EB 112.3. Preparing for the delivery of the second group of electrical safety
Good day to all. In the course of the work path, valiant engineers are required to take exams in electrical safety, obtaining, confirming or increasing their group. Even if the gallant engineers sit on the chair all the time. Even if the chair is grounded.
When this task stood in front of me, I googled a couple of hours and sweated before I found everything I needed. The problem is that useful information is lost among advertisements, expensive courses and heaps of spam. Reading this post will help in memorizing the correct answers of the tickets and tearing away the covers from why electrical safety is needed.
Under the cut, I collected everything that is needed for the delivery of the second group on DL - elements of legislation, preparation methods, tickets with answers and theory. Large amounts of information collected in spoilers. Open what you need. No ads, and of course, ducks!
When an engineer is assigned to a group, he is issued an appropriate certificate. This certificate says that the lyrical hero has the right to perform certain works, and the responsibility that falls on him in case of emergency situations is strictly regulated. It all begins, as a rule, from group II.
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Electrical Safety Tolerance Groups
Groups, skill subtleties and staff requirements
In accordance with PTEEP (Rules of Technical Operation of Electrical Installations of the Consumer) and PTB (Rules of Safety Engineering) for the personnel serving electrical installations, 5 electrical safety qualification groups are established:
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Groups:
- I qualification group is assigned to non-electrical production personnel: serving electric furnaces, etc.
- Qualification group II is assigned by the qualification commission to non-electrical personnel servicing installations and equipment with electric drive - electric welders (without right of connection), thermistors of HDTV installations, machinists of lifting machines, mobile machines and mechanisms with electric drives working with manual electric machines and other portable electrical receivers, and t .d
- III qualification group is assigned only to electrical personnel. This group gives the right of sole maintenance, inspection, connection and disconnection of electrical installations from the mains voltage up to 1000 V.
- IV qualification group is assigned only to persons of electrotechnical personnel. Persons with a qualification group of at least IV are entitled to maintenance of electrical installations with voltages above 1000 V.
- V qualification group is assigned to persons responsible for electrical equipment and other engineering and technical personnel in installations with a voltage higher than 1000 V.
Notes:
- Persons with V qualification group have the right to give orders and supervise work in electrical installations with voltages up to 1000 V or higher.
- Persons from electrical personnel with electrical safety group II-V, who have expired certificates or have not passed the knowledge test, are equal to individuals with group I.
- Trainees under the age of 18 are not allowed to assign a group above II.
- A safety engineer of a controlling electrical installation (assigned to Group IV of the Russian Industrial Class 016-2001) requires a total work experience of at least 3 years (not necessarily in electrical installations).
Staff Requirements:
- Group II:
- Elementary technical knowledge about electrical installation and its equipment.
- A clear view of the danger of electric current, the danger of approaching to live parts.
- Knowledge of basic precautions when working in electrical installations.
- Practical skills in first aid to victims.
- Group III:
- Elementary knowledge in general electrical engineering.
- Knowledge of electrical installations and the order of its maintenance.
- Knowledge of general safety regulations, including rules for admission to work, rules for use and testing of protective equipment, and special requirements for work performed.
- Ability to ensure safe operation and to supervise those working in electrical installations.
- Knowledge of the rules for the release of the victim from the action of electric current, first aid and the ability to practically render it to the victim.
- Group IV:
- Knowledge of electrical engineering in the volume of a specialized vocational school.
- A complete picture of the danger when working in electrical installations.
- Knowledge of these Rules, rules for the technical operation of electrical equipment, rules for the use and testing of protective equipment, electrical installations and fire safety in the volume of his position.
- Knowledge of electrical installation schemes and equipment serviced site, knowledge of technical measures to ensure the safety of work.
- The ability to instruct, organize the safe conduct of work, to supervise the members of the brigade.
- Knowledge of the rules for the release of the victim from the action of electric current, first aid and the ability to practically render it to the victim.
- The ability to train staff in safety regulations, practical methods of first aid.
- Group V:
- Knowledge of electrical installation diagrams, equipment layout of technological processes of production.
- Knowledge of these rules, rules of use and testing of remedies, a clear idea of ​​what caused this or that requirement.
- Knowledge of the rules of technical operation, the rules of electrical installations and fire safety in the amount of his position.
- Ability to organize safe work and direct the work in electrical installations of any voltage.
- The ability to clearly designate and state the requirements for safety measures when instructing employees.
- The ability to train staff in safety regulations, practical techniques of medical care.
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Categories of electrical personnel
There are 4 of them and there are questions about it in the tickets
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- Administrative and technical staff - Managers and specialists charged with organizing technical and operational services, carrying out repair, installation and commissioning work in electrical installations.
