Electrical protective equipment and safety devices. Basic and additional means of protection in electrical installations Which insulating electrical protective means are considered additional

When working with high-voltage equipment and installations, it is imperative to protect yourself from electric shock, especially if the voltage at the facility exceeds 1 kV. For protection, basic means are used that can be used under load, and additional ones, whose main purpose is to protect from touching dangerous live parts, as well as from exposure. Now we will talk about the basic and additional electrical protective equipment used in electrical installations above 1000 V. Information is provided on the basis of the regulatory document RD 34.03.603.

Basic

The most important safety equipment includes:

As you can see, the list of electrical protective devices is small, but all of them must absolutely be present when personnel work in electrical installations above 1000 V.

Additional

Additional devices and protective equipment include:

1. . Protect the worker's hands from electric current. Please note that in the list, gloves refer to the main set of protective devices, and not an additional one (according to the same RD 34.03.603).
   
2. Dielectric bots. They are used to completely protect the electrician from the foundation underneath.
   
3. Rubber mat. Like bots, it isolates working personnel from the ground.
   
4. Insulating stand. When operating at voltages above 1000 V, it must be equipped with porcelain insulators.
5. Insulating linings and caps. They prevent short circuits and are also an electrical protective device.
   
6. Extension ladders and stepladders made of fiberglass.
   
7. Bars for leveling and transferring potential. They are used to transfer the dangerous potential of an overhead line to the place where the electrician is working.
   

Basic electrical protective equipment in electrical installations

The main electrical protective equipment in electrical installations with voltages above 1000 V are insulating and electrical clamps, voltage indicators, as well as insulating devices and devices for repair work (platforms, insulating links of telescopic towers, etc.).

Insulating rods consist of three parts: a working part, which, depending on the purpose of the rod, is made in the form of a finger, gripper, cutter, brush, etc.; insulating, serving to isolate the worker from the live part (the length of the insulating part is determined by the operating voltage of the rod); handles for holding the barbell in your hands.

Depending on the purpose rods are divided into operational, repair and measuring. Operational isolation rods designed for operations in distribution areas; devices - turning switch blades on and off, checking, etc. Repair insulating rods are used to carry out work on live parts under voltage (cleaning insulators from dust, connecting temporary electrical receivers, tying wires, etc.). Measuring insulating rods used to monitor the voltage distribution on individual insulators in garlands, as well as to measure the transient resistance of contact connections.

Work with a barbell permitted only to specially trained personnel in the presence of a person supervising the worker’s actions. When operating with an insulating rod, it is necessary to use additional insulating protective equipment - dielectric gloves and insulating bases (stands, mats) or dielectric boots.

Clamp meter designed to measure current without breaking the circuit. They consist of a current transformer with a detachable magnetic core and a secondary winding loaded with an ammeter, as well as handles of the appropriate length. Currently, current clamp meters Ts90 (up to 10 kV) are used for currents up to 600 A. The rules for using current clamps are the same as insulating clamps.

Voltage indicators are designed to determine the presence of voltage without measuring its value. Voltage indicators above 1000 V are manufactured in two modifications: with a gas-discharge indicator lamp, the operating principle of which is based on the glow of a gas-discharge indicator lamp when a capacitive current flows through it, and non-contact type, which operate on the principle of electrostatic induction.

Voltage indicator with gas discharge lamp consists of a working, insulating part and a handle. The working part includes a contact tip, a gas-discharge lamp, the combustion of which indicates the presence of voltage on the part of the electrical installation being tested, and capacitors. Currently, UVN-10 and UVN-80M indicators are used (for electrical installations with a voltage of 2-10 kV) and UVN-90 (for electrical installations with a voltage of 35-110 kV). The non-contact high voltage indicator UVNB 6-35 kV is designed to determine the presence or absence of voltage on overhead lines, indoor switchgear and outdoor switchgear with voltage 6-35 kV. Its signal is the intermittent glow of an incandescent lamp, and the lamp's blinking frequency increases as the pointer approaches live parts. The individual voltage detector SNI 6-10 kV is designed to warn a person about the presence of voltage when approaching the wires of a 6-10 kV overhead line at an unacceptable distance. Its signal is an intermittent sound, the interruption frequency increases as it approaches the unacceptable distance zone, and in the zone itself the indication turns into a continuous sound; The indicator belongs to additional electrical protective equipment and cannot be used instead of voltage indicators.

