Section 7. Electrical equipment of special installations

Electrolysis installations and installations of galvanic coatings. General requirements

Encyclopedia of radio electronics and electrical engineering / Rules for the installation of electrical installations (PUE)

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7.10.8. The power supply circuit (group or individual) of electrolysis plants and electroplating plants, as well as the types, types, parameters and number of rectifier units and their design, material and cross section of the connecting current ducts and the busbars of the baths themselves should be selected, as a rule, on the basis of a technical and economic analysis taking into account the provision of the necessary reliability of power supply.

7.10.9. For enterprises that have electrolysis plants with converter substations of large installed capacity of rectifier units, it is recommended to adopt schemes for separate power supply of the process load of electrolysis production with electrical loads of power equipment and electric lighting of all main and auxiliary facilities of the enterprise through separate step-down transformers connected by transmission lines to switchgears located near generating sources or to electric networks of the power supply system for a voltage of 110-500 kV according to the "deep input" scheme, with a minimum number of transformation and switching stages (voltage class is determined on the basis of technical and economic calculations, depending on the power consumption of electricity by the enterprise).

Rectifier units of electrolysis plants for producing hydrogen, intended for cooling turbogenerators, are connected to the 0,4 kV switchgear for auxiliary needs of the power plant.

7.10.10. The on-site power supply system for technological and other electrical loads of electrolysis plants and galvanic coating plants should be carried out taking into account the conditions for ensuring in the distribution network of the enterprise and at the interface of the balance sheet of electrical networks, acceptable power quality indicators (PQE) in accordance with GOST 13109.

In order to limit the content of higher harmonic voltage components in the general-purpose supply network at converter substations of electrolysis plants and electroplating plants, it is recommended to use rectifier units with a large number of rectification phases, with an equivalent multi-phase rectification mode on each of the units (group of units) and other technical solutions for compensation of harmonic components. Specific decisions on compensation of harmonic components in the distribution network of the enterprise are made on the basis of relevant technical and economic calculations.

7.10.11. In electrolysis installations, a series of electrolysis baths-electrolyzers should be attributed to category I electrical receivers in terms of the degree of reliability of power supply.

The categories of other electrical receivers of electrolysis installations and electrical receivers of electroplating installations should be determined in accordance with industry standards for technological design.

7.10.12. With regard to the danger of electric shock to people, the premises of installations, workshops¹⁾ (stations, buildings, departments) of electrolysis and galvanic coatings are classified as premises with increased danger.

1. Electrolysis shop - a set of electrolysis buildings (buildings) of one or more series. The electrolysis shop may also include a foundry department, auxiliary and utility rooms.

7.10.13. The voltage of electrical receivers installed in the workshops (stations, buildings) of electrolysis, as a rule, should not exceed 1 kV of alternating and rectified current. With an appropriate feasibility study, it is allowed to use rectifiers with a higher rated voltage to power a series of electrolysis cells.

7.10.14. Luminaires for general lighting - the "upper light" of the halls (buildings) of electrolysis - can be powered by electricity from general-purpose transformers with a secondary voltage of 0,4 kV with a dead-earthed neutral. At the same time, on the ground floor of two-story buildings and in one-story buildings, metal cases of lamps, ballasts, junction boxes, etc. electrical wiring elements must be isolated from the building structures of the building.

Metal housings of overhead light fixtures, ballasts and junction boxes located at a height of more than 3,5 m from the electrolyzer maintenance site do not need to be isolated from steel structures.

7.10.15. Stationary local lighting in workshops (buildings, halls) of electrolysis, as a rule, is not required. An exception is the main production premises of electrolysis plants for the production of chlorine (see 7.10.47).

7.10.16. Portable (manual) electric lamps used in electrolysis halls (buildings) and in auxiliary workshops (workshops) must have a voltage of not more than 50 V and be connected to the electrical network through a class II safety isolating transformer according to GOST 30030.

