Purpose and Application

The KSO-394 series are modular medium-voltage switchgear cubicles for receiving, distributing, and switching three-phase AC power at 50 Hz with rated voltages of 6–10 kV. The equipment is suitable for systems with isolated or effectively earthed neutral and is used in indoor switchgear (AIS) of packaged transformer substations, at industrial and infrastructure substations, in auxiliary switchgear of power plants, as well as at municipal and transport facilities.

KSO-394 follows a “metal-enclosed, air-insulated (AIS)” concept: all live parts are housed in a metallic enclosure; insulation is air with proven post insulators and bushings. This simplifies maintenance and lowers lifecycle cost versus gas-insulated solutions while maintaining high operational readiness.

Service Conditions

Base environmental category - EN/IEC 60721-3-3 (indoor, weather-protected). On request, variants for other environmental categories are available, including cold climates, tropical design, and enhanced corrosion resistance. Typical enclosure protection degree - IP20 to IEC 60529. For dusty rooms, reinforced protection of specific compartments and installation of ventilation filters can be provided.

Rated voltage levels align with standard series: 6 kV (Ur = 7.2 kV) and 10 kV (Ur = 12 kV). Design solutions ensure compliance with normative lightning/switching overvoltage levels as well as mechanical effects arising during short-circuit currents.

Layout and Construction

The frame is available in two variants:

• Welded steel frame with powder-polymer coating - optimal for most industrial and power facilities; provides high resistance to abrasive and chemical exposure.
• Rivet-bolted steel enclosure with alu-zinc (or zinc) coating - enhanced corrosion resistance; ensures stable geometry in serial production.

The internal layout is traditionally divided into compartments: apparatus (withdrawable or fixed), busbar, and cable. This separation improves safety (localizes fault effects), eases access for maintenance, and reduces commissioning time. In the base version, all controls are accessible from the front (single-front service). The front includes viewing windows and mechanical position indicators of drives.

The cable compartment is arranged for bottom entry (top entry available by design). Connections are made via appropriate class cable terminations; installation of current and voltage transformers, arc-flash sensors, and temperature sensors for condition monitoring is supported. Internal service lighting is standard: a lamp holder and a socket outlet for a portable lamp; the switch is on the front. Lamp replacement is safe and does not require de-energizing main or auxiliary circuits.

Safety and Interlocking

KSO-394 is equipped with a set of mechanical and electrical interlocks preventing hazardous operations and typical human errors, including:

• interlock preventing disconnector operation with the circuit-breaker closed;
• interlock preventing earthing switch closing with the disconnector or circuit-breaker closed;
• interlock prohibiting truck racking-out with the circuit-breaker closed;
• interlock preventing opening of medium-voltage compartments’ doors unless the earthing switch is closed;
• option for trapped-key interlocking and inter-section logic.

All circuit-breaker operations are performed with the door closed, reducing risks during switching. For enhanced operational safety, voltage presence indication systems (VDIS) with an LRM interface can be installed for portable detectors and built-in interlocking logic.

On request, internal arc solutions are implemented: directed gas relief, reinforced latches and hinges, PM/PI partitioning rated for the specified arc current and protection clearing time. The specific IAC classification is assigned after type-testing of the configured panel.

Versions and Options

• Switching devices. Vacuum medium-voltage circuit-breakers are used as the main device with the required interrupting ratings. For special tasks, load-break switches, contactors, or “switch-fuse” combinations can be applied.
• Protection and automation. Microprocessor-based protection relays, AR/ATS devices, SCADA/telecontrol panels, and power-quality meters are available. Integration via standard protocols (incl. IEC 60870-5-104/IEC 61850) and implementation of special protection schemes are supported.
• Measurement and metering. Current/voltage transformers of required accuracy classes, metering cabinets, and modular measurement panels can be installed.
• Condition monitoring. Optional predictive diagnostics: temperature sensors on cable lugs and busbars, partial discharge sensors, arc-flash sensors with fast local tripping.
• Corrosion resistance. Enclosures can be made from powder-coated steel or alu-zinc coated steel; selection depends on site corrosion category and service-life requirements.
• Seismic and fire safety. Versions with calculation/testing to the specified seismic category are available, as well as the use of non-combustible insulation and cable fire-stopping.

Typical Configurations

The KSO-394 range covers the full set of typical indoor AIS panels: incomers/sectionalizers with a circuit-breaker, feeder panels, transformer feeder panels, measuring and tie panels. Based on unified schemes (e.g., “incoming-section-feeder”, “incoming-transformer”), switchboards of the required capacity and supply reliability category are easily formed. Where necessary, compatibility can be provided for mating dimensions and interlocking logic with existing KSO-series (incl. KSO-3xx) using transition panels.

