ЩО-90 at 2000 A: a main LV switchboard with withdrawable air circuit breakers

The task

The site needed a 0.4 kV main switchboard for a high current — 2000 A — with two incomers and bus sectionalising.

The decisive requirement was not electrical but operational: the main incomer breaker is exactly the device you cannot leave out of service for long. The design had to let the switching device be serviced without removing the panel and without dismantling the busbars.

The solution

We built the board on ЩО-90 panels in the withdrawable-element version.

• Withdrawable air circuit breakers. Each breaker sits on a racking carriage: it rolls out of the panel for inspection, overhaul or replacement while the busbars stay untouched. This is what separates this board from a standard ЩО-90 with fixed devices.
• Microprocessor trip units with a display and settings adjustable on the breaker front.
• Three panels: "Ввід №1", "Ввід №2", "Секційна" — the classic dual-supply arrangement with bus sectionalising.
• Control and indication on the front. Every panel carries labelled pushbuttons and status lamps: closing and opening of the incomers and the bus-section device, position, alarms. The operator works from the front without opening the board.
• Busbars with phase colour marking, rated for 2000 A.
• Secondary circuits with tagged conductors and terminal rows for every bay.
• A passport and factory nameplate for each panel separately.

The series product card: ЩО-90 panels up to 4000 A. For designers: the typical solution "ЩО-90 for a package substation". Similar withdrawable breakers inside a substation — in the case study КРП-4000/0.4 У1: 14 power cabinets in a containerized block.

Figures (from the passports)

ЩО-90 series distribution switchboard panels, 2024

Why the withdrawable version pays off in service

• Overhaul without shutting down the whole board — the device rolls out, the busbars stay in place.
• Replacing a device means replacing an element, not a panel.
• Safer maintenance — work is done outside the main-circuit compartment.
• Shorter downtime during planned maintenance of the main incomer.

Photo report: from the withdrawable element to the panel fronts

We'll size a main switchboard for your current

Send us the single-line diagram — we'll work out the number of panels, the ratings and the device version: fixed or withdrawable. From questionnaire to factory testing and a passport for every panel.