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 {#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 | Amazon | Common thermal trip cause |
| Keypad | Amazon | For damaged display/buttons |
| Replacement FR-D700 drive | Amazon | For CPU faults |
| Braking resistor | Amazon | If fast stop is application-critical |
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.