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Air Circuit Breaker (ACB’s)

Air circuit breakers (ACBs) protect the largest LV lines, carrying currents up to 6300 A. They can be used for source coupling or changeovers. To all high-level electrical professionals, MasterPact sounds like a saga of innovative breakthroughs. Experience the full connectivity of the latest generation, Masterpact MTZ, with embedded algorithms enabling ever-higher energy reliability and efficiency.

Category: Product ID: 29817



The worldwide benchmark for high current circuit breakers

MasterPact NW circuit breakers are equipped with MicroLogic control units that offer built-in power and energy metering in addition to basic or advanced protection functions. Two sizes are sufficient to cover applications from 800 to 6300 A, with a breaking capacity from 42 to 150 kA.
The range comes with a wide choice of standardized accessories. The universal design of the MasterPact circuit breaker line allows most accessories to be used across the entire line. It enables the standardization of electrical switchboards by providing peace of mind in terms of choice, installation, and operation.


  • Rated current: 800 to 6300 A
  • Breaking capacity: 42 to 150 kA at 220/415 V AC
  • Voltage rating: up to 1150 V AC
  • There are two physical sizes: 800 to 4000 A and 4000 A to 6300 A.
  • Draw out and fixed mount
  • 3-pole and 4-pole construction
  • Electronic MicroLogic control units, integrating current, voltage, power, and energy metering enabling energy management, earth leakage protection, and other advanced protection or network analysis functions
  • Switch disconnectors version available
  • Optimized a range of field-installable auxiliaries and accessories
  • Different offers complying with different international standards include: IEC 60947, UL489, ANSI/UL1066
  • CCC, EAC, and other local certifications
  • Compliance with specifications of marine classification companies: Bureau Veritas, Lloyd’s Register of Shipping, Det Norske Veritas, etc.

MicroLogic control unit specifications:

  • Four levels of protection against overloads and short circuits: 2.0 (LI), 5.0(LSI), 6.0(LSIG), 7.0 (LSIV, built-in earth leakage protection)
  • Four types of measurement: A (Ammeter), E (Energy), P (Power), and H (Harmonics)
  • Energy reduction maintenance setting (ERMS) function available for arc flash protection for MicroLogic P and MicroLogic H
  • Measurement accuracy: Class 0.5 for voltage, Class 1.5 for current, and Class 2 for active power and energy
  • Compatible with both Ethernet and Modbus SL protocol
  • Operating assistance to diagnose tripping cause and maintenance information


MasterPact NW circuit breakers contribute to the reliability and continuity of service of your electrical installation thanks to the:

Optimized safety

  • Faultless protection
  • Increased uptime with improved coordination with MicroLogic electronic trip unit adjustability
  • Complete selectivity and coordination
  • High resistance to environmental stresses

Integrated monitoring for energy efficiency

  • Improved uptime with a complete monitoring solution in Smart Panels
  • Seamless integration into power monitoring systems enables to track of energy consumption trends, anticipate potential damage and improve network reliability
  • Local and remote communication with trip cause (earth leakage, overload, short-circuit) and alarms (earth leakage, overload) allow proactive operational and energy efficiency
  • Advanced MicroLogic control unit can assist in providing corrective, preventive, and predictive maintenance, and energy management to identify potential savings: energy consumption data, operation follow-up, network monitoring, preventative and predictive maintenance information, pre-alarm and alarm events


General applications in all types of low voltage electrical installations

Suitable in most applications for protection, measurement, monitoring, and quality of energy, including generator protection and motor protection, in standard applications and specific applications demanding high performance, including:

  • Industry: mining operations, minerals, metals, and cement production, water & wastewater industry, automotive, food, and beverage, etc.
  • Oil & Gas extraction and processing, Chemicals industries
  • Data centers infrastructure
  • Healthcare infrastructure, hospitals
  • Marine and offshore industry
  • Infrastructures: airports, railways, subways, tunnels, power plants, etc.
  • Buildings: commercial buildings, hotels, offices
  • Wind turbines, solar, gensets

Special applications

  • Photovoltaic and DC networks (MasterPact NW DC & DC PV)
  • Corrosive industrial environments (special versions)
  • Mining industry (special 1000V versions)
  • High short-circuit current limiting (ultra-rapid MasterPact UR)
  • Navy (MasterPact NT and NW Navy)
  • UL 489 (MasterPact NT and NW UL 489 listed)
  • Source-changeover systems (TransferPact): service sector (hospital operating rooms, computer rooms, etc.), industry (assembly lines, ship engine rooms, etc.), infrastructures (runway, railway, etc.)


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