Yaskawa A1000 Er-02 — What It Means
The Yaskawa A1000 VFD does not have an AL-02 fault code. The code you are seeing is Er-02, a minor fault that indicates the auto-tuning process failed. This happens when the motor parameters you entered (voltage, current, frequency, speed, poles) do not match the actual motor nameplate data, or when the drive detected a problem during tuning such as faulty wiring, a shorted phase, or excessive mechanical load preventing the motor from accelerating smoothly.
The drive uses auto-tuning to measure the motor’s electrical characteristics (resistance and inductance) so it can control the motor precisely. If the data you entered in parameters T1-02 through T1-07 is wrong, or if the motor cable has a poor connection or short, or if the load is too heavy or jammed, the tuning algorithm cannot complete and throws Er-02. The drive will not run until you correct the problem and clear the fault.
Before You Replace Anything
Technicians sometimes replace the drive or motor when Er-02 appears, but the real problem is usually a data-entry error or a loose wire. Check all motor parameters against the nameplate and inspect U/V/W connections with a multimeter before ordering parts.
Common Causes
- Wrong motor parameters (~50%) The voltage, current, frequency, speed, or pole count entered in T1-02 to T1-07 does not match the motor nameplate, so the drive cannot calculate correct tuning values.
- Faulty motor wiring (~25%) Poor connections, open circuits, or shorted phases in the motor cable prevent the drive from measuring motor resistance and inductance during auto-tuning.
- Excessive mechanical load (~15%) The motor is coupled to a load that is too heavy, jammed, or has broken parts, preventing smooth acceleration during the tuning process.
- Ground fault in motor circuit (~7%) A short to ground or phase-to-phase fault near the motor or in the cable trips the tuning algorithm before it can finish.
- Tuning mode mismatch (~3%) Parameter E1-01 is set to the wrong auto-tuning mode for the motor type or application, causing the algorithm to fail.
Quick Diagnosis
Answer these to narrow it down fast.
Does every value in T1-02 through T1-07 exactly match the motor nameplate?
No: Correct all mismatched parameters, then press RESET and restart auto-tuning (E1-01).
Do you measure continuity and no shorts to ground between U-V, V-W, and W-U at the motor terminals?
No: Repair or replace the motor cable and connections, then retry tuning.
Can you rotate the motor shaft freely by hand with the load decoupled?
No: Fix the mechanical jam, broken bearing, or coupling, then retry tuning with the load decoupled.
Step-by-Step Fix
- Check the motor nameplate and write down voltage, current, frequency, speed (RPM), and number of poles.
- Access drive parameters T1-02 through T1-07 on the digital operator and verify each value against the nameplate (T1-02 is motor voltage, T1-03 is motor current, T1-04 is motor frequency, T1-05 is motor speed, T1-06 is motor poles, T1-07 is motor resistance if known).
- Correct any mismatched parameters and save the changes.
- Inspect motor wiring at the drive output terminals (U, V, W) and at the motor terminal box for loose connections, corrosion, or damage.
- Use a multimeter to check phase-to-phase continuity (U-V, V-W, W-U) and verify no short to ground on any phase.
- Decouple the motor from the load if possible (open the shaft coupling) and check for mechanical jams, broken bearings, or obstructions.
- Set parameter E1-01 to the correct auto-tuning mode (consult your model’s manual for mode definitions, typically 1 for simple tuning).
- Press the RESET key on the operator to clear Er-02, then press the Tuning key or run command to restart auto-tuning.
- Monitor the tuning process and verify the fault does not return; if it completes successfully, re-couple the load and test normal operation.
Parts Often Needed
| Part | Notes |
|---|---|
| Motor power cable (U/V/W) | Amazon | Replace only if you find visible damage, open conductors, or insulation breakdown during inspection. |
| Motor terminal block | Amazon | Replace if terminals are corroded, cracked, or cannot hold a secure connection. |
When to Call a Pro
Call a qualified electrician or VFD technician if you are not trained to work with three-phase power and motor drives. Auto-tuning requires verifying and entering motor nameplate data, inspecting high-voltage wiring, and using a multimeter to check for shorts and opens. If you correct all parameters and wiring but Er-02 persists, a technician with an oscilloscope or motor analyzer can test the motor windings for internal faults or verify the drive’s tuning algorithm is functioning correctly. Any work on the drive input or output terminals carries shock and arc-flash hazards and should be done with proper PPE and lockout procedures.
Rough cost: A pro service call runs about $150-400 for service call and tuning.