- Operational personnel - Personnel engaged in the operational management and maintenance of electrical installations - inspection, operational switching, workplace preparation, admission and supervision of workers, and performance of works in the order of current operation.
- Repair personnel - Personnel providing maintenance and repair, installation, commissioning and testing of electrical equipment.
- Maintenance-repair personnel - Repair personnel specially trained and trained for operational service in the approved scope of electrical installations assigned to them.
(POT R M-016-2001 RD 153-34.0-03.150-00 "Terms and definitions").
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What is an electrical installation
From the point of view of
In the Rules of technical operation of electrical installations of consumers, as well as the Rules on labor protection during the operation of electrical installations, the following definition is given to the term electrical installation:
Electrical installation is a set of machines, devices, lines and auxiliary equipment (together with the facilities and premises in which they are installed) intended for the production, transformation, transformation, transmission, distribution of electrical energy and its transformation into another type of energy. (Rules of technical operation of electrical installations of consumers. "Terms and definitions"). At the same time, if the electrical installation or its part is under voltage, or to which the voltage can be supplied by switching on the switching devices, then such installations are called the existing electrical installation. (POT R M-016-2001 153-34.0-03.150-00 “Terms and definitions ").
1. Electrical switchgear or switchgear - electrical installation that serves to receive and distribute electricity and contains switching devices, busbars and connecting buses, auxiliary devices (compressor, battery, etc.), as well as protection devices, automation and measuring instruments. (( POT R M-016-2001 RD 153-34.0-03.150-00 "Terms and definitions") In turn, switchgears can be:
Switchgear open - switchgear, where all or the main equipment is located in the open air (POT R M-016-2001 RD 153-34.0-03.150-00 "Terms and Definitions").
Switchgear Closed - switchgear, the equipment of which is located in the building. (POT R M-016-2001 RD 153-34.0-03.150-00 "Terms and definitions").
Switchgear complete - switchgear consisting of fully or partially closed cabinets or units with built-in appliances, protection devices and electrics, supplied in assembled or fully prepared for assembly. (POT R M-016-2001 RD 153-34.0-03.150-00 "Terms and definitions").
2. Electrical substation - electrical installation designed to convert and distribute electrical energy. (Rules of technical operation of electrical installations of consumers. "Terms and definitions").
In turn, the set of substations, switchgears and electrical lines connecting them, located on the territory of a district, settlement, and consumers of electrical energy form an electrical network. (POT R M-016-2001 RD 153-34.0-03.150-00 "Terms and definitions").
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Electrical installation is a set of machines, devices, lines and auxiliary equipment (together with the facilities and premises in which they are installed) intended for the production, transformation, transformation, transmission, distribution of electrical energy and its transformation into another type of energy. (Rules of technical operation of electrical installations of consumers. "Terms and definitions"). At the same time, if the electrical installation or its part is under voltage, or to which the voltage can be supplied by switching on the switching devices, then such installations are called the existing electrical installation. (POT R M-016-2001 153-34.0-03.150-00 “Terms and definitions ").
Types of electrical installations:
1. Electrical switchgear or switchgear - electrical installation that serves to receive and distribute electricity and contains switching devices, busbars and connecting buses, auxiliary devices (compressor, battery, etc.), as well as protection devices, automation and measuring instruments. (( POT R M-016-2001 RD 153-34.0-03.150-00 "Terms and definitions") In turn, switchgears can be:
Switchgear open - switchgear, where all or the main equipment is located in the open air (POT R M-016-2001 RD 153-34.0-03.150-00 "Terms and Definitions").
Switchgear Closed - switchgear, the equipment of which is located in the building. (POT R M-016-2001 RD 153-34.0-03.150-00 "Terms and definitions").
Switchgear complete - switchgear consisting of fully or partially closed cabinets or units with built-in appliances, protection devices and electrics, supplied in assembled or fully prepared for assembly. (POT R M-016-2001 RD 153-34.0-03.150-00 "Terms and definitions").
2. Electrical substation - electrical installation designed to convert and distribute electrical energy. (Rules of technical operation of electrical installations of consumers. "Terms and definitions").
In turn, the set of substations, switchgears and electrical lines connecting them, located on the territory of a district, settlement, and consumers of electrical energy form an electrical network. (POT R M-016-2001 RD 153-34.0-03.150-00 "Terms and definitions").
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How to call your PC, bespereboynik or router, decide for yourself.
Theory recommended for reading
The spoiler contains information that may be asked at the oral exam. If you are preparing to surrender to a category, this is definitely not superfluous. By the way, it is written in such a way that it does not tend to sleep.
