What is stress-free work. Performing work under voltage in electrical installations of different voltage classes: methods, means of protection

Often, emergencies arise when a section of an electrical installation, an electrical network needs to be taken out for repair to eliminate the malfunction, but for certain reasons this cannot be done. For example, a broken contact connection was detected on a 750 kV line.

This line is very critical and can supply a significant part of the power system within several regions of the country. If in this moment there is no way to power the power system from the backup line, then the only option for troubleshooting is performing work under voltage, that is, without first disconnecting the power line.

Also, live work in electrical installations is considered one of the modern methods maintenance of electrical installations. The removal of sections of electrical installations, in particular, is a rather laborious process, especially if it is a very important trunk line, the disconnection of which cannot be coordinated within a year.

In this case, carrying out repair or maintenance work without relieving voltage significantly saves the time required to coordinate the work performed and take measures to bring the power line into repair.

Consider methods of work under the operating voltage of the electrical installation and appropriate means of protecting maintenance personnel from electric shock, appropriate to each method.

The first method is to work directly at the potential of a live wire, while the person is reliably isolated from the ground. The technology of work under stress involves the work of a person standing on an insulated stand, isolated work site truck crane. At the same time, the person is in a special shielding set of clothing. Before starting the ascent to the live parts, the worker's shielding suit is connected to an insulated working platform.

Electrical voltage- this is . Therefore, in order to avoid electric shock, before starting work, it is necessary to equalize the potential of the shielding set and the working platform with live parts that are energized. To equalize the potential, the insulated working platform is connected to the live part (wire, bus) by a flexible copper conductor, which is fastened with an insulating rod using a special clamp.

Grounded parts of metal structures, supports have a potential that is different from the potential of live parts, approaching them leads to an electric shock to a person. Therefore, to ensure safety when performing work under the potential of the wire, a person should not approach the grounded parts closer than the value of the permissible distance, which is determined for a given class of line voltage.

For example, if work is performed on a line with a voltage of 330 kV, then a person working under the potential of the wire is prohibited from approaching the metal structures of the supports at a distance of less than 2.5 m.

Due to the increased danger during work on this method, employees must undergo specialized training, knowledge testing on the method of conducting work under voltage. For each type of work, instructions are drawn up, and when planning work, special technological maps are drawn up.

The second method is to work with the isolation of a person from live parts, without isolating a person from the ground... Work according to this method is carried out using insulating electrical protective equipment, which are selected in accordance with the nature of the work performed and the voltage class of the electrical installation.

There are electrical protective equipment with voltages up to and above 1000 V, which, in turn, are divided into basic and additional.

The main protective equipment protects a person from the action of electric voltage and arc, they allow you to work long time under the operating voltage of the electrical installation site.

Additional protective equipment does not allow working under operating voltage, they are additional protection to the main electrical protective equipment, and allow you to protect the worker from and touch voltage.

This method of performing work under voltage is the most common in electrical installations. One example is checking the presence of voltage on the line or checking the operability of the voltage indicator in electrical installations with voltages above 1000 V. The voltage indicator itself is the main electrical protective agent... A pointer with a voltage higher than 1000 V should be used - in this case, they act as an additional electrical protective device.

The third method provides for the isolation of the person performing the work, both from the ground and from the live parts of the electrical installation that are under operating voltage. The most common example is work in electrical circuits up to 1000 V: switchboards, relay protection cabinets and automation equipment for electrical installations.

In this case, to ensure human safety in relation to electric shock, electrical protective equipment is used. To isolate a person from live parts, dielectric gloves and tools with insulating handles (screwdrivers, pliers, pliers, wire cutters, an electrician's knife for cable termination, etc.) are used - these protective equipment in electrical installations with voltages up to 1000 V belong to the group of basic electrical protective equipment ... To isolate a person from the ground, additional protective equipment is used - dielectric mat or an insulating stand.

4.15.21. When performing work on overhead lines without removing the voltage, the safety of personnel is ensured according to one of two schemes:

The first scheme. Live wire - insulation - human earth. The scheme is implemented in two ways:

work in contact when dielectric gloves and insulated tools are the main protective equipment. This method is used to perform work on overhead lines with voltage up to 1000 V;

work at a distance, when work is performed using basic (insulating rods, pliers) and additional (dielectric gloves, boots, pads) electrical protective equipment. This method is used on overhead lines with voltages above 1000 V.

Second scheme. Live wire - man - earth insulation. Works according to this scheme are allowed under the following conditions:

isolation of the person working from the ground with special devices of appropriate voltage;

the use of a shielding kit in accordance with GOST 12.4.172;

potential equalization of the shielding set, the working platform and the wire with a special bar for potential transfer. The distance from the employee to the grounded parts and elements of the equipment during work must be at least the distance indicated in table. 1.1.

4.15.22. Specific types of work under the potential of the wire must be carried out according to special instructions or according to technological maps, POR (PPR).

4.15.23. Employees who have the right to perform work under the potential of the wire (with direct contact with live parts) of overhead lines with a voltage above 1000 V must have group IV, and the rest of the team members must have group III.

4.15.24. It is not allowed to touch insulators and fittings of insulating suspensions that have a potential other than the wire, as well as transfer or receive tools or accessories to workers who are not on the same work site when working from the site of an insulating device that is at the potential of the wire.

