What this code means
The oL2 fault on a Yaskawa A1000 is an inverter overload or drive overload alarm. This is distinct from an oL1 motor overload. The drive’s internal electronic thermal overload model has calculated that the output current and time-at-load exceeded the drive’s safe operating limit, so the drive shut down to protect its own power electronics from overheating. One technical source states the fault triggers when output current exceeds the drive’s normal duty or heavy duty rating for approximately 60 seconds.
This fault does not primarily indicate a motor thermal problem. It indicates the drive itself is being pushed too hard. The drive is telling you it cannot sustain the current demand being placed on it under the present operating conditions.
Before You Replace Anything
Technicians sometimes replace the motor or motor cable first, assuming oL2 is a motor fault. Instead, disconnect the motor leads and run the drive with a start command. If oL2 persists with the motor disconnected, the drive itself is faulty and needs repair or replacement.
Common Causes
- Load too heavy The driven machine, process, or mechanical system is demanding more torque and current than the drive can sustain, causing continuous high output current and thermal buildup.
- Acceleration or deceleration times too short Aggressive ramp settings force the drive to deliver very high current during starts and stops, exceeding the drive’s thermal capacity before the ramp completes.
- Drive undersized for application The A1000 model installed does not have sufficient current or power rating for the actual load profile, and replacement with a larger frame size is required.
- Mechanical binding or jammed load A stuck coupling, misaligned shaft, failed bearing, jammed gearbox, or other mechanical fault forces the motor and drive to work against high friction or a locked rotor condition.
- Internal drive fault If oL2 occurs even with the motor disconnected, the drive’s inverter section, IGBT module, or current-sensing circuit is faulty and the drive must be repaired or replaced.
- Carrier frequency set too high Excessive switching frequency increases heat generation inside the drive’s IGBT power stage, reducing the drive’s effective overload capacity and triggering oL2 under normal load.
Step-by-Step Fix
- Stop the drive and lock out power. Record the operating conditions when the oL2 fault occurred, including load level, speed, and whether the fault happened during start, run, or stop.
- Inspect the mechanical load. Verify the driven machine, coupling, gearbox, and motor shaft spin freely by hand. Look for binding, jamming, misalignment, failed bearings, or any source of excessive friction or locked-rotor condition.
- Review drive sizing and load profile. Compare the actual load current and torque demand against the A1000 nameplate rating. If the application legitimately exceeds the drive’s normal duty or heavy duty rating, replacement with a larger A1000 frame is the correct fix.
- Lengthen acceleration and deceleration times. If the fault occurs during ramps, increase the acceleration time and deceleration time parameters to reduce peak current demand during starts and stops.
- Check and adjust carrier frequency. If the carrier frequency parameter is set high (above 8-10 kHz), lower it to reduce drive heating and increase overload capacity. Consult the A1000 manual for the recommended range for your frame size.
- Verify input power quality. Inspect all three input phases for tight connections, balanced voltage, and absence of phase loss. Measure input voltage at the drive terminals under load to confirm stable supply.
- Isolate the motor and retest. Disconnect the motor leads at the drive output terminals. Apply power and issue a run command. If oL2 still appears with the motor disconnected, the drive’s inverter section is faulty and the drive must be repaired or replaced. If oL2 does not appear, the problem is on the load side: inspect the motor, motor cable, and driven machine for shorts, ground faults, miswiring, or mechanical overload before reconnecting and retesting under load.
Parts Often Needed
| Part | Notes |
|---|---|
| Yaskawa A1000 VFD (larger frame size) | Amazon | Required if the existing drive is undersized for the actual load profile. Select the next frame size up based on continuous current and overload duty requirements. |
| Yaskawa A1000 IGBT/inverter power module | Amazon | Factory or authorized service center replacement if oL2 persists with motor disconnected and the drive’s internal inverter section is confirmed faulty. |
| Motor or motor cable | Amazon | Replace only if oL2 clears with motor disconnected and inspection reveals shorted windings, damaged cable insulation, or ground fault on the load side. |
When to Call a Pro
Call a qualified electrician, automation technician, or drive service center if you are not trained to work with three-phase power and VFD programming. Diagnosing oL2 requires measuring three-phase voltage, interpreting drive parameter settings, isolating the motor under live conditions, and potentially replacing high-voltage power electronics. If the drive faults with the motor disconnected, internal repair or replacement of the inverter section is a factory or authorized service task. If the mechanical load or process is complex, involve a mechanical technician to rule out binding, misalignment, or process overload before changing electrical components.