ABB NBRA Series Brake Chopper Units — NBRA-659

Technical Dossier

Product Details And Specifications

ABB NBRA Series: Comprehensive Module Range and Technical Overview

The ABB NBRA series comprises air-cooled and liquid-cooled brake chopper units designed for integration with ABB ACS and DCS series AC and DC drives. These units are deployed across heavy industrial sectors including petrochemical refineries, nuclear power auxiliary systems, offshore platforms, pulp and paper mills, and steel rolling lines — environments where controlled deceleration and regenerative braking energy dissipation are operationally critical. The NBRA series provides a standardized interface to the drive's DC bus, enabling rapid braking torque without grid feedback, which is the preferred configuration in facilities where regenerative units are not permitted by grid code or where installation cost constraints apply. Installed base spans multiple continents, with particularly high density in European and Asian process industries where ABB ACS600, ACS800, and ACS880 drives dominate the installed base.

The Evolution of NBRA Series Architecture

The NBRA series was introduced as a modular accessory to ABB's frequency converter platforms in the mid-1990s, initially targeting the ACS600 drive family. Early units such as the NBRA-655 and NBRA-656 were designed for lower power ratings and operated with a fixed chopper threshold voltage, requiring manual parameter alignment with the drive's DC bus nominal voltage. As the ACS800 platform emerged in the early 2000s, ABB revised the NBRA architecture to support wider DC bus voltage ranges (nominally 513–675 VDC for 400 V class systems) and introduced improved IGBT chopper transistors with faster switching characteristics, reducing thermal stress on the braking resistor circuit.

The NBRA-659 represents the mature generation of this series, rated for higher continuous braking current and compatible with both ACS800 and ACS880 drive families when paired with appropriate braking resistors. Units in this series are now in the mature-to-end-of-life phase of their product lifecycle. ABB has transitioned newer installations toward integrated brake chopper options embedded within the ACS880 drive cabinet, reducing the need for external NBRA units in greenfield projects. However, the installed base of NBRA-equipped drives in brownfield facilities remains substantial, and replacement demand for maintenance and emergency repair continues at high volume. Compatibility between NBRA generations is not guaranteed; bus connector pinouts and control signal interfaces differ between NBRA-655/656 and NBRA-658/659 variants.

NBRA Series Full Catalog & Functionalities (SKU List)

The following SKUs represent the documented NBRA series product range. Units are classified by function and power rating. All models interface with the drive DC bus and require an external braking resistor sized to the application.

Brake Chopper Units — Standard Air-Cooled:

• NBRA-655: Brake chopper, 400 V class, low current rating, ACS600 compatible
• NBRA-656: Brake chopper, 400 V class, mid current rating, ACS600/ACS800 compatible
• NBRA-657: Brake chopper, 400 V class, increased duty cycle rating, ACS800 series
• NBRA-658: Brake chopper, 400 V class, high continuous braking current, ACS800
• NBRA-659: Brake chopper, 400 V class, highest air-cooled current rating in series, ACS800/ACS880
• NBRA-662: Brake chopper, 690 V class, low current rating, ACS800 high-voltage variant
• NBRA-663: Brake chopper, 690 V class, mid current rating, ACS800/ACS880 HV
• NBRA-664: Brake chopper, 690 V class, high current rating, ACS880 HV compatible
• NBRA-665: Brake chopper, 690 V class, extended duty cycle, industrial crane/hoist applications

Liquid-Cooled Brake Chopper Units:

• NBRA-671: Liquid-cooled brake chopper, 400 V class, compact cabinet integration
• NBRA-672: Liquid-cooled brake chopper, 400 V class, high power density, marine/offshore
• NBRA-673: Liquid-cooled brake chopper, 690 V class, high-voltage marine drives

Accessory and Interface Modules:

• NBRA-01: Parallel connection kit for NBRA units, enables multi-unit braking capacity expansion
• NBRA-02: Termination and bus bar connection kit for NBRA-658/659 cabinet mounting
• NBRA-03: Status and fault signal interface board for NBRA series remote monitoring integration
• NBRA-04: Braking resistor thermal protection relay interface module

Sourcing Hard-to-Find & Obsolete NBRA Series Parts

DriveKNMS maintains a dedicated inventory program for ABB NBRA series units, including models that have reached end-of-sale status with ABB's standard distribution network. For facilities operating ACS600-era drives with NBRA-655 or NBRA-656 units, OEM replacement stock is no longer available through standard channels. DriveKNMS sources these units through certified secondary market channels, including decommissioned drive cabinets from refinery and power generation facility shutdowns, ensuring traceability of unit history and operating hours where documentation is available.

For NBRA-658 and NBRA-659 units, DriveKNMS holds both new-old-stock (NOS) and refurbished inventory. Refurbished units undergo full IGBT chopper transistor inspection, gate driver circuit verification, and DC bus capacitor ESR testing before release. Units are supplied with a test report and a 12-month warranty against manufacturing defects. Emergency same-day dispatch is available for in-stock units to minimize unplanned downtime in critical process environments.

Quality Control for the NBRA Series Range

NBRA series units present specific test challenges due to their high-voltage DC bus interface and IGBT-based chopper topology. DriveKNMS applies the following test protocol to all NBRA units processed through its facility:

• DC bus insulation resistance test at 1000 VDC (Megger test) across all power terminals to chassis ground, minimum acceptance threshold 100 MΩ
• IGBT chopper transistor static characterization: gate threshold voltage, on-state collector-emitter voltage, and leakage current measurement
• Gate driver circuit functional test: verification of gate pulse timing, dead-time insertion, and fault latch behavior under simulated overcurrent condition
• Chopper threshold voltage calibration verification: confirmation that the unit activates at the correct DC bus overvoltage setpoint (typically 780 VDC for 400 V class units)
• Thermal imaging under load: unit operated at 50% rated braking current for 10 minutes; infrared scan performed to identify hot spots on IGBT modules, bus bars, and gate driver PCBs
• Control signal interface test: fault output relay continuity and signal level verification for integration with drive control board
• Final functional test: unit connected to a calibrated DC bus simulator and braking resistor load bank; full braking cycle executed at rated current

For NBRA series availability, pricing, and technical support:

• Email: [email protected]
• WhatsApp: +86 18359293191
• Web: driveknms.com