The concept of electrical safety. Electrical injury. Information on the classification of injuries, loops of passage and step voltage (about how, which go goose step).
Electrical safety is understood as a system of organizational and technical measures to protect a person from the effects of damaging factors of electric current.
Electrical injury - the result of human exposure to electric current and electric arc.
An electric current passing through a living organism produces:
Electrical injuries include:
Depending on the effects of electric shocks are divided into four degrees:
The main adverse effects that may occur due to electric shock:
The flow of electric current through human organs can cause cardiac arrest, respiration; muscle breaks, brain damage, burns. Such damages are characteristic of a striking current of more than 10 milliamperes, but even the sensation current (1-2 mA) can scare a person, as a result of which mechanical injuries are not excluded (for example, due to a fall from a height).
The main factors determining the outcome of a lesion are:
Current and voltage
Electric current, as a striking factor, determines the degree of physiological effects on humans. Voltage should be considered only as a factor causing the flow of a particular current in specific conditions - the greater the voltage of touch, the more damaging the current.
According to the degree of physiological impact, the following striking currents can be distinguished:
It should be noted that no voltage can be considered completely safe and work without protective equipment.
So, for example, a car battery has a voltage of 12-15 volts and does not cause an electric shock when touched (the current through the human body is less than the threshold sensible current). But if the battery terminals are accidentally closed, a powerful arc arises, which can severely burn the skin or retina of the eyes; mechanical injuries are also possible (a person instinctively recoils from the arc and may fall unsuccessfully). Similarly, a person instinctively recoils when touching a network of temporary lighting (36 volts, current is already felt), which threatens to fall from a height, even if the current flowing through the body is small and could not cause defeat by itself.
Thus, arbitrarily low voltage does not negate the use of protective equipment, but only changes their nomenclature (type), for example, when working with a battery, you should use protective glasses. Work on current-carrying parts without the use of protective equipment is possible only with the complete removal of voltage!
The duration of the current.
It has been established that electric shock is possible only in the standing of complete rest of the human heart, when there is no contraction (systole) or relaxation (diastole) of the ventricles of the heart and atria. Therefore, for a short time, the effect of the current may not coincide with the phase of complete relaxation, but anything that increases the pace of the heart’s work contributes to an increased likelihood of heart failure when an electric shock of any duration occurs. These reasons include: fatigue, agitation, hunger, thirst, fear, taking alcohol, drugs, certain drugs, smoking, illness, etc.
Body resistance
The value is non-constant, depends on the specific conditions, varies from a few hundred ohms to several meg. With a sufficient degree of accuracy, we can assume that when exposed to a voltage of industrial frequency of 50 Hertz, the resistance of the human body is an active quantity consisting of internal and external components. The internal resistance of all people is about the same and is 600 - 800 ohms. From this we can conclude that the resistance of the human body is mainly determined by the size of the external resistance, and specifically the state of the skin of the hands with a thickness of only 0.2 mm (first of all, its outer layer - the epidermis).
There are many examples of this, here is one of them. The worker lowers the middle and index fingers of the hand into the electrolytic bath and receives a fatal blow. It turned out that the cause of death was a cut on the skin of one of the fingers. The epidermis did not exert its protective effect, and the defeat occurred at a clearly safe loop of current.
Indeed, if we evaluate this fact in relative terms and take the skin resistance for 1, then the resistance of internal tissues, bones, lymph, blood will be 0.15 - 0.20, and the resistance of nerve fibers is only 0.025 (“nerves” are excellent conductors of electric current!) . By the way, this is why the application of electrodes to the so-called acupuncture points is dangerous. Since they are connected by nerve fibers, a striking current can occur at very low voltages. It is one of these cases described in the literature, when the defeat of a person occurred at a voltage of 5 volts. The resistance of the body is not constant: in conditions of high humidity, it decreases 12 times, in water 25 times, sharply reduces its alcohol intake.
Thus, the factors of a person’s condition that significantly increase the probability of a fatal injury to a person by electric current include:
The path ("loop") of the current through the human body.
When investigating accidents related to exposure to electric current, first of all it turns out which way the current flowed. A person can touch current-carrying parts (or metal non-current-carrying parts that may be under stress) with a variety of body parts. Hence the variety of possible paths of current.
The most likely are the following:
All loops, except the last, are called “big” or “full” loops, the current captures the heart area and they are the most dangerous. In these cases, 8-12 percent of the total current flow through the heart. The leg-leg loop is called “small”; only 0.4 percent of the total current flows through the heart. This loop occurs when a person is in the area of ​​current spreading, falling under the step voltage.
