First splitHigh current before material enters points toward mechanical or electrical drag; current that rises with feed points toward material resistance or duty.
Do not mask the faultIncreasing motor size or overload settings before finding the resistance can convert a process blockage into mechanical damage.
Root-cause orderCheck event chronology, upstream feed, downstream availability, then inspect deposits, bearings, alignment, flights and actual duty.
1. Read the Motor-Current Pattern First
Cement screw-conveyor blockage with high motor current is best diagnosed by separating mechanical drag from material-loading resistance. If current is abnormal before material enters, investigate bearings, alignment, screw-to-casing contact, gearbox condition and electrical supply. If current rises mainly after feeding starts, investigate excessive feed, wet or compacted material, restricted discharge or a conveying duty that no longer matches the original design.
Safety ruleStop feed and follow the plant isolation procedure before opening covers or approaching moving parts. Do not repeatedly reset an overload, defeat protection or increase overload settings simply to keep production running.
2. Separate Process Resistance from Mechanical Drag
Wet or compacted cementMoisture ingress and stagnant material can create lumps and deposits at the inlet, around flights or near the outlet. Falling capacity with rising current is a useful clue.
OverfeedingA suddenly opened valve or collapse of bridged silo material can deliver more cement than the conveyor can move. Review the feed sequence and actual inlet flow.
Restricted dischargeA healthy screw cannot discharge into a blocked chute or unavailable receiver. Material accumulates from the outlet backward and resistance rises.
Bearing or alignment dragBearing distress, shaft misalignment or damaged supports can cause rubbing. Heat, vibration, scraping or high current with little material point toward this area.
Worn or damaged flightsWorn flights reduce conveying effectiveness, leaving material in the trough longer and increasing the chance of buildup or recirculation.
Changed operating dutyHigher throughput, different bulk density, changed inclination or operating cycles can make the original conveyor selection unsuitable.
3. Troubleshooting Matrix
| Observation | Investigate | Next check |
|---|---|---|
| High current before feed | Bearings, alignment, casing contact, gearbox, electrical supply | Run-down/mechanical drag and electrical condition |
| Sharp rise when feed opens | Overfeed, compacted material, inlet restriction | Silo discharge and inlet loading |
| Current rises over time | Outlet restriction or progressive buildup | Discharge path and deposits |
| Low output without high current | Poor inlet flow or worn flights | Confirm inlet delivery and internal flight condition |
| Scraping plus high current | Misalignment, bearing wear, bent shaft | Inspect supports, shaft and flights after isolation |
4. Treat a Full-Load Restart as a Special Condition
A conveyor that stopped full can require substantially more starting torque than one starting empty. Determine why it stopped and whether material remains compacted inside before another attempt. Repeated loaded starts can turn a process blockage into coupling, gearbox, shaft, bearing or motor damage. If the original duty did not include loaded restart, compare present operating practice with the approved conveyor and drive design.
5. Root-Cause Sequence
- Establish whether overload occurs empty, at initial feed, or after loaded running.
- Review motor-current trend and identify the first credible event in the control-system chronology.
- Confirm upstream flow and downstream receiving equipment were available.
- Check the silo outlet, inlet transition and discharge path for compacted material or restriction.
- Under isolation, inspect deposits, foreign objects, bearings, rubbing, damaged flights, supports and shaft alignment.
- If no discrete defect is found, compare actual throughput, bulk density, incline and operating cycle with the original design.
- Correct the initiating cause, then verify stable current and conveying performance under controlled load.
6. Prevention Checklist
Keep material dryPrevent moisture ingress at the silo, inlet, casing and discharge connections.
Interlock the flow pathUpstream feeding should depend on conveyor operation and downstream availability.
Trend currentUse motor current and conveying time as condition indicators instead of waiting only for overload trips.
Inspect the mechanicsInclude bearings, seals, supports, couplings, flights and casing in planned maintenance.