The single-front metal-enclosed switchgear series KSO-2 (KSO-2U) is intended for the reception, distribution, and switching of three-phase 50 Hz AC in 6–10 kV networks with isolated, resonant-earthed (compensated) or effectively earthed neutrals. The panels belong to the class of metal-enclosed medium-voltage switchgear and are used in indoor switchrooms (MV switchgear lineups), package transformer substations, and factory-built modular block-substations. The design of the cubicles is focused on high operational availability, personnel safety, and easy integration into existing lineups.

KSO-2U panels are used in:
- indoor MV switchgear of package transformer substations;
- substations of industrial plants;
- auxiliary services switchgear of power stations;
- municipal infrastructure nodes and distribution centers;
- distribution points and sectionalizing nodes of urban/industrial grids;
and other power-supply facilities.

KSO-2U can be installed both in permanent switchrooms and in rapidly deployed factory-built modules. Key construction features:
- enclosures are available in two versions: (1) welded steel frame with durable powder-polymer coating; (2) bolted sheet-steel enclosure with Aluzinc (or zinc) coated panels and non-welded fasteners;
- simple and safe operation enables maintenance by mid-level staff when procedures are followed;
- all breaker operations are performed with the door closed; front windows are provided to check the position of primary devices;
- each cubicle includes a lamp holder for internal lighting; a front-mounted light switch and service outlet for a portable lamp allow lamp replacement without de-energizing main and auxiliary circuits;
- KSO-2U can be interfaced with other KSO-2-type panels using transition panels, which simplifies modernization of existing lineups.

Purpose and application

KSO-2U is used to build incomer, bus-section and feeder bays, to connect power transformers, capacitor banks, process drives and external supply lines. The panels support protective relaying and automation functions (instantaneous/time-delay overcurrent, earth-fault/zero-sequence, neutral displacement, autoreclose, automatic transfer), revenue/technical metering, and remote control. Thanks to a modular base, cubicles are easily configured for the required schemes (single-bus, double-bus with sectionalizer, bypass bus system, bus tie/couplers and reserve incomers) and are scalable within switchrooms and package substations.

Service conditions

Standard environmental classification and location type - per EN/IEC 60721-3-3 (indoor, weather-protected locations). The base enclosure degree of protection is IP20, providing protection against access to hazardous parts and ingress of large solid objects; on request, selected compartments and facades can be supplied with higher protection (e.g., IP31/IP41) while maintaining thermal limits. Optional filters/louvers, anti-condensation heaters, temperature and humidity sensors, and micro-climate controllers are available. Versions with enhanced vibration/seismic resistance, anti-corrosion coatings for aggressive environments, and dust/water-protected cable glands and feed-throughs can be supplied.

Layout and construction

Each cubicle is split into functional compartments: low-voltage (relay), apparatus/withdrawable unit (depending on version - withdrawable vacuum circuit-breaker, load-break switch, disconnector or switch-fuse unit), busbar and cable compartments. Metallic partitions and shutters prevent access to live parts during truck withdrawal. Busbars are copper or aluminum with sections and hardware sized for declared short-time and peak withstands. The cable compartment provides convenient earthing points, cable cleats, extra shelves for CTs/VTs, and provisions for arc-flash sensors.

Primary devices include: medium-voltage vacuum circuit-breakers, disconnectors and earthing switches with independent operating mechanism, load-break switches, and combined switch-fuse units for transformer feeders. Instrument transformers (CTs/VTs) are selected to meet protection and metering accuracy classes. Protection IEDs, metering cabinets, RTUs and communication interfaces (Modbus RTU/TCP, IEC 60870-5-104, IEC 61850/GOOSE) are supported.

Safety and interlocking

KSO-2U implements a set of mechanical and electrical interlocks to prevent hazardous operations:
- blocking of disconnector operation with the breaker closed;
- blocking of disconnector closing with the earthing switch closed;
- blocking of earthing switch closing with the disconnector closed;
- door interlocks (no opening unless the circuit is earthed, etc.);
- breaker operation only with the door closed;
- viewing windows and mechanical position indicators of devices.

On request, panels can be supplied with internal arc classification (IAC) with accessibility class (A) and directions (F/L/R - front/side/rear) and with specified current/time ratings (e.g., IAC AFLR 20 kA 1 s). Pressure-relief paths discharge hot gases to a safe area or into a vent duct/hood. Type tests and IAC marking are agreed within the project scope and FAT/SAT programs.

