Cooling fan
Common VFD, drive, UPS, and cabinet overheating failure point.
Yaskawa U1000 Fault Codes
The Yaskawa U1000 is a matrix drive (no DC bus capacitors) designed for energy recovery and ultra-low harmonics in pump and fan applications. It shares some fault codes with the A1000 family but has unique faults related to its matrix converter topology.
U1000 Fault Code Table
| Code | Fault Description | Common Cause | Action |
|---|---|---|---|
| OC | Overcurrent | Motor winding, short circuit, accel | Check motor and increase ramp |
| OV | Overvoltage | Excess regenerative energy | Check matrix converter operation |
| UV1 | DC bus undervoltage | Low supply voltage | Check supply voltage |
| UV2 | Control power undervoltage | Control board fault | Check control power supply |
| OH | Heatsink overtemperature | High ambient, cooling blocked | Clean heatsink, check fan |
| OL1 | Motor overload | Motor running above FLA | Reduce load, check cooling |
| OL2 | Drive overload | Drive oversized load | Check drive current rating |
| GF | Ground fault | Motor winding ground | Megger test motor |
| SC | Short circuit output | Output short circuit | Check motor cable |
| CF | Control fault | Control board error | Check control power and connections |
| BB | Base block | External fault triggered | Check external fault contact |
| EF0 | External fault | Fault input active | Check input terminal wiring |
| LF | Output phase loss | Missing output phase | Check motor cable connections |
| PF | Input power fault | Input phase loss | Check input fuses and supply |
Most Common U1000 Faults
OC - Overcurrent
The U1000 matrix topology is sensitive to output impedance changes. Perform motor auto-tuning (T1-01 = 2, stationary tuning). Increase acceleration time (C1-01). Check motor connection for loose terminals.
OH - Heatsink Overtemperature
The U1000 uses active cooling. Check heatsink fan operation on both the matrix converter and output stage. Measure ambient temperature - rated to 45 degrees C without derating. U1000 can be installed in vertical orientation only.
UV1 - DC Bus Undervoltage
The U1000 matrix drive does not have a traditional DC bus capacitor. UV1 triggers when input voltage drops below minimum. Check all three input phases - a single phase loss causes immediate UV1 on the U1000.
GF - Ground Fault
Matrix drives are sensitive to ground faults due to the direct AC-to-AC conversion. Megger test all motor windings at 500 VDC. Check cable shielding termination.
Parts Commonly Needed
| Part | Notes |
|---|---|
| Cooling fan | Match U1000 frame size |
| Control board | Contact Yaskawa before ordering |
| Input filter | Required for matrix drive installations |
| Bypass contactor | For maintenance bypass configurations |
Technician Tips
When diagnosing VFD faults, always check the drive’s fault history before resetting. Modern drives store the last 5-10 faults with the drive state at the time (running, accelerating, decelerating, stopped). An overcurrent fault that occurs only during acceleration points to incorrect motor data or mechanical binding. The same fault during deceleration suggests regeneration issues. A ground fault that clears after disconnecting the motor and returns when reconnected means the motor or cable insulation has failed.
Prevention: Schedule annual infrared scanning of drive cabinets. Loose power connections and failing capacitors produce heat long before they cause faults. A 5-minute scan can prevent hours of unplanned downtime.
Need Replacement Parts?
Before ordering, match the drive part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
Pro tip: Yaskawa U1000 drive data can be monitored via DriveWizard Industrial software. Connect via USB or DeviceNet to log operating parameters and fault data. Always perform a motor auto-tune after any parameter reset.