The KRUN (outdoor metal-enclosed switchgear) series K-37 is a modular solution for the reception and distribution of three-phase AC power at 50 Hz with rated voltages of 6 and 10 kV. These units are used in power plant auxiliary switchboards, step-down and distribution substations, and across industrial, oil & gas, mining, transport and agro-industrial facilities, as well as within packaged transformer substations and skid/block substations for a wide range of climatic conditions. The K-37 is engineered for long-term outdoor service, simplifying installation, improving maintainability, and enhancing personnel safety by means of comprehensive mechanical interlocking, internal arc-fault containment measures, and a convenient compartment layout.

Purpose and applications

KRUN K-37 is intended for 6/10 kV power reception and distribution; busbar sectionalizing and bus tie/backup; (3) connection of cable and overhead feeders; (4) feeding of station service transformers (SST) and MV measuring/metering circuits at 6–10 kV; (5) housing of protection, automation and telecontrol equipment. A typical K-37 cubicle can perform the functions of an incoming or feeder panel, bus tie circuit-breaker, sectionalizing disconnector, VT (voltage transformer) panel, SST panel, or a combined feeder. This flexibility allows standardized modules to be configured into switchboards of different ratings and schemes-from compact auxiliary boards to fully sectionalized distribution nodes at 35/6–10 and 110/6–10 kV substations.

K-37 cubicles are divided into independent compartments (incoming/feeder connections, busbar compartment, drawout unit compartment, relay cabinet), improving fault localization, reducing the risk of damage propagation, and easing maintenance. Each compartment has its own pressure-relief channels (relief flaps and rupturable panels) and automatic shutter mechanisms that block access to live parts when the truck is withdrawn.

Technical data

Service conditions

KRUN K-37 is manufactured for outdoor use with a walk-in control corridor and two-sided access, in environmental categories per EN/IEC 60721-3-4, with standard or enhanced external insulation. For the temperate option a splash-proof enclosure is provided (typical IP34 per EN/IEC 60529); for the cold-climate option-dust- and water-protected, up to IP54, with insulated panels to ensure reliable starting and operation at low temperatures and in dew formation conditions. Permissible installation altitude-up to 1000 m (higher altitudes by agreement with the manufacturer with appropriate insulation and cooling adjustments). The standard design allows operation at ambient temperatures up to +40 °C and down to -45 °C (temperate) and -60 °C (cold-climate), under site wind loads and with monthly mean relative humidity up to 90%. To mitigate condensation/icing, compartments are equipped with space heaters with automatic temperature/humidity control; cable and secondary wiring are routed in metallic trays/conduits for shielding and mechanical protection.

Design features and materials (dew-resistant insulators, gaskets, canopies, insulated corridor panels) are adapted for regions with high insolation, wind and snow loads, icing and dust. External canopies, interior/exterior lighting (typically 220 V), ventilation louvers and service hatches are provided for safe inspection with adjacent compartments de-energized.

Layout and construction

K-37 is built as a block of one, two or three side-by-side MV cubicles on a rigid common base frame, integrated by a walk-in control corridor. Multiple blocks can be coupled in a straight lineup by busbars or via a sectionalizing device. Each cubicle’s fixed frame carries through-type insulators with fixed contacts, current transformers, an earthing switch, and bus/feeder bars; the drawout truck accommodates the medium-voltage circuit-breaker (or isolating contacts/fuses), VTs/SST per the selected configuration. For overhead terminations, roof brackets and bushings are provided; for cable terminations-entry clamps and cable brackets. The default bus system is single bus, with bare copper bars; phasing and color coding follow IEC practice and the site convention. Line feeder terminations are accessible from the rear; doors with guarding allow visual checks without de-energizing the bus.

The relay cabinet is located above the drawout compartment; its door carries local controls, indication and metering. Inside are protection, automation, metering and communications devices (including microprocessor IEDs per IEC/ANSI function codes, AR-automatic reclosing, ATS-automatic transfer for auxiliaries, UFLS-under-frequency load shedding, undervoltage protection, etc.). The connection between the truck and the relay cabinet is via plug-in connectors with flexible shielded cables; secondary wiring is routed in metallic ducts for EMC robustness and maintainability. The corridor is of panelized construction with standardized wall/roof sections, lighting, and platforms/ladders at both ends.

To localize internal faults, roof-mounted pressure-relief flaps and differential/rupture panels in partitions redirect hot gases upward and away from the service side; louvered panels between MV compartments and the corridor close under overpressure. In the drawout compartment, automatic shutters close the bus and feeder contact windows when the truck is moved to the test/isolated position. The truck has positive latching in “test” and “service (connected)” positions with mechanical run-in; final movement to the “service” position is performed with the standard lever.

