GF: Ground Fault Diagnostic Route

Official protection context

The A1000 technical manual describes GF as a current-to-ground condition on the output side exceeding the protection threshold, and lists damaged motor cable or output grounding conditions among causes. The first technical discipline is therefore not internal board replacement; it is establishing whether the external motor and cable path has genuinely failed to earth.

Fault timing remains important. A GF event under a run command, after repairs or with the external output path already cleared raises a different internal investigation than a cable visibly damaged in the machine.

When board-level mapping becomes relevant

If external insulation evidence is acceptable and GF behaviour remains, the technician must consider the inverter output stage and its protection/sensing route. The reviewed DB4 sheet shows CT input conditioning, ±15 V analogue support, a 2.5 V reference and comparator/transistor paths. Such circuits can be assessed for symmetry or obvious damage by qualified repair specialists; the page does not claim that every GF originates there.

Completion criteria

A valid return-to-service decision records the fault trace, insulation separation, relevant internal evidence and controlled verification. Merely resetting GF without identifying the ground path invites repeat downtime or destructive failure.

Distinguish an external earth fault from an internal protection case

The official manual describes a ground fault in terms of output-side current to ground exceeding a protection threshold and identifies damaged motor cable as a possible cause. This makes the external branch the first responsible investigation: motor, cable, junctions and contamination at the application side should be assessed before internal board work is considered.

When a GF-type event remains after the external circuit is responsibly excluded, the owned drawing set helps route the internal investigation toward output-module damage, current-feedback/scaling paths and the supply/protection circuits that make a drive capable of detecting and responding to a fault. It does not justify defeating protection or re-energising visible damage.

Fault history first, power-stage suspicion second

On an industrial drive, the displayed protection code is a starting point rather than a component verdict. Capture the fault record and timing before repeated resets. Establish whether the event occurs during control power, immediately after run command, during acceleration, or after a disturbance. Then remove the external motor/cable branch from the decision only through appropriate qualified testing and manufacturer-safe procedures.

Where SC or GF persists after external causes are excluded, the reviewed drawing set supports a more disciplined internal branch: isolated driver-supply rails, CT/current-feedback conditioning, DC-bus or phase scaling, comparator protection and the output power stage. The correct question becomes which evidence separates these branches, not which expensive module should be changed first.

Do not bypass protection as a repair strategy

Any temporary diagnostic method that changes or suppresses a protective input carries a risk of destroying the drive or creating an unsafe motor condition. Such methods belong only in an appropriately protected specialist bench procedure with a documented purpose and a restoration check. They are not field reset instructions and should never be used merely to make a drive run.

Completion is not “fault no longer displayed.” Completion requires restored protection, stable supply and feedback evidence, an understood original cause, and an authorised functional test plan. That standard is particularly important for a high-value A1000 drive where repeat failure can multiply cost and downtime.