4.15.25. Before starting work on insulating hangers, check the dielectric strength of porcelain insulators with a measuring rod. If there are release clamps, they should be wedged on the support on which the work is performed, and on adjacent supports, if required by the relief of the route.

4.15.26. Work on an insulating suspension for its re-connection, replacement of individual insulators, fittings carried out by fitters located on insulating devices or traverses are allowed if the number of serviceable insulators in the suspension is at least 70%, and on overhead lines with a voltage of 750 kV - if there are no more than five defective insulators in one suspension.

4.15.27. When interconnecting insulating suspensions on overhead lines with a voltage of 330 kV and above, performed from the traverse, the necessary devices should be installed and disconnected from the traverse in dielectric gloves and in a shielding kit.

4.15.28. It is allowed to touch on overhead lines with a voltage of 35 kV to the cap of the first insulator with two serviceable insulators in an insulating suspension, and on overhead lines with a voltage of 110 kV and above - to the caps of the first and second insulators. Insulators are counted from the traverse.

4.15.29. Installation of energized tubular arresters on overhead lines with a voltage of 35-110 kV is allowed provided that insulating overhead gauges are used, which exclude the possibility of approaching the external electrode of the arrester to the wire at a distance less than a specified one.

4.15.30. It is not allowed to be in the area of ​​possible exhaust gases when the external electrode of the arrester approaches the wire or the electrode outlet when removing the arrester. The outer electrode of the arrester should be approached or removed using an insulating rod.

It is not allowed to approach the lightning protection cable isolated from the support at a distance of less than 1 m.

4.15.31. When using a cable in the ice melting scheme, the permissible distance of approach to the cable should be determined depending on the melting voltage.

4.15.32. It is not allowed to work on overhead lines and overhead lines that are energized, in fog, rain, snow, in dark time days, as well as when the wind makes it difficult to work on the supports.

4.15.21. When performing work on overhead lines without removing the voltage, the safety of personnel is ensured according to one of two schemes:

The first scheme. Live wire - insulation - human - earth. The scheme is implemented in two ways:

Work in contact when dielectric gloves and insulated tools are the main protective equipment. This method is used to carry out work on overhead lines with voltage up to 1000V;

Work at a distance, when work is performed using basic (insulating rods, pliers) and additional (dielectric gloves, boots, pads) electrical protective equipment. This method is used on overhead lines with voltages above 1000V.

Second scheme. Live wire - human - insulation - earth. Works according to this scheme are allowed under the following conditions:

Isolation of the person working from the ground with a special device of the appropriate voltage;

Application of a shielding kit in accordance with GOST 12.4.172;

Equipotential bonding of the shielding kit, work platform and wire with a special potential transfer bar. The distance from the worker to the grounded parts and elements of the equipment during work must be at least the distance specified in Table 1.1.

4.15.22. Specific types of work under the potential of the wire must be carried out according to special instructions or according to flow charts, ERP (PPR).

4.15.23. Employees who have the right to perform work under the potential of the wire (with direct contact with live parts) of overhead lines with a voltage above 1000V must have group IV, and the rest of the team members must have group III.

4.15.24. It is not allowed to touch insulators and fittings of insulating suspensions that have a potential other than the wire, as well as transfer or receive tools or accessories to workers who are not on the same work site when working from the site of an insulating device that is at the potential of the wire.

4.15.25. Before starting work on insulating hangers, check the dielectric strength of porcelain insulators with a measuring rod. If there are release clamps, they should be wedged on the support on which the work is performed, and on adjacent supports, if required by the relief of the route.

4.15.26. Work on an insulating suspension for its interconnection, replacement of individual insulators, fittings carried out by fitters on insulating devices or traverses are allowed if the number of serviceable insulators in the suspension is at least 70%, and on overhead lines with a voltage of 750 kV - if there are no more than five defective insulators in one suspension.

4.15.27. When interconnecting insulating suspensions on overhead lines with a voltage of 330 kV and above, performed from the traverse, the necessary devices should be installed and disconnected from the traverse with dielectric gloves and in a shielding kit.

4.15.28. It is allowed to touch on overhead lines with a voltage of 35 kV to the cap of the first insulator with two serviceable insulators in an insulating suspension, and on overhead lines with a voltage of 110 kV and above - to the caps of the first and second insulators. Insulators are counted from the traverse.

4.15.29. Installation of energized tubular arresters on overhead lines with a voltage of 35 - 110 kV is allowed provided that insulating overhead gauges are used, which exclude the possibility of approaching the external electrode of the arrester to the wire at a distance less than a specified one.

4.15.30. It is not allowed to be in the area of ​​possible exhaust gases when the external electrode of the arrester approaches the wire or the electrode outlet when removing the arrester. The outer electrode of the arrester should be approached or removed using an insulating rod.

It is not allowed to approach the lightning protection cable isolated from the support at a distance of less than 1m.

4.15.31. When using a cable in the ice melting scheme, the permissible distance of approach to the cable should be determined depending on the melting voltage.

4.15.32. It is not allowed to work on overhead lines and overhead lines that are energized, in fog, rain, snow, in the dark, as well as in wind that makes it difficult to work on supports.