TL;DR
Granulator motor overload trips are usually from large or thick feed pieces jamming the rotor, or from dull blades increasing cutting force. Clear the jam, check the blade gap, then reset the overload.
What you might see
- motor overload relay trips during operation
- rotor stalls audibly before trip
- motor current spikes visible on the ammeter before trip
- machine trips on first large feed piece of the shift
Likely causes
Feed piece too large or too thick for the machine capacity creating a sudden load spike
Dull blades requiring more force to cut, pushing motor current above the trip point
Foreign material such as metal components jamming the rotor
Overload relay set too low relative to the motor full-load ampere rating
Required tools
- Clamp ammeter
- Rotor lock pin
- Clearing hook or puller for jammed material
- LOTO kit
Safety first
- Never reach into the cutting chamber without the rotor lock. The rotor can shift unexpectedly when clearing jams.
- Metal in the feed stream can fracture blades and cause projectile hazards. Inspect all feed material for metal before granulating.
Procedure
- 1
Do not reset the overload without first locking out the granulator and clearing the cutting chamber of any jammed material.
Warning: Do not reach into the cutting chamber without the rotor lock installed. A jam does not mean the rotor is fully stopped. - 2
Lock out the granulator and install the rotor lock. Open the cutting chamber access door.
- 3
Clear any jammed material from between the rotor blades and the bed knife. Inspect for metal contamination.[1]
- 4
After clearing the jam, reset the overload relay.
- 5
Measure motor current at full load with a clamp ammeter. Compare to the motor nameplate Full Load Amps.[1]
- 6
If current is above FLA under normal feed, inspect and adjust the blade clearance gap as described in the blade maintenance procedure.
- 7
If overload trips occur only on large feed pieces, reduce feed piece size by pre-cutting before feeding to the granulator.
- 8
Verify the overload relay is set to 110 to 115 percent of the motor FLA. An undersized setting will cause nuisance trips.
Sources
Cumberland (ACS Group) Cumberland 3600 / 5800 / 6800 Granulator / Shredder general technical documentation, Cumberland (ACS Group)
Cumberland granulator maintenance manual, jam clearing and motor protection settings (general)
More guides for Cumberland (ACS Group) Cumberland 3600 / 5800 / 6800
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Rotor bearing overheating indicates lubrication failure, contamination, or bearing wear. Check bearing temperature and regrease before condemning the bearing.
How to restore regrind quality on a Cumberland 3600 / 5800 / 6800 granulator
Poor regrind quality with fines, dust, or uneven particle size almost always means dull or improperly gapped rotor blades. Inspect the blade edge and gap setting before running more material.
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