Single-front metal-enclosed switchgear KSO-220 for 6–10 kV is intended for the reception, distribution and switching of three-phase 50 Hz AC power in systems with isolated, compensated or effectively earthed (grounded) neutral. The design belongs to the class of medium-voltage metal-enclosed switchgear and ensures a high level of personnel safety, installation efficiency and maintainability when used as part of indoor switchgear (indoor substations), package transformer substations and modular block-type substations. The panels are oriented toward long-term operation with minimal downtime and support modernization and staged expansion of existing switchboards.

Typical applications of KSO-220:
- indoor switchgear of package transformer substations (prefabricated substations);
- substations of industrial facilities;
- auxiliary switchgear of power plants;
- municipal and infrastructure facilities (water and heat utilities, metro systems, etc.);
- distribution points, supply centers and sectioning nodes of urban and industrial networks;
and other power-supply installations.

KSO-220 can be installed both in permanent indoor substation buildings and in specially designed factory-built modular enclosures. Each panel is a bolted/riveted sheet-metal framework of corrosion-resistant steel (including hot-dip galvanized versions) using riveted and/or non-welded fasteners. Service is provided from one side for single-row or back-to-back layouts. A panel with a vacuum circuit-breaker for a key feeder includes segregated compartments - low-voltage (relay), withdrawable unit (apparatus), busbar and cable - enabling selective access and localization of possible fault conditions.

The relay compartment, the withdrawable unit compartment and the cable compartment have individual doors with keyed access. The relay compartment is segregated from the primary circuits and accommodates protection, metering and telecontrol equipment. Withdrawable units include vacuum circuit-breakers, bus-section disconnectors and drawout voltage-transformer trucks. The truck has three positions: service (main and auxiliary circuits engaged), test (main circuits open, auxiliaries engaged) and maintenance (all circuits open, truck fully on the service platform).

A system of interlocks eliminates hazardous operations:
- prohibition of moving the withdrawable unit between service and test positions with the breaker closed;
- prohibition of breaker closing with the truck in an intermediate position;
- interlock against racking in/out with plug-in contacts under load;
- prohibition of transfer from test to service with the earthing (grounding) switch closed;
- prohibition of closing the earthing switch in service or intermediate positions (allowed only in test);
- interlock of the cable-compartment door when the earthing switch is open;
- interlock of the feeder door with a load-break switch when the earthing switch is open;
- closed-door operation of the breaker; device positions are visible through viewing windows and mechanical indicators.

Purpose and application

KSO-220 is used to build incoming, bus-section and outgoing feeder connections of 6–10 kV distribution networks; to connect power transformers; to distribute power via cable and overhead lines; to connect reactive-power compensation banks, process drives and special loads. The cubicles implement protection and automation functions (instantaneous/time overcurrent, earth-fault, sensitive earth-fault, autoreclosing, automatic transfer, etc.), as well as commercial/technical metering and remote control/monitoring through standard dispatching interfaces (SCADA/DCS). The modular concept enables scalable indoor switchgear, bypass bus arrangements, sectioning, bus bridges between rooms, and implementation of incomer redundancy without major enclosure redesign.

Service conditions

Standard environmental category - EN/IEC 60721-3-3 (indoor, weather-protected locations in temperate climates). Default degree of protection - IP31 (selected nodes optionally IP41/IP54 subject to thermal management). Degrees of protection are defined by IEC 60529 (IP Code). Enhanced requirements for dust/moisture, condensation and corrosion are met by installing filter-fan units, space heaters, sealed cable glands and protective coatings; permissible temperature/humidity ranges and service altitude follow the general specifications for switchgear and controlgear in IEC 62271-1.

Layout and construction

The KSO-220 design provides functional segregation into low-voltage (relay), apparatus/withdrawable-unit, busbar and cable compartments. Inter-compartment metal partitions, shutters and screens prevent access to live parts when the apparatus is racked out. Primary busbars (copper/aluminium) and contact joints are rated for the declared short-circuit thermal/dynamic stresses; provisions are made for CTs/VTs, arc/temperature sensors, current inlets and bus bridges. The relay compartment is segregated from primary circuits and houses protection IEDs, measuring devices, communication modules and DC auxiliary power sources. The cable compartment has independent earthing points, cleats/brackets for cable fixing and a dedicated area for safe termination of screens/armours.

Safety and interlocking

Personnel protection combines mechanical and electrical interlocks, clear visual indication and organizational measures. On request the panels are supplied with internal arc classification (IAC) with accessibility class (A) and directions (F/L/R - front/side/rear) for a specified current/time (e.g., IAC AFLR 20 kA 1 s). The methodology and acceptance criteria for internal-arc tests of metal-enclosed switchgear 1–52 kV are defined by IEC 62271-200. In practice, it is recommended to state IAC requirements explicitly in the specification because under IEC they belong to type tests performed upon user request.

