Purpose and Application

KSO-399 single-front metal-enclosed (AIS) medium-voltage switchgear is intended for the reception, distribution and switching of electrical energy in three-phase 50 Hz AC networks with rated voltages of 6–10 kV. The panels are used to feed load centers, protect feeders and transformers, sectionalize busbars and ensure operational reliability at power, industrial, transport and utility facilities. The design belongs to the air-insulated, metal-enclosed class (AIS), combining maintainability, intuitive operation and a moderate life-cycle cost.

Typical applications include indoor substations (MV switch rooms) of package transformer substations, power-plant auxiliary switchgear, substations of industrial and infrastructure sites, as well as supply centers for residential and commercial developments. The single-front (front-access) concept allows rows of panels to be placed along a wall or in constrained rooms, providing access to all controls from the front and reducing installation-space requirements.

Service Conditions

Baseline environmental category - per EN/IEC 60721-3-3 (indoor, weather-protected locations). Other categories can be supplied on request (including options comparable to U1/U2, UHL) as well as versions for higher corrosion categories. The typical enclosure degree of protection is IP20 per IEC 60529; higher local protection for specific compartments, dust filters and screens can be provided on request. The construction ensures mechanical and thermal withstand under short-circuit currents and resistance to standard indoor environmental factors of MV switch rooms.

Rated voltage levels follow the standard series: 6 kV (highest voltage 7,2 kV) and 10 kV (highest voltage 12 kV). Insulation levels are selected to withstand lightning and switching overvoltages and to provide adequate air clearances in accordance with safety and dielectric-strength requirements.

Configuration and Design

KSO-399 features a modular layout with clearly separated compartments: apparatus, cable and busbar. This segregation increases safety, localizes potential fault effects, speeds installation and simplifies maintenance. All operating controls are accessible from the front; viewing windows, mechanical position indicators and ergonomic operators are provided. Internal lighting is implemented by a built-in lamp with a socket and a front-mounted switch, plus an outlet for a portable lamp. The lamp can be replaced safely without de-energizing main or auxiliary circuits.

The frame and enclosure are available in two manufacturing options:

• Welded steel frame made of structural steels with powder-polymer coating, providing high rigidity, dimensional stability and resistance to abrasive and chemical exposure typical for indoor MV rooms.
• Non-welded steel body with AluZinc (or zinc) coating using riveted/bolted joints - for sites requiring enhanced corrosion resistance and dimensional repeatability in serial production.

The cable compartment is designed for bottom entry of power cables; top entry is available if required. Space is provided for current and voltage transformers of required accuracy classes, temperature sensors and arc-flash sensors for fast protection systems, as well as for proper cable clamping with controlled bending radii and convenient service loops.

To unify assembly, the design provides standard mounting holes, inserts for components from different manufacturers, and standard locations for microprocessor protection relays, SCADA/telecontrol panels and local control units.

Safety and Interlocking

KSO-399 is engineered for safe operation throughout its life cycle. A set of mechanical and electromechanical interlocks prevents hazardous actions:

• blocking of disconnector operations when the circuit-breaker is closed;
• blocking of the earthing switch when the disconnector or breaker is closed;
• blocking of truck withdrawal when the breaker is in the closed position;
• blocking of HV-compartment doors unless the earthing switch is closed;
• provision for trapped-key interlocks and inter-section logics.

All breaker operations are performed with the door closed, reducing switching risks. Ducts, guides and pressure-relief flaps route gases safely in case of an internal fault, minimizing impact on personnel and adjacent panels.

Versions and Options

• Main switching device. Vacuum circuit-breakers (MV) with required continuous and short-circuit ratings as standard. Load-break switches, contactors or switch-fuse combinations can be installed for specific duties.
• Protection and control. Modern microprocessor relays for feeders, transformers and bus sections; automatic transfer and auto-reclosing (ATS/AR); telecontrol/SCADA with communication protocols (incl. IEC-compatible); local control panels.
• Measurement and metering. Current and voltage transformers with metering and protection classes; energy meters, power-quality panels, measuring modules with data logging.
• Arc-flash and thermal protection. Arc sensors, high-speed tripping schemes, temperature sensors on cable terminations and busbars with output to the diagnostic system.
• Voltage presence indication. Integration of stationary indicators (VDIS) with front-panel display and test-point interface.
• Enclosure modifications. Two-coat powder painting; AluZinc/zinc coating for extended durability; options with reinforced door hardware and multi-point rod locks for high-vibration sites.
• Seismic and fire safety. Equipment supplied with calculation and/or testing to the specified seismic category; use of non-combustible insulation materials and fire-rated cable glands and seals.

Typical Configurations

The KSO-399 lineup covers all common MV switchboard panels: incoming and bus-section panels with a breaker, line feeders, transformer feeders, metering and coupling panels, as well as spare bays for future expansion. Based on unified schemes (e.g., “incoming - section - feeder”, “incoming - transformer”), complete switchboards are assembled to the required power and supply-reliability category. Transition panels can be used to interface with previously installed KSO series (including KSO-3xx) without changing room geometry.