Configurations may include bus bridges, bus section disconnectors, bypass and measuring panels, cable test facilities, and sections with independent interlocking logic to improve maintainability (LSC categories up to LSC2B - project-specific).

Compliance with Standards

Design and manufacturing of KSO-394 comply with applicable international and national standards. Depending on selected configuration and devices, the following standards are relevant:

1. IEC 62271-200 - AC metal-enclosed switchgear and controlgear above 1 kV and up to 52 kV (LSC categories, PM/PI partitions, IAC classification).
2. IEC 62271-1 - Common specifications for high-voltage switchgear and controlgear.
3. IEC 62271-100 - AC circuit-breakers for medium voltage.
4. IEC 62271-102 - Disconnectors and earthing switches.
5. IEC 62271-105 - Switch-fuse combinations.
6. IEC 62271-213 - Voltage presence indication systems (VDIS) and LRM interface.
7. IEC 61869-2 and related parts - Instrument transformers (CTs/VTs).
8. IEC 60038 - Standard voltages; EN/IEC 60721-3-3 - environmental conditions for stationary use in weather-protected locations; IEC 60529 - Degrees of protection (IP code).
9. EN 10346 - Continuously alu-zinc/zinc coated steel flat products (for relevant enclosure versions).

Engaging Contractors, Manufacturers, and Investors

We are open to cooperation with manufacturers of switchgear devices, metal structures, and semifinished products, as well as contractors (installation, commissioning, service) and investors interested in localization and serial production of KSO-394. Flexible collaboration models are available:

Offered Documentation (AutoCAD, SolidWorks, DXF, DWG, Parasolid)

• Pre-tender package: single-line diagrams, equipment lists, questionnaires, standards compliance matrices, 3D visualizations, and a technical note. The package helps objectively evaluate manufacturability within the required schedule and budget.
• Manufacturing drawings: assembly drawings, main and auxiliary circuit schematics, bills of materials, cable schedules. Formats - DWG/DXF (AutoCAD), STEP/Parasolid; models for SolidWorks/Inventor.
• Interlocking schemes and algorithms: inter-panel and intra-panel logic, trapped-key interlocking, conditions tables, and tolerance matrices. The schemes reflect the sequence of safe operations and are suitable for staff training.
• Commissioning & O&M instructions: checklists, crimping/torque programs, insulation test methods, control-circuit checks, and preventive maintenance routines.
• Make/buy cooperation: if in-house capacities are limited, assistance with outsourcing enclosure parts, busbar systems, harnesses, and mounting panels to third-party plants under your technology.

Additional Technical Notes

Thermal withstand under short-circuit current characterizes the ability of live parts to endure heat release for the specified time without exceeding permissible temperatures and without residual deformations that impede operation. Dynamic withstand is the ability to withstand electrodynamic forces in the initial short-circuit period (peak current) without displacement and mechanical damage to bus bridges and fasteners.

Protection settings are chosen using calculated short-circuit currents at the point of installation, considering the network topology and impedances of transformers, cables, and busbars. Final current values and protection clearing times are coordinated with the selected switching devices and their time-current characteristics, as well as with the strength of live parts and busbar systems.

Particular attention is paid to EMC: proper routing of secondary harnesses, shielding, and standardized bonding jumpers reduce interference and improve the immunity of digital protection and control. To enhance maintainability, we use terminal marking, service loops in cable management, and standardized interfaces for the telecontrol panel.

Технические данные

Documentation Package for KSO-394

We prepare a complete set of engineering documentation - from the tender package to manufacturing drawings and commissioning manuals - adapted to your project requirements, selected device lineup, and production capabilities. If in-house fabrication of certain assemblies is not planned, we will help organize cooperation with third-party manufacturers: enclosure parts, busbar systems, harnesses, control panels, etc.

• Tender package: single-line diagrams, specifications, questionnaires, standards compliance matrices, 3D models/renders, and an explanatory note for estimating effort and cost.
• Working documentation: assembly drawings, primary and secondary schematics, bills of materials, cable schedules, harness tying sheets. Formats - DWG, DXF, STEP, Parasolid; models - for AutoCAD, SolidWorks, Inventor.
• Interlocking schemes and algorithms: sequence of safe operations (close/open/earth/rack-out/access), inter-panel trapped-key logic, signal/condition tables.
• VDIS and arc-flash integration: wiring diagrams, test procedures, staff briefing, inclusion into overall protection and telecontrol logic.

Benefits of Working with Us

No need to maintain a large engineering staff: our documentation set enables starting serial production without costly prototypes. Your specialists receive guidance on all manufacturing and commissioning nuances, including fastener selection, torque charts, quality control of welded and bolted joints, labeling, and harness routing.

For additional information on KSO-394, contact: inbox@proekt-energo.com

…and, as is well known, an error made in design results in tenfold costs in manufacturing and a hundredfold in operation. Choose proven solutions and standardized assemblies.

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