Step voltage is the voltage between two points of the earth, due to the spreading of current in the ground, while simultaneously touching them with the feet of a person. In this case, the wider the step, the more current flows through the legs.
Such a current path does not pose a direct danger to life, but under its action a person can fall and the path of current flow becomes life-threatening.
For protection against step voltage are additional means of protection - dielectric bots, dielectric mats. In the case when the use of these means is not possible, one should leave the spreading area so that the distance between the feet on the ground is minimal - short steps. It is also safe to move on a dry board and other dry, non-conductive objects.
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Electrical safety is understood as a system of organizational and technical measures to protect a person from the effects of damaging factors of electric current.
Electrical injury - the result of human exposure to electric current and electric arc.
An electric current passing through a living organism produces:
- thermal (thermal) action, which is expressed in burns of certain parts of the body, heating of blood vessels, blood, nerve fibers, etc .;
- electrolytic (biochemical) action - expressed in the decomposition of blood and other organic liquids, causing significant disruption of their physico-chemical compositions;
- biological (mechanical) action - expressed in the stimulation and stimulation of living tissues of the body, accompanied by involuntary convulsive contraction of muscles (including the heart, lungs).
Electrical injuries include:
- electric burns (current, contact arc, and also combined);
- electrical signs ("tags"), skin metallization;
- mechanical damage;
- electrophthalmia;
- electric shock (electric shock).
Depending on the effects of electric shocks are divided into four degrees:
- muscle contraction without loss of consciousness;
- muscle contraction with loss of consciousness;
- loss of consciousness with impaired breathing or cardiac activity;
- a state of clinical death due to cardiac fibrillation or asphyxiation (asphyxiation).
The main adverse effects that may occur due to electric shock:
The flow of electric current through human organs can cause cardiac arrest, respiration; muscle breaks, brain damage, burns. Such damages are characteristic of a striking current of more than 10 milliamperes, but even the sensation current (1-2 mA) can scare a person, as a result of which mechanical injuries are not excluded (for example, due to a fall from a height).
The main factors determining the outcome of a lesion are:
- current and voltage value;
- duration of exposure to current;
- body resistance;
- loop ("path") current;
- psychological readiness to strike.
Current and voltage
Electric current, as a striking factor, determines the degree of physiological effects on humans. Voltage should be considered only as a factor causing the flow of a particular current in specific conditions - the greater the voltage of touch, the more damaging the current.
According to the degree of physiological impact, the following striking currents can be distinguished:
- 0.8 - 1.2 mA - threshold sensible current (that is, the lowest current value that a person begins to sense);
- 10 - 16 mA - threshold non-releasing (riveting) current, when, due to convulsive contraction of hands, a person cannot free himself from current-carrying parts;
- 100 mA - threshold fibrillation current; It is a calculated shock current. It should be borne in mind that the probability of hitting such a current is 50% with a duration of exposure to at least 0.5 seconds.
It should be noted that no voltage can be considered completely safe and work without protective equipment.
So, for example, a car battery has a voltage of 12-15 volts and does not cause an electric shock when touched (the current through the human body is less than the threshold sensible current). But if the battery terminals are accidentally closed, a powerful arc arises, which can severely burn the skin or retina of the eyes; mechanical injuries are also possible (a person instinctively recoils from the arc and may fall unsuccessfully). Similarly, a person instinctively recoils when touching a network of temporary lighting (36 volts, current is already felt), which threatens to fall from a height, even if the current flowing through the body is small and could not cause defeat by itself.
Thus, arbitrarily low voltage does not negate the use of protective equipment, but only changes their nomenclature (type), for example, when working with a battery, you should use protective glasses. Work on current-carrying parts without the use of protective equipment is possible only with the complete removal of voltage!
The duration of the current.
It has been established that electric shock is possible only in the standing of complete rest of the human heart, when there is no contraction (systole) or relaxation (diastole) of the ventricles of the heart and atria. Therefore, for a short time, the effect of the current may not coincide with the phase of complete relaxation, but anything that increases the pace of the heart’s work contributes to an increased likelihood of heart failure when an electric shock of any duration occurs. These reasons include: fatigue, agitation, hunger, thirst, fear, taking alcohol, drugs, certain drugs, smoking, illness, etc.
Body resistance
The value is non-constant, depends on the specific conditions, varies from a few hundred ohms to several meg. With a sufficient degree of accuracy, we can assume that when exposed to a voltage of industrial frequency of 50 Hertz, the resistance of the human body is an active quantity consisting of internal and external components. The internal resistance of all people is about the same and is 600 - 800 ohms. From this we can conclude that the resistance of the human body is mainly determined by the size of the external resistance, and specifically the state of the skin of the hands with a thickness of only 0.2 mm (first of all, its outer layer - the epidermis).
