231-8080

Check Braking Resistor Status

Navigate to MOD function → Service → Diagnosis → Drive diagnosis and check braking resistor status indicators for axis 1.

Look for resistance values outside 47-68 ohm range for standard systems

Measure Braking Resistor Continuity

Power down system and measure braking resistor resistance with multimeter. Check for open circuit or significantly high resistance values.

Ensure complete power isolation before resistance measurements

Inspect Braking Resistor Connections

Examine all connections to braking resistor terminals, checking for loose connections, corrosion, or burnt contacts at the power supply unit.

Thermal imaging can reveal hot spots indicating poor connections

Verify MP1021 Braking Resistor Parameters

Check machine parameter MP1021 (braking resistor power rating) matches actual installed resistor specifications.

Incorrect MP1021 values can cause premature braking resistor protection

Check PSU Status LEDs

Examine the power supply unit front panel LEDs for fault indicators, particularly the regenerative feedback status LED.

Flashing red LED typically indicates regenerative feedback fault

Monitor DC-Link Voltage

Access MOD → Service → Diagnosis → Power diagnosis and monitor real-time DC-link voltage during programmed moves with rapid deceleration.

Normal DC-link voltage should remain below 800V for 400V systems

Verify Mains Supply Quality

Check incoming mains voltage stability and phase balance using the TNC's built-in mains monitoring in the power diagnosis screen.

Voltage imbalance >3% can cause regenerative feedback issues

Test Regenerative Feedback Function

Perform controlled deceleration test while monitoring energy flow direction in power diagnosis screen to verify regenerative capability.

Energy should flow back to mains during deceleration phases

Review Program Deceleration Rates

Examine CNC program for rapid feed rate changes and check F MAX values against machine parameter MP1010 maximum axis velocities.

Look for rapid transitions from high feed rates to positioning moves

Adjust MP1030 Acceleration Parameters

Review and potentially increase MP1030 (acceleration/deceleration time constants) for axis 1 to reduce regenerative energy peaks.

Increase values by 20-30% initially and test

Implement Feed Rate Override

Test problematic program sections with reduced feed rate override to verify if lower deceleration rates eliminate the alarm.

If 80% override eliminates alarm, deceleration rates are likely the cause

Optimize Program Path Planning

Use CYCLE 32 (tolerance for contour accuracy) to allow smoother velocity transitions and reduce sharp deceleration events.

Tolerance values of 0.01-0.05mm typically provide good results

Check Main Supply Fuses

Inspect all main supply fuses in the electrical cabinet, including those feeding the Heidenhain power supply unit.

Use proper PPE and lockout procedures when accessing electrical panels

Verify Supply Voltage Stability

Monitor supply voltage in MOD → Service → Diagnosis → Power diagnosis during machine operation to identify voltage drops or fluctuations.

Voltage should remain within ±10% of nominal throughout operation

Inspect Main Supply Contactors

Check main supply contactors for proper operation, contact wear, and secure connections to the power supply unit input terminals.

Pitted or burnt contacts can cause supply instability

Test Under Load Conditions

Monitor supply stability during high-load machining operations to identify supply inadequacy or wiring issues under full load.

Supply issues often only manifest under high regenerative energy conditions