K-104 Medium-Voltage Switchgear 6(10) kV

The K-104 line is a modern generation of metal-clad 6-10 kV medium-voltage switchgear focused on maximum configuration flexibility and a short commissioning cycle. The panels receive, distribute, and switch three-phase 50 Hz power in networks with an isolated or compensated neutral, providing selective interruption of short-circuit currents up to 31.5 kA. The design is modular: all cubicles share the same overall dimensions and component platform, except cable feeder panels whose depth is increased by 170 mm to accommodate four cables of 3 × 240 mm². This unification simplifies the engineering of single-row and L-shaped indoor switchgear rooms and shortens manufacturing time for series deliveries.

The enclosure is made of sheet steel with an aluzinc (AZ150) coating; joints use structural blind rivets rated for dynamic loads up to 6 kN. Each panel is divided into the medium-voltage (primary), busbar, cable, and relay/control compartments, separated by solid 2 mm partitions. Internal-arc overpressure is vented through dedicated exhaust ducts that direct hot gases upward, protecting operating personnel. A glass-reinforced polyester shutter system automatically covers the primary receptacles when the breaker is racked out, while mechanical and electrical interlocks prevent incorrect operations in line with IEC interlocking principles.

The primary equipment is based on 12 kV vacuum circuit-breakers to IEC class M2/E2/C2 with a mechanical endurance of 30,000 cycles. Motor operators for the circuit-breaker and earthing (grounding) switch are available for integration with remote SCADA and smart grid systems. Secondary wiring runs in shielded cable ducts with single-point grounding to minimize HF interference; mounting provisions are prepared for IEC 61850 Ed. 2 IEDs to streamline deployment of digital protection and telecontrol.

Installation is detail-oriented: cable entry is possible from the top, bottom, or externally (options A/B/C), with the option letter indicating entry direction in the BOM. For space-constrained MV rooms, two-sided maintenance with an 800 mm rear aisle is supported. All primary contacts are positioned at 900-1100 mm height to ease torque checks. Average assembly labor per cubicle is just 12 man-hours versus 18 man-hours for the previous generation, and the yearly monitored availability factor K_gt = 0.998 on pilot sites.

Standards and type tests:

IEC 62271-200 - Internal Arc Classification IAC AFL 31.5 kA / 1 s;
IEC 62271-100 - 12 kV vacuum circuit-breakers, class M2/E2/C2;
IEC 62271-102 - earthing switches with mechanical endurance of 5,000 operations;
IEC 60071-1 - insulation coordination: LI 75 kV / SI 42 kV (standard level);
EN/IEC 60721-3-3 - environmental conditions for stationary indoor use; EN/IEC 60529 - degree of protection IP31 (option IP41).

Scope of use

K-104 panels are installed in permanent indoor switchgear rooms and factory-built modular e-houses across various facilities:

6-10 kV package substations for urban and industrial networks;
auxiliary medium-voltage switchgear of thermal power plants, CCGT blocks;
plant substations: metallurgy, chemicals, pulp & paper, agro-clusters;
pumping stations, public utilities, data centers;
retrofit of legacy KSO-366 / KRUN-6 line-ups without building rework.

Technical data

Rated voltage, kV	6; 10
Highest system voltage, kV	7.2; 12
Rated current of main circuits, A	630; 1250; 1600; 2000; 2500; 3150
Rated busbar current, A	1250; 1600; 2500; 3150
Short-time withstand (3 s), kA	20; 25; 31.5
Peak (dynamic) withstand, kA	51; 64; 81
Maintenance access	two-sided
Insulation level per IEC 60071-1	standard
Environmental conditions	EN/IEC 60721-3-3
Degree of protection (IP)	IP31
Overall dimensions, mm - width - depth - height	750; 1125 1465 2100