Organizational and technical measures for safe work on electrical equipment:
I. Organizational measures to ensure safety.
1 ⒈ work ticket system: work on electrical equipment should first fill out a work ticket.
Peak work permit system: work on electrical equipment should be authorized before proceeding.
3 work monitoring system: the work site must have a person to monitor the work of all staff.
Sunglasses: Work interruption, transfer and termination system: work interruption, the work shift personnel from the work site after the withdrawal of the person in charge of the work is still monitored.
II. Technical measures to ensure safety.
Electrocution accidents, although there are a variety of, but the most common is the accidental touch in the normal situation is not electrified and accidentally electrified conductor. As long as you can grasp its laws to take appropriate safety measures, many can be avoided.
The main technical measures to prevent electrocution, the use of safe voltage, to ensure that the insulation of electrical equipment, to take the screen, to ensure that the safety distance, a reasonable choice of electrical devices, installed leakage protection devices and protection of the grounding, grounding and so on.
1, protective measures
Effective isolation of the charged body is to prevent the human body suffered a direct electric shock accident is an important measure, usually used in the following ways:
2, insulation
The so-called insulation, refers to the use of insulating materials to the charged body is closed up, through the isolation of the charged body or a different potential of the conductor, so that the current can be circulated according to a certain pathway.
Good insulation is to ensure the normal operation of the equipment and lines of the necessary conditions, but also to prevent electrocution is an important measure. Insulation often also plays other roles: cooling, mechanical support and fixed, energy storage, arc extinguishing, moisture, mold and protect the conductor.
3, screen protection
The so-called screen protection, is the use of barriers, fences, shrouds, boxes and other electrically charged body isolated from the outside world. Distribution lines and electrical equipment, if the charged part of the package is not easy to insulate or rely on insulation alone is not enough to ensure the safety of the occasion, screen protection can be used. In addition, for high-voltage electrical equipment, whether or not there is insulation, should be taken to screen protection or other measures to prevent access.
4, spacing
In order to prevent the human body from touching or excessive proximity to the charged body, or to prevent vehicles and other objects collision charged body, as well as to avoid the occurrence of a variety of short circuits, fires and explosions, in the human body and the charged body, the charged body and the ground, the charged body and the charged body, the charged body, the charged body, and other objects and facilities, must maintain a certain distance between the distance called Electrical safety distance, referred to as spacing.
The size of the distance depends on factors such as the voltage, the type of equipment and the way it is installed.
5, the use of safe voltage
Safety voltage, in order to prevent electrocution accidents by a specific power supply voltage series. The upper limit of this voltage series, that is, the voltage between the two conductors or between any conductor and the ground, in any case, do not exceed the AC rms value of 50 volts.
China stipulates that the level of safe voltage rating is 42, 36, 24, 12, 6 volts. When the voltage used in the electrical equipment exceeds the safe voltage, must be taken in accordance with the provisions of the protective measures to prevent direct contact with the charged body.
Where portable lighting, especially dangerous environment of portable power tools, such as no special safety structure or safety measures, should be used 42V or 36V safety voltage; metal containers, tunnels and other workplaces are narrow, inconvenient to move around the environment with a large area of grounded body, should be used 24V or 12V safety voltage.
6, protective grounding
Protective grounding is the normal situation is not charged, but in the insulating material is damaged or other circumstances may be charged metal parts of electrical appliances (i.e., insulated with the charged part of the metal structure part of the wire and the grounding of the body is reliably connected to a protective wiring, also referred to as grounding. Grounding device:
①Earth. There are natural and artificial grounding body and two kinds of grounding body.
② grounding wire. That is, the connection between the grounding body and electrical equipment should be grounded part of the metal conductor, there are natural and artificial grounding line points and grounding trunk and grounding branch line points.
3 grounding device installation and connection. Grounding device should be avoided near sidewalks and building entrances and exits, electrical equipment grounding branch should be connected to the grounding trunk or grounding body alone, do not allow series connection. Grounding trunk should be connected to the grounding body in two places.
The distance between the grounding body and the building should not be less than 1.5m, and the distance between the grounding body and the independent lightning rod should not be less than 3m. the color and simarouba of the grounding wire should be in accordance with the national standard.
7, leakage protector
Leakage protector is also called leakage protection switch, is mainly used in the equipment leakage faults as well as a fatal risk of personal electric shock protection. The earth leakage protector mainly includes several parts such as detecting element (zero sequence current transformer), intermediate link (including amplifier, comparator, striker, etc.), executing element (main switch) and testing element.
