Applicable Systems
DR-PRO 50t
Symptoms
The crane reports a main contactor fault. The main power contactor has failed to operate correctly.
Possible Causes
- Contactor coil burned out or open
- Contactor contacts welded from arcing
- Control circuit voltage low preventing pickup
Troubleshooting Steps
- Step 1: Test the contactor coil for continuity
Coil shows proper resistance - Step 2: Inspect contacts for welding or pitting
Contacts are clean and move freely - Step 3: Verify control circuit voltage
Voltage is sufficient for contactor pickup
How to Reset
To reset: Replace the faulty contactor or restore control voltage, then reset.
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Source: Demag DR Rope Hoist Manual, Demag Cranes & Components GmbH
Category: Crane
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