Purpose and scope of application

The K-224 “Omega” series of medium-voltage switchgear is intended for receiving, distributing, switching, and selective protection of three-phase AC power at a rated voltage of 20 kV (maximum system 24 kV) and frequency 50 Hz (60 Hz on request). The switchgear is used in indoor substations of package transformer substations, in utility and industrial distribution substations, for auxiliary power systems of power plants, and at municipal and infrastructure facilities.

The metal-clad concept with a withdrawable vacuum circuit-breaker and segregated compartments confines the effects of any internal arc to a single compartment and enables safe maintenance. The modular architecture allows flexible configuration of feeder schemes, top/bottom cable entry, and one-sided/two-sided maintenance to suit the site requirements.

Typical applications include primary and secondary distribution at main and distribution substations, supply of 6-20 kV outgoing cable feeders, bus-sectioning and automatic transfer between bus sections, transformer incomers/outgoers, starting and protecting medium-voltage motors (pump stations, compressor rooms, large fans), connection of power-factor correction banks and harmonic filter banks, as well as auxiliary service transformers/voltage transformers for metering and measurements. “Omega” panels are equally effective in radial and ring networks, with single- or double-bus arrangements, including “incomer - section - incomer” schemes.

Industry users: upstream/downstream oil & gas (field MV substations, gathering/booster stations), mining & metals (concentrators, rolling mills), power & heat (TPP/CHP, CCPP, micro-generation), transport and urban infrastructure (metro, traction substations, airports, medical and business centers), data centers, and RES sites (wind/solar - 20 kV grid-integration nodes). For critical loads (reliability categories I and II), functions such as AR/ATS, remote control, telecontrol, and SCADA/DCS integration are supported.

Layout and construction

The cabinet is made of galvanized steel; elements are joined with high-strength blind steel rivets. The internal volume is divided by solid metallic and insulating partitions into independent compartments, each equipped with an individual pressure-relief duct with limit switches.

• - Withdrawable unit (circuit-breaker) compartment with shutter mechanism and padlocking capability in the test position.
• - Cable compartment: current transformers, surge arresters, earthing switch, capacitive dividers/voltage-presence indicators; top/bottom cable entry.
• - Busbar compartment: bare copper busbars; take-offs may use solid insulation as specified.
• - Relay/low-voltage compartment (secondary circuits) for protection & control IEDs, control, annunciation, and revenue metering.

For convenient service access, the floor of the withdrawable-unit compartment is removable. A common copper earthing bar runs along the cabinet base, bonding all panels in the section; it shall be connected to the substation earthing grid at no fewer than two points.

Safety and interlocks

• - Built-in arc-flash protection with accelerated tripping of incomer/section breakers (typical clearing time ≤ 0.2 s) with current/voltage supervision to avoid mis-operations.
• - Mechanical, electrical, and key interlocks: prohibition on opening MV-compartment doors with the ES open or the truck in the in-service position; truck movement only with the door closed.
• - Spring-operated high-speed earthing switch with visible position indication and status output to the front panel/P&C system.
• - Pressure-relief flaps for each MV compartment to vent arc products in a safe direction.

Configurations and options

• - Panels with auxiliary service transformer (AST) and/or voltage transformers on a withdrawable truck; interlocks preventing truck movement with the AST LV breaker closed.
• - Motorized drives for the truck and earthing switch for remote operation; integration of optical arc protection, contact-temperature monitoring, and mimic indication.
• - Bus-tie bridges and transition panels for coupling to existing switchgear, including inter-row connections.

Standards compliance

• - IEC 62271-200 - metal-enclosed/metal-clad MV switchgear, LSC/PM categories; internal-arc classification IAC (A/FL/FLR - as specified).
• - IEC 62271-100 - AC circuit-breakers (vacuum);
• - IEC 62271-102 - earthing switches and their drives;
• - IEC 60071-1 - insulation coordination and dielectric tests;
• - EN/IEC 60721-3-3 - environmental conditions (indoor, weather-protected);
• - IEC 60529 - degrees of protection (IP);
• - IEC 61000-6-2 / 61000-6-4 - EMC for industrial environment (immunity/emission);
• - IEC 60068-2 - environmental/mechanical tests (vibration, shock, temperature, humidity).

Technical data

We offer documentation for manufacturing the 20 kV KRU K-224 “Omega”:

• - Base tender package: technical description, principal single-line diagrams, and data sheets confirming manufacturing readiness.
  - Full production dossier: drawings, 3D models, and all design documentation required to start manufacturing at your site; if needed, we will arrange subcontracting for assemblies and parts.
  - Rapid document adaptation to the specific project requirements and your plant’s process capabilities.
  - Transition solutions for integrating installed third-party equipment, ensuring proper interfacing and extension of the switchgear line-up.

Why work with us:

• - No need to maintain a large senior engineering staff: the documentation set is tailored to a mid-level engineer.
  - No prototype stage: we launch series using proven technical solutions.
  - Advisory support for your specialists on all aspects of manufacturing KRU K-224 “Omega”.

For additional information on the 20 kV KRU K-224 “Omega”, contact: inbox@proekt-energo.com

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

PDF - Download technical information for the 20 kV KRU K-224 “Omega”