Scope of this technical record
Evidence record for ATV61 / ATV71 power-stage and driver-boundary cases where OCF or SCF remains credible after motor/cable/load evidence has been separated.
This record is not a public repair procedure or a permission to energize a damaged inverter. Use it to prepare evidence for qualified repair or replacement review after isolation and discharge procedures are complete.
ATV61 / ATV71 power-stage evidence route
The record defines what evidence makes a power-stage repair request actionable.
Power-stage repair decision matrix
The record makes a repair request auditable before another module or board is energized.
| Evidence area | Decision | Required proof |
|---|---|---|
| Identity | Correct hardware boundary | Type code, frame, board/module labels |
| External proof | Repeat failure risk | Motor/cable/load evidence |
| Driver / feedback | Module survival risk | Channel and current-feedback evidence |
When the power stage becomes the suspect
The power stage becomes suspect when the external output path has been proven, the fault timing is consistent with drive-side current or switching failure, or a previous module repair did not survive. It should not be the first assumption when OCF appears under load or when SCF appears with an untested motor cable.
This record is intentionally evidence-oriented. It asks for the facts that make a board or module repair request actionable: exact frame, board/module labels, static output evidence, driver-channel suspicion, current-feedback evidence, DC-link condition and the sequence of previous repairs.
Evidence matrix
A useful repair request should let the bench decide whether the next step is inspection, component-level repair, module replacement, driver repair, control-board review or replacement/retrofit planning.
Power-stage evidence needed before repair decision
| Evidence area | What to capture | Why it matters |
|---|---|---|
| Identity | Drive type code, frame, voltage/current rating, board/module labels | Prevents incompatible board or module assumptions |
| Fault history | OCF/SCF timing and first-fault order | Separates load event from destructive bridge event |
| External proof | Motor/cable/load evidence already collected | Prevents repeat failure after repair |
| Static output evidence | Qualified non-powered checks and phase comparison | Shows whether the bridge is already damaged |
| Driver/current feedback | Channel imbalance, previous driver work, current-sense plausibility | Finds the cause that can destroy a new module |
| DC-link and environment | Bus condition, contamination, fan/cooling, repair marks | Explains secondary failure causes |
Stop conditions before another power-up
The safest way to handle repeated output faults is to define when not to power the drive. A missing insulation record, unknown cable condition, unresolved gate-driver concern, biased current feedback or undocumented module replacement should stop another full-power test.
- Motor/cable route has not been isolated or documented
- Output bridge static evidence is abnormal
- Gate-driver or isolated supply channel differs from other phases
- Current feedback is implausible or unbalanced
- The previous module failed immediately after replacement
- Drive identity or module/frame compatibility is uncertain
Repair versus replacement decision
If evidence points to a clean, isolated power-stage failure with clear identity and no external root cause, specialist repair or compatible replacement may be justified. If the root cause is uncertain, a replacement can become another failed part. If boards are scarce, contaminated or repeatedly damaged, the same evidence can support a migration discussion instead of more blind repairs.
The record's job is to make that decision auditable. It does not disclose proprietary schematics or promote unsafe component substitution; it collects the facts needed for a qualified repair path.
Field record checklist
- Drive/frame/module identity
- First fault and timing
- External output proof
- Static bridge evidence
- Driver/current feedback evidence
- Repair or migration decision
Technical basis and reference documents
This is an independent editorial technical reference. Original manufacturer documentation remains controlling for installation, repair and commissioning decisions.
Used to anchor OCF around hardware current limitation, motor data, high inertia, excessive load and mechanical blockage.
Used to anchor SCF1 around drive output short/grounding, motor cable checks, motor insulation and transistor test routing.
OEM programming and fault-reference context for Altivar 71 diagnostic pages.
OEM installation and wiring context for safe output and motor-cable evidence collection.
Linked circuit records
Turn this record into a qualified service request
A repair decision is much more reliable when the request includes the exact identity of the drive, the first fault evidence and the machine condition when the symptom appeared.
- Complete drive type code / MLFB or nameplate model
- Fault code, fault value and first event before reset
- When the event appears: power-up, enable, ramp, run, decel or stop
- Motor/cable connected or isolated during the symptom
- Visible board, option-card, module and connector identifiers
- Previous repair history, replacement parts and repeat-failure pattern