VFD fault codes
Common VFD fault codes and what they mean
What is an OC / Overcurrent fault?: The drive has detected excessive output current; heavy or jammed loads, short acceleration times, motor/cable faults and the power stage are typical areas to investigate.
What is an OV / Overvoltage fault?: The DC-bus voltage has risen above the permitted level, often during rapid deceleration, regenerative operation or unusually high supply voltage.
What is a UU / LU Undervoltage fault?: The supply or DC-link voltage has fallen below the drive's acceptable range; check the mains supply, phase connections and DC-link condition.
What is an OH / Heatsink Overtemperature fault?: The drive heatsink has become too hot; cooling fans, airflow, cabinet temperature and drive loading should be checked.
What is an OL / Overload fault?: The motor or drive has been operating above its permitted thermal or load capability for too long.
What does Output Short Circuit mean?: A short circuit may exist in the motor cable, motor windings, terminals or the drive's output power stage.
What is a Ground Fault?: The drive has detected an unintended current path from the motor or output wiring to earth, commonly associated with cable or motor-insulation problems.
What is a Phase Loss fault?: One supply or motor phase may be missing or severely unbalanced; the exact meaning should be confirmed in the drive manufacturer's fault manual.
What is Motor Overload Protection?: The drive protects the motor when its calculated or measured thermal loading exceeds the permitted operating level.
What is a Motor Stall fault?: The motor cannot accelerate or maintain the commanded motion under load; mechanical jamming, excessive load and current limits are common checks.
What is a Low Torque error?: The motor or process torque has fallen below a configured threshold, which may indicate a load, coupling, motor or process condition depending on the application.
What is an Emergency Stop error?: A safety or emergency-stop input is preventing drive operation; the reason for the safety demand should be identified before resetting the system.
What is Overshoot?: Motor speed or another controlled process value temporarily exceeds its target, often as a result of ramp or control-loop tuning.