There are many examples of this, here is one of them. The worker lowers the middle and index fingers of the hand into the electrolytic bath and receives a fatal blow. It turned out that the cause of death was a cut on the skin of one of the fingers. The epidermis did not exert its protective effect, and the defeat occurred at a clearly safe loop of current.
Indeed, if we evaluate this fact in relative terms and take the skin resistance for 1, then the resistance of internal tissues, bones, lymph, blood will be 0.15 - 0.20, and the resistance of nerve fibers is only 0.025 (“nerves” are excellent conductors of electric current!) . By the way, this is why the application of electrodes to the so-called acupuncture points is dangerous. Since they are connected by nerve fibers, a striking current can occur at very low voltages. It is one of these cases described in the literature, when the defeat of a person occurred at a voltage of 5 volts. The resistance of the body is not constant: in conditions of high humidity, it decreases 12 times, in water 25 times, sharply reduces its alcohol intake.
Thus, the factors of a person’s condition that significantly increase the probability of a fatal injury to a person by electric current include:
- anything that increases the pace of the heart - fatigue, arousal, taking alcohol, drugs, certain drugs, smoking, illness;
- anything that reduces skin resistance - sweating, cuts, alcohol intake.
The path ("loop") of the current through the human body.
When investigating accidents related to exposure to electric current, first of all it turns out which way the current flowed. A person can touch current-carrying parts (or metal non-current-carrying parts that may be under stress) with a variety of body parts. Hence the variety of possible paths of current.
The most likely are the following:
- “Right hand - legs” (20% of cases of defeat);
- “Left hand - legs” (17%);
- “Both arms are legs” (12%);
- “Head - legs” (5%);
- “Hand - hand” (40%);
- “Leg - leg” (6%).
All loops, except the last, are called “big” or “full” loops, the current captures the heart area and they are the most dangerous. In these cases, 8-12 percent of the total current flow through the heart. The leg-leg loop is called “small”; only 0.4 percent of the total current flows through the heart. This loop occurs when a person is in the area of ​​current spreading, falling under the step voltage.
Step voltage is the voltage between two points of the earth, due to the spreading of current in the ground, while simultaneously touching them with the feet of a person. In this case, the wider the step, the more current flows through the legs.
Such a current path does not pose a direct danger to life, but under its action a person can fall and the path of current flow becomes life-threatening.
For protection against step voltage are additional means of protection - dielectric bots, dielectric mats. In the case when the use of these means is not possible, one should leave the spreading area so that the distance between the feet on the ground is minimal - short steps. It is also safe to move on a dry board and other dry, non-conductive objects.
To the spoiler cap To the beginning of the article
Electrical safety in existing electrical installations up to 1000 volts. Manufacturing jobs.
Electrical installations are those in which electricity is produced, converted and consumed. Electrical installations include mobile and stationary sources of electricity, electrical networks, switchgear and connected current collectors.
The existing electrical installations are installations that are fully or partially under voltage or to which voltage can be supplied at any time by switching on the switching equipment.
According to the degree of danger of injury to personnel by electrical current, electrical installations are subdivided into electrical installations up to 1000 volts and above 1000 volts .
To give an order to perform work in existing electrical installations up to 1000 Volts has the right to employee management staff, having a group of electrical safety not lower than 4th.
Work in electrical installations in relation to security measures are divided into the following:
The works with the removal of voltage include work performed in the electrical installation (or part of it), in which voltage is removed from the current-carrying parts.
Works without stress relief on current-carrying parts, and in the vicinity of them, are works performed directly on these parts or in the vicinity of them. In installations with voltages higher than 1000 volts, as well as on overhead lines up to 1000 volts, the same works include those that are performed at distances from live parts less than acceptable. Such work should be performed by at least two persons: the producer with a group not lower than IV, the rest not less than III.
Technical measures to ensure the safety of works with stress relief.
When preparing the workplace for stress relieving by operating personnel, the following technical measures should be performed in the order indicated:
All these technical measures can be carried out with a qualifying group of at least III.
Work with stress relief can be done either with the imposition of grounding, or without the imposition of grounding, but with the adoption of technical measures to prevent the erroneous supply of voltage to the workplace.
Production outages.
At the work site, the live parts on which the work is performed must be disconnected, as well as those that may be accessible to the touch when performing work.
Non-insulated live parts that can be touched can not be disconnected if they are securely shielded with insulating plates of dry insulating materials.