7.10.17. Power tools (electric drills, electric drills, electric vacuum cleaners, etc.) used in the halls (cases) of electrolysis must be double insulated and connected to the mains through an isolating transformer.

7.10.18. Electric motors, electric heaters and other AC electrical receivers, the housings of which are directly connected to the electrolyzer housing insulated from the ground, as a rule, should have a voltage of no more than 50 V. It is recommended to use special electric motors for a voltage of 50 V with reinforced insulation in a design that meets the conditions of the environment.¹⁾

Electric motors for voltage from 50 to 380 V AC may be used subject to the following conditions: electric motors or a group of electric motors installed on no more than 15 electrolyzers are connected to a general purpose network (to a general purpose transformer with isolated neutral) through an isolating transformer.

Portable electric heaters with a power of up to 120 kW (installed in the electrolyzer for the heating period) can be connected to the supply network through one isolating transformer located outside the room with electrolysis baths, provided that the total length of the secondary voltage distribution network does not exceed 200 m and blocking is provided that excludes simultaneous inclusion of heaters of several electrolyzers.

1. The requirement for reinforced insulation of electric motors does not apply to electrolysis plants for the production of chlorine, in addition, in such installations, it is allowed to connect one electric motor or a group of electric motors related to only one electrolyzer to a common isolation transformer.

7.10.19. The rooms of electrolysis plants, in which hydrogen is released or circulated in the sealed equipment during electrolysis, must be equipped with exhaust ventilation with natural induction (with deflectors or aeration lanterns), which excludes the formation of unventilated spaces under the ceiling.

Such premises, where, according to the conditions of the technological process, the formation of an overpressure of an explosion calculated in accordance with NPB 105-95 in a room exceeding 5 kPa is excluded, according to the classification given in GOST R 51330.9, an explosive zone of class 2 and only in the upper part of the room. The explosive zone is conditionally accepted from the mark of 0,75 of the total height of the room from the floor level, but the lower boundary of the zone cannot be higher than the crane runway.

In this zone, under the ceiling of the room, sensors should be placed (as a rule, at least two for every 36 m2 of the room area), connected to an automated system for monitoring the hydrogen concentration in the air. The system should provide sound and light alarms, as well as blocking (or turning off) the starting devices of electric motors and other electrical receivers of handling equipment (if such electric devices are available in this room), when the hydrogen content in the controlled area of ​​the room exceeds 1,0 vol. %.

7.10.20. In the premises of electrolysis plants with explosive zones for electric lighting, as a rule, complete lighting devices with slotted light guides (KOU) should be used. The light sources in these devices are placed in the chambers that are part of the COA. The junction of the chambers with the light guides must ensure the degree of protection of the light guides on the side of the chambers is not lower than IP 54. The CCU chambers must be placed outside the explosive atmosphere in the wall adjacent to the adjacent non-explosive room, or in the outer wall.

In addition to the KOU, it is recommended to use general-purpose luminaires installed:

• behind non-opening double-glazed windows without transoms and vents;
• in special niches with double glazing in the wall;
• in special lanterns with double glazing in the ceiling;
• in glass boxes.

Niches and lanterns must be ventilated with natural air from outside.

Glazed boxes must be blown under positive pressure with clean air. In places where glass breakage in the box is possible, safety glass should be used for glazing.

7.10.21. Halls (cases) of electrolysis are recommended to be equipped with hoisting and transport mechanisms for installation, technological and repair work. In the premises of electrolysis plants, in the upper zones of which there may be explosive zones (see 7.10.19), these mechanisms (their electrical equipment) must be designed in accordance with the requirements of Ch. 7.3.

In electrolysis buildings with overhead cranes, ladders for lowering the crane operator from the crane cab must be made of non-conductive material. If such buildings do not have a gallery for servicing crane runways, a design must be made to ensure the safe descent of the crane operator when the crane cabin is stopped not at the landing site (for example, in the event of an accident).