Insulating pliers used in electrical installations up to 35 kV for live operations with fusible inserts of tubular fuses, as well as for putting on and removing insulating caps on the blades of single-pole disconnectors.

When using insulating pliers, the operator must wear dielectric gloves and be isolated from the floor or ground; When changing tubular fuse holders, he must wear glasses. The pliers must be held in outstretched arms.

Additional electrical protective equipment in electrical installations

Additional insulating electrical protective equipment includes dielectric gloves, boots, rubber mats and tracks, insulating stands on porcelain insulators, and portable grounds.

Portable grounding are used to protect people working on disconnected live parts from erroneously applied or induced voltage. They consist of clamps for connection to grounded wires, a grounding conductor for grounding and short-circuiting the current-carrying parts of all phases of the installation and a tip or clamp for connection to a ground electrode or grounded structures.

Portable groundings, using special conductors and clamps, short-circuit live parts and connect them to the ground. They are made from flexible copper wire with a core cross-section designed for thermal stability when short-circuit currents flow, but not less than 25 and 16 mm2 for electrical installations above 1000 V and up to 1000 V, respectively.

Application of portable grounding performed in the following sequence: first, the grounding conductor is connected to the grounding device, and then short-circuiting conductors are applied to the phase wires. Remove the portable grounding in the reverse order. The operator performs operations with portable grounding using an insulating rod wearing dielectric gloves, standing on an insulating base (mat or stand) or wearing dielectric boots.

Hello, dear readers of the Electrician's Notes website.

The purpose of my article today is to bring to you information about protective equipment in electrical installations.

I will say right away that all protective equipment used in electrical installations must meet the requirements of the relevant GOSTs.

When working in switchgears, the following types of protective equipment are used:

Let's look at each tool in more detail.

Electrical protective equipment when working in electrical installations

First, let's get acquainted with this definition.

Electrical protective equipment is a means of protection that is used against electric shock and is necessary to ensure effectiveness when working in switchgear.

All electrical protective equipment is divided into 2 groups:

• basic
• additional

The main electrical protective equipment is insulating electrical protective equipment, in which the insulation is capable of withstanding the operating voltage of the network for a long time, and with the help of which it is allowed to carry out live work on live parts.

Additional electrical protective equipment is an insulating electrical protective equipment that does not protect a person from electric shock, but is only an addition to the main protective equipment. They are also designed to protect workers from step voltage and touch voltage.

Electrical protective equipment is divided according to voltage class:

• up to 1000 (V)
• above 1000 (V)

Basic electrical protective equipment above 1000 (V)

Here is a list of all insulating electrical protective equipment belonging to the basic category above 1000 (V).

• various
• various devices for and in switchgears (voltage indicators for phasing, devices for puncturing cables, etc.)
• various devices and special protective equipment required for work in electrical installations above 110 (kV) are not included here

Basic electrical protective equipment up to 1000 (V)

Here is a list of all insulating electrical protective equipment belonging to the basic category up to 1000 (V).

• (UNN, )
• dielectric gloves
• (insulating)

Additional electrical protective equipment above 1000 (V)

Here is a list of all insulating electrical protective equipment belonging to the additional category above 1000 (B).

• insulating stand
• insulating caps and linings
• rods for leveling and transferring potential

Additional electrical protective equipment up to 1000 (V)

Here is a list of all insulating electrical protective equipment belonging to the category additional up to 1000 (V).

• dielectric mat
• insulating stand
• insulating caps, coverings and linings
• rods for leveling and transferring potential
• insulating fiberglass (dielectric) stepladders and ladders

The second type of protective equipment is protection against high-intensity electric fields.

These include:

1. Individual shielding kit - required to perform work on the ground potential in the outdoor switchgear (open switchgear) and on the potential of the overhead power line (overhead power line)

2. Various shielding devices (portable and removable)

Personal protective equipment (PPE)

Well, we’ve reached the third type of protective equipment - personal protective equipment, i.e. protective equipment used by one person.

