KRN-10 Complete outdoor switchgear assembly 6–10 kV

Purpose and scope of application

KRN-10 is a complete outdoor switchgear (cell) for operation in three-phase AC networks with a frequency of 50 Hz and a voltage of 6–10 kV. The device is designed for receiving, distributing, sectioning, and metering electrical energy, as well as for implementing relay protection and automation functions in medium-voltage overhead and cable lines.

KRN-10 cells are used in power supply and distribution substations of power systems, as part of KTP and block-modular substations 35/6–10, 110/6–10 kV, at industrial and mining enterprises, in oil and gas production, and at transport facilities (electric traction substations, metro substations, and urban electric transport substations). The design is specifically geared towards outdoor operation near 6–10 kV overhead lines, allowing the KRN-10 to be placed directly at power line supports or on a foundation in the area of technological sites. >Depending on the project, KRN-10 can perform the functions of an input, line, sectional, or metering cell. Based on a standard range of cells, distribution nodes of various configurations are formed: from a single input with one feeder to several interconnected cabinets with bus sectioning, automatic reserve input (AVR) and remote control. The design is intended for operation without permanent maintenance personnel, with periodic inspections and remote monitoring of line parameters.

Technical data

Nominal voltage, kV	6; 10
Maximum operating voltage, kV	7.2; 12
Nominal frequency, Hz	50
Nominal current of main circuits, A	400; 630; 1000; 1600
Nominal current of busbars, A	630; 1000; 1600
Rated breaking current of vacuum circuit breaker, kA	20; 31.5
Thermal withstand current (3 s), kA	20; 25; 31.5
Dynamic withstand current (1 s), kA	51
Nominal voltage of control and auxiliary circuits, V	110 / 220 (DC; AC)
Climatic design and placement category according to GOST 15150	U1 (on request – UHL1)
Degree of protection of the enclosure according to GOST 14254	IP34 on the front side; IP21 on the bottom side
Type of linear high-voltage connections	overhead (through roof entries), cable
Insulation level according to GOST 1516.1	normal insulation for 6/10 kV
Availability of roll-out elements	stationary design; on request – with roll-out trolley block
Service method	One-sided service from the front, without a service corridor
Dimensions of a standard cell, mm - width - depth - height	900 1200 2300
Cell weight, kg, max.	up to 350 (depending on configuration)

Operating conditions

KRN-10 is designed for outdoor operation in climatic version U1 at ambient temperatures from –40 to +40°C (the range can be extended according to the project). The normal installation altitude is up to 1000 m above sea level; when installed in high-altitude areas, the insulation levels and cooling parameters are adjusted. The permissible relative humidity is up to 100% at a temperature of +25 °C without moisture condensation on live parts.

IP34 protection protects the devices from rain, snow, and water jets at an angle, as well as from the ingress of solid particles typical of industrial dust aerosols. The enclosure and doors are equipped with seals around the perimeter, and the roof is equipped with drip caps and visors. Anti-corrosion protection is provided by a multi-layer paint coating with a service life of at least 15 years in a moderately aggressive atmosphere.

For areas with cold climates, sharp temperature changes, and an increased risk of condensation, heating elements and anti-condensation ventilation are provided. Heaters are installed in the compartments of the vacuum circuit breaker, current and voltage transformers, as well as in the relay compartment, and are controlled by thermostats or controllers. The design is resistant to transport impacts, vibrations, and shock loads that occur when installed on a foundation or metal structures near power line supports. p>

Layout and design solutions

The KRN-10 cell is designed as a welded metal cabinet on a frame with the internal volume divided into several functional compartments. As a rule, the following are distinguished:

high-voltage switch compartment;
line disconnector and busbar compartment;
cable/air input compartment with surge arresters and current transformers;
relay compartment and secondary circuit compartment;
compartment for mechanical device drives.

Metal partitions are installed between the compartments, forming local volumes and increasing electrical safety. Access to the interior is provided through doors with bolt locks; if necessary, the doors can be equipped with viewing windows made of tempered glass or polycarbonate. Protective screens and mesh partitions are used for visual inspection of the condition of disconnectors and busbars, preventing contact with live parts.

Depending on the circuit, the KRN-10 is equipped with:

a 6–10 kV vacuum circuit breaker with a service life of at least 10,000 switching operations;
line and bus disconnectors with earthing blades;
phase and zero-sequence current transformers;
voltage transformers with fuses;
surge arresters (SAR) on the line and busbar side;
electricity metering equipment and measuring instruments.

Assembled busbars are made of aluminum or copper busbars of the required cross-section, which ensures long-term operation at rated currents up to 1600 A and withstands short-circuit currents up to 31.5 kA without compromising mechanical and thermal stability. Overhead lines are connected via bushing insulators on the cabinet roof, and cable lines are connected via cable entries at the bottom with clamps for single- or three-core cables.

