Basics of electrical safety

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                                             Basics of electrical safety.

                                            Training technology

Time - 2 hours	Number of students: 30-60
The form of training	Visual lecture
Teaching technology	Problematic
The plan of the lecture session	1. Effects of electric current on the human body. 2. Provide first aid to a person affected by electric current. 3. Causes of electric shock, injury and measures to prevent it. 4. Grounding and zero protection, protective shutdown devices. 5. Requirements for the installation of electrical devices.
The purpose of the training session: to learn the requirements for the safe use of electricity, protective equipment, providing first aid to a person injured by electric current.
Pedagogical tasks: — the effects of electric current on the human body are explained; — explains the causes of electric shock and injuries and measures to prevent it; — providing first aid to a person exposed to electric current; — Grounding and neutral protection, protective shutdown devices are explained; — The requirements for the installation of electrical devices are taught.	Learning outcomes: Students: — describe the effect of electric current on the human body; - tell the methods of providing first aid to a person affected by electricity; — they tell the reasons for falling under the influence of electric current, injury and measures to prevent it; — yThey imagine protection, protective shutdown devices by connecting to ground and zero; — state the requirements for the installation of electrical devices.
Teaching methods and techniques	Visual presentation, blitz-questioning, debriefing, clustering, yes-no technique
Teaching tools	Text of lectures, projector, handouts, graphic organizers.
Teaching form	Team, group and pair work.
Teaching conditions	Auditorium equipped with projector, computer.
The name of the base phrases of the subjects:	Basic Phrases Learning Objectives: 1. Effects of electric current on the human body. 2 Explain the causes of electric shock, injury and measures to prevent it. 3. Provide first aid to a person affected by electric current. 4. Grounding and neutral protection, protective shutdown devices are studied and implemented. 5. The requirements for the installation of electrical devices are studied and implemented.
Independent work: — studying the effect of electric current on the human body. — to learn the methods of first aid to a person affected by electricity. — causes of electric shock, injuries and development of measures to prevent it. — Drawing a scheme of earthing and neutral protection, protective shutdown devices. — a thorough study of the requirements for the installation of electrical devices.	Students: — to study the effect of electric current on the human body; — to study the causes of electric shock, injury, measures and methods of its prevention; — collects information on first aid and prevention of electrocution; — learns the requirements for the installation of electrical devices; — Grounding and neutral protection, protective shutdown devices are studied by students; — collects Internet news related to the topic.
Educational and scientific literature	1. NH Avliyokulov Modern teaching technologies Tashkent- 2001. 2. NH Avliyokulov Practical bases of teaching module system and pedagogic technology Bokhoro 2002y. 3. NH Avliyokulov, NNMusaeva Pedagogical technologies. Science and Technology Publishing House, 2008. 4. AT Murodov, SN Shodiev Labor protection. Text of lectures. B, 2003. 5. G'. Yormatov, YO. Isomuhamedov Labor protection. T., "Uzbekistan", 2002. 6. H. Azimov. Labor safety in construction Science 1997y 7. O'. Yoldoshev, U. Usmanov, O. Kudratov Labor protection labor 2001. 8. PVSoluyanov Praktikum po Okhrane truda. 9. IntYernet information:

1. 1. Effects of electric current on the human body.

The most dangerous aspect of electric shock is that it is not possible to foresee and sense this danger, to establish organizational and technical measures against the danger of electric current, to provide barrier devices, to avoid personal and collective protection systems. efficient use is extremely important.

Electric current is not only limited to biological effects, but it is divided into electric arc effects, magnetic field effects and static electricity effects, which are necessary for everyone to know.

1. A) The thermal effect of electric current is observed as a burn in some part of the human body, heating of blood vessels, nYerv and cells.

2. B) Electrolytic effect means a condition that causes changes in the physical and chemical properties of blood as a result of the breakdown of salts in blood or cells. In this case, the electric current can affect only some parts of the body without crossing the central nervous system and cardiovascular system.

3. V) Biological effect of electric current - this is a characteristic characteristic only for a living organism, as a result of this effect, due to the sharp contraction of the muscles, the living cells in the body vibrate, mainly the bioelectric processes in the organism (the human body is controlled by bioelectric currents) are disturbed and the current a beat condition occurs.

THE EFFECTS OF ELECTRIC CURRENT ARE DIVIDED INTO TWO GROUPS.

1. A) As a result of local electrical effects:

— burns occur when a voltaic arc forms between the body and the electrical conductor;

— the formation of electric signs — is the appearance of a clear gray or light-yellow 1-5 mm mark in the upper part of the surface;

- Metallization of the ground - this condition also occurs when an electric arc is formed;

1. B) Electric shock - considered in four levels

— as a result of sharp contraction of the muscles, the person gets out of the current and does not lose consciousness (0,6 - 1,5mA);

— as a result of sharp contraction of the muscles, the person loses consciousness, but the heart and breathing work (10-15mA);

— the person loses consciousness, the respiratory system or the heartbeat stops (25-50mA);

— the state of clinical death, in which no signs of life are visible in a person (100mA).