Versions and options

• Incoming/bus section - vacuum circuit-breaker or disconnector; ATS/AR implementation; measurement and metering.
• Outgoing feeder - withdrawable circuit-breaker, CTs/VTs, protection IED (IOC/TOC/SEF/EF), telecontrol (Modbus RTU/TCP, IEC 60870-5-104, IEC 61850).
• Transformer feeder - switch-fuse combination to IEC 62271-105 or circuit-breaker with protection; gR/aR fuses selected to transformer power and prospective fault currents.
• Reactive-power compensation - capacitor-bank feeder with appropriate switching and protections for stepped/dynamic cos φ control.
• Disconnectors/earthing switches - per IEC 62271-102 for indoor installations; motor drives and remote interlocking available.
• Switches/load-break switches - per IEC 62271-103 (switching without short-circuit interruption), including three-pole drawout versions.
• Instrument transformers - selection and placement per IEC 61869-2 (CTs) and IEC 61869-3 (VTs) to ensure correct metering and protection performance.
• Enhanced enclosure protection - local facias/compartments at IP41/IP54, anti-corrosion finishes, sealed cable entries to IEC 60529.

Typical configurations

• Single-section busbar system with one incomer and a group of feeders; line or transformer backup can be implemented.
• Two-section busbar system with a bus-section circuit-breaker and automatic transfer on incomers; bus bridges between switchboards are possible.
• Bypass bus arrangement for maintenance without interruption to critical loads.
• Module for packaged substation - a set of KSO-220 panels in a climate-controlled container with ventilation, gas relief and integrated micro-climate systems to IEC 62271-202.
• Commercial metering node - dedicated cubicle with VTs/CTs, metering cabinet and communication channels to AMR/SCADA.

Compliance with standards

Design, manufacture and testing of KSO-220 are carried out to applicable international and harmonized standards for 6–10 kV medium-voltage switchgear (to be confirmed for each project):

• IEC 62271-200 - AC metal-enclosed switchgear and controlgear for 1–52 kV (incl. internal-arc classification, IAC).
• IEC 62271-1 - Common specifications for switchgear and controlgear >1 kV (applies to MV equipment 1–52 kV).
• IEC 62271-102 - AC disconnectors and earthing switches.
• IEC 62271-103 - AC switches/load-break switches for 1–52 kV.
• IEC 62271-105 - Switch-fuse combinations for 1–52 kV.
• IEC 60529 - Degrees of protection (IP Code).
• IEC 61869-2/-3 - Instrument transformers (CTs and VTs) for measurement and protection.
• IEC 60071-1 - Insulation coordination: selection of withstand voltage levels.
• IEC 62271-202 - Prefabricated substations for AC 1–52 kV (for containerized indoor switchgear).

Technical characteristics

We offer documentation to manufacture KSO-220:

- Preliminary technical documentation for tender participation: single-line diagrams, equipment lists, short-circuit calculations, data sheets, explanatory notes and a delivery plan.
- A full “production-ready” design/fabrication package for your plant: specifications and lists of purchased components, assembly drawings, sheet-metal flat patterns/bend tables, connection and wiring diagrams, cable schedules, protection-settings tables, FAT/SAT programs and acceptance checklists.
- If you have no in-house metalworking, we assist with cooperation: selection of subcontractors for laser cutting/bending and powder coating, procurement of busbar fittings and cabinet hardware; supply of primary and secondary devices with factory certificates.
- Adaptation of documentation to project requirements, local regulations and your manufacturing capabilities; support of initial series and personnel training.

• 3D models and assemblies: SolidWorks (SLDPRT/SLDASM), Parasolid (x_t/x_b), STEP, IGES - for BIM/PLM integration.
• Drawings and flat patterns: AutoCAD (DWG), DXF - for laser cutting, stamping and sheet-metal bending.
• Secondary-circuit packages: schematic and connection diagrams, signal lists, terminal/wire tables, HMI templates.
• Protection IED configurations and exchange files (CID/SCD) per IEC 61850, settings for IEC 60870-5-104/Modbus, test reports and settings logs.
• Installation & commissioning manuals, procedures to verify interlocks and arc protection, operation & maintenance instructions.

Why work with us

- No need to maintain a large engineering staff: we provide a production-ready design package that can be executed by a mid-level engineer following the instructions.
- Faster time-to-series: a library of proven subassemblies allows you to avoid or minimize a “zero series”.
- Technology support: consulting on protection-relay commissioning, interlock verification, protocol setup (Modbus/IEC 60870-5-104/IEC 61850), preparation of FAT/SAT programs, and support for certification and production audits.

For more information on KSO-220 contact: inbox@proekt-energo.com

…and, as is well known, an error made at the design stage costs tenfold in manufacturing and a hundredfold in operation.

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