WhatsApp: +86 16626708626
Email: 
Phone: +86 16626708626Description
Key Technical Specifications
- Catalog Number: 1394-SR9A
- Manufacturer: Allen-Bradley
- Product Family: 1394 Digital AC Multi-Axis Motion Control System
- Module Type: External shunt module
- Continuous Rating: 300 W
- Peak Rating: 160,000 W
- Resistance: 4 ohm
- Cooling: No fan
- Shipping Weight: 3.63 kg (8 lb)
- Mounting: Panel-mounted
- Series Letter: B
- Use Case: Regenerative energy dissipation on 1394 servo systems
Product Introduction
The Allen-Bradley 1394-SR9A is an external shunt module for the 1394 Digital AC multi-axis motion control system. It is used to absorb regenerative energy during servo deceleration and protect the DC bus from overvoltage trips.
This unit is specified for 300 W continuous dissipation, 4 ohm resistance, and fanless operation. It is a direct fit where the original 1394 shunt module must match the existing 1394 rack and braking setup.
- 1394-SR9A
- 1394-SR9A
Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to this Part | Quick Check Method | Recommendation |
|---|---|---|---|---|
| DC bus overvoltage during decel | Shunt module missing, open, or undersized | ✅ High | Measure DC bus rise during braking and inspect shunt wiring | Verify 1394-SR9A presence and match the required resistance/rating |
| Shunt fault or brake resistor alarm | Open resistor, bad connection, or thermal issue | ✅ High | Check continuity across the shunt and inspect terminals | Replace if open or physically damaged |
| Servo faults only on heavy regeneration | Braking load exceeds module capacity | ⚠️ Medium | Compare load inertia and decel profile to 300 W rating | Consider whether the application needs the 900 W version instead |
| No visible heat during aggressive decel | Module not being driven or wiring open | ✅ High | Monitor DC bus voltage and confirm regenerative events | Inspect bus connections and controller settings |
| Frequent nuisance trips after replacement | Wrong model, wrong series, or loose wiring | ✅ High | Verify part number, series, and mounting orientation | Confirm the exact 1394-SR9A before assuming a drive failure |
If you are stuck, send photos of the nameplate, shunt wiring, and fault history to technical support.
Frequently Asked Questions
Q: What does the 1394- do?
It is a shunt module for the 1394 system. Its job is to dump regenerative energy when the servo decelerates so the DC bus does not trip on overvoltage.
Q: Is this the same as a drive or amplifier?
No. It is not the servo drive itself. It only handles braking energy on the 1394 platform.
Q: Is the 1394- hot-swappable?
No. Power down the system first. Treat it like a cabinet-mounted power component, not a live-swap accessory.
Q: How do I know if I need the or SR9AF?
Use the exact part number called out by the machine documentation. The is the 300 W, 4 ohm version with no fan; the SR9AF is the higher-capacity fan-cooled variant.
Q: Why does this part fail in the field?
Most of the time it is not the shunt itself. Loose wiring, incorrect sizing for the load, or a decel profile that is too aggressive are the usual causes.
Q: Is this new surplus or refurbished?
That depends on the inventory lot. For procurement, ask for the condition, test status, and photos before you place the order.
Q: What should I verify before installing a replacement?
Check the exact catalog number, series letter, resistance value, mounting fit, and the braking demand of the machine. If the load is high inertia, confirm the 300 W rating is enough before you close the cabinet.