Functionality and control

KRN-10 provides the implementation of the basic operating modes of overhead and cable lines: switching on/off, sectioning, power backup, automatic shutdown in case of short circuits and overloads, as well as selective protection in case of ground faults. KRN-10 cells are used to build radial and ring network diagrams, diagrams with dead-end substations, as well as distribution points operating in automated control systems.

The vacuum circuit breaker can be controlled locally (from the front panel) or remotely via DC circuits from relay protection and automation devices, process control systems, or SCADA systems. The front panel is equipped with controls, light indicators, measuring instruments, a mnemonic diagram, and device position control elements. For simple circuits, electromagnetic relays may be used, while for modern complexes, microprocessor terminals with functions for recording emergency events and communication via Modbus, IEC 60870-5-104, and IEC 61850 protocols (depending on the design) may be used.

Safety and interlocks

The design of the KRN-10 ensures a high level of safety for operating personnel through a combination of mechanical and electrical interlocks. The following are provided:

the grounding knife cannot be activated when the switch or disconnector is on;
the switch cannot be activated when the grounding knives are closed;
locking of high-voltage equipment compartment doors when the connection is turned on;
control of the “off/on/grounded” positions by limit switches;
the ability to install interlock locks under a single key system.

Relay protection provides current cut-off, MTZ, ground fault protection, overload and minimum voltage protection functions, and may also include APV and AVR. To increase the survivability of distribution networks, it is possible to implement sectioning logic and selective disconnection of damaged sections. According to the design, the KRN-10 cell can be equipped with light or current arc protection with sensors in the busbar and circuit breaker compartments.

Versions and options

KRN-10 input/line cells – with vacuum circuit breaker, current transformers, surge arresters, line and bus disconnectors, earthing knives, and metering equipment.
Sectional cells – with a switch or disconnector for dividing busbars into sections, organizing redundancy and automatic transfer switching.
Cells with voltage transformers – for powering metering and relay protection circuits, with fuses and busbar disconnectors.
Auxiliary cells – with a 6(10)/0.4 kV power transformer with a capacity of 25–63 kVA, protection, and low-voltage distribution equipment.
Climatic versions – heating kits, anti-condensation protection, reinforced seals, special coatings for marine or chemically active climates.
Automation and telemechanics – preparation for connection to SCADA systems, data transfer interfaces, time synchronization, integration into existing energy metering systems.

Typical configurations

KRN-10-BB – cell with vacuum circuit breaker: cable or air entry, line protection and metering.
KRN-10-S – sectional cell for busbar splitting and power backup.
KRN-10-TN – cell with voltage transformers for measurement and commercial metering.
KRN-10-TSN – 6(10)/0.4 kV auxiliary transformer cell.
Additional options – outgoing line cells, metering units, communication and telemechanics panels.

By combining these types of cells, outdoor switchgear of any complexity can be formed: from small units for powering a single consumer to node switchgear with multiple inputs, sectioning, and redundancy according to power system diagrams.

Compliance with standards

GOST 15150 – climatic design and placement categories (design U1 for outdoor installation).
GOST 14254 – degrees of protection by enclosures (IP code).
GOST 17516.1 – resistance to external mechanical influences.
GOST 1516.3 – requirements for the electrical strength of insulation of electrical equipment 1–750 kV.
PUE-7, Chapter 1.8 – standards for acceptance tests of switchgear.
IEC 62271-200 – complete AC distribution devices 1–52 kV (according to the project with a focus on international certification).

Proposed documentation

A complete set of design and operational documentation is being developed in accordance with KRN-10: single-line diagrams, primary and secondary connection diagrams, connection and harness diagrams, equipment and material specifications, lists of purchased items, test cards, and protocols. For production, working drawings of parts and assemblies, 3D models in STEP/Parasolid formats, and drawings in DWG/DXF formats are prepared for integration into the enterprise's CAD/CAM systems.

At the customer's request, source files for AutoCAD, Kompas-3D, SolidWorks, as well as files for automated marking of wires, terminals, and devices can be provided. All solutions are adapted to the specific project, the range of devices used, and the technological capabilities of production.

Advantages of working with us:

– No need to maintain highly qualified IT specialists – you receive a set of documentation for the KRN-10 cell, which can be used by an engineer with average qualifications.
– No need to manufacture prototypes – our accumulated experience allows us to immediately launch serial production of products.
– Working with our documentation, your specialists receive advice on the specifics of designing, assembling, and testing the KRN-10, as well as support during the implementation stages.

For more information on the KRN-10, please contact: inbox@proekt-energo.com

... and, as we know, a mistake made during product design results in 10 times the cost during manufacturing and 100 times the cost during operation...