7 -2Protective and Diagnostic FunctionsThis section describes the alarm functions of the Inverter. The alarm functions include fault detection,alarm detection, operation error detection, and autotuning error detection. Fault DetectionWhen the Inverter detects a fault, the fault contact output operates, and the Inverter output is shut OFF causingthe motor to coast to a stop. (The stopping method can be selected for some faults, and the selected stoppingmethod will be used with these faults.) A fault code is displayed on the Digital Operator.When a fault has occurred, refer to the following table to identify and correct the cause of the fault.Be sure to turn Run Command to OFF first, use one of the following methods to reset the fault before restart-ing the Inverter.• Set a multi-function contact input (H1-01 to H1-06) to 14 (Fault Reset) and turn ON the fault reset signal.• Press the RESET Key on the Digital Operator.• Turn the main circuit power supply OFF and then ON again.Table 7.1 Fault Displays and ProcessingDisplay Meaning Probable Causes Corrective ActionsOvercurrentThe Inverter output current exceededthe overcurrent detection level. (200%of rated current)• A short-circuit or ground faultoccurred at the Inverter output. (Ashort or ground fault can be causedby motor burn damage, worn insu-lation, or a damaged cable.)• The load is too large or the accelera-tion/deceleration time is too short.• A special-purpose motor or motorwith a capacity too large for theInverter is being used.• A magnetic switch was switched atthe Inverter output.Reset the fault after correcting itscause.Ground Fault*The ground fault current at theInverter output exceeded approxi-mately 50% of the Inverter rated out-put current.A ground fault occurred at the Inverteroutput. (A ground fault can be causedby motor burn damage, worn insula-tion, or a damaged cable.)Reset the fault after correcting itscause.Fuse BlownThe fuse in the main circuit is blown.The output transistor has failedbecause of a short-circuit or groundfault at the Inverter output.Check whether there is a short-circuitbetween the following terminals. Ashort-circuit will damage the outputtransistor:B1 ( 3) ←→ U, V, W←→ U, V, WReplace the Inverter after correct-ing the cause.Main Circuit OvervoltageThe main circuit DC voltage exceededthe overvoltage detection level.200 V Class: Approx. 410 V400 V Class: Approx. 820 VThe deceleration time is too short andthe regenerative energy from themotor is too large.Increase the deceleration time orconnect a braking resistor (orBraking Resistor Unit).The regenerative energy when anovershoot occurs after acceleration iscompleted is too large.In vector control, enable (Set to 1)the overvoltage inhibit selection(L3-11).The power supply voltage is too high. Decrease the voltage so it's withinspecifications.* The ground fault here is one which occurs in the motor wiring. A ground fault with low resistance which occurs in motor cables or terminals may not be detected.
