ABB NBRA-658C

ABB NBRA-658C

Product Brief:​ The NBRA-658C is a free-standing aluminum-housed wire-wound resistor bank designed to absorb regenerative energy from overhauling loads (e.g., crane hoist lowering, centrifuge decel, elevator down-travel) that would otherwise cause DC-link overvoltage in the VFD. It is switched by the drive’s brake chopper transistor (internal or external NRED unit) when DC-link voltage exceeds the brake activation threshold (~780–820 V DC for 400 V class, ~410–420 V for 200 V class — parameter-adjustable).

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Category: SKU: ABB NBRA-658C

Description

ABB NBRA-658C

  • Technical Specifications (typical for NBRA-658C class resistor):
    • Rated Resistance: Typically 40–100 Ω (exact value depends on drive power & braking torque requirement — verify selection table)
    • Power Rating (continuous / intermittent): Continuous ≈1–5 % of drive rating; Intermittent braking power = drive rated power × braking duty cycle (typical 5–20 s ON, 60–300 s OFF); e.g., 22 kW drive may use 10 kW peak / 500 W avg resistor
    • Duty Cycle: Intermittent, IEC 60204-1 compliant (short-time rating)
    • Max Chopper Voltage: Matches drive DC link — 690 V DC class (for 400 V AC drives) or 900 V DC (for 500–690 V AC drives) — confirm before ordering
    • Construction: Aluminum-housed wire-wound resistor element with mounting brackets; ceramic core, silicone-coated; sometimes fan-cooled (forced air on larger units)
    • Cooling: Natural convection (small) or forced-air fan (medium/large) with thermostat
    • Cable Entry: Stud terminals or lug terminals; cable size per resistor rating (typically 6–35 mm²)
    • Protection: IP20 (standalone resistor) / IP23 with louvered enclosure; overheating thermostat (NC contact) available on some versions to signal drive
    • Operating Temp.: –25 °C to +40 °C (ambient for rated duty); +40 °C to +70 °C with derating
  • Functional Features:
    • Absorbs kinetic energy from overhauling load — prevents “DC Overvoltage” trip during rapid deceleration
    • Compatible with ABB ACS800/ACS880 internal brake chopper (frames R2–R8) or external NRED brake unit (larger)
    • Thermostat contact can be wired to drive digital input to inhibit further regeneration if resistor overheats
  • Application Scenarios:
    • Crane / hoist main hoist brake — lower travel regenerates; resistor dissipates energy
    • Elevator drive (down direction) — dynamic braking for smooth stop
    • Centrifuge / winder with frequent decel from high speed
    • Test rigs simulating load braking
  • Material & Structure / Working Principle / Installation / Precautions:
    • Mount resistor in well-ventilated area — HOT during braking​ (surface >200 °C possible briefly) — maintain clearance ≥100 mm from combustibles
    • Connect resistor + / – to drive brake terminal (UDC+/UDC– or B+/B– per drive manual) — observe polarity (some drives mark B+ and BR–)
    • If resistor has over-temp thermostat: wire NC contact to drive DI configured as “Brake Resistor Fault” → drive will fault or warn
    • In drive parameter: set brake chopper enable = YES; set activation voltage (typically 780 V for 400 V class); set brake resistor ohmic value & max braking power (drive calculates duty)
    • Precautions:
      • Resistor gets DANGEROUSLY HOT​ — install in vented enclosure with guard; add high-temp warning label
      • Verify ohmic value matches drive’s minimum allowed brake resistance (parameter 21.04 / 27.xx in ACS800/ACS880) — too-low resistance causes chopper overcurrent / damage
      • Do NOT operate resistor continuously at full braking power beyond duty cycle — thermal accumulation causes failure
      • For long downhill runs (e.g., mine winder), consider regenerative (active front-end) instead of resistor — resistor may overheat on sustained regeneration

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