KRU K-12 (K-XII) is a complete medium-voltage switchgear system for receiving, distributing, and switching three-phase AC at 50 Hz with rated voltage up to and including 10 kV. The layout is intended for general-purpose distribution switchgear, thermal and hydro power plants, utility substations, and industrial electrical installations.

Environmental conditions comply with EN/IEC 60721-3-3. The equipment is operable at ambient air temperatures down to -25 °C (room heating may be required). The atmosphere must be non-hazardous and non-flammable, free of aggressive gases/vapors that attack metals and insulation, and free of conductive dust.

A typical K-12 panel follows the metal-clad concept with segregated compartments: the base enclosure, a withdrawable unit (truck), a relay/control compartment, and a busbar compartment. For K-12 variants (breaker panels, voltage-transformer panels with fuses, surge-arrester panels, and panels with separable primary contacts) a truck is provided; for other functional panels the truck may be omitted.

The functions of bus and line disconnectors are performed by separable primary contacts: the fixed parts are mounted in the cabinet, the moving parts are on the truck. The truck has three positions: in-service, test (isolated), and maintenance; latching is provided in the in-service and test positions. Transfer to maintenance is performed after racking to test.

The enclosure is a welded sheet-steel structure divided by horizontal and vertical partitions into compartments:

• truck (withdrawable unit) compartment;
• upper separable-contact compartment (fixed contacts on post insulators);
• lower separable-contact compartment (CTs with fixed contacts, earthing switch, zero-sequence CT, cable bar/termination assembly);
• busbar compartment (busbars on post insulators, separated by a plate with bushing insulators; for double-row line-ups a bus-tie bridge is used).

Protective folding shutters separate the truck from the upper and lower contact compartments; a horizontal shutter is kinematically linked to the leaves and closes/opens automatically as the truck moves. With the truck withdrawn, the shutters can be padlocked. The vertical shutters are split horizontally: with the lower contacts de-energized, only the lower leaves can be opened without touching the upper ones. Pivoting lower edges ensure the required clearances when open.

Earthing switch - moving and fixed contacts with a lever drive; positive latching in the ON/OFF positions and padlocking capability. Interlocks prevent energizing external connections and block truck racking from test to in-service with the earthing switch closed (a mechanical stop tracks the earthing-switch shaft position).

The front door of the truck compartment has a viewing window (per data sheet) and allows truck operations in all fixed positions with the door closed. The façade carries voltage-presence indicators (feeder/busbars) and a mimic diagram showing the truck position (test/in-service), breaker status, and earthing-switch status - helping to prevent operator error.

Standards compliance.

• IEC 62271-200 - requirements for metal-enclosed MV switchgear; internal-arc classification IAC (as specified);
• IEC 62271-100 - 12 kV circuit-breakers; IEC 62271-102 - earthing switches;
• IEC 60071-1 - insulation coordination (standard insulation level);
• EN/IEC 60721-3-3 - environmental conditions (indoor); IEC 60529 - degree of protection IP31.

Scope of application

K-12 (K-XII) is intended for new and retrofit indoor MV switchgear and factory-built modular substations:

• auxiliary switchgear of TPP/NPP/CCPP units; sectioning and metering;
• utility and plant substations at 6-10 kV for industrial facilities;
• oil & gas power systems, water utilities, and public infrastructure;
• modernization of existing switchgear retaining interface dimensions and cable routes.

Service conditions

• Environmental class - EN/IEC 60721-3-3; operating ambient range: -25…+40 °C;
• Altitude - up to 1000 m a.s.l. (above this - insulation/thermal checks by calculation);
• Atmosphere - non-hazardous, free of aggressive gases/vapors and conductive dust;
• Degree of protection - IP31 (higher IP on request).

Design features of K-12 (K-XII)

• Compartmentalization: truck ⋅ upper/lower separable-contact compartments ⋅ busbars;
• Separable primary contacts perform bus/line disconnector functions;
• Folding shutters with mechanical interlock and padlock; split vertical leaves;
• Bus-tie bridge for coupling sections in double-row arrangements;
• Mimic and indication on the façade: truck position, breaker, earthing switch, voltage presence.

Reliability and safety

• Internal-arc effects confined within a compartment by shutters and partitions;
• Interlocks: no racking with earthing switch closed; positive latching of ES and truck positions;
• Removable covers and viewing windows for safe inspections and service;
• Shielded routing of secondary wiring - improved EMC robustness.

Technical data

We offer documentation for manufacturing KRU K-12:

Tender package. Single-line diagrams, data sheets, and technical description for bids and feasibility assessment.

Manufacturing drawings and 3-D models. Layout/assembly drawings, BOMs, secondary schematics, and cable schedules - tailored to your production.

Contract manufacturing of subassemblies. We arrange fabrication of enclosures and mechanisms with partners; you perform assembly, wiring, and routine factory tests.

Adaptation and integration. Drop-in panels for interfacing with existing busbars/secondary circuits and third-party equipment.

Why work with us:

No staff expansion needed. Documentation is designed for a mid-level engineer.

Fast series launch. Standardized modules and proven solutions reduce schedule and risk.

Technical support. Guidance on assembly, commissioning, and digital integration of P&C/SCADA.

For more details on KRU K-12 contact: inbox@proekt-energo.com

PDF - Download KRU K-12 technical information