7.10.22. Conductors (busbars) of electrolysis plants, as a rule, should be made of aluminum or aluminum alloy tires with increased mechanical and fatigue strength. Conductor busbars should be protected with corrosion-resistant, and in areas with an operating temperature of 45 ºС and above - with heat-resistant varnishes (with the exception of busbars in aluminum electrolysis cases).

Contact connections of busbars of busbars must be made by welding, with the exception of inter-bath, as well as shunting busbars (busbars) and the connection of busbars to rectifiers, switching and other devices, to covers or end plates of electrolyzers.

Wires or cables with heat-resistant insulation and sheath should be used for laying along electrolyzers in high temperature areas.

To shunt the electrolytic cell (electrolysis bath) removed from the operating series, a stationary or mobile shunt device (disconnector, switch, short circuit, liquid metal switching shunt device) should be provided. The mobile shunt device must be isolated from earth.

The reduction of the influence of magnetic fields on the operation of devices and instruments located in the hall (building and other industrial premises) of electrolysis, as well as on the operation of the electrolyzers themselves, must be ensured by compliance with the industry standards of the relevant production.

7.10.23. Electrical insulation of a series of electrolysis baths, building structures of the building, communications (current conductors, pipelines, air ducts, etc.) should exclude the possibility of introducing the ground potential into the electrolysis hall (building) and removing the potential from the hall (building) (see also 7.10.24, 7.10.29 .7.10.30 - XNUMX).

Electrical isolation from the ground of a series of electrolyzers and baths of galvanic coatings and current conductors to them must be available for inspection and control of its condition.

7.10.24. In electrolysis halls (buildings) (with the exception of halls with electrolysis plants for hydrogen production by water electrolysis), in addition to the elements specified in 7.10.23, they must have electrical insulation from the ground:

• internal surfaces of walls to a height of up to 3 m and columns to a height of up to 3,5 m from the level of working platforms of the first floor in one-story buildings or the second floor in two-story buildings;
• metal and reinforced concrete structures of work sites located near electrolyzers;
• overlapping of bus channels and floors near electrolyzers;
• metal manhole covers;
• metal parts of ventilation devices located on the floor and near the walls of the housing;
• metal pipelines, brackets and other metal structures located within the premises at a height of up to 3,5 m from the floor level;
• lifting and transport mechanisms (see 7.10.21).

7.10.25. Metal and reinforced concrete structures of work sites near electrolyzers should be covered (with the exception of structures near electrolyzers of magnesium and aluminum electrolysis plants) with gratings made of wood impregnated with a fire-resistant composition that does not adversely affect its dielectric properties, or from another dielectric material.

7.10.26. The inputs of busbars of current conductors into the body (building) of electrolysis must be protected by metal meshes or a structure made of electrically insulating materials on a metal frame to a height of at least 3,5 m from the floor level. Grids or metal frame structures must be insulated from the conductor.

7.10.27. Conductors of electrolysis installations, with the exception of inter-bath, shunt conductors and current leads (descents) to end baths, must have a fence in the following cases:

• when horizontal sections of current ducts are located above the passages at a height of less than 2,5 m above the floor level or when they are in the zone of movement of cranes and shop transport1;
• at a distance of less than 2,5 m between current conductors located at a height of less than 2,5 m above floor level and grounded pipelines or grounded equipment¹⁾;
• when current conductors are located near the landing sites of overhead cranes, if the distance from them to these sites is less than 2,5 m.

7.10.28.1 In electrolysis halls (with the exception of halls with electrolysis plants for hydrogen production by water electrolysis), it is not allowed to install a grounding line for three-phase AC receivers of production mechanisms. For such electrical receivers, exposed conductive parts should be connected to the PE conductor. As an additional measure, a residual current device can be used.

Open conductive parts of AC electrical receivers at a distance from them to the current-carrying parts of the electrolyzers of less than 2,5 m must have a removable insulating sheath.