Correct and reasonable selection of leakage protector rated leakage current is very important: on the one hand, in the event of electric shock or leakage current exceeds the permissible value, the leakage protector can be selective action; on the other hand, the leakage protector in the normal leakage current should not be acted on, to prevent the power supply is interrupted and cause unnecessary economic losses.
Leakage protector rated leakage current should meet the following three conditions:
①In order to ensure personal safety, the rated leakage current should be no greater than the value of the human body's safety current, internationally recognized as the value of the human body's safety current of 30mA;
②In order to ensure the reliable operation of the grid, the rated leakage current should be avoided over the normal leakage of low-voltage grid current;
③In order to ensure the reliable operation of the grid, the rated leakage current should be avoided over the normal leakage of low-voltage grid;
③ In order to ensure the selectivity of multi-level protection, the next level of rated leakage current should be less than the last level of rated leakage current, all levels of rated leakage current should be 112 ~ 215 times the level difference. The action time of the leakage protector is the maximum segmentation time of the action. Should be determined according to the protection requirements, there are fast, fixed-time type.
Expanded Information:
1) the main power conductor in the work of the pipe through the wall, the first thing to consider is the size of the rated current for the load of this power conductor, as well as special circumstances of the short-circuit current after the impact of the thermal effect caused by the wire, should first think of is that, when the wire is worn into the tube, the space is limited, and narrow and small, resulting in a small area of heat dissipation, and in the long run, prompting insulation Aging dangerous accidents.
Secondly, the construction of wires through the wall pipe when the raw pulling and tugging, but also very likely to cause insecurity, it can be seen that the wires through the wall is a simple and common work methods, but often in this a common misuse, the consequences are: reduce the whole set of power supply line life, and thus also a waste of manpower, material and financial resources.
2) in the ground in the electromechanical engineering, selection is also very critical, should first calculate the total power of all electrical equipment, reactive power, and then in accordance with the value of the calculated power to select and match the qualified adaptive transformer. In the meantime, some electromechanical personnel but the selection is oversized capacity, that only large capacity will be safe.
In fact, the selection of large capacity, first of all, a waste of financial resources, and secondly, a waste of material resources, and most importantly, increased insecurity, for example, the rated capacity of 100kv A/380v power transformer, the protection of integrating the range of 10A-200A, and 800kv A power transformer protection integrating the range of 100A
This shows that if the current at 50A caught fire, if the capacity of the power transformer protection of small rectification exactly at 50A, can immediately act to cut off the power supply, while the capacity of the protection of the large but no notice, because it is the lowest at 100A, this shows that it is necessary to choose the appropriate, because it is economic and reasonable, but also safe. So it is important to choose the right power transformer.
Selection is completed to start wiring, in the three-phase four-wire power supply, should first pay attention to the three-phase firewire current equalization and matching problems, followed by the three-phase firewire separate and with the center line (ground) wiring, first of all, to the households of the main switch (with leakage of the main switch), and then to the sub-switch.
Special attention is paid to the switch above, there is a fire wire and zero line marking, must not be connected to the reverse, otherwise, the protection of the loss of action, the consequences are serious, unthinkable.
Secondly, due to the constructor's carelessness, in the electrical installation process, the standard is the firewire into the switch, the zero line into the lamp, and due to the constructor's negligence to the location of the change, and even the firewire into the lamp head, the zero line into the switch, which makes the lamps and lanterns are not bright, however, but still with a single-phase 380v dangerous voltage directly jeopardizes personal safety.
This kind of situation, the general public think, the lights do not light up when there is no electricity, and then due to the paralysis of the construction workers, it is very easy for the construction workers to cause physical insecurity.
3)In each substation output power lines, are through the wall of the pre-positioned iron pipe through the delivery to the various households, through the wall piping design should be the first to pay attention to is that the iron pipe should be chamfered at both ends, and then polished with gauze before it is safe.
Otherwise, through the wall iron pipe ends of the sharp spines can make this project of the transmission line outside insulation scratch, light is to speed up the insulation aging, reduce the service life of this project, heavy is to cut through the wire, directly affecting the power supply, especially in the wall pipe inside the part if it is bad, the consequences will be very serious, first of all, check the failure of the effort, and secondly, the handling of the failure is not good to deal with.
4) in the installation of lightning protection system in the construction process, should first of all be clear that this lightning protection system in this place to install the importance and practical safety, and then is the welder constructor's power and construction attitude and method, is serious or confused dry, will directly affect the safety of the power system.
Because of the construction of the welding of the bad and cause false welding, false welding and other ways, resulting in the whole lightning protection system can not function properly, thus causing the security consequences and economic losses will be unimaginable.
Reference: