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Phone: +86 16626708626Description
Key Technical Specifications
| Parameter | Value |
|---|---|
| Motor Type | AC synchronous servo motor, 3-phase, self-cooled, construction type A |
| Frame Size | 4L (Size 4, Large) |
| Feedback Device | R0 resolver |
| Rated Voltage Class | 330 V (consistent across confirmed 8MSA4-series R0/E0 motors) |
| Rated Speed | ⚠️ Not confirmed for this exact frame/suffix — family range runs 3,000–6,000 rpm depending on winding |
| Rated Torque | ⚠️ Not confirmed — do not assume Small-frame (8MSA4S) values apply |
| Rated/Stall Current | ⚠️ Not confirmed for Large frame |
| Insulation Class | F (typical across this series) |
| Protection Class | IP64 (typical across this series) |
| Mounting | Flange mount, self-cooled construction type A |
I have confirmed nameplate data for the same resolver/suffix combination (R0, “-31”) on the Small frame variant of this size class, but torque scales directly with frame size in this series and I won’t present Small-frame numbers as Large-frame specs. Pull the nameplate off the physical unit or request the B&R drawing before quoting performance to a buyer.
Product Introduction
The B&R 8MSA4L.R0-31 is a Size 4, Large-frame synchronous servo motor from B&R’s legacy 8MS series, using R0 resolver feedback for position control on ACOPOS-driven axes. The “Large” designation within the size-4 family puts it above the Small and Medium frame variants for torque output, but the exact rated torque and current for this frame haven’t turned up in a verifiable source yet.
Rather than interpolate from the Small-frame 8MSA4S.R0-31 data we do have confirmed, we’re treating this one as needing a direct nameplate or datasheet check. If you’re sourcing this to replace a failed unit, the fastest path to an accurate quote is sending us a photo of the existing motor’s nameplate.
8MSA4L.R0-31
8MSA4L.R0-31
Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to this Part | Quick Check Method | Recommendation |
|---|---|---|---|---|
| Axis faults on power-up with resolver error | Resolver wiring fault or connector seating issue | ❌ Low | Check resolver cable continuity and connector seating at both motor and ACOPOS ends | Inspect wiring before assuming the motor’s resolver has failed |
| Drive throws overcurrent/overload fault | Mechanical bind or load exceeding the motor’s rated torque | ❌ Low | Disconnect the load and jog free — if clean unloaded, the fault is mechanical | Confirm the rated torque figure from the nameplate before assuming the motor is undersized |
| No rotation, resolver reads correctly, drive shows no fault | Winding open or stator fault | ✅ High | Measure phase-to-phase stator resistance and check for shorts to case | If resistance is open or grossly abnormal and wiring checks clean, the motor winding has failed |
| Suffix mismatch on replacement (-31 vs adjacent codes) | Connector or shaft-end variant mismatch | ✅ High | Compare connector orientation and shaft end against the removed motor | Confirm exact suffix match before ordering if physical fitment matters |
| Motor runs hot under load | Undersized frame for the application, or duty cycle exceeding thermal rating | ❌ Low | Compare actual RMS torque demand against the confirmed nameplate rating once obtained | Get the nameplate torque figure confirmed before condemning the motor |
If you’re troubleshooting at 3 AM: read the motor’s nameplate directly — on this specific part, the nameplate is your fastest and most reliable source of the actual torque/current rating, more reliable than any generic 8MS-series reference.
Frequently Asked Questions (FAQ)
Can you confirm the exact torque and current rating before I buy?
Yes — and we recommend it. We have confirmed data for the Small-frame version of this same resolver/suffix combination, but the Large frame carries higher torque and current ratings that we haven’t independently verified yet. We’ll pull the nameplate reading off the physical unit before it ships.
Is this a direct swap for my existing 8MSA4L motor?
If your existing motor carries the exact same part number (8MSA4L.R0-31), yes. If it’s a different suffix or a different letter code (S/M/L), don’t assume interchangeability — frame size and suffix both affect fit and rating in this series.
Will my ACOPOS drive recognize this motor without extra configuration?
This depends on your drive’s motor database entry for the legacy 8MS naming scheme. If your machine already runs this exact motor, the drive configuration should already be in place — confirm before replacing if firmware has changed since original commissioning.
Why don’t you have the full spec table for this exact part?
Because we couldn’t verify it against a reliable source, and we’d rather tell you that than hand you numbers borrowed from a smaller frame in the same family. Send us a photo of your existing motor’s nameplate and we’ll confirm the exact rating before quoting.
Why is this priced below current B&R equivalents?
This is New Original / New Surplus stock of a legacy 8MS motor — sourced through the secondary market rather than a current factory build. Once we confirm the nameplate specs, you’re getting genuine B&R hardware without the cost of a full drive/motor requalification onto a current-generation replacement.
What’s your testing process on this unit before it ships?
Inbound visual inspection for shaft and connector damage, a stator resistance check, and nameplate confirmation of the exact part number and rating. Tell us upfront if you need a powered functional test on an ACOPOS bench before it ships.