To increase maintainability, selections are made with regard to LSC categories and partition classes PM/PI, allowing work in individual compartments without de-energizing adjacent feeders (within the chosen category). Solutions are available for bus bridges, bypass and measuring circuits, as well as for cable testing via dedicated sockets/plugs in the cable compartment.

Standards Compliance

Design and manufacture of KSO-399 comply with relevant international and national standards. Depending on configuration and fitted apparatus, the following documents are taken into account:

1. IEC 62271-200 - AC metal-enclosed switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV (LSC categories, partition classes PM/PI, internal-arc requirements).
2. IEC 62271-1 - general requirements for switchgear and controlgear (series title: “High-voltage switchgear and controlgear”).
3. IEC 62271-100 - AC circuit-breakers (medium-voltage).
4. IEC 62271-102 - disconnectors and earthing switches.
5. IEC 62271-105 - switch-fuse combinations.
6. IEC 61869 (series) - instrument transformers (current and voltage).
7. IEC 60038 - standard voltages.
8. EN/IEC 60721-3-3 - classification of environmental conditions (indoor, weather-protected); IEC 60529 - degrees of protection (IP code).

Partnering with Contractors, Manufacturers and Investors

We welcome technology partnerships with manufacturers of switchgear apparatus, metal structures, cable and busbar systems, as well as with installation and service companies. Various cooperation models are available: supply of metal kits and spare-parts sets, licensing of production documentation, outsourcing of assemblies (enclosures, withdrawable trucks, harnesses, mounting panels), joint preparation and conduct of qualification/type tests, and customer staff training. For investors, serial production of KSO-399 can be localized under a specific regional grid-infrastructure program.

When establishing cooperation, we provide route cards, quality-control plans, tooling lists and fastener standards, corrosion-protection and powder-coating recommendations, as well as incoming-inspection procedures for purchased items.

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

• Tender package: single-line diagrams, equipment lists, data sheets, compliance checklists, 3D visuals and an explanatory note for quick, objective assessment of effort and budget.
• Manufacturing documentation: assembly drawings, BOMs, main and auxiliary circuit schematics, cable schedules, purchased-parts lists. Formats - DWG, DXF, STEP, Parasolid; models - for AutoCAD, SolidWorks, Inventor.
• Interlocking schemes and logic: safe-operation sequences (close/open, earthing, truck movement, access), trapped-key interlocks, signal/condition matrices.
• Commissioning and O&M instructions: checklists, insulation-test programs, control-circuit verification, maintenance routines, torque charts and lists of inspection measurements.
• Co-manufacturing of assemblies and parts: contractor selection for enclosures, busbar systems, harnesses and mounting panels; tolerance, coating and marking alignment.

Additional Technical Notes

Thermal withstand under short-circuit current characterizes the ability of live parts to dissipate heat over a specified time without exceeding permissible temperatures and without deformation that would hinder normal operation. Dynamic (peak) withstand reflects resistance to electrodynamic forces at the initial short-circuit moment (peak current) and defines requirements for busbar rigidity, fasteners and insulating supports. These parameters are selected on the basis of short-circuit studies at the installation point and coordinated with protection time–current characteristics and the interrupting capability of the main apparatus.

To ensure electromagnetic compatibility (EMC), secondary harnesses are routed with separation between power and signal circuits; shielded cables are used; earthing is arranged to avoid stray currents and induced voltages. Terminal and cable marking follows the operation and maintenance documentation to simplify service.

Technical Data

We Offer Documentation for Manufacturing KSO-399:

We provide a complete set of engineering documentation - from a preliminary package for tenders to production documentation for serial manufacture and commissioning. The package is adapted to project requirements, selected apparatus and your plant’s manufacturing capabilities. If self-manufacture of some parts and assemblies is not planned, we will help organize co-production at external facilities: enclosure parts, busbar systems, withdrawable trucks, harnesses, mounting panels and more.

• Pre-tender technical documentation: single-line diagrams, equipment lists, data sheets, compliance checklists, 3D models/visuals, explanatory note with effort and schedule estimates.
• Working drawings and 3D models: assembly drawings, BOMs, main and secondary circuit schematics, cable journals, purchased-parts lists. Formats - DWG, DXF, STEP, Parasolid; models - for AutoCAD, SolidWorks, Inventor.
• Interlocking schemes and algorithms: sequences for safe operations (close/open, earthing, truck movement, access), inter-panel trapped-key interlocks, signal/condition matrices.
• Commissioning and operation manuals: checklists, insulation-test programs, control-circuit verification, maintenance procedures, torque charts and a list of control measurements.
• Co-manufacturing of parts and assemblies: contractor selection, alignment of tolerances, coatings and marking; preparation of route cards and quality-control plans.

Why Work with Us

There is no need to maintain a large team of highly qualified engineers: our documentation set enables a mid-level engineer to organize production without costly prototypes. At every stage - from selecting parameters and specifications to launching serial production - your specialists receive guidance on assembly nuances, electrical tests, harness routing, terminal marking and connection-quality control.

For additional information on KSO-399, please contact: inbox@proekt-energo.com

…and as is well known, an error made at the design stage results in tenfold costs in manufacturing and a hundredfold in operation. Rely on correct standards, proven assemblies and competent co-production.

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