Regenerative Braking Solution – Fuji Electric BU55-4C | FRENIC Series
Where This Product Is Used
The Fuji Electric BU55-4C braking unit is engineered for industrial applications where rapid deceleration, load holding, and regenerative energy dissipation are critical. Typical deployment environments include:
- Crane & Hoist Systems — Prevents overspeed during lowering of heavy loads; ensures safe, controlled descent.
- Elevator & Lift Drives — Absorbs regenerative energy during cabin deceleration, protecting the DC bus from overvoltage trips.
- Centrifuge & High-Inertia Machinery — Enables fast stop cycles without mechanical brake wear.
- Conveyor & Packaging Lines — Maintains precise stop positioning on high-speed lines.
- Winding & Unwinding Machines — Controls tension during deceleration phases in paper, film, and textile processing.
- Test Benches & Dynamometers — Dissipates regenerative power during motor load testing.
Technical Specifications
| Parameter | Value |
|---|---|
| Model | BU55-4C |
| Manufacturer | Fuji Electric Co., Ltd. |
| Series | FRENIC (Compatible) |
| Applicable VFD Capacity | 55 kW (400 V class) |
| Voltage Class | 3-Phase 380–480 V AC |
| DC Bus Voltage Range | 500–820 V DC |
| Braking Transistor | Built-in IGBT |
| Braking Duty Cycle | 10% ED (standard); consult datasheet for continuous duty |
| Activation Threshold | ~760 V DC (400 V class) |
| External Braking Resistor | Required (sold separately) |
| Protection Class | IP00 (open chassis, panel-mount) |
| Cooling Method | Forced air (internal fan) |
| Ambient Temperature | -10°C to +50°C (operating) |
| Weight | Approx. 3.5 kg |
| Country of Origin | Japan |
Why Engineers Specify This Model
- Dedicated IGBT braking transistor — Eliminates the need for an external chopper module, reducing panel footprint and wiring complexity.
- Wide DC bus compatibility — Operates across 500–820 V DC, making it suitable for both 380 V and 480 V supply systems.
- Seamless FRENIC integration — Designed to interface directly with Fuji FRENIC-Multi, FRENIC-Ace, and FRENIC-MEGA series drives without additional signal conditioning.
- Overvoltage suppression — Clamps DC bus voltage during regenerative events, preventing nuisance OV faults and drive trips.
- Compact DIN-rail / panel-mount form factor — Fits standard MCC and control panel layouts.
Complete System Bill of Materials
For a fully functional regenerative braking system using the BU55-4C, engineers typically specify:
- Fuji Electric BU55-4C Braking Unit (this item)
- Compatible braking resistor (e.g., DBR series, sized for 55 kW / duty cycle)
- Fuji FRENIC-series VFD (FRENIC-Ace FRN0110E2S-4 or equivalent 55 kW drive)
- DC bus interconnect cables (rated ≥ 1000 V DC, appropriately sized)
- Thermal overload relay or PTC thermistor for resistor protection
- Panel-mount fuse or circuit breaker on DC bus connection
Compliance & Industry Standards
- CE Marking — Low Voltage Directive (LVD) 2014/35/EU
- UL Listed / cUL (verify current listing on Fuji Electric official documentation)
- RoHS Compliant
- Designed in accordance with IEC 61800-5-1 (Adjustable speed electrical power drive systems — safety requirements)
Quality Assurance & Sourcing
Konmask.com sources the FUJI BU55-4C exclusively through verified industrial distribution channels. Every unit undergoes:
- Visual inspection and label verification against Fuji Electric OEM packaging standards
- Serial number traceability check
- Functional continuity test prior to dispatch
We do not supply grey-market, refurbished, or counterfeit components. All products ship with original manufacturer documentation where available.
How to Source This Part
Ready to order the Fuji Electric BU55-4C? Here’s how to proceed:
- In-stock orders: Add to cart and complete checkout. Standard lead time: 3–7 business days (international shipping available).
- Bulk / project orders: Contact support@konmask.com for volume pricing and project BOM support.
- Technical pre-sales: Our engineering team can assist with drive-to-braking-unit compatibility verification. Reach us at +0086 19859288691.
- Lead time for out-of-stock: Typically 2–4 weeks via factory order. Inquire for confirmed ETA.
Application-Specific FAQ
Q: Can the BU55-4C be used with non-Fuji VFDs?
A: The BU55-4C is optimized for Fuji FRENIC-series drives. Use with third-party VFDs requires careful DC bus voltage matching and may void warranty. Consult our technical team before specifying.
Q: What braking resistor value should I use with the BU55-4C?
A: For a 55 kW / 400 V application at 10% ED, a typical resistor value is approximately 8–12 Ω at 55 kW power rating. Exact sizing depends on deceleration time and duty cycle — contact us for a free sizing calculation.
Q: Does the BU55-4C include built-in overtemperature protection?
A: Yes. The unit includes thermal protection for the internal IGBT. However, external braking resistor thermal protection must be provided separately (PTC thermistor or thermal relay recommended).
Q: Is this unit suitable for crane hoist applications?
A: Yes. Crane and hoist are primary use cases. Ensure the braking resistor is sized for the actual lowering duty cycle, which may exceed 10% ED in continuous lowering operations.
Q: What is the difference between BU55-4C and BU55-4?
A: The “-C” suffix typically denotes a revised or regional variant. Verify the exact specification against your Fuji Electric regional datasheet or contact Konmask for clarification.
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Contact: support@konmask.com | +0086 19859288691