Disconnection must be made in such a way that the parts of the electrical installation or electrical equipment allocated for the work are separated from all current-carrying parts under voltage, switching devices or removing fuses, as well as disconnecting the ends of cables (wires) that can be energized. work place.
Disconnection can be performed:
The procedure for checking the disconnected state of switching devices is established by the person issuing the order or giving the order.
To prevent the supply of voltage to the workplace due to transformation, all power, measuring and various special transformers connected to both the electrical equipment being prepared for repair should be disconnected from both the high and low voltage side.
In cases where the work is performed without the use of portable grounding, additional measures should be taken to prevent the erroneous supply of voltage to the workplace: mechanical locking of drives of disconnected devices, additional removal of fuses connected in series with switching devices, use of insulating plates in switches, automatic machines, etc. p. These technical measures should be specified when issuing a work order. If it is impossible to take these additional measures, the ends of the supply or outgoing lines on the shield, assembly or directly at the work site should be disconnected; when disconnecting the cable from the fourth (zero) core, this core should be disconnected from the zero bus.
Hanging warning posters, fencing work place.
On the handles, keys and control buttons of all switching devices, as well as on the contact racks (bases) of the fuses, with the help of which voltage can be applied to the place of work, posters “Do not turn on - people work”, “Do not turn on - work on lines. "
Neighboring workplace parts not disconnected from live parts accessible to a random touch should be fenced during operation.
Temporary fences can be dry, well fortified screens, lining of wood, micanite, getinaksa, textolite, rubber, etc. On temporary fences should be posted posters "Stop - dangerous to life."
Before installing fences, dust must be carefully wiped off.
The installation of fences applied directly to live parts should be made with care, in dielectric gloves and glasses, in the presence of a second person with the IV qualifying group.
At all prepared work places after applying grounding, a poster “Work here” is posted.
During the work of the brigade personnel it is PROHIBITED to rearrange or remove the posters and installed temporary fences and to enter the territory of the fenced areas.
Check the absence of voltage.
Before starting all work on electrical installations with the removal of voltage, you must check the absence of voltage in the work area. The absence of voltage is checked by a voltage indicator with a neon lamp.
Immediately before checking for the absence of voltage, it is necessary to make sure that the pointer used is in good condition by checking it on current-carrying parts located nearby and knowingly under voltage.
DO NOT use pointers with low input resistance (test lamps, LED voltage indicators, audible “controls”, etc.) for checking the absence of voltage, as they do not indicate induced voltage that is dangerous to human life.
The absence of voltage should be checked:
Stationary devices, signaling the disconnected state of the installation, are only an aid, on the basis of indications of which it is not allowed to conclude that there is no voltage.
Ground overlays.
Grounding should be imposed on the current-carrying parts of all phases disconnected for the production of the electrical installation from all sides, from where voltage can be applied, including due to reverse transformation.
It is sufficient to overlay one side of the ground on each side. These earthing can be separated from the current-carrying parts or equipment on which the work is performed, disconnected by disconnectors, switches, circuit breakers or fuses removed.
The imposition of grounding directly on the live parts on which the work is performed, is required when these parts may be under induced voltage (potential) or they may be energized from an external source of dangerous magnitude. , . , , .
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Electrical installations are those in which electricity is produced, converted and consumed. Electrical installations include mobile and stationary sources of electricity, electrical networks, switchgear and connected current collectors.
The existing electrical installations are installations that are fully or partially under voltage or to which voltage can be supplied at any time by switching on the switching equipment.
According to the degree of danger of injury to personnel by electrical current, electrical installations are subdivided into electrical installations up to 1000 volts and above 1000 volts .
To give an order to perform work in existing electrical installations up to 1000 Volts has the right to employee management staff, having a group of electrical safety not lower than 4th.
Work in electrical installations in relation to security measures are divided into the following:
- with stress relief;
- without removing the voltage on the current-carrying parts and near them.
The works with the removal of voltage include work performed in the electrical installation (or part of it), in which voltage is removed from the current-carrying parts.
Works without stress relief on current-carrying parts, and in the vicinity of them, are works performed directly on these parts or in the vicinity of them. In installations with voltages higher than 1000 volts, as well as on overhead lines up to 1000 volts, the same works include those that are performed at distances from live parts less than acceptable. Such work should be performed by at least two persons: the producer with a group not lower than IV, the rest not less than III.
Technical measures to ensure the safety of works with stress relief.
