in electric shock to staff. .

(6) The working distance from the working place to the live equipment meets the requirements, but in the course of work, the safety distance between the place where the equipment or tool is put down and the live equipment is insufficient, resulting in electric shock.

(7) The closed grounding wire was not installed in the workplace, and there was a back-propagation of electricity that caused the worker to get an electric shock.

(8) The insulation of the power tool is damaged, and its metal shell is not grounded, causing the power tool housing to be charged.

(9) Stop and deliver electricity.

3 Typical precautions

In order to guard against the occurrence of personal electric shock and arc injury accidents and effectively control the personal risks during the operation, Jiangmen Power Supply Bureau organized a special campaign to prevent personal electric shock and arc damage accidents in 2012 . The main measures for preventing electric shock and arc-injury accidents were summarized, and “ten prohibitions” and “ten guidelines” for preventing personal electric shocks and “ten guidelines” for preventing electric arc injuries were proposed.

3.1 Measures against personal electric shock "Ten forbidden"

(1) Work performed on electrical equipment must be carried out on the listed work items. No ticket or over-range work is strictly prohibited.

(2) When working in the vicinity of the electrified electrification equipment, reliable and obvious isolation measures and safety signs shall be set around the working point, and it is forbidden to move, dismantle, and cross the fence during work.

(3) It is forbidden to work on live 10 kV and 35 kV line tower crossbars, as well as one side power failure and 110 kV isolation barrier on one side .

(4) Install the grounding wire before installing the grounding end. Remove the live wire before removing the grounding wire and maintain the safety distance of the corresponding voltage level. After the grounding wire on the tower is removed, it shall be considered that the line is live, and it is forbidden to perform any work on the pole.

(5) Temporary power supply should use a portable power supply rack equipped with an electrical leakage protector and socket. It is strictly forbidden to use wires to directly plug into the socket to obtain power.

(6) It is forbidden to bring non-insulating materials such as bamboo sticks and wooden sticks with a length of more than 2 m into the substation as a tool.

(7) If there is a crossing over of the wire during the transformation, it is forbidden to forcefully pull the wire during the process of releasing the new wire in the demolition line so as to prevent the wire from being broken and touching the adjacent or crossing bare wire, thereby causing an electric shock accident.

(8) When a power transformer fails to perform the test, no one is allowed on the gantry. The ground test area should be fenced, the "stopping, high-pressure danger" signboard should be hung outwards, and there should be special person custody.

(9) It is forbidden to carry out work without taking safety measures to prevent reverse power transmission. Dual power users must install dual power conversion devices with double-throwing knife gates to lock the Internet (two power supplies must have obvious disconnection points and a reliable locking device ) to prevent reverse power transmission.

(10) It is forbidden to work on capacitors without taking complete measures. The power should be disconnected first, and the capacitors should be discharged several times and grounded. The neutral point of the capacitor bank can be grounded.

3.2 Ten Guidelines for Preventing Electric Shock

(1) The staff must carefully check the equipment name, number and location before climbing the equipment and structure. Check the site safety measures before starting climbing.

(2) When carrying out high-voltage tests on electrical equipment, a barrier shall be installed at the test site, a “stopping, high-voltage hazard!” signboard shall be hung outward, and a guard shall be assigned to prevent other non-testers from approaching.

(3) When the multi-layer power line erected on the same tower is connected to the grounding line, the low voltage and the high voltage shall be hung beforehand. The lower layer and the upper layer shall be hung and the qualified and effective grounding wire and short-circuit wire shall be used.

(4) When conducting the work of partial line blackout in a multi-circuit line with parallel lines or the same pole, check the line name, tower number, logo, and color mark carefully before boarding.

(5) In the construction of power lines, it is necessary to consider whether there is a need for blackouts on the cross-over lines above them, and to take into account the danger of the construction guides and ground lines popping up to touch the lines.

(6) After the low-voltage distribution network reconstruction project is completed, it must be carefully checked whether the old line has been detached to prevent accidental electric shocks and deaths due to mixed old and new lines.

(7) Before installing the grounding wire in the working area of ​​the power outage line , the power must be checked phase by phase. After the inspection has confirmed that there is no voltage on the line, each working team should immediately hang grounding wires at both ends of the working site.

(8) To perform maintenance work on the distribution transformer bench, the low-voltage side load switch must be pulled first, then the high-voltage side isolation switch or drop-type insurance must be opened, and then on the high-voltage lead of the power cut and the low-voltage side transformer The three-phase short circuit on the line side of the brake is grounded.

