10 kV switching station on КСО-Е cells: four bays with microprocessor protection (Chornomorsk)

The task

The site needed a small but complete 10 kV switching station: four bays, one of them a standby supply.

The particular challenge is scale. With four cells rather than seventeen, each one carries more functions: the incomer holds metering, protection and voltage measurement at once. Hence the requirements:

• metering and protection from a single set of current transformers — rather than separate CTs per task inside a cramped cell;
• an identical operator interface across all four cells despite their different roles;
• visible position of the switching devices — on a site without permanent staff, the station's state has to be readable from the front.

The solution

We built the station on four КСО-Е-393В single-side-maintenance cells — a design that mounts against a wall and is serviced from the front only.

• Switching. A 10 kV / 630 A vacuum switching module with a solenoid operating mechanism. 10 kV / 630 A disconnectors with manual drives, labelled right on the front — "load-break switch drive", "earthing switch drive" — so the operator is never guessing which handle is which.
• Metering and protection from one CT set. Current transformers rated 300/5 A with two secondary windings: class 0.5S for metering and 10P for protection. One set of devices, two duties, without duplication in a tight cell.
• Voltage measurement. A 10 kV voltage transformer in its own compartment, with HV fuses on post insulators.
• Protection. A РС83 microprocessor protection and automation relay on every cell front, in Ukrainian, with a display and identical control logic across the row.
• Surge protection — arresters on the 10 kV side and on the auxiliary circuits.
• Control circuit supply — a dedicated single-phase dry transformer 220/110 V.
• Front-panel instruments — a 300/5 A ammeter and a 300 V voltmeter: current and voltage visible without the inspector's own meter.
• Documentation. Each of the 4 cells has its own factory passport with serial number and a full bill of components.

For designers: the typical solutions "10 kV switching station on КСО cells" and "КСО protection schemes".

Figures (from the passports)

КСО-Е-393В single-side-maintenance switchgear cells, 2026

Serial Nos. 174119 (variant 21В), 174120 (17В), 174121 and 174122 (04) · passports Э-25-358 ПС · Odesa

Incomer cell contents (from the bill of supply, passport No. 174119)

Why four cells is not simply "less"

In a large station the functions are spread across dedicated cells: a metering cell, feeder cells, a separate bus-section cell — as in our case study of the 17-cell station in Uman. With four bays that is not an option — the functions have to share one 800 mm wide body: metering, protection, voltage measurement, control-circuit supply. This is exactly where design-to-scheme matters rather than picking cells from a catalogue: one CT set serving two duties, compartments laid out around the actual cable entries, coordinated settings on identical relays.

Photo report: the station and its documentary nameplates

We'll size a switching station for your number of bays

Send us the single-line diagram — we'll select the cell variants, the ratings and the equipment. From four cells to a complete switching station, with a passport for every cubicle.