Clinical death is the interval between life and death, when a person lives for a certain amount of time at the expense of internal capabilities, this state lasts 5-8 minutes, and if there is no external help, the cells in the cerebral cortex disintegrate and become biological. passes into a state of death.

 Provide first aid to a person affected by electric current.

If the injured person has difficulty breathing, there is a state of trembling, but the heartbeat rhythm is relatively good, then it is necessary to give artificial respiration to this person.

In case of clinical death, it is necessary to massage the heart from the upper side along with artificial respiration.

Artificial respiration is called "mouth-to-mouth" in which the rescuer fills the lungs with air and blows this air through the victim's mouth into the lungs.

In this case, the helper should completely cover the injured person's mouth with his mouth and cover his nose with the help of his face or paws.

Blowing about 10-12 times a minute can be done through a gauze napkin and a tube, artificial respiration is continued until the patient regains consciousness.

External massage of the heart is performed in order to artificially restore blood circulation in the injured person's body.

After moving from the abdomen to the chest, 2 fingers mark the place to be massaged from above, put the hands on top of each other in the form of a right angle, and the body weight of the injured person on the chest with a force of 15-25 kg. The pressure should be 1 time per second with sharp force. In this case, the chest should drop inwards by 3-4 cm and it should be continued in accordance with the rhythm of the heartbeat. After every two puffs, it is necessary to press the chest 15 times. The injured person's heart rate and pulse are checked. For this, the above tasks are stopped for 2-3 seconds and pulse is tested.

Figure 1. Methods of artificial respiration and heart massage.

Appendix 3.

 Causes of electric shock, injury and measures to prevent it.

If any part of the human body falls into the electrical network, then there is a risk of electrocution. Depicting such a situation graphically, shorting can be defined as shorting between two phases and single-phase shorting.

Let's assume that a person falls into a single-phase line. In it, the current flow path can pass from the phase through the human body to the Earth.

The electricity used in industry is mainly 380 V. Such a current consists of three phases, and each phase has a voltage of 220 V relative to the Earth. The amount of current flowing through the body of a person exposed to such a current can be determined based on Ohm's law.

I = U / R

Here, I is the amount of current flowing through the human body; U - phase voltage;

R is resistance to current flow. For a single-phase person, the voltage is 220 V. And R consists of the sum of series resistances

R = Rt + Rn + R0 + R1

In this, Rt is the resistance of the human body, 1000 Ohm is accepted in technical calculations; Rn-the resistance of the floor on which a person is standing, if it is a wooden floor, its resistance is in the range of 20000 - 60000 Ohm; R0 - shoe resistance, this resistance is around 20000 - 50000 Ohm depending on the material of the shoe; The resistance of the R1 (neutral) wire when connected to Earth (usually any Earth connection resistance is required to be no greater than 4 Ohms).

If an electrocuted person stands on a conductive floor and his shoes are also conductive, then

This amount of electric current is dangerous for a person (2,2 times more than fibrillation current)

In this case, some factors can change the result of the damage caused by the electric current. For example, a person who is electrocuted is on a dry wooden floor and has non-conductive rubber shoes on his feet. In it, the amount of current that passed through his body

will be This is less than the amount allowed for long-term exposure to the human body.

 Grounding and neutral protection, protective shutdown devices.

Any electrical device, regardless of where it is used and in what kind of building, if there is a risk of electric voltage generation in its metal casing, its body is connected to the Earth, and this is called earthing protection of electrical devices.

Figure 2. Working diagram of protective earth connection:

a – general scheme, b – placement scheme, 1 – body, 2 – Earth connector

The main purpose of grounding protection is to transfer it to the ground when the metal casings of the electrical devices in use are energized, and one of its main features is to reduce the electric current to a safe level, as well as to create a potential difference around the grounding area. is to ensure that it does not

A grounding protection device means a metal stake that is grounded and designed to transmit electric current to the ground, and a metal conductor connecting this stake to an electrical device.

Grounding protection devices are mainly of two types:

1. a) Collective grounding, metal piles driven into the ground are installed outside the shop in a certain area.

2. b) Metal piles intended for grounding, placed along the contour, are connected by welding to each other by means of a conductor made of a metal strip along the perimeter of the area where the electrical device is installed. When grounding with a contour, electrical safety is equalized due to the piles connected to the ground, the difference of electric potentials across the area disappears.

Pre-connecting non-current-carrying metal parts of electrical devices with a zero wire is protection by connecting to zero.

Protective neutral wire, starting with solid grounding of the neutral parts of the power supply coil, is pulled along the entire network as a fourth neutral wire along with three phases, and is connected to the Earth as much as possible (at a certain distance).

The function of neutral protection is the same as that of earthing protection, that is, to neutralize the voltage that has flowed into the body of the electrical appliance.