These include:

• safety plastic helmets
• protective glasses
• various respirators and gas masks
• mittens
• safety belts and safety ropes
• kits for protecting workers from electric arc ()

Read the article about how I went to, where many options for personal protective equipment were presented, both for energy workers and for fire services (EMERCOM), oil workers, railway workers, etc.

Afterword

In this article, I introduced you to three types of protective equipment used in electrical installations. We will talk about each means of protection in more detail in the following articles. After reading all the material, you will learn how to independently select and use protective equipment depending on the conditions of the work being performed.

You can learn how IMPORTANT it is to use protective equipment in electrical installations from articles about and.

P.S. This concludes the article on the topic of protective equipment in electrical installations. Be the first to know about new articles on the site by subscribing to the newsletter. And now you can watch an interesting video on the topic of the article:

The human body is very sensitive to electrical current flowing through it.

So, when a current of more than 10-15 mA flows through the body, a person experiences convulsions, he cannot independently tear himself away from the live wire and, as a result, death is possible within a few seconds.

At currents of 25-50 mA, spasms of the respiratory tract occur, and the victim may die from suffocation. At currents of 100–150 mA, fibrillation of the heart muscles occurs. In this case, death from electric shock and thermal burns is possible.

Therefore, when working in electrical installations, personnel must use personal protective equipment against exposure to electric current up to 1000V and above 1000V.

During the actions of workers in electrical installations, there is always the possibility that even the most advanced protective equipment used will not be able to ensure their safety. For example, when people are near live parts, there is a possibility of accidentally touching them.

To prevent the negative impact of such phenomena on the body, special isolation is required for the employee and tool. Another example is the accidental supply of power to disconnected networks that are being repaired.

To prevent possible electric shock to repair workers in this case, it is also necessary to use some methods to prevent an accident.

The number of such funds is quite large. Moreover, for their different types has its own set of characteristics, which is different from each other. For example, for items such as gloves, overshoes or boots, the operating temperature range, material from which they are made, size, and testing requirements are given.

For more complex devices, for example, electrical clamp meters, which are a transformer with a digital indication of the amount of current flowing, the characteristics of the device include a large number of parameters. Along with the conditions, operation and dimensions of the device, the ranges of measured network parameters are given.

A protective equipment (PP) is considered a device that can be used to prevent the effects of hazardous production factors on a person.

Classification, types and applications

In electrical installations there are collective (KSZ) and individual (PPE) protective equipment. KSZ include methods such as fencing, automatic control systems or protective grounding and grounding. PPE can be used by one person.

Depending on the voltage of electrical installations, SZ are divided into 2 classes:

• for installations with voltage up to 1000 V;
• for installations with voltage above 1000 V.

In addition, electrical installations may have primary or (auxiliary) protective measures. The first of them have insulation, which ensures the ability to operate under voltage for a long time.

The latter cannot fully ensure safety for a given voltage. They complement the main safety protection and, in addition, protect against the effects of current when a person touches live parts or comes under step voltage.

Fixed assets in networks above 1000 V include:

• insulating rods and pliers;
• voltage indicators;
• devices to ensure safety during network testing (clamp meters, cable puncture devices).

Additional means in electrical networks above 1000 V include:

• and bots;
• dielectric carpets and stands;
• rods for potential equalization;

The main personal protective equipment in electrical installations up to 1000 V include:

• insulating rods and pliers;
• voltage indicators;
• measuring clamps;
• insulated hand tools;

Additional means in electrical networks up to 1000 V include:

• galoshes, carpets and dielectric stands;
• capes;
• insulating ladders and stepladders.

To prevent personnel from being exposed to high-intensity electric fields, special shielding suits are used.

Gloves and goggles are used as PPE to protect various organs and parts of the body (head, respiratory organs, hands, eyes). To prevent falls, special suits are used and to protect against electric arcs.

