Description
The NBRA-653C is a Dynamic Braking Chopper Module manufactured by ABB, part of the NBRA series designed to work with ABB ACS800, ACS850, and select ACS600 low-voltage drives. It connects in parallel with the drive’s DC link via the brake terminal (UDC+/UDC−) and monitors the DC-bus voltage: when regenerative energy from a decelerating high-inertia or overhauling load raises the bus above a preset threshold, the NBRA-653C switches on internally and routes current through an externally connected brake resistor, dissipating the energy as heat and preventing a “DC Overvoltage” trip.
Application Scenarios
Imagine a container port where a ship-to-shore crane’s trolley drive (ABB ACS800) must stop a 40-ton load traveling at full speed. The rapid deceleration forces the motor into generator mode, pumping energy back to the DC link. Without a braking chopper the drive would fault on DC Overvoltage and the mechanical brakes would have to absorb all the energy—accelerating lining wear. By installing a NBRA-653C with a properly sized external resistor, the regenerative energy is dissipated electronically. When the original NBRA unit in one crane fails after 12 years, the maintenance team powers down the drive, unbolts the old unit, mounts the new NBRA-653C, reconnects the resistor cables and DC-link terminals, and resumes operation—no drive replacement, no re-termination of motor leads. The NBRA-653C directly solves the pain point of frequent DC-OV trips on overhauling/cyclic loads and extends the service life of proven drive assets.
Parameter
| Main Parameters | Value/Description |
|---|---|
| Product Model | NBRA-653C (Also referenced: NBRA-653C-IE, NBRA-653C-UL depending on certification) |
| Manufacturer | ABB |
| Product Category | Dynamic Braking Chopper Module (External Brake Chopper for VSDs) |
| Compatible Drives | ABB ACS800-01, ACS800-04, ACS800-11 (with brake terminal), ACS850, ACS600 (select frames with external brake option) |
| Supply Voltage (Monitored DC Link) | Derived from Drive DC Bus — corresponds to 3-phase input 380–500 V AC (~540–710 V DC typical) |
| Chopper Activation Voltage | Adjustable / Fixed per drive DC-link threshold (typically kicks in at ~780–820 V DC for 400 V class; factory set) |
| Max Continuous Braking Power | Depends on duty cycle & resistor; typical continuous dissipation 1.5–5 kW, peak up to 30 kW for short durations (refer to resistor selection) |
| External Brake Resistor | Required — NOT included; connected to Brake Resistor Terminals (R+/R−) of NBRA-653C |
| Switching Element | Internally fused IGBT chopper transistor with thermal protection |
| Protection Features | Overtemperature protection (via resistor thermal switch if fitted), short-circuit protection on brake output, DC-link undervoltage lockout |
| Indicators | LED: Power / Chopper Active / Fault (per revision) |
| Mounting | DIN-rail or panel-mounted adjacent to drive; DC-link & resistor cables landed on screw terminals |
| Operating Temp. | 0 °C to +50 °C (derating above 45 °C; storage -40 °C to +85 °C) |
| Certifications | CE, UL, cUL, GOST (variant-dependent) |
| Dimensions (Approx.) | 175 × 110 × 135 mm (H × W × D — typical NBRA-653 format) |
| Weight (Approx.) | 1.2–1.6 kg |
Technical Principles and Innovative Values
- Innovation Point 1 — Direct DC-Link Shunt Regulation via IGBT Chopper: The NBRA-653C continuously monitors the drive’s DC-bus voltage via its UDC+/UDC− terminals. When VDCexceeds the preset chopper-on threshold, an internal IGBT turns ON at high frequency (PWM), connecting the external brake resistor across the DC link and clamping the bus. When VDCfalls below the hysteresis band the IGBT turns OFF. This active clamping prevents overvoltage trips while minimizing average resistor power loss.
- Innovation Point 2 — Seamless Integration with ABB Drive Protection Logic: The module’s fault output (where fitted) can be wired to the drive’s digital input or the drive auto-detects chopper presence via DC-link characteristics (ACS800 with brake option enabled). If the chopper or resistor overheats / fails, the drive can be programmed to coast-to-stop or fault — giving controlled failure response rather than uncontrolled overspeed.
- Innovation Point 3 — Compact DIN-Rail Format with Screw-Terminal Resistor Connection: Unlike improvised chopper circuits, the NBRA-653C packages the IGBT, gate-drive, snubber, and fusing in a UL-listed enclosure with clearly marked terminals for DC link (+ / −) and resistor (R+ / R−). This simplifies panel layout, reduces wiring errors, and keeps the brake-circuit separate from the drive’s power terminals for safer troubleshooting.
