Description

The ABB NRED-61 is a thick-film hybrid voltage reducer module engineered specifically for ABB ACS800 and ACS600 series variable frequency drives, serving as a critical overvoltage protection component for the drive’s power supply and control boards . This specialized module employs advanced thick-film hybrid circuit technology to provide robust transient voltage suppression and DC bus voltage regulation in demanding industrial environments.

As a key component in ABB’s drive protection architecture, the ABB NRED-61 (also designated as NRED-61-E in certain variants) functions as a voltage clamping device that limits the DC bus voltage supplied to sensitive control electronics . The module is particularly essential in applications involving regenerative braking—such as cranes, elevators, and wind turbine converters—where motor-generated energy can cause dangerous voltage spikes on the drive’s DC link .

 

Application Scenarios

In a 2MW wind turbine operating with an ABB ACS800 converter, the DC bus voltage can spike dangerously during grid faults or sudden load dumps, threatening the APOW-01C power supply board and NBRC-61 chopper control board. The ABB NRED-61 acts as the first line of defense, clamping the DC bus voltage to safe levels—typically limiting the input to the APOW-01C board to below DC 1000V . This protection is so critical that the NBRC-61 chopper control board includes a dedicated jumper (X6) to configure whether the ABB NRED-61 is present, with the module enabled by default for maximum protection . By absorbing transient overvoltage events, the ABB NRED-61 prevents catastrophic failure of the drive’s power supply, extending the service life of the entire converter system and reducing unplanned maintenance costs for wind farm operators.

 

Parameters

Main Parameters	Value/Description
Product Model	NRED-61 / NRED-61-E
Manufacturer	ABB
Product Category	Thick-Film Hybrid Voltage Reducer / Overvoltage Protection Module
Core Technology	Thick-Film Hybrid Circuit with varistor-based clamping
Varistor Voltage	610 V ±10% (at 1 mA DC)
Maximum Clamping Voltage	1,000 V (at 25 A surge current)
Peak Surge Current (8/20 µs)	2,500 A
Energy Absorption Capacity	150 J (at 2 ms)
Response Time	< 25 ns
Power Dissipation (NRED-61-E)	6 kW braking power rating
Operating Temperature	-40°C to +125°C
Storage Temperature	-55°C to +150°C
Dimensions	Approx. 145 mm × 55 mm × 205 mm
Weight	0.11 kg
Compatible Drives	ABB ACS800 series, ACS600 Multidrives
Compatible Brake Chopper	NBRA-669 (with NBRC-61 control board)

 

 

Technical Principles and Innovative Values

Innovation Point 1: Thick-Film Hybrid Overvoltage Clamping Architecture
The ABB NRED-61 employs thick-film hybrid circuit technology that combines varistor-based voltage clamping with advanced thermal management in a compact, rugged package . The module’s core component is a metal-oxide varistor that exhibits high impedance under normal operating conditions but rapidly conducts when the DC bus voltage exceeds the clamping threshold—typically 1,000V. This <25 ns response time ensures that transient overvoltage events are suppressed before they can damage sensitive control electronics .

Innovation Point 2: Dedicated Protection for Drive Control Boards
The ABB NRED-61 is specifically engineered to protect the APOW-01C power supply board in ACS800 drives operating at AC 690V, where the DC bus voltage can reach dangerous levels during regenerative braking or grid disturbances . By limiting the voltage input to APOW-01C to below DC 1000V, the module prevents catastrophic failure of the drive’s power supply and control logic—a common failure mode in high-power drives operating in demanding environments.

Innovation Point 3: Integrated Brake Chopper Protection
In ABB’s brake chopper systems, the ABB NRED-61 serves as an essential protective component for the NBRC-61 chopper control board. The NBRC-61 board includes a jumper (X6) that must be set to OFF when the ABB NRED-61 is installed, enabling the module’s protection circuitry . This integrated protection ensures that the brake chopper can safely dissipate regenerative energy without exposing the control board to damaging voltage transients.

Innovation Point 4: Wide Temperature Range for Harsh Environments
With an operating temperature range of -40°C to +125°C and surge current capability of 2,500A, the ABB NRED-61 is designed for the most demanding industrial applications . This thermal resilience makes it suitable for wind turbines (both onshore and offshore), steel mills, mining equipment, and other environments where temperature extremes and electrical stress are commonplace.