The single-front metal-enclosed switchgear KSO-285 for 6–10 kV systems is intended for reception, distribution, and protection of three-phase 50 Hz AC in networks with isolated or earthed neutral. The equipment is installed in indoor MV switchgear lineups of package transformer substations (PTS), at industrial and power-plant substations, on municipal and infrastructure sites, and in factory-built modular indoor switchrooms. The baseline operating concept is “door-closed operation” of the primary device, combined with comprehensive interlocking and service convenience that does not require advanced operator skills.

Purpose and application

KSO-285 cubicles serve as incomer, bus-section and feeder units in medium-voltage distribution. Typical applications include: intake and distribution from 6–10 kV power transformers; connection of cable and overhead lines; busbar sectionalizing and automatic transfer (ATS); auxiliary services supply; connection of voltage transformers (VTs), measurement and protection circuits. Unified interfaces for switching devices and instrument transformers (CTs/VTs) allow easy project-specific adaptation and integration into existing lineups during refurbishment. Applicable requirements for normal service conditions, dielectric tests, internal-arc behavior and construction follow the IEC 62271 series for MV switchgear.

Service conditions

Standard environmental classification and location type - EN/IEC 60721-3-3 (stationary use at weather-protected locations, i.e. indoor). The enclosure degree of protection is IP20 per IEC 60529, providing protection against access to hazardous live parts and ingress of large solid objects; the selection of higher local IP ratings by zones is performed as required by the standard and thermal checks. For high-altitude installations, derating and clearance adjustments follow IEC 62271-1 and are reflected in insulation design and verification tests.

Layout and construction

Two enclosure concepts are available: (1) a welded structural-steel frame with powder-polymer coating; (2) a bolted sheet-steel enclosure with Aluzinc/galvanized panels on non-welded fasteners. Inside the cubicle are the vacuum circuit-breaker (or alternative on request), disconnector/earthing switch, current and voltage transformers, main busbars, protection & control IEDs, and terminal blocks of secondary circuits. Front viewing windows enable visual status checks. A service light and outlet allow routine work while main and auxiliary circuits remain energized, subject to operating procedures.

Instrument transformer selection for KSO-285 follows the IEC 61869 series (superseding IEC 60044) - notably Parts 2 and 3 for CTs and VTs - ensuring correct accuracy classes, thermal/dynamic withstand, magnetization behavior and compatibility with protection devices.

Safety and interlocking

KSO-285 implements coordinated mechanical interlocks to prevent hazardous actions: blocking operation of the disconnector with the breaker closed; blocking closing of the earthing switch with the disconnector closed; blocking closing of the disconnector onto an earthed circuit; and blocking door opening unless the circuit is earthed. Core requirements for switching devices and interlocking are defined by IEC 62271-1 and the product parts IEC 62271-100 (circuit-breakers) and IEC 62271-102 (disconnectors and earthing switches), including endurance, operating forces, clearances, and power-frequency/impulse withstand levels.

On request, cubicles can be supplied with Internal Arc Classification (IAC) to IEC 62271-200, with accessibility class A and directions F/L/R (e.g., IAC AFLR 20 kA 1 s). Pressure-relief paths discharge hot gases into a safe area or vent hood to minimize consequences of arc faults and direct the energy away from personnel.

Variants and options

Baseline KSO-285 variants include: incomers; bus-section units with breaker or disconnector; outgoing feeders; VT/CT panels; auxiliary-services panels; metering sections; and bus couplers between sections. Options:
- breaker choice (vacuum breaker to IEC 62271-100 switching-duty requirements; alternative types on agreement);
- manual or motor operators, withdrawable or fixed arrangements;
- microprocessor protection and automation terminals (differential, directional, auto-reclose/ATS), communications and IEC 61850 (MMS/GOOSE/SV) for SCADA/DCS integration;
- anti-corrosion systems, thermal insulation and heaters, seismic design, temperature & partial-discharge monitoring, arc-flash sensors;
- interfacing with other cabinet series (incl. KSO-2) via transition panels. IEC 61850 support ensures multi-vendor interoperability and fast exchange of operational data, events and oscillography.

