Scope of this technical record
ABB DC UNDERVOLT / 3220 routing for users deciding whether a low DC-link fault is caused by incoming supply, phase loss, fuses, contactor/precharge, rectifier bridge, bus measurement or weak control supply behaviour.
Undervoltage on the display does not mean the DC link is safe. Treat the drive as energized until isolation and discharge verification are complete.
ABB 3220 DC undervoltage route
Follow the energy path to the DC bus before blaming capacitors or boards.
ABB 3220 DC undervoltage image
Searcher intent coverage
3220 searchers need the energy path proven from input terminals to DC link before capacitor or board decisions.
| Observed situation | Decision needed | Evidence that satisfies the search |
|---|---|---|
| Fault at power-up | Line/fuse/contactor/precharge | Input phase measurements and bus-rise observation |
| Fault at run command | Supply sag or charge collapse | DC-link trend and contactor behaviour |
| Intermittent | Loose input or weak DC-link path | Event timing, thermal pattern and terminal evidence |
What 3220 users are trying to decide
A 3220 search usually means the drive will not become ready, trips during start, or drops out when the machine loads the line. The useful page must separate three conditions: the drive never builds a correct DC bus, the bus builds but collapses under load, or the drive is reporting bus trouble because of precharge/measurement/control-supply behaviour.
Official and public fault descriptions point to insufficient intermediate-circuit DC voltage, often from missing supply phase, blown fuse or rectifier-bridge fault. That is only the beginning. In the field, the page must force measurement at the drive terminals, not at an upstream assumption, then move through fuses, contactors, precharge, rectifier and DC-link evidence.
3220 timing map
| When 3220 appears | Likely first boundary | Evidence to record |
|---|---|---|
| Immediately on power-up | Missing phase, fuse, input contactor, precharge path | Three-phase voltage at drive terminals, fuse continuity, contactor state |
| After relay clicking / weak display | Precharge, control supply, DC-link build-up problem | Display stability, relay behaviour, qualified DC-link measurement |
| Only when motor starts | Line sag, weak supply, load-related bus collapse | Terminal voltage under start, DC-link trend, load condition |
| After recent repair | Wrong wiring, loose terminals, missed rectifier/precharge damage | Before/after photos, torque marks, rectifier/static checks |
| Intermittent in production | Contactor, phase loss, utility sag, loose connection | Event timing, upstream logs, thermal/vibration evidence |
Field checking order that avoids wasted parts
Start with the supply at the drive input terminals. A measurement upstream of a fuse, disconnect, contactor or terminal block does not prove what the rectifier sees. Record all three phase-to-phase values and whether they remain stable during the start or load event.
Next inspect fuses, line contactor, terminals and precharge behaviour. A drive that clicks, flashes, weakly displays or repeatedly attempts to charge is not the same as a drive with a stable bus that trips only when loaded. If the DC link is low with all input evidence normal, rectifier bridge, precharge resistor/relay, bus capacitor condition and voltage-detection path become legitimate boundaries.
Your repair sources add a practical warning: low-voltage or weak-output symptoms can be caused by ageing electrolytics, rectifier/open-phase conditions and driver/control supply faults. Do not replace a keypad or main board before proving the main power chain.
3220 evidence table
| Evidence | Supports external/input route | Supports internal drive route |
|---|---|---|
| One missing phase at drive terminals | Yes: supply/fuse/contactor/wiring | No board conclusion yet |
| All phases correct but DC bus does not charge | Input route weaker | Rectifier/precharge/DC-link measurement route stronger |
| Bus charges then collapses at start | Supply sag or load issue possible | Capacitor/precharge/rectifier under-load issue possible |
| Weak or cycling control display | Could be line/precharge instability | Control supply or capacitor ageing route possible |
| Blown input fuse repeats | Upstream short or rectifier path likely | Internal rectifier/precharge fault must be checked |
What to capture before repair or replacement
A useful 3220 request includes full type code, voltage class, input measurements at the drive terminals, fuse status, contactor/precharge behaviour, whether the bus ever reaches expected value and whether the trip occurs before or after a run command. If someone already replaced a fuse or rectifier, include that history because repeat fuse failures change the boundary.
Do not clear the history and replace parts first. In undervoltage cases, the pattern of supply, contactor and bus behaviour is the diagnostic asset. Without it, a repair shop may only be able to say “test required”, not which path is most likely.
Stop conditions for 3220
| Condition | Reason | Next action |
|---|---|---|
| No qualified DC-link measurement procedure | DC bus remains hazardous even during undervoltage faults | Do not open; request qualified service |
| Missing phase or blown fuse not corrected | Drive-side diagnosis is premature | Correct input boundary first |
| Fuse blows again after replacement | Possible rectifier/precharge/internal short | Stop repeated energizing and collect static evidence |
| Bus voltage collapses under load | Could damage parts during repeat starts | Record load and supply trend before another run |
Field record checklist
- Full ABB type code, voltage class and supply configuration
- Exact 3220 text/code and when it appears
- Input phase-to-phase measurements at drive terminals
- Fuse, contactor, disconnect and precharge behaviour
- Qualified DC-link evidence and display/relay behaviour
- Recent fuse, rectifier, capacitor or board replacement history
Technical basis and reference documents
This is an independent editorial technical reference. Original manufacturer documentation remains controlling for installation, repair and commissioning decisions.
Formal ABB wording for DC UNDERVOLT as intermediate circuit voltage below limit.
Public fault description links 3220 to missing phase, blown fuse or rectifier bridge fault.