When choosing electrical protection means, the following general recommendations must be taken into account:

• The insulating dielectric handle of the device must have a ring at the end. At the same time, the height of such a ring for devices operating in networks above 1000 V must be at least 5 mm, and for devices operating in networks with lower voltages - 3 mm.
• The insulating part of the device must be made of dielectric, does not absorb moisture, has stable dielectric and mechanical characteristics.
• The surface of the handles should be smooth and have no cracks or chips.
• The design of the electrical protective device must not allow the possibility of a phase short circuit or a phase-to-ground fault.

Requirements

To a hand-held insulated tool

The tool includes the following elements:

• screwdrivers;
• pliers;
• pliers;
• wire cutters;
• keys;
• assembler's knives.

This tool can be made in two versions:

• made of conductive material, fully or partially covered with insulating material;
• made of insulating material with metal inserts.

The purchased tool must be checked for compliance with the following requirements:

• the insulating layer must be permanent and made of durable, moisture-resistant material;
• the insulation of the screwdriver shaft should end no closer than 10 mm from the end of its tip;
• pliers, wire cutters and pliers on the handles must have stops of at least 5-10 mm;
• For assembly knives, the insulating handle must be at least 10 cm. On the side of the working part of the knife there must be a stop of at least 5 mm.

To dielectric gloves

Gloves can be seamless, with seam, three-fingered and five-fingered. Their length should be about 350 mm, the size should allow gloves to be put on fabric mittens, and the width should allow them to be pulled over the sleeves of clothing.

When purchasing gloves, you must check them for mechanical damage and contamination, as well as for punctures.

To safety shoes

Special footwear includes boots and galoshes. Galoshes are used when working in networks up to 1000 V, and bots are used in any networks. Safety shoes should consist of a rubber upper, grooved sole and textile lining. Boots must be at least 160 mm high, and, in addition, they must have cuffs.

General storage rules

Protective equipment needed store in conditions that preserve their serviceability and usability. These conditions are:

• protection from mechanical damage, moisture and dirt;
• storage in closed premises;
• storage in specially equipped places.

Large devices such as rods or pliers should be stored on special boards with hooks, and small-sized devices should be stored on racks or in cabinets.

Work on electrical installations has a potential danger to personnel associated with electric shock.

To protect personnel, it is necessary to use electrical protective equipment, which can be collective and individual, basic and additional.

When choosing electrical protection means, it is necessary to check their appearance and compliance of their quality with state standards.

The main insulating electrical protective agent is called an insulating electrical protective agent, the insulation of which can withstand the operating voltage of the electrical installation for a long time and which allows you to work on live parts that are energized.

Additional insulating electrical protective agent is called an insulating electrical protective agent, which itself cannot provide protection against electric shock at a given voltage, but complements the main means of protection, and also serves to protect against touch voltage and step voltage.

Before each use of protective equipment staff is obliged check its serviceability, absence of external damage and contamination, and also check the expiration date using the stamp.

Not allowed use expired protective equipment.

When using electrical protective equipment not allowed touch their working part, as well as the insulating part behind the restrictive ring or stop.

All electrical protective equipment and personal protective equipment in use must be numbered, with the exception of protective helmets, dielectric carpets, insulating stands, safety posters, protective barriers, transfer bars and potential equalization. Serial numbers may be used. The inventory number is usually applied directly to the protective equipment with paint or stamped on metal parts. It is possible to apply the number to a special tag attached to the protective equipment.

In departments of enterprises and organizations it is necessary to conduct Magazines accounting and maintenance of protective equipment

When preparing the workplace with stress relief, the following technical measures must be carried out in the specified order:

· Carry out the necessary shutdowns and take measures to prevent the supply of voltage to the work site due to erroneous or spontaneous switching on of switching devices;

· Prohibition posters must be posted on manual drives and on remote control keys of switching devices "DO NOT TURN ON! PEOPLE WORK!” "DO NOT OPEN! PEOPLE WORK";

· Checked the absence of voltage on live parts that must be grounded to protect people from electric shock;

· Grounding is applied (grounding blades are included, and where they are absent, portable grounding connections are installed);

· Indicative posters “Grounded” have been posted; If necessary, workplaces and live parts remaining under voltage are fenced, and warning and instructional posters are posted.

