Description
Product Introduction
The Yaskawa JUSP-RA05 is an external regenerative braking resistor unit engineered to absorb and dissipate regenerative energy generated during high-speed deceleration or vertical axis lowering in Yaskawa AC servo drive systems. When a servo motor rapidly decelerates high-inertia loads, it acts as a generator, dumping energy back onto the DC bus link of the connected Servopack. When internal drive braking capacity is exceeded, the JUSP-RA05 steps in to burn off this excess energy as heat.
Connecting across the B1/B2 or B1/B3 terminals of compatible Yaskawa drives, the unit allows machines to run tighter duty cycles, faster acceleration profiles, and heavier vertical loads without triggering overvoltage alarms. When an aging braking resistor burns out under severe dynamic braking cycles, dropping in a bench-verified JUSP-RA05 restores continuous operation without thermal tripping.
Key Technical Specifications
| Parameter | Value / Specification |
| Model Number | JUSP-RA05 |
| Manufacturer | Yaskawa Electric |
| Product Category | Regenerative Braking / Dynamic Resistor Unit |
| Compatible Series | Yaskawa Sigma II, Sigma V, Sigma 7 Servopacks |
| Power Terminals | High-Current Screw Terminal Block |
| Cooling Method | Natural Convection (Perforated Enclosure Ventilation) |
| Protection Mechanism | Built-in Thermal Overload Interlock Wiring |
| Mounting Format | Panel-Mount Inside Enclosure |
| Operating Temperature | 0°C to +55°C (32°F to 131°F) |
Application Scenarios & The “Trench” Experience
We got an urgent call from a high-speed gantry robot site handling palletizing operations. During peak production, whenever the Z-axis made a rapid downward drop with a full load, the Yaskawa Servopack threw an un-clearable Overvoltage Fault (A.400 / A.410). The internal drive capacity was overwhelmed by the kinetic energy returning from the vertical motor. Installing an external JUSP-RA05 braking resistor unit and modifying the drive’s regenerative parameter selection immediately provided the required dissipation capacity, allowing the gantry to run at maximum line speed without throwing fault codes.
- High-Speed Gantry Cranes & Hoists: Absorbing kinetic feedback during rapid vertical downward movement.
- Fly-Cutting & Shear Machinery: Dissipating large energy spikes during instantaneous dynamic stops.
- High-Inertia Turntables: Stopping heavy rotary indexing tables within short cycle times.
- Packaging & Wrapping Skids: Enabling high-frequency start-stop sequences without thermal derating.
JUSP-RA05
JUSP-RA05
Transparency SOP: Quality Assurance & Testing
Every Yaskawa JUSP-RA05 resistor unit undergoes a 5-step engineering bench check before entering static-shielded storage:
- Inbound Physical Inspection: Inspect perforated metal housing, mounting flanges, terminal covers, and wire insulation for thermal degradation or mechanical strain.
- Cold Resistance Audit: Measure resistance value across primary power leads with a calibrated DMM to confirm the resistor elements match factory ohm ratings with zero internal opens.
- Thermal Protection Line Continuity: Verify the closed-state continuity of internal thermal overload switches and thermal cutouts.
- Hi-Pot & Insulation Testing: Conduct 1000V DC insulation resistance testing between terminal blocks and the metal chassis ground to ensure zero current leakage or grounding breakdown.
- Clean & ESD Protective Packaging: Clean outer metal surfaces, blow out internal dust, and pack the unit in heavy protective cushioning.
The Veteran’s Tech Trap Guide (Crucial Value-Add)
⚠️ Set Drive Parameters Correctly! Simply wiring the JUSP-RA05 to your Servopack is not enough. You must update the drive parameter for regenerative resistor selection (e.g., parameter Pn600 in Sigma-V / Sigma-7 drives) to inform the amplifier firmware that an external resistor is connected. Failing to update this setting means the drive won’t utilize the resistor’s full capacity or monitor its duty cycle correctly.
❗ Thermal Overload Interlock Safety: Always wire the JUSP-RA05’s thermal relay contact into your main power control circuit or drive safety interlock loop. If a drive transistor shorts out, continuous DC current will flow into the resistor, creating an extreme fire hazard. The thermal interlock must be set to drop the main contactor if the resistor overheats.
⚠️ Heat Dissipation Clearance: Braking resistors get hot during active braking! Mount the JUSP-RA05 vertically with at least 100mm (4 inches) of clearance from adjacent wiring ducts, plastic components, or heat-sensitive PLC modules.
Frequently Asked Questions (FAQ)
Q: Can I run multiple JUSP-RA05 units in parallel?
A: Only if the overall combined resistance does not drop below the minimum allowable braking resistance specified in your Servopack user manual. Wiring below the minimum resistance limit will damage the drive’s internal braking transistor.
Q: What causes a braking resistor like the JUSP-RA05 to burn out?
A: Common causes include excessively high duty cycles, improper deceleration ramp times, or a shorted braking IGBT inside the connected servo drive.
Q: How do I test if my JUSP-RA05 unit is damaged?
A: Measure the resistance across the main power leads using an ohmmeter. If the reading is infinite (open circuit) or significantly higher than nominal rating, the internal wirewound elements have burned out and need replacement.
Q: What warranty comes with this unit?
A: Every Yaskawa JUSP-RA05 unit supplied includes a full 12-month operational replacement warranty backed by our engineering testing facility.
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