When preparing the workplace for stress relieving by operating personnel, the following technical measures should be performed in the order indicated:
- necessary disconnections were made and measures were taken to prevent the supply of voltage to the work site due to the erroneous or inadvertent switching on of the switching equipment;
- Manual prohibitions and remote control switches of switching equipment contain prohibitive posters (“Do not turn on, people work”, “Do not turn on, work on the line”) and, if necessary, barriers are installed;
- portable earths are connected to the “Earth”, the absence of voltage on the current-carrying parts, on which grounding should be applied to protect people from electric shock, is checked;
- immediately after checking the absence of voltage, grounding should be applied (grounding knives are included, and portable grounding should be installed where they are absent);
- warning and prescriptive posters were posted, workplaces and current-carrying parts that remained under voltage were fenced if necessary. Depending on local conditions, live parts are shielded before or after grounding is applied.
All these technical measures can be carried out with a qualifying group of at least III.
Work with stress relief can be done either with the imposition of grounding, or without the imposition of grounding, but with the adoption of technical measures to prevent the erroneous supply of voltage to the workplace.
Production outages.
At the work site, the live parts on which the work is performed must be disconnected, as well as those that may be accessible to the touch when performing work.
Non-insulated live parts that can be touched can not be disconnected if they are securely shielded with insulating plates of dry insulating materials.
Disconnection must be made in such a way that the parts of the electrical installation or electrical equipment allocated for the work are separated from all current-carrying parts under voltage, switching devices or removing fuses, as well as disconnecting the ends of cables (wires) that can be energized. work place.
Disconnection can be performed:
- switching devices with manual control, the position of the contacts can be seen from the front or can be installed by inspecting the panels from the rear, opening the shields, removing the covers. Perform these operations must comply with security measures. If there is full confidence that in switching devices with closed contacts, the position of the handle or pointer corresponds to the position of the contacts, then it is allowed not to remove the covers to check for tripping;
- Contactors or other switching devices with automatic drive and remote control with available inspection contacts after taking measures to eliminate the possibility of erroneous switching on (removing the fuses of the operating current, disconnecting the ends of the switching coil).
The procedure for checking the disconnected state of switching devices is established by the person issuing the order or giving the order.
To prevent the supply of voltage to the workplace due to transformation, all power, measuring and various special transformers connected to both the electrical equipment being prepared for repair should be disconnected from both the high and low voltage side.
In cases where the work is performed without the use of portable grounding, additional measures should be taken to prevent the erroneous supply of voltage to the workplace: mechanical locking of drives of disconnected devices, additional removal of fuses connected in series with switching devices, use of insulating plates in switches, automatic machines, etc. p. These technical measures should be specified when issuing a work order. If it is impossible to take these additional measures, the ends of the supply or outgoing lines on the shield, assembly or directly at the work site should be disconnected; when disconnecting the cable from the fourth (zero) core, this core should be disconnected from the zero bus.
Hanging warning posters, fencing work place.
On the handles, keys and control buttons of all switching devices, as well as on the contact racks (bases) of the fuses, with the help of which voltage can be applied to the place of work, posters “Do not turn on - people work”, “Do not turn on - work on lines. "
Neighboring workplace parts not disconnected from live parts accessible to a random touch should be fenced during operation.
Temporary fences can be dry, well fortified screens, lining of wood, micanite, getinaksa, textolite, rubber, etc. On temporary fences should be posted posters "Stop - dangerous to life."
Before installing fences, dust must be carefully wiped off.
The installation of fences applied directly to live parts should be made with care, in dielectric gloves and glasses, in the presence of a second person with the IV qualifying group.
At all prepared work places after applying grounding, a poster “Work here” is posted.
During the work of the brigade personnel it is PROHIBITED to rearrange or remove the posters and installed temporary fences and to enter the territory of the fenced areas.
Check the absence of voltage.
Before starting all work on electrical installations with the removal of voltage, you must check the absence of voltage in the work area. The absence of voltage is checked by a voltage indicator with a neon lamp.
Immediately before checking for the absence of voltage, it is necessary to make sure that the pointer used is in good condition by checking it on current-carrying parts located nearby and knowingly under voltage.
DO NOT use pointers with low input resistance (test lamps, LED voltage indicators, audible “controls”, etc.) for checking the absence of voltage, as they do not indicate induced voltage that is dangerous to human life.
The absence of voltage should be checked:
- between three pairs of phases;
- between each phase and PE-conductor ("earth");
- between zero working (N) and zero protective conductor (PE).
Stationary devices, signaling the disconnected state of the installation, are only an aid, on the basis of indications of which it is not allowed to conclude that there is no voltage.
Ground overlays.
Grounding should be imposed on the current-carrying parts of all phases disconnected for the production of the electrical installation from all sides, from where voltage can be applied, including due to reverse transformation.