In electrical installations with voltage up to 1000 V when working under voltage necessary:

· protect other live parts located near the workplace that are energized and which may be accidentally touched;

· work using protective equipment:

· in dielectric galoshes or

· standing on an insulating stand or on a rubber dielectric carpet,

· use an insulated tool (screwdrivers must have an insulated shaft),

· use dielectric gloves.

All personnel working in rooms with electrical equipment (except for control panels, relay rooms and the like) in closed and open switchgears, in wells, tunnels and trenches, as well as those involved in the maintenance and repair of overhead power lines, must use safety helmets.

Not allowed:

· work in clothes with short or rolled up sleeves, and also use hacksaws, files, metal meters, etc.;

· work in electrical installations in a bent position, if when straightened, the distance to live parts is less than established by the RULES;

· when working near unprotected live parts, be positioned so that these parts are behind the worker or on both sides;

· touch insulators and insulating parts of live equipment without using electrical protective equipment;

· work in unlit places.

QUESTION 37.

Technical means of protection (TSP) are designed to reduce the current through the human body to a safe value in case of accidental contact with live parts or when it is necessary to perform work under voltage. This effect is achieved in one of two ways: either the touch voltage (that is, the voltage applied directly to the human body) is reduced to a safe value, or it becomes equal to zero.

Depending on the network parameters (operating voltage, levels of insulation resistance and capacitance relative to ground, neutral mode, etc.), technical requirements for ensuring the continuity of power supply to electrical receivers, economic considerations, operating features (for example, level of personnel qualifications) and other conditions, various types are used TSZ.

Classification

The need to use a specific type of TSZ during the operation of electrical installations is indicated in the PUE and PEEP. However, issues of ensuring safety conditions are worked out not during the operation period, but at the design stage (of a product, an object, a technological process). According to GOST 2.119-73, even at the preliminary design stage, a safety program (SAP) of the designed facility must be developed. The art of the developer and operator lies in a competent analysis of the possible causes of dangerous situations at the site and in choosing the most effective and economical means of protection.

Currently, the following TPS are most widely used:

• protective grounding;
• zeroing;
• equalization of potentials;
• protective shutdown;
• protective separation of networks;
• potential equalization;
• protection against the danger of high voltage transfer to the low side;
• protective shunting;
• capacitive current compensation;
• ensuring the inaccessibility of live parts;
• insulation control;
• double insulation;
• protective equipment.

QUESTION 38.

Protective grounding – intentional electrical connection to the ground or its equivalent of metal non-current-carrying parts that may be energized due to a short circuit to the body and for other reasons (inductive influence of adjacent live parts, potential removal, lightning discharge, etc.).

The equivalent of land can be river or sea water, coal in a quarry, etc.

Purpose of protective grounding- eliminating the danger of electric shock in the event of touching the electrical installation housing and other non-current-carrying metal parts that are energized due to a short circuit to the housing and for other reasons.

Protective grounding should be distinguished from other types of grounding, for example, working grounding and lightning protection grounding.

Working ground- deliberate connection to the ground of individual points of the electrical circuit, for example, the neutral points of the windings of generators, power and instrument transformers, arc extinguishers, transverse compensation reactors in long-distance power lines, as well as phases when using the ground as a phase or return wire. Working grounding is intended to ensure proper operation of the electrical installation under normal or emergency conditions and is carried out directly (i.e. by connecting the grounded parts with a ground electrode by a conductor) or through special devices - breakdown fuses, arresters, resistors, etc.

Lightning protection grounding- intentional connection of lightning rods and arresters to the ground in order to divert lightning currents from them into the ground.

Operating principle of protective grounding- reduction to safe values ​​of touch and step voltages caused by a short circuit to the body and other reasons. This is achieved by reducing the potential of the grounded equipment (by reducing the resistance of the ground electrode), as well as by equalizing the potentials of the base on which the person stands and the grounded equipment (by raising the potential of the base on which the person stands to a value close to the potential of the grounded equipment).

Let's consider two cases. The electrical installation housing is not grounded. In this case, touching the body of the electrical installation is as dangerous as touching the phase wire of the network.