Variants and options

• Incomer/Reserve/Bus section - with vacuum circuit-breaker or disconnector, with optional ATS/AR, measurement and metering.
• Outgoing feeder - withdrawable breaker, CTs/VTs, protection IED (overcurrent/earth-fault/neutral-displacement), telecontrol interfaces.
• Transformer feeder - switch-fuse unit or breaker with relay protection; fast overcurrent protection and gR/aR current-limiting fuses are supported.
• Measuring/metering cubicle - VT block, metering cabinet (including revenue metering) with AMI/AMR integration.
• Reactive-power compensation - capacitor-bank feeders with suitable switching devices and protections.
• Digitalization - arc/temperature sensors, position readers, SCADA/DCS integration, IEC 61850/GOOSE.
• Enhanced enclosure protection - selected facades/compartments to IP31/IP41, anti-corrosion coatings, seismic design.

Typical configurations

• Single-bus system with one incomer and multiple feeders, with allowance for future extension.
• Double-bus with sectionalizer with bus-section breaker and automatic transfer.
• Bypass-bus scheme for maintenance without service interruption.
• Module for PTS/MV switchroom - a KSO-2U set packaged in a conditioned container with ventilation and arc-gas exhaust.
• Metering node - a dedicated cubicle with VTs/CTs, metering cabinet and communication channels to AMI/AMR.

Standards and compliance

KSO-2U is engineered and manufactured to applicable international standards for medium-voltage switchgear (project-specific lists can be finalized during engineering):

• IEC 62271-200 - metal-enclosed switchgear and controlgear 1–52 kV, including internal-arc classification (IAC) and type/routine tests.
• IEC 62271-1 - general requirements (service conditions, insulation levels, electrical and mechanical tests).
• IEC 62271-100 - AC circuit-breakers.
• IEC 62271-102 - disconnectors and earthing switches.
• IEC 62271-103 - switches and switch-disconnectors.
• IEC 62271-105 - AC switch-fuse combinations.
• IEC 60529 - degrees of protection (IP Code).
• EN/IEC 60721-3-3 - environmental classes for stationary use in weather-protected locations.
• IEC 61869-2/-3 - instrument transformers (CTs/VTs) for protection and metering.
• IEC 61936-1 - power installations exceeding 1 kV AC (design and erection rules).
• IEC 62271-202 - AC prefabricated substations (for containerized/block-substation applications).

Partnering with manufacturers and investors

We are open to cooperation with manufacturers of switchgear components and steelwork, engineering and installation companies, as well as investors interested in localizing KSO-2U production. We provide technical-support packages: transfer of design/manufacturing documentation, training for design and process engineers, first-series support, site audit, development of FAT/SAT programs and interlock-verification methods, and assistance with type-test programs and certification protocols. For regional markets we align to local codes, specify components with accessible logistics, and agree labeling and documentation languages.

Documentation and deliverables

• Design/manufacturing documentation set: one-line and schematic diagrams, wiring diagrams, bills of materials, specifications, cable schedules, and protection-setting tables.
• 3D models and assemblies: SolidWorks (SLDPRT/SLDASM), Parasolid (x_t/x_b), STEP, IGES - for BIM/PLM workflows.
• Drawings and flat patterns: AutoCAD (DWG), DXF - for laser cutting, stamping and sheet-metal bending.
• Protection IED templates, HMI/SCADA configurations, IEC 60870-5-104/IEC 61850 protocol mappings.
• Installation and commissioning manuals, FAT/SAT procedures, interlock and arc-protection test instructions.

Operation, maintenance and lifecycle

The service strategy includes scheduled inspections, periodic torque checks of busbar joints, insulation condition checks and dielectric tests, verification of breaker performance, disconnector/earthing-switch drives, arc-sensor operation and pressure-relief paths. Based on diagnostics, risk maps and modernization plans are developed: migration to digital protection IEDs, online monitoring of heating and partial discharges, raising enclosure IP by zones, and refinement of cable entries. Retrofit kits are available (replacement of breakers and drives on withdrawable trucks without changing the enclosure), extending the lineup life without a full rebuild.

Technical data

We offer documentation for manufacturing KSO-2U:
- Preliminary technical package for tenders to supply KSO-2/KSO-2U, including input data for feasibility checks, compliance with tender requirements and questionnaires.
- Working drawings, 3D models and other necessary documents for manufacturing KSO-2 at your facility. If you do not plan to fabricate parts and subassemblies in-house, we will place them with partner shops; you will perform overall assembly and installation.
- All documents can be adapted to your project and manufacturing capabilities (tooling, sheet-metal processing, bending, powder coating, etc.).
- If your substation contains equipment from another manufacturer, we will prepare compatible add-on designs, including adapter joints and transition panels.

Why work with us:

- No need to maintain a large team of senior engineers: you receive a complete document set that a mid-level engineer can confidently work with.
- No need for lengthy pilot builds: our library of proven solutions lets you launch serial batches immediately after design approval.
- With our documentation you will get consulting on all manufacturing nuances, including protection IED setup, interlock verification, FAT/SAT preparation and O&M documentation.

For additional information on KSO-2U please contact: inbox@proekt-energo.com

…as practice shows, an error made at the design stage can multiply fabrication costs by ten and lifecycle costs by a hundred.

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