The KSO-319 single-front medium-voltage switchgear (rated for 6–10 kV) are modular cubicles for receiving, distributing, and switching three-phase AC power at 50 Hz in systems with isolated, effectively earthed, or solidly earthed neutral. The equipment is intended for indoor air-insulated switchgear (AIS) of packaged transformer substations (PTS), industrial substations, plant auxiliary switchgear of power stations, municipal utilities and urban infrastructure, as well as other power-supply facilities. The cubicles can be installed both in permanent indoor substations and in rapidly deployable factory-built modular blocks, which significantly shortens implementation time and reduces civil/installation scope.

Purpose and application

Functionally, KSO-319 forms incomer, bus-section, and feeder connections of medium-voltage switchgear. The cubicles provide: switching of 6–10 kV transformers and lines; busbar sectioning with automatic transfer capability; supply of plant auxiliaries and process loads; energy metering; signalling and data exchange with monitoring and SCADA/DCS systems. During brownfield upgrades, KSO-319 is convenient thanks to unified mating dimensions, transition panels, and coordinated busbar centerlines-this eases interfacing with installed equipment and enables staged commissioning of renewed sections without prolonged outages.

Service conditions

Base environmental category - EN/IEC 60721-3-3 (indoor, weather-protected, replaces GOST 15150 U3). The design accounts for temperature, humidity, dust, as well as storage and transportation conditions. Degree of enclosure protection - IP20 per IEC 60529, preventing access to hazardous live parts and ingress of solid objects. Project-specific local increases of IP in individual compartments (e.g., apparatus) are possible subject to thermal and ventilation calculations. For high-altitude sites, the effect of reduced air pressure on dielectric strength is considered in insulation clearances and acceptance test methods per the general requirements for switchgear.

Layout and construction

The KSO-319 enclosure is supplied in two main variants: (a) a welded structural-steel frame with powder-polymer coating for high mechanical durability and long-term protection; (b) a bolt/rivet-assembled design made of galvanized/Al-Zn steel for fast assembly, manufacturability, and service convenience. The cubicle is divided into functional compartments: busbar (main busbars and inter-panel links), apparatus (circuit-breaker, disconnector, earthing switch), cable (entries, terminations, current transformers), and a low-voltage compartment (protection and control IEDs, measuring instruments, marshalling panels). Viewing windows on the front provide visual indication of device positions; internally, a service light and a receptacle for a portable lamp are provided. For measuring circuits, current and voltage transformers per the IEC 61869 series (incl. Parts 2 and 3) are recommended to ensure proper accuracy classes, thermal/dynamic withstand, and compatibility with modern protection and metering IEDs.

Safety and interlocking

KSO-319 incorporates mechanical interlocks that prevent hazardous or incorrect operations: blocking disconnector operation with the circuit-breaker closed; blocking closing of the earthing switch with the disconnector closed; blocking disconnector closing when the circuit is earthed; blocking door opening unless the earthing switch is positively engaged. Circuit-breaker operation is performed with the door closed, reducing personnel risk during switching. Requirements for sequence of operations, drive endurance, insulation distances, and verification tests follow IEC 62271-1 general provisions and the relevant product parts IEC 62271-100 (AC circuit-breakers) and IEC 62271-102 (disconnectors and earthing switches). For sites with higher safety demands, arc-resistant versions with confirmed Internal Arc Classification (IAC) and accessibility types AFLR/ALR/AR per IEC 62271-200 can be provided, routing energy to safe zones.

Versions and options

The KSO-319 range includes incomers, bus-section panels (with breaker or disconnector), feeder panels, VT/CT panels, metering, plant auxiliaries, as well as bus-tie (coupler) panels. Available options:
- vacuum circuit-breakers with endurance and interrupting ratings per IEC 62271-100;
- manual and motor operators; fixed or withdrawable arrangements;
- microprocessor protection IEDs (differential, directional, autoreclose/automatic transfer), disturbance recorders;
- digital integration per IEC 61850: MMS for supervisory exchange, GOOSE/SMV for high-speed events/measurements over station/process bus;
- additional industrial-safety measures: arc-flash detection, temperature monitoring of busbars and cable lugs, partial discharge monitoring;
- corrosion-resistant coatings, insulation/heaters, seismic versions, extended spare-parts kits, and standardized bus links.