1. Does not apply to aluminum electrolysis plants.

7.10.29. Pipelines in aluminum electrolysis buildings, in workshops and in electrolysis halls (with the exception of halls with electrolysis plants for hydrogen production by water electrolysis) are recommended to be made of non-conductive materials.

When using metal pipelines (including rubber-lined ones), protective pipes and ducts, electrically insulating inserts, suspensions and insulators must be used.

Measures should be provided to reduce leakage currents - to remove current from solutions that enter or are removed from electrolyzers through insulated or made of non-conductive materials (fiolite, vinyl plastic, fiberglass, etc.) pipelines. The use of jet breakers or other effective measures is recommended.

7.10.30. Armored cables, metal pipelines, protective pipes, as well as communication boxes for technological, steam, water supply, ventilation, etc. in electrolysis halls (buildings) should be placed, as a rule, at a height of at least 3,5 m from the level of working platforms ( not less than 3,0 m - for halls of electrolysis of aqueous solutions), isolated from the ground or fenced, have electrically insulating inserts at the entrance and exit from the hall (building), as well as in the places of taps to electrolyzers and connection to them.

When located in the electrolysis halls (buildings) of the listed communications below the specified height, they, in addition, must have two stages of electrical insulation from building structures, as well as electrical insulating inserts along the length of the hall (building), placed in accordance with the requirements of industry standards.

The cable, on which wires or cables are attached in the electrolysis hall (building), must be electrically insulated from building structures.

7.10.31. Cable lines of electrolysis plants should be laid along routes where emergency situations are unlikely (for example, it is impossible for molten electrolyte to enter during emergency electrolyte leaving the electrolyzer).

7.10.32. Electrical equipment installed on foundations, frames and other structures should not have detachable electrical connections hidden from observation. Detachable electrical connections must be easily accessible for maintenance and repair.

7.10.33. Electrical switchgear with voltage up to 1 kV for power and lighting networks must be located at a distance of at least 6 m from unenclosed current conductors or parts of electrolyzers that are energized with rectified current.

7.10.34. The central switchboard and (or) instrumentation and automation (if their need is justified) must be equipped with appropriate means for regulating and controlling the technological processes of electrolysis and monitoring the operation of equipment, including converters, as well as an alarm system that notifies of the start, stop and violations of the equipment operation or on insulation damage in controlled electrical circuits.

7.10.35. To enable equipment that is out of sight, a start alarm must be provided. It is also recommended to use, in justified cases, optical devices (mirrors, telescopic tubes, etc.) and industrial television devices.

7.10.36. In electrolysis plants, in which, in case of emergency, an immediate shutdown of the electrolytic power supply is required, in the electrolysis room and in the room of the central control panel and (or) the instrumentation panel, push-button switches for emergency shutdown of the rectifiers must be installed. The possibility of using these devices for the subsequent inclusion of rectifiers in operation should be excluded.

7.10.37. Electrolysis plants, on the electrolyzers of which increased voltage may appear (for example, due to the "anode effect"), must be equipped with an alarm to alert personnel about this.

7.10.38. Loudspeaker and (or) telephone communication should be provided in the premises of the electrolysis production, including at the converter substation, in accordance with the accepted service system at the enterprise (pilot plant).

7.10.39. To control the operation mode of a series of baths in the premises of buildings, stations (shops) of electrolysis or at a converting substation, the following should be provided:

• ammeter for each series;
• voltmeter for each series and each housing, if they are powered by busbars;
• a voltmeter for each bath (or a voltmeter with a multi-position switch for a group of baths) in cases where the technological process is carried out on the baths according to the operating voltage;
• devices (devices) for monitoring the insulation of each system of rectified current buses or a group of electrolyzers, powered either from a controlled rectified current network, or from an alternating current network through individual or group isolating transformers;
• counters of volt-hours or ampere-hours (depending on technological requirements) for a series or group of baths;
• electrical energy consumption meter installed on the primary side of the converter transformer of the rectifier unit.

See other articles Section Rules for the installation of electrical installations (PUE).

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