(9) When cutting trees close to live lines, the safety distance between workers, ropes and conductors should be greater than the specified safety distance, and the trees and ropes must not be approached within this safety distance.

(10) For electrical equipment and various types of power tools or electrical equipment, the motor housing must be well grounded. The welding machine must be reliably grounded, and the high and low voltage side terminals must be provided with guards to prevent accidental collision during operation.

Russia MT3500 plasma multi-function welding machine

3.3 Arc Injury Ten Guidelines

(1) Recognize the classification of arc-proof clothing. One type is arc-resistant operation suits, which are used when workers perform electrical operations; the other is arc-proof overalls , mainly jackets and trousers, which can be used as daily work clothes.

Arc protection work clothes

(2) The anti-arcing service clothing is a personal safety protection product used during on-site operation, and is required to be worn during the local operation of the high-voltage equipment.

(3) Arc-proof overalls may be worn during operations such as inspections, maintenance tests, circuit inspections, maintenance, repairs, etc. that do not operate directly.

(4) When wearing the arc-proof operation clothing, it must be used together with the arc-proof mask, insulating gloves and high- insulated boots ( shoes ) . The anti-arcing service clothing does not have insulation function. It is forbidden to use the anti-arcing service clothing as insulation clothing.

GB 20KV insulated boots

(5) During the use of arc-protective clothing, susceptibility to arc hazard may be reduced due to the superior performance of the arc-proof product and the characteristics of the arc, and paralysis may easily occur. It is required to overcome the irritability of mind during work and to maintain a high degree of vigilance against arc hazards and to strictly implement the electrical switching operation regulations.

(6) The arc protection clothing should be stored in a place away from light, dry and clean, and kept below 40 °C relative to the room temperature . A special closet is set up, which is neatly placed in a hanging and hanging manner. If it is constrained by the storage space, it can also be placed in a special cabinet by folding.

(7) The anti-arcing service shall be scrapped if it meets one of the following requirements: (1) Any part of the garment is bleached, and the visual inspection of the garment is damaged, cracked, cut, or damaged in the front projection range; (2) The garment will rapidly swell in the event of an arc accident. , Carbonization thickening to achieve the effect of flame-retardant insulation, after the process of clothing material organization has changed, should be scrapped; 3 out of service life after the factory; 4 the same batch of products after the detection of loss of flame-retardant protective performance, should be the whole Batch scrapped.

(8) Arc burn refers to an acute skin injury caused by an arc of high heat material. According to the depth of burns can be divided into one degree burns, second degree burns, third degree burns.

(9) When a high-voltage arc electric shock occurs, the power switch should be turned off quickly. If it is not possible to turn off the power switch, use an insulated tool suitable for this voltage level to remove the electric shock from the power supply.

(10) The emergency treatment of the electric shock and electric arc burn wounded after disconnection from the power supply should be performed on the spot ( sent to the hospital ) : 1 For those who are mildly coma or have weak breath, they may be acupunctured or deafened by Zhong Xuan, Xuan Xuan, Yongquan, etc. Acupuncture point, and sent to the hospital for treatment; 2 pairs of breathless but heart beat, should immediately use artificial respiration method for rescue; for those who have breathing but the heart stops beating, then immediately use chest cardiac compression method for rescue; 3 such as If the heartbeat and breathing of the person with electric shock have stopped, the cardiopulmonary resuscitation is used for treatment.

4 Experiences

Pay attention to the implementation of personal electric shock prevention measures, on the one hand is to do a good job in the management and use of safety tools and traditional protective equipment, and on the other hand to gradually promote the application of anti-arc operation clothing in the prevention of arc damage, in practice to obtain the following experience.

(1) Places where arc-resistant operation clothing is used include local high-pressure operations, GIS rooms, high-voltage rooms, capacitor rooms, reactor rooms, arc-extinguishing device rooms, switch stations, power distribution rooms, and switch boxes. Far-end operation and climbing operations are not required to wear long-type arc-proof operation clothing.

(2) Arc-protective clothing and overalls, safety helmets, etc. shall be used as safety protection products and shall be used as required in the place where it is required to be used, regardless of whether it is sunny or rainy.

(3) In the summer when the high temperature wears arc-proof clothes for outdoor operation, the operator may easily cause heat stroke. For this reason, one can actively seek protective products with more comfortable materials on the one hand, and on the other hand, it is recommended to reduce wearing time and use it only at the operating point.

(4) The full-enclosed arc-proof mask may affect the operator's hearing ( reception task ) and visual ( breathing steam ) sensitivity during use. It is recommended to use a helmet and a face shield. The transparent colored faceplate makes the sight more clear, and is more favored by front-line employees.

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.