ABB Main Distribution Board (MDB)

The ABB Main Distribution Board (MDB) is a factory-assembled, IEC 61439-2 compliant low-voltage distribution solution engineered for primary power distribution in industrial plants, utilities, data centres, hospitals and EPC projects. The assembly integrates ABB type-rated components — Emax 2/3 air circuit-breakers (ACB) for incoming protection and metering, Tmax XT molded-case circuit-breakers (MCCB) for outgoing feeders, AF series contactors for motor feeders, and withdrawable or fixed functional units from the MNS platform where high availability or plug-in maintenance is required. The MDB uses a type-tested busbar system with verified temperature-rise and rated short-circuit withstand (Icw) typically specified 50–100 kA / 1 s and rated currents up to 6300 A at 690 VAC. Design verification and type-testing are performed in accordance with IEC 61439-1 and IEC 61439-2 (verification of clearances, temperature rise, dielectric properties, short-circuit withstand, and mechanical operation). Circuit-interruption and coordination follow IEC 60947 series requirements for ACBs/MCCBs and contactors, while hazardous-area variants can be designed to IEC 60079 series for Ex environments. Form of internal separation is available from Form 2b through Form 4b to segregate incoming, busbar, and outgoing feeder compartments, facilitating safe operation and selective maintenance. Protection schemes include adjustable thermal-magnetic and electronic trips in Tmax XT devices, earth-fault and residual current protection, overcurrent discrimination studies per IEC 60947-2, and optional digital protection relays and energy metering (integrated meter modules or external CT/VT-based metering). Communication and integration options support Modbus RTU/TCP and substation protocols such as IEC 61850 for remote monitoring and SCADA integration. For comparison, ABB’s MNS and ArTu families provide MCC/MDB hybrid options and are often selected over alternative platforms like Siemens SIVACON or Schneider Prisma Set when withdrawable units, type-tested fault withstand, or specific ABB product-line compatibility is required. Real-world deployments include transformer main distribution in petrochemical plants (with IEC 60079 compliance), main switchboards for renewable-energy substations, and high-availability feeds in data centres where selective coordination, high Icw, and predictable temperature rise are mandatory. Patrion-engineered ABB MDBs can be supplied as type-tested assemblies or as project-specific assemblies validated by calculation and partial testing to meet IEC 61439 verification clauses; optional features include arc-mitigation layouts, IP protections from IP31 to IP54, remote I/O and PLC integration, and factory FAT documentation with full type-test reports and coordination studies.