Key takeaways
A tripped ABB variable frequency drive leaves you two clues: the code on the display and the data frozen in the fault log. This guide covers the fault types technicians see most often on ACS series drives, the usual causes in rough order of probability, and the first checks that separate a five minute fix from a motor rewind. It is written for maintenance technicians, maintenance managers, and plant engineers standing in front of a drive that will not restart.
Every modern ABB drive stores a fault log: the fault code, an auxiliary code that narrows the cause, and a snapshot of operating values at the moment of trip (output current, DC bus voltage, output frequency, drive temperature). On keypad-equipped drives you can scroll this history directly; over fieldbus you can read it from the diagnostics parameters.
Resetting the fault first throws away context you cannot get back. Note the code, the aux code, and the trip time values before you cycle power. One more caution: code numbers are not interchangeable between series. An ACS355 flags overcurrent as F0001, while an ACS880 logs 2310 for the same condition. Meanings also shift between firmware revisions, so always confirm against the firmware manual for your specific drive and firmware version.
Across ACS355, ACS580, and ACS880 drives, the same physical events account for most trips, even though the code numbers differ:
| Symptom | Most likely cause | First check |
|---|---|---|
| Overcurrent trip at start | Mechanical jam, shorted cable or windings, accel ramp too short | Confirm the load turns freely, then insulation test motor and cable after lockout, disconnected from the drive |
| Overvoltage trip during decel | Load regenerating into the DC bus | Extend the decel ramp, or fit a braking chopper and resistor if cycle time cannot grow |
| Undervoltage trip | Supply dip, blown fuse, loose lug | Measure all three phases at the drive input terminals under load |
| Earth fault trip | Insulation breakdown in motor or cable, moisture | Megger the motor and cable separately, only after lockout and disconnection from the drive |
| Drive overtemperature | Blocked filters, failed fan, high ambient | Verify the cooling fan spins, clean filters and heatsink, check cabinet temperature |
| Motor overload trip | Overloaded machine, wrong motor data, poor cooling at low speed | Compare motor nameplate data against drive parameters, check actual load current |
| Input phase loss | Blown supply fuse, loose connection, upstream switchgear | Check fuses and the upstream contactor or starter feeding the drive |
| Communication loss | Fieldbus cabling, master offline, timeout too tight | Check link status LEDs, cabling, and the comm loss timeout parameters |
The fault code tells you what tripped; the pattern tells you why. Overvoltage that only appears during stops is regeneration: extend the deceleration ramp or add a braking chopper and resistor, and check whether supply voltage is running high. Overcurrent at the instant of start points to a short or a jammed load, and our VFD overcurrent troubleshooting guide walks the full sequence check by check.
Overtemperature that creeps in over weeks is a cooling problem: filters, fans, heatsink dust, or a cabinet that got hotter after someone added equipment. Repeated motor thermal trips deserve the same structured approach you would apply to a motor overload relay that keeps tripping: verify actual load, motor data, and cooling before raising any limit. Earth faults are insulation talking to you: megger the motor and cable (separately if possible) and trend the readings, because insulation rarely fails without warning. And if input phase loss keeps recurring, look upstream: contactor and motor starter failures such as burned contacts are a classic hidden cause of single phasing.
Safe torque off is the most misdiagnosed event on ABB drives. When the STO inputs open, the drive removes torque and reports it (on an ACS880, typically warning A5A0 at standstill or fault 5091 if it opens while running). Nothing inside the drive has failed: the safety circuit opened.
Never bridge or jumper STO terminals to "test" the drive. Bypassing a safety circuit, an interlock, or a guard switch is how people get hurt, and it masks the real failure instead of finding it.
Drive work is electrical work for qualified personnel only. Apply lockout tagout before opening the enclosure, and remember the DC bus capacitors hold a lethal charge after the supply is removed. ABB manuals specify a minimum wait, commonly five minutes, and then require you to verify zero voltage with a meter before touching anything. Never insulation test (megger) a motor with the cable still landed on the drive: the test voltage will damage the output stage. Also account for non-electrical stored energy on the machine itself: suspended loads, chain and belt tension, hydraulic pressure, and gravity can all move a "stopped" machine.
A drive fault that gets reset and forgotten will come back. Treat every trip as a downtime event with a cause code: which asset, which fault code, what the log values showed, what was done. Once trips are logged consistently, MTBF and MTTR for the asset tell you whether you have a chronic problem that needs an engineering fix (a braking resistor, a cable replacement, a cooling upgrade) or an occasional nuisance.
This is also where drive faults meet plant performance: repeated short trips rarely make it into manual logs, yet they quietly erode availability, the first pillar of OEE in manufacturing. If the data is incomplete, the chronic offender never gets budget.
Fault codes explain why a drive tripped; they do not show what the trips cost you. Fabrico is computer-vision-verified OEE plus closed-loop maintenance execution: cameras catch stops and micro-stops that manual logs and sensors miss, and maintenance work orders close the loop from detection to fix. A drive that trips for ninety seconds at a time, ten times a shift, stops hiding.
If drive trips keep eating into your uptime, book a Fabrico demo and see the pattern on your own lines.
Use the control panel to open the fault log (or diagnostics menu, depending on series). Record the fault code, the auxiliary code, and the values stored at trip time before resetting. Over fieldbus, the same data is available in the diagnostics parameter group.
Output current exceeded the drive's instantaneous trip limit. Common causes are a mechanical jam, a short in the motor cable or windings, or an acceleration ramp set too short for the load inertia. Check the mechanics first, then insulation test the motor circuit after lockout with the cable disconnected from the drive.
During deceleration the motor acts as a generator and pumps energy into the DC bus. If the bus exceeds its limit, the drive trips to protect itself. Extend the deceleration ramp, or add a braking chopper and resistor if the cycle time cannot be increased.
STO means the safety circuit connected to the drive's STO terminals opened, so the drive removed torque as designed. It is not a drive failure. Check emergency stops, safety relays, and STO wiring, and never jumper the STO terminals to bypass it.
No. The fault types are similar, but the numbering differs by series and can change between firmware versions. Overcurrent is F0001 on an ACS355 and 2310 on an ACS880, for example. Always confirm the meaning in the firmware manual for your exact model and firmware.
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