The electrical installation housing is grounded (Fig. 4.2). In this case, the voltage of the electrical installation body relative to the ground will decrease and become equal to:

The touch voltage and current through the human body in this case will be determined by the formulas:

Where  1 - touch voltage coefficient.

Reducing the value of the grounding resistance to current spreading R 3, it is possible to reduce the voltage of the electrical installation body relative to the ground, as a result of which the touch voltage and current through the human body are reduced.

Grounding will be effective only if the ground fault current I Z practically does not increase with decreasing grounding resistance. This condition is met in networks with an insulated neutral (IT type) with a voltage of up to 1 kV, since in them the ground fault current is mainly determined by the insulation resistance of the wires relative to the ground, which is significantly greater than the resistance of the ground electrode (Fig. 4.2).

Fig.4.2. Network diagram with isolated neutral (IT type) and protective grounding of the electrical installation

In alternating current networks with a grounded neutral voltage up to 1 kV, protective grounding is not used as the main protection against electric shock during indirect contact, because it is not effective (Fig. 4.3).

Fig.4.3. Network diagram with a grounded neutral and protective grounding of an electricity consumer

Scope of application of protective grounding:

• electrical installations with voltage up to 1 kV in three-phase three-wire AC networks with an insulated neutral (IT system);
• electrical installations with voltage up to 1 kV in single-phase two-wire AC networks isolated from the ground;
• electrical installations with voltage up to 1 kV in two-wire DC networks with an isolated midpoint of the current source windings (IT system);
• electrical installations in networks with voltages above 1 kV AC and DC with any mode of neutral or midpoint of the windings of current sources.

Types of grounding devices.Grounding device called a set ground electrode And grounding conductors.

Depending on the location of the grounding electrode relative to the equipment being grounded, two types of grounding devices are distinguished: remote and loop.

Remote grounding device(Fig. 4.4) is characterized by the fact that the ground electrode is located outside the site on which the grounded equipment is located, or is concentrated on some part of this site. Therefore, a remote grounding device is also called focused.

Fig.4.4. Remote grounding device

Essential flaw remote grounding device - the distance of the grounding conductor from the protected equipment, as a result of which the contact coefficient  1 in all or part of the protected territory = 1. Therefore, grounding devices of this type are used only for low ground fault currents, in particular in installations up to 1000V, where the grounding potential does not exceed the permissible touch voltage U ex.add (taking into account the touch voltage coefficient, which takes into account the voltage drop in the resistance to spreading of the base on which a person stands,  2):

Where I h – current flowing into the ground through the grounding device; r h – resistance to current spreading of the grounding device.

In addition, with a large distance to the grounding conductor, the resistance of the grounding device as a whole can significantly increase due to the resistance of the grounding conductor.

Dignity a remote grounding device is the ability to select the location of the grounding electrodes with the lowest soil resistance (damp, clayey, in lowlands, etc.).

The need for a remote grounding device may arise in the following cases:

• if for some reason it is impossible to place a ground electrode in the protected area;
• with high earth resistance in a given area (for example, sandy or rocky soil) and the presence of places outside this area with significantly better earth conductivity;
• with a dispersed location of grounded equipment (for example, in mine workings), etc.

A loop grounding device (Fig. 4.5) is characterized by the fact that the electrodes of its grounding conductor are placed along the contour (perimeter) of the site on which the grounded equipment is located, as well as inside this site. Often the electrodes are distributed as evenly as possible on the site, and therefore the loop grounding device is also called distributed.

Rice. 4.5. Loop grounding device

Safety with a distributed grounding device can be ensured not only by reducing the grounding potential, but also by equalizing the potentials in the protected area to such values ​​that the maximum touch and step voltages do not exceed the permissible ones. This is achieved through the appropriate placement of single grounding conductors in the protected area.

Zeroing- this is an intentional electrical connection of open conductive parts of electrical installations that are not normally energized with a solidly grounded neutral point of a generator or transformer in three-phase current networks; with a solidly grounded output of a single-phase current source; with a grounded source point in DC networks, performed for electrical safety purposes.

Protective grounding is the main measure of protection against indirect contact in electrical installations up to 1 kV with a solidly grounded neutral.