Typical configurations

For standard 6–10 kV schemes the following configurations are typical:
1) Incomer - transformer/line connection with metering and ATS;
2) Bus-section - bus splitting for maintenance and system flexibility;
3) Feeder - outgoing lines with full protection and current/voltage diagnostics;
4) VT/CT panel - supply of measuring and protection circuits, energy metering;
5) Auxiliary services - supply of control power and life-support systems;
6) Bus coupler - inter-section bus links. Each configuration can be factory-pre-equipped with cable terminations, bus links and P&C interfaces to reduce site work.

Standards and compliance (key references)

• IEC 62271-200 - metal-enclosed MV switchgear and controlgear; internal-arc classification (IAC), LSC/partition classes, type & routine tests.
• IEC 62271-1 - general requirements (service conditions, insulation levels, electrical & mechanical tests).
• IEC 62271-100 - AC circuit-breakers (switching duties, endurance and test sequences).
• IEC 62271-102 - disconnectors and earthing switches (drives, interlocking, endurance).
• IEC 60529 - degrees of protection by enclosures (IP code) - selection of IP20 and locally increased IP by zone.
• EN/IEC 60721-3-3 - environmental classification for stationary use at weather-protected locations (indoor).
• IEC 61869-2/-3 - instrument transformers (CTs/VTs) for protection and metering.

Partnering with contractors, manufacturers and investors

We are open to cooperation with manufacturers of switchgear and steelwork, EPC contractors and investors interested in organizing production of MV cubicles. We provide a technology package for localization: material specifications, purchased-parts lists, coating/galvanizing requirements, quality control plans, installation and commissioning instructions. Step-by-step localization is possible - from assembly to full cycle with enclosures and busbars - including staff training and process audits. This approach enables serial production without pilot prototypes, shortens validation and ensures conformity to current IEC practices.

Documentation offered (drawings and 3D models)

A complete set of design and manufacturing documents is available for KSO-285: tender package (questionnaires, specifications, one-line/functional diagrams), working drawings, purchased-parts specifications, 3D models of enclosures and assemblies, cable schedules, and nameplate/marking templates. File formats: AutoCAD (DWG/DXF), SolidWorks (SLDPRT/SLDASM), Parasolid (x_t/x_b). Documentation is adapted to your production capabilities (sheet-metal bending/welding/powder coating), component range and site HSE procedures.

Integration into digital substations and automation systems

On request, KSO-285 is supplied with IEC 61850-enabled IEDs: logical-node data models, MMS/GOOSE/SV services for high-speed protection and control messaging, and SCADA/HMI integration. This ensures multi-vendor interoperability, reduces copper wiring volume and increases observability of the switchroom.

Operational advantages

- Door-closed breaker operation reduces injury risk and simplifies switching.
- Comprehensive interlocking prevents operator error.
- Modularity and unified parts simplify spares logistics and speed up repairs.
- Internal-arc-classified designs improve industrial safety and alignment with corporate HSE rules.
- Full compatibility with modern protection IEDs and digital-substation protocols streamlines modernization and integration.

Technical data

We offer documentation for manufacturing KSO-285:
- Preliminary technical package for tenders: questionnaires, specifications, one-line diagrams, equipment lists - for quick compliance checks and quotation preparation.
- Working drawings, 3-D models and a complete design set to launch KSO-285 production at your facility. If you lack in-house capacity for enclosures, busbars or steelwork, we can place fabrication with certified partners; you perform assembly, routine tests and installation on site.
- All documentation can be promptly adapted to project requirements, plant standards and local procedures.
- If your substation already uses other manufacturers’ cubicles, we will develop compatible add-on designs (bus/cable interfaces, transition panels, P&C and communications interfacing).

Why work with us

- No need to maintain a large team of senior engineers: the package is structured so a mid-level engineer can work confidently.
- No pilot builds required: proven modules and test programs allow immediate serial launch.
- Consulting across the entire process: from component sourcing to commissioning, including IEC/GOST test programs (dielectric, functional, protection checks).
- Digital integration support: IED configuration, IEC 61850 data models and MMS/GOOSE setup.

For additional information on KSO-285 please contact: inbox@proekt-energo.com

As practice shows, every design-stage error multiplies fabrication and lifecycle costs. Proper specification and adherence to standards (IEC 62271, IEC 61869, IEC 60529, etc.) minimize risks.

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