Current sensing and fault feedback

Yaskawa A1000 22 kW Current Feedback and Protection Comparator Path

DB4-based map of CT1–CT3 signal conditioning, reference generation and comparator/transistor stages relevant when SC, GF or overcurrent evidence is inconsistent with external testing.

Practice-oriented technical reference4 min read

Scope of this technical record

CT channels, analogue rails and protection feedback relationship.

Safety boundary

High-voltage industrial-drive work and power-stage testing must be undertaken only by qualified personnel using controlled procedures.

Purpose and functional boundary

A1000 Feedback / Fault Path is published as a practical technical record rather than a replacement-parts advertisement. It identifies which hardware or evidence path matters after a protection event or destructive module failure, and which observations must be established before the repair can safely proceed.

Investigation sequence

Begin with equipment identification, stored fault information and safe external isolation where applicable. Continue only with circuit-relevant comparison of supply rails, phase channels, sensing references or suppression components identified by the linked record. A symptom never proves a replacement board by itself.

Stop conditions and repair decision

Stop powered investigation if a protection event persists, a supply/channel is asymmetric, board identity is uncertain, an external insulation fault is unresolved or testing would require defeated protection. The appropriate commercial outcome may be board evaluation, power-stage repair, controlled replacement planning or retrofit advice—not a speculative part shipment.

Use channel and reference comparisons before assigning a failed board

The examined A1000 22 kW drawings expose more than one functional area: isolated low-voltage supply generation, phase and DC-bus scaling networks, CT-based current feedback and comparator/reference sections. A protection trip can therefore be created by the output power stage, by a damaged gate supply, by feedback/protection circuitry or by an external motor/cable condition. It is not safe to jump from an SC or GF display directly to one board replacement.

For assessment, preserve board identifiers and connector orientation, compare equivalent phase paths, document supply/reference behaviour under isolated diagnostic conditions and keep the fault history before clearing it. These observations allow a repair centre to decide whether the likely work concerns the power module, driver/supply area, measurement/protection layer or the external circuit.

A1000 board-to-fault evidence map

Observed clueCandidate areaWhy it matters
Short-circuit or ground-fault with external load excludedOutput module / driver / feedback protectionInternal failure becomes credible
Abnormal one-phase feedback compared with peersCT/scaling/comparator branchMay create false or genuine protection response
Missing or unstable isolated driver railMulti-rail supply sectionGate switching cannot be judged safely
Burned driver components after module eventCoupled failure pathA replacement module can be destroyed again

What constitutes repair-ready evidence

An A1000 board case is repair-ready only when the model and capacity are confirmed, the exact display and fault history are recorded, the motor and cable branch has been assessed by qualified personnel, and the visible board/module condition is documented. Without these items, a spare-board request can be the wrong commercial outcome.

IndustrialDriveData records this as a board-and-diagnostic relationship rather than offering a dangerous generic “replace the IGBT” instruction. The service value lies in narrowing the root-cause branch and helping an owner present a defensible repair or replacement inquiry.

Signal integrity before replacement decisions

The current-feedback and protection path is where genuine output stress is converted into a trip decision. An assessment should not begin by altering protection thresholds or clearing alarms repeatedly. It should preserve the event, compare phase-related feedback paths where accessible in a safe bench process, review whether contamination or flash damage exists, and correlate any abnormal feedback branch to the affected output phase.

This evidence can change a commercial recommendation. A confirmed external fault routes away from board replacement; an internal feedback abnormality may justify board repair; a feedback abnormality together with destroyed power devices can justify a combined repair evaluation rather than replacement of only the visible failed part.

Technical basis and reference documents

This is an independent editorial technical reference. Original manufacturer documentation remains controlling for installation, repair and commissioning decisions.

A1000-22KW DB1–DB5 drawing review record (AB4A0044FAA)IndustrialDriveData technical review

Circuit-function mapping of auxiliary supply, voltage/current sensing and interface paths; original drawings are not redistributed.

YASKAWA AC Drive A1000 Technical Manual, SIEP C710616 27CYaskawa / Omron-hosted reference

Official fault, trace-data, maintenance and troubleshooting reference.