Mitsubishi FR-D700 cooling fan
Use for THT thermal trips after cleaning the cabinet and confirming the fan is weak or stopped.
$20-$80
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Mitsubishi FR-D700 VFD Fault Codes - What They Mean
The Mitsubishi FR-D700 is a compact inverter drive used on conveyors, small pumps, and packaging equipment. It displays fault codes directly on the built-in keypad in short alphanumeric form. The FR-D700 is reliable, but it is often installed in tight cabinets where heat, poor wiring, and abrupt parameter changes create nuisance trips.
Mitsubishi FR-D700 Common Fault Code Reference
| Code | Meaning |
|---|---|
| OC1 | Overcurrent during acceleration |
| OC2 | Overcurrent during constant speed |
| OC3 | Overcurrent during deceleration |
| OV1 | Overvoltage during acceleration |
| OV2 | Overvoltage during run |
| OV3 | Overvoltage during deceleration |
| THT | Inverter overtemperature |
| THM | Motor thermal overload |
| UVT | Undervoltage |
| GF | Ground fault |
| OLT | Stall prevention / overload trip |
| CPU | Internal control fault |
Common Causes by Fault
- OC1/OC2/OC3 - Mechanical binding, bad motor cable, or acceleration/deceleration set too aggressively.
- OV3 - Most common on fast stop commands. Extend deceleration time.
- THT - Dust-clogged fan path or failed internal fan.
- THM - Motor current above rating for too long. Check parameterized motor FLA against nameplate.
- GF - Insulation breakdown in motor or cable.
Step-by-Step Fix
- Capture the exact code - Mitsubishi faults are phase-of-operation specific, so OC1 and OC3 point to different root causes.
- For OC faults - Remove the load if possible and test the motor alone. Review acceleration and torque boost parameters.
- For OV faults - Increase decel time. If the application requires rapid stopping, use a braking resistor if supported.
- For THT - Check ambient temperature, clean the drive, and confirm fan movement.
- For GF - Disconnect the motor leads and insulation test each phase to ground.
Parts Often Needed
| Part | Notes |
|---|---|
| Cooling fan | Common thermal trip cause |
| Keypad | For damaged display/buttons |
| Replacement FR-D700 drive | For CPU faults |
| Braking resistor | If fast stop is application-critical |
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.
When to Call a Pro
Persistent CPU faults or repeated GF trips with the motor disconnected usually mean internal inverter damage. Mitsubishi drive service or a qualified controls technician should evaluate before the drive is put back into production.