Safety and interlocking

The interlocking system follows safe-operation practice for KRUN: the truck cannot be moved with the circuit-breaker closed; insertion into the “service” position is blocked if the earthing switch is closed; isolating contacts cannot be operated under load; “local/remote” and “reclose-block” interlocks are provided; in sectionalizing panels, earthing cannot be enabled with adjacent incoming/tie trucks in the “service” position. Earthing-switch drives are fitted with key interlocks and limit switches to support inter-panel and inter-equipment interlocks (including from power transformer sides). For arc-flash protection, optical sensors in MV compartments provide fast breaker tripping and block reclosing upon bus faults.

The control corridor and relay cabinets are separated from the MV part by gas-dynamic barriers with back-draft louvers preventing flame ejection into the service zone; the outer enclosure and structural elements meet mechanical performance requirements per EN/IEC 62271-200/-1. Frames and enclosures are solidly bonded to the substation grounding grid, with continuous earthing of the drawout truck through sliding ground contacts.

Versions and options

• Environmental options: temperate (no thermal insulation); cold-climate (enhanced insulation of enclosure and corridor, additional heaters and sealing).
• Termination types: cable and overhead terminations; VT panels; SST panels (integrated up to ~40 kVA and free-standing 25–250 kVA); panels with vacuum circuit-breakers and/or isolating contacts with fuses.
• Protection & control package: microprocessor IEDs for lines/incoming/tie, ATS for auxiliaries, UFLS, telecontrol, metering, time sync; DC 110/220 V or AC 220 V secondary systems.
• Corrosion protection & finish: multi-stage metal prep; powder/enamel coatings for outdoor service; weather canopies and sealed entries.
• Modifications: bus-to-bus or via sectionalizing device coupling to existing switchboards (incl. series K-VI, K-IX, K-37M, K-59) via transition panels; higher enclosure IP ratings, anti-icing systems, and corridor HVAC options.

Typical configurations

Common lineups include: (a) 6(10) kV boards with 4–12 feeders (incoming, bus-tie breaker, 1–8 outgoing feeders, VT, feeder to SST); (b) two-section 6(10) kV boards for 35/6(10) kV substations with ATS for auxiliaries; (c) extensions of existing K-VI/K-IX/K-37M boards by bus or section coupling; (d) 6(10) kV overhead-line sectionalizing nodes with overhead terminations and surge arresters; (e) boards for electric furnaces and RF links-per project. The selection of main circuit scheme, bus ratings and switching devices, termination type (cable/overhead), enclosure IP rating and protection package is defined by the inquiry sheet and project documentation for the specific site.

Compliance with standards

• EN/IEC 62271-200 - AC metal-enclosed switchgear and controlgear for rated voltages >1 kV and ≤52 kV (type-tested metal-enclosed switchgear).
• EN/IEC 62271-1 - Common specifications for MV/HV switchgear and controlgear (incl. dielectric/insulation tests).
• EN/IEC 62271-100 - AC circuit-breakers; EN/IEC 62271-102 - Disconnectors and earthing switches.
• EN/IEC 60529 - Degrees of protection (IP code).
• EN/IEC 60721-3-4 (and, where applicable, -3-3) - Environmental categories for stationary use at non-weather-protected / weather-protected locations.
• EN/IEC 61936-1 - Power installations exceeding 1 kV AC (design and erection); site testing/commissioning as specified therein and in the project documentation.

Partnering and subcontracting

We welcome cooperation with manufacturing sites (metalwork, machining, powder coating, secondary harnesses, protection & control assembly), design and commissioning firms, and investors interested in localization and serial production of K-37 cubicles. We provide complete manufacturing documentation and process sheets, inspection and test routes, BOMs, busbar and component specifications, master models and gauges for base tooling. We arrange supervisory installation and staff training, transferring assembly, setup and commissioning expertise. Designs can be adapted to regional markets and to locally available switching devices and protection/automation equipment.

Documentation available for manufacture

On request we supply a full documentation set to manufacture KRUN K-37 at your facility: production drawings (DWG/DXF), 3D models of parts and assemblies (Parasolid, STEP, SolidWorks), master specifications, main and auxiliary circuit schematics, harness and cable logs, assembly/adjustment/test instructions, FAT procedures, product passports and forms, templates for recording routine and acceptance test results; if needed-adaptation to your equipment fleet, tooling and process capabilities. For tenders we prepare a preliminary package (inquiry forms, commercial/technical proposal, 3D visuals, layout schemes, explanatory notes). 

Why work with us

- No need to maintain a large engineering staff: you receive a complete, production-ready documentation set with accompanying instructions-an engineer of average qualification can start the line.
- Deep module standardization and assembly templates eliminate costly prototyping: production lots can start immediately, with quality support.
- Expert advice on all aspects: selection of circuit-breakers/VTs/CTs, busbar optimization, relay cabinet layout, protection algorithms, installation and commissioning method statements, recommended spare parts kits.
- Flexible partnering model for manufacturers and investors: licensed assembly, localization, cooperation on machining and coating, joint deliveries to utility and industrial customers.

For additional information on KRUN K-37 please contact: inbox@proekt-energo.com

…and as is well known: an error made in design costs tenfold in manufacturing and a hundredfold in operation. Do it right the first time.

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