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KUKA Robot Controller
Servo/Axis · Basic
KUKA Robot KRC0226 - ACKN. FAILURE OF MOTOR PHASE <axis>
This alarm indicates a failure in the motor phase acknowledgment circuit for a specified axis, typically caused by insufficient backup battery voltage in the KRC controller. The backup battery is critical for maintaining encoder data and axis position information during power loss or controller resets. When voltage drops below the minimum threshold (typically 2.4V for a 3V lithium battery), the controller cannot reliably acknowledge motor phase signals, triggering this safety alarm.
KRC0226
KUKA Robot KRC0226 - ACKN. FAILURE OF MOTOR PHASE <axis>
ACKN. FAILURE OF MOTOR PHASE <axis>
This alarm indicates a failure in the motor phase acknowledgment circuit for a specified axis, typically caused by insufficient backup battery voltage in the KRC controller. The backup battery is critical for maintaining encoder data and axis position information during power loss or controller resets. When voltage drops below the minimum threshold (typically 2.4V for a 3V lithium battery), the controller cannot reliably acknowledge motor phase signals, triggering this safety alarm.
Common Causes
- Backup battery voltage depleted or near end of life (primary cause as indicated in current description)
- Defective or loose backup battery connection on the control board
- Failed diode or charging circuit preventing proper battery charging
- Motor encoder or phase feedback connector corrosion or poor contact
- Faulty motor power stage or drive electronics for the affected axis
Troubleshooting Steps
- 1Power cycle the KRC controller completely and observe if alarm clears; if persistent, proceed to next step
- 2Locate and measure the backup battery voltage on the control board using a multimeter; compare against specification sheet (typically 2.7-3.3V for nominal operation)
- 3Replace the backup battery with an identical part (commonly a 3V CR2032 or equivalent lithium cell) if voltage is below 2.4V
- 4Inspect and clean the motor encoder connector and phase feedback wiring for corrosion, contamination, or loose pins; reseat connections firmly
- 5Check motor phase feedback signals using the KRC diagnostics menu or oscilloscope to verify signal integrity at the drive electronics
- 6If alarm persists after battery replacement and connector verification, request a control board replacement or contact KUKA service, as internal charging circuit or phase detection circuitry may be defective
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