Legrand DMX3 Air Circuit Breaker

The Legrand DMX3 Air Circuit Breaker (ACB) is a high-power switching and protection device spanning the current range from 630 A to 6300 A, designed for incoming, bus-coupler, and outgoing applications in main low-voltage power distribution centres, utility substations, and large industrial facilities. The DMX3 is available in fixed and drawout (withdrawable) versions — the drawout variant being essential in facilities requiring live bus maintenance, where withdrawing the breaker to the isolated position allows the circuit to be de-energised and isolated without shutting down the entire switchboard. The Micrologic electronic trip unit, available in protection grades from basic overload/short-circuit (Micrologic 2.0) through full power quality measurement and energy logging (Micrologic 8.0), transforms the DMX3 from a simple protective switch into an intelligent power management device providing real-time current, voltage, power, and energy measurements directly at the incomer — data that is increasingly required under Saudi Arabia's SEC smart metering and power quality reporting obligations.

The DMX3's making capacity of up to 220 kA and breaking capacity up to 150 kA make it suitable for the highest fault-level environments in Saudi Arabia — including ARAMCO's main oil-field power distribution centres fed by large gas turbine generators in Khurais, Shaybah, and Haradh, and SABIC's central power distribution centres in Jubail I and Jubail II where multiple 63 MVA bulk-power transformers can generate aggregate fault currents exceeding 100 kA. The breaker's arc chute system is designed for a minimum of 3000 electrical operations at rated current, with IEC 60947-2 Category B selectivity guaranteed — meaning the DMX3 will withstand the mechanical and thermal stresses of multiple high-current fault events without loss of function, a critical requirement in process plant switchboards where breaker failure during a fault could initiate a cascading outage.

Saudi Arabia's Vision 2030 giga-projects demand ACBs at a scale never previously seen in the Kingdom's electrical infrastructure. NEOM's main 33/11 kV receiving substations — several with installed transformer capacity exceeding 200 MVA — require 6300 A DMX3 ACBs on the 11 kV LV busbars to handle the full load current of individual transformer banks. The Qiddiya Entertainment City main power hub, with its diverse loads from stadium lighting, theme park drives, and hospitality facilities, relies on DMX3 ACBs for its flexible power management architecture. SWCC's latest seawater reverse osmosis (SWRO) mega-plants at Ras Al Khair and Shuqaiq use DMX3 drawout ACBs in their main switchboards to allow breaker maintenance without interrupting the desalination process — a 24/7 operation that cannot tolerate planned outages.

Razz Middle East is Legrand's authorised partner for DMX3 ACB supply and technical support in Saudi Arabia. Our engineering team provides a complete service including fault-level verification, Micrologic trip unit setting calculations, type-test documentation, and factory acceptance test (FAT) support at Legrand's facilities. We maintain buffer stock of the most common DMX3 ratings in Riyadh and coordinate rapid delivery from Legrand's regional distribution centre in Dubai for less common configurations, ensuring competitive lead times for both direct sales and EPC contractor projects.