Typical configurations

Proven schemes for 6–10 kV AIS based on KSO-319:
1) Incomer - connection of a transformer or MV line; metering; automatic transfer;
2) Bus-section - bus sectioning to improve maintainability and contingency flexibility; with breaker or disconnector;
3) Feeder - outgoing cable/overhead lines with full protection suites and I/U diagnostics;
4) VT/CT panel - supply for measuring circuits, commercial/technical metering, system monitoring;
5) Plant auxiliaries - supply of DC/AC auxiliaries, life-support systems of the switchgear, and control circuits;
6) Bus coupler/tie - bus links for flexible network topology, redundancy, and bypass modes during maintenance.

Compliance with standards

• IEC 62271-200:2021 and Amd.1:2024 - AC metal-enclosed switchgear 1–52 kV; construction requirements, internal arc confirmation, accessibility types.
• IEC 62271-1:2017 - Common specifications for high-voltage switchgear and controlgear (service conditions, insulation levels, type tests).
• IEC 62271-100:2021 and Amd.1:2024 - AC circuit-breakers: endurance, interrupting capability, test duties.
• IEC 62271-102:2018 - AC disconnectors and earthing switches: requirements for drives and interlocks.
• IEC 61869-2/-3 - Instrument transformers (CTs/VTs): additional requirements and accuracy classes for protection and metering.
• IEC 61850 - MMS/GOOSE/SMV communication services for digital substations and SCADA/DCS.
• IEC 60529 - Degrees of protection (IP code).
• EN/IEC 60721-3-3 - Environmental conditions for stationary use in weather-protected locations (replaces GOST 15150 U3).

Engaging contractors, manufacturers, and investors

We are open to cooperation with manufacturers of switchgear and HV/MV equipment, EPC contractors, and investors interested in localizing production of medium-voltage cubicles. A technological documentation package is provided for industrialization: material and purchased-parts specifications, quality-control plans, assembly and commissioning instructions, coating/galvanizing requirements, and typical routines for routine/functional tests. A phased transition is possible-from screwdriver assembly to full-cycle production (enclosures, busbars, coating)-including staff training and production-process audits. This approach enables serial launch without costly prototypes and minimizes validation risks.

Offered documentation (drawings and 3D models)

A complete set of design and shop documentation is available for KSO-319: data sheets, single-line and functional diagrams, purchased-parts lists, assembly drawings and detailing, cable schedules, and nameplate/label templates. File formats: AutoCAD (DWG/DXF), SolidWorks (SLDPRT/SLDASM), Parasolid (X_T/X_B). On request, we adapt to your production capabilities (press-brake, stamping, welding, powder coating), corporate standards, and digital interfaces (IEC 61850 data models and services for SCADA/HMI integration).

Operation and maintenance

The closed-door breaker operation concept reduces injury risk and makes switching predictable. Modularity and unified parts simplify spares management and speed up post-fault recovery. Options include arc-flash protection, temperature monitoring of busbars and cable lugs, and partial-discharge monitoring. Maintenance routines are set considering breaker duty statistics, disturbance recorder data, and the requirements proven by type tests.

Technical data

We offer you the documentation set for manufacturing KSO-319:

- Preliminary technical package for tenders (data sheets, specifications, single-line/functional diagrams) for fast compliance checks and preparation of a commercial offer.
- Full design package and 3-D models to launch KSO-319 production at your site. If in-house enclosure and busbar fabrication is unavailable, we will arrange manufacturing at certified partner plants; your factory performs final assembly, routine/acceptance tests, and installation.
- Prompt document updates to your project requirements and manufacturing capabilities; support during component procurement, supervisory installation and commissioning; preparation of test programs (insulation - per the IEC 60060 series; functional - per applicable parts of IEC 62271).

Benefits of working with us

- No need to maintain a large team of highly qualified engineers: the documentation set is structured for confident work by a mid-level engineer.
- Serial production launch without building a prototype: a portfolio of proven solutions and unified modules enables immediate transition to repeatable batches.
- Support for digital integration: configuration of IEDs and communications per IEC 61850 (MMS/GOOSE/SMV), interaction with SCADA/HMI, optimization of secondary wiring and cable routing.

For additional information on KSO-319 please contact: inbox@proekt-energo.com

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