Purpose and application

The K-203 switchgear bays are intended for receiving, distributing, switching, and selectively protecting three-phase AC power at a rated voltage of 20 kV (highest system voltage 24 kV) and frequency 50 Hz (60 Hz optional per project). Applications include indoor substations (MV switchrooms), factory-built package substations, station-service boards of power plants, industrial distribution points, and utility/infrastructure sites.

K-203 belongs to air-insulated switchgear (AIS) per IEC 62271-200 with sectionalized architecture, and is intended for operation in 6-24 kV networks with various neutral regimes (isolated, grounded via arc-suppression reactor or active resistor). The design achieves the required service continuity categories LSC and partition classes PM/PI (as specified), allowing safe work in one compartment while adjacent compartments remain energized in line with the user-oriented classification of the standard.

• - Networks with an isolated neutral or a neutral grounded via arc-suppression reactor / active resistor.
• - Typical schemes: transformer incomers/outgoers, bus section/coupler, outgoing cable feeders, capacitor/reactive-power compensation feeders, metering/measurement, reserve incomers.
• - Sectors: power & utilities, oil & gas, mining & metals, machinery, transport & logistics, water and district-heating utilities, large commercial & data-center sites, urban infrastructure.
• - Short-circuit and internal-arc levels are project-defined; configurations comparable with best-in-class AIS 24 kV are available (IAC AFLR up to 25-31.5 kA 1 s; LSC2B; PM partitions).

Layout and construction

The enclosure is made of steel with an Aluzinc coating; external panels are powder-coated (project RAL) for long-term corrosion resistance. The internal volume is divided into independent compartments by solid metallic and insulating partitions; each compartment has its own pressure-relief duct to localize internal-arc effects (upward venting through flaps/ducts). The design allows front servicing, "back-to-wall" installation, and section coupling without rear access, simplifying retrofit projects.

• - Truck (withdrawable unit) compartment for CB/contactor/VT, with shutter mechanism, mechanical interlocks, and guides for precise positioning; "test/check/service" operations are performed with the door closed.
• - Cable compartment: CTs, surge arresters, earthing switch with making capacity (class E per IEC 62271-102), top/bottom power-cable entries (per project), provision for voltage-presence indicators and test sockets.
• - Busbar compartment - copper/aluminium busbars, bay-by-bay sectioning by insulating partitions, optional bus-duct bridges/taps for inter-row connections.
• - Secondary (LV/controls) compartment - protection & automation IEDs and SCADA, telecontrol terminals, meters, terminal strips, marshalling panels; support for IEC 61850 / IEC 60870-5-104 (as specified); space for contact-temperature and partial-discharge monitoring modules.
• - Directed pressure-relief flaps and reinforced hinges/locks on HV-compartment doors for safe arc-energy exhaust.

Safety and interlocking

• - Internal-arc classification per IAC (access class A for operators; protection directions F/L/R - front/side/rear) with upward exhaust; typical configurations - AFLR for 1 s (fault current per spec). IAC definitions per IEC 62271-200.
• - Comprehensive mechanical/electrical interlocks: truck movement only with door closed; earthing switch cannot close with truck in the service position; HV-compartment access blocked unless earthing is applied; truck positively latched in "test/check/service" positions.
• - Optical/current-based arc-flash protection with accelerated tripping of incomer/section CBs; optional dedicated arc-protection modules in cable and busbar compartments to minimize arc energy.
• - Voltage-presence indicators on the front; sockets for phasing/tests; key interlocks and/or key-transfer systems for process-safe sequences.
• - Degrees of protection per IEC 60529 (typical front IP3X/4X; secondary compartments up to IP4X/54 per project).
• - "Closed-door operation" and "logical interlocking" principles follow best practices for AIS 24 kV.

Variants and options

• - Bays: incomers/section couplers, outgoing feeders, measurement/metering, VT/SST on a truck, feeders for capacitor banks/reactive-power units (including detuned), AR/ATS.
• - Switching devices: vacuum circuit-breakers (ratings per project), vacuum contactors for frequent operations, load-break switches per IEC 62271-103 (as specified).
• - Motor operators for the truck and earthing switch for remote control; front-panel mimic with position indication and alarms; SCADA/PCS integration readiness.
• - Systems: joint-temperature monitoring (busbar and cable lugs), partial-discharge monitoring, HV-compartment CCTV, anti-condensation heaters, smart micro-climate sensors.
• - Transition bays, bus-duct bridges, and cable jumpers for interfacing with existing switchgear; transportable sections for faster site installation.
• - Environmental classes per EN/IEC 60721-3-3 (replaces GOST 15150 U3; cold-climate options per project), seismic capability per spec, high-altitude execution; corporate color schemes.
• - Regulatory note: when designing AIS 24 kV in the EU, consider restrictions on new MV equipment using SF₆ as of 01-01-2026 (Regulation (EU) 2024/573); K-203 uses vacuum CBs and air insulation.

Standards compliance

• - IEC 62271-200 - metal-enclosed/metal-clad switchgear, LSC categories and partition classes PM/PI, internal-arc classification IAC (A/FL/FLR - per spec).
• - IEC 62271-100 - AC circuit-breakers (vacuum); IEC 62271-106 - contactors;
• - IEC 62271-103 - load-break switches.
• - IEC 62271-102 - earthing switches (classes M1/M2, E1/E2 - per spec).
• - IEC 60071-1 - insulation coordination and dielectric tests.
• - EN/IEC 60721-3-3 - environmental conditions for weather-protected indoor locations (replaces GOST 15150);
• - IEC 60529 - degrees of protection (IP code).
• - ISO 12100 / IEC 60204-1 (as applicable) - machinery safety / electrical equipment of machines.
• - Target safety/performance levels benchmarked against leading AIS 24 kV solutions (typ. IAC AFLR, LSC2B, PM) used in primary distribution.

Technical data

We offer documentation for manufacturing 20 kV K-203 switchgear:

- Preliminary tender package: technical description, diagrams, questionnaires, manufacturability confirmation.
- Working drawings, 3-D models, and a complete design dossier for production at your facility; we can arrange supplier cooperation for assemblies if needed.
- Prompt adaptation of documentation to the project requirements and your manufacturing capabilities.
- Transition solutions for interfacing with installed third-party equipment and expanding existing switchgear.

Benefits of working with us:

- No need to maintain a large team of senior engineers - the documentation set is tailored for a mid-level engineer.
- Series launch without prototypes - we use proven technical solutions.
- Full support for your team across all aspects of manufacturing K-203 switchgear.

For additional information on 20 kV K-203, contact: inbox@proekt-energo.com

...and, as is well known, an error made at the design stage costs 10× in manufacturing and 100× in operation...

PDF - Download 20 kV K-203 technical information