It is sufficient to overlay one side of the ground on each side. These earthing can be separated from the current-carrying parts or equipment on which the work is performed, disconnected by disconnectors, switches, circuit breakers or fuses removed.
The imposition of grounding directly on the live parts on which the work is performed, is required when these parts may be under induced voltage (potential) or they may be energized from an external source of dangerous magnitude. , . , , .
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Rules for the use of protective equipment used in electrical installations
Questions ticket with the correct answers. Split on 7 themes in spoilers
Topic 1. General information about electrical installations
- What electrical installation is considered valid?
, , . - How are zero working (neutral) conductors?
N . - What letter and color designation should protective earth conductors have in electrical installations?
PE ( 15 100 ) . - What kind of letters and colors should tires have for alternating three-phase currents?
A – , B – , C – . - What kind of letters and colors should tires have at constant current?
(+) – , (-) – M – . - ?
380/220 . - ?
. - What neutral should 10 kV power grids work with?
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, : , , , , , . - What safety requirements are imposed on OES for enclosing and closing devices?
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Topic 2. General provisions of existing rules and regulations when working in electrical installations
- What electrical installations are covered by the requirements of the Electrical Installation Rules?
750 , - How are electrical installations divided according to electrical safety conditions?
1000 1000 - To whom do the Inter-sectoral rules on labor protection (safety rules) apply when operating electrical installations?
On employees of organizations, regardless of the form of ownership and organizational-legal forms, and other individuals engaged in maintenance of electrical installations, conducting operational switching in them, organizing and performing construction, installation, commissioning, repair work, testing and measurement - ?
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, 60%
Topic 3. Requirements for personnel and its preparation
Topic 4. The procedure for the construction of works in electrical installations.
Topic 5. Grounding and protective measures of electrical safety. Lightning protection
Topic 6. Rules for the use of equipment
To the spoiler cap To the beginning of the article
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1000 - How are dielectric gloves checked for punctures?
By twisting them in the direction of the fingers - In which electrical installations dielectric galoshes are used?
In electrical installations with voltage up to 1000 V - What electrical systems do dielectric bots use?
In all electrical installations - What are protective helmets for?
To protect against all of the above. - Which posters from those listed are prohibitive?
Do not turn on! People work. - Which posters of the following are warning signs?
Caution! Electrical voltage - Which posters from the above are indicative?
Grounded - What type of safety posters is a poster that says “Caution! Electrical voltage ”?
To the warning - What background should be at the warning sign “Caution! Electrical voltage ”, which is strengthened on the outer door of transformers?
Yellow - What background should be at the warning sign “Caution! Electric voltage ”, which is applied by means of a stencil to the reinforced concrete support of a power line?
The background is the color of the concrete surface.
To the spoiler cap To the beginning of the article
Topic 7. Rules for the release of victims of electrical current and the provision of first aid to them
To the spoiler cap To the beginning of the article
- What is the specific effect on the human body has an electric current?
All listed actions refer to specific - What electrical current is more dangerous for a person: constant or alternating?
Alternating current - What are the main “current loops” - the path for the passage of electric current through the human body?
Hand-hand, hand-foot, hand-head, foot-foot, head-foot - What needs to be done first of all in case of defeat of a person by electric current?
Disconnect electrical current - How should move in the zone of "step" voltage?
“Goose step” - Does a person who is under the influence of electric current and who feels normal after that need medical care?
Needs anyway - Mortally dangerous value of the electric alternating current flowing through the human body should be considered:
100 mA - In what is the maximum radius from the place where the earth touches the ground by the electric wire can you fall under the “stepping” voltage?
Within a radius of 8 m from the place of contact
To the spoiler cap To the beginning of the article
How to prepare for a pile of scattered information
- First of all, decide on-line tickets. Just like that, without preparation. See what the instructor wants from you and what the tickets are about.
There are many services with such an opportunity, for example such .
- Having understood that you should learn, read the theory. It is given in this article, there is still a good link . If all this is not enough for you, for the full and final enlightenment, read and . But the chances of falling asleep under this are much higher. And the documents on 200 p. - Fiction on an amateur.
- Reading the theory, solve tests. There are not so many questions, they will be remembered.
- Do not come to the test formally. All these rules are written not only in blood, but also in soot, for the reasons stated above. Yes, and extra knowledge is never superfluous.
PS or what else
After 4-5 months, apparently, I will pass the third category, I plan to write a similar article. Good luck to us all, and grounded chairs!
PSS and most importantly
Never, never try to measure the current in the outlet! Electrical safety in this case, you just do not pass!
Source: https://habr.com/ru/post/176219/
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