Figure 3. Scheme of connection of the protective zero conductor in electrical devices: a - connection of the zero conductor to three-phase electrical consumers, b - connection of the zero conductor in the lighting fixtures, v - simultaneous connection of the zero and grounding conductors in electrical equipment connection

The main function of the neutral wire in the system protected by neutral connection is to create a short circuit without resistance with the current flowing into the body of the electrical system, activate the shutdown system that protects the amount of current flowing through the system, and ensures that no current is transferred to the device.

Requirements for the installation of electrical devices.

Special requirements are imposed on electric motors, protective shells of their connecting conductors, circuit breakers and protective devices, as well as their installation and use.

Providing electrical conductors of electrical devices with protective shells plays an important role.

1. a) Prevents large amounts of electrical current loss.

2. b) Does not allow the working employee to fall under the influence of electric current.

3. c) Eliminates the risk of fire caused by sparks from alternating voltages of electrical systems.

According to the rules for the installation of electrical devices, the resistance of the protective sheath between two protective devices, in electrical systems or between the last protective device and any conductor is required to be not less than 0,5 M Ohm.

In dangerous rooms, this resistance should be 20-50 percent more.

The resistance of the protective shell of the electrical device is measured after its installation and during the period of use it is measured and checked at least 1 time per year, at least 2 times in hazardous rooms.

When unshielded open wires are used, it is recommended to install them at a height of at least 3,5 m, and in case of wire breakage, they must have automatic shutdown systems.

The protective devices of electrical systems are very simple in design, and if the power in the system exceeds the nominal (25 percent) amount, it automatically cuts off the current.

If the current suddenly increases by 2,5 times, the Melting Part will Melt for 0,2s. It is not allowed to use the standard quality of the melting part, instead of it it is allowed to use artificial devices made of copper wires. Because such artificial devices do not work on time, heat up other parts and conductors in the system and cause a fire as a result of the burning of protective shells.

Retainers are available in plug, plate, and tube types, all of which are replaceable.

To replace protective devices, it is recommended to turn off the electricity, and in most cases, personal protective equipment is used.

Devices and devices that serve to protect workers working on electrical devices from injury, falling from a height, and the effects of an electric field are called electrical protection devices.

According to their application, protective equipment can be divided into the following main systems:

1. a) Tools and devices for working under voltage (insulating bars for operational work, insulating storage and tensioners, tools with an insulated handle);

2. b) Tools and devices for voltage detection and measurement under voltage (measuring rods used to check the presence - absence and phase of voltage, current measuring amburs);

3. v) Means of isolating a person from electric current (insulating vaults with fuses, insulating ladders and platforms, dielectric gloves made of rubber, boots, blankets, blankets, insulating underwear);

4. g) Portable Earth connectors and rods for laying them;

5. d) Protective equipment (temporary barrier, insulating caps and casts, overcasts, protective glasses, suits made of metal-coated fabric for work in the region of electromagnetic field influence, fitters' belts, helmets warning posters).

Basic protective equipment refers to protective equipment whose insulation can reliably withstand the operating voltages of electrical devices and which can be used to touch live parts.

The main protective devices are tested under a voltage that depends on the operating voltage of the electrical device, which voltage should be three times higher than the mains voltage.

The main means of protection are made of dielectric materials (plastics, bakelite, porcelain ebonite, getinax, wood-layered plastics soaked in fast-drying wood oil).

Additional protective devices are devices that cannot independently protect against electric shock at high voltage. They are an auxiliary tool for protection against accidental touching of live parts, electric arc and its combustion products, and burns (dielectric gloves, boots, dielectric rubber mats, insulating undergarments).

Additional protective devices are tested at a voltage independent of the voltage of the electrical equipment they are used in, and they must be used in electrical equipment operating at a voltage not exceeding the rated voltage.

Personal protective equipment. These include shielding protection systems, safety glasses, gloves, gas masks, restraint belts and safety wings.

— Shielding protection systems protect the human body from the effects of the electric field.

— Protective glasses are used for welding, brazing, sharpening tools, working with electrolyte and servicing batteries.

— Storage belts are used when working at height, on the supports of power transmission systems.

— Protective wing — as an additional safety measure, they are definitely used when it is not possible to be attached to the support using straps or chains.

The safety belt and protective wing are tested for mechanical strength once every six months with a force of 225 kg for 5 minutes.

Figure 4. Means of protection against electricity:

1- insulating bars, 2- insulating storage, 3- dielectric gloves,

4-dielectric boots, 5-dielectric pads, 6-rubber mats,

7-insulating pads, 8- insulated handle fitter's tools,

9- current measuring warehouses.

Figure 5. Fitter's belt: 1- strap, 2- buckle, 3- tool holder, 4- carabiner, 5- belt straps, 6- belt, 7- protective wing.

Figure 6. Temporary barriers:

a - textolite for switches, an insulating overlay made of hetinakels, b - a rubber glove to be put on the splitter blades, v - a hanging cover for blocking insulators and wires, g - a portable shield

Figure 18.7. SH311 portable grounding connector with bar:

1 - wire sleeve, 2 - flexible copper wires, 3 - insulating part of the bar, 4 - limiting ring, 5 - clamp, 6 - ground wire.