Yaskawa A1000 oL6 Fault — What It Means
The oL6 fault on a Yaskawa A1000 VFD indicates Motor Overload (2), a software-based protection triggered when the drive calculates the motor has operated at an overload level beyond the preset time limit. This is tied to the thermal overload model and protects against prolonged, low-level overloads that cause excessive heating over time. The drive accumulates a thermal capacity value based on output current, and when this exceeds 100 percent for the duration defined in parameter L6-03, the fault trips. It differs from oL1 by focusing on cumulative thermal stress rather than sudden current spikes.
Before You Replace Anything
Technicians often replace motors or drives when the real cause is incorrect motor parameter settings (E2-01 through E2-05). Always verify nameplate data matches drive parameters before swapping hardware.
Common Causes
- Excessive mechanical load (~45%) The motor drives a load heavier than rated capacity, such as a jammed conveyor, clogged pump impeller, seized bearings, or tight belts causing high friction and prolonged current draw.
- Incorrect motor rated current parameter (~30%) Parameter E2-01 (Motor Rated Current) is set too low compared to the actual motor nameplate, causing the drive to overestimate thermal stress and trip prematurely.
- Motor cooling failure (~12%) The motor fan is broken, air vents are blocked, or ambient temperature is too high, preventing heat dissipation even under normal loads.
- Thermal overload time set too short (~8%) Parameter L6-03 (Thermal Overload Time) is configured too aggressively, causing the drive to trip on normal transient loads.
- Low-speed high-load operation (~5%) Running the motor at very low speeds under high load reduces cooling effectiveness and accumulates thermal capacity faster than the motor can dissipate heat.
Quick Diagnosis
Answer these to narrow it down fast.
Does the output current (monitored on the drive display) stay near or above the motor nameplate rated current during normal operation?
No: The load is within range. Check motor parameter settings and thermal protection configuration next.
Does parameter E2-01 match the motor nameplate rated current exactly?
No: Incorrect parameter will cause false trips. Correct E2-01 and all other motor parameters (E2-02 through E2-05) to match the nameplate, then reset the fault and retest.
Is the motor fan running and are all air vents unobstructed?
No: Poor cooling will cause legitimate thermal overload. Clean vents, replace the motor fan, or improve ambient ventilation, then reset and retest.
Step-by-Step Fix
- Clear the fault by pressing the reset button on the keypad or cycling power to the drive, then monitor whether the fault returns immediately or after a period of operation.
- Inspect the mechanical load by stopping the drive and checking for jams, clogs, seized bearings, tight belts, or damaged gears in the conveyor, pump, fan, or gearbox.
- Measure output current using the drive monitor function (parameter U1-01 or U1-02) or a clamp meter on the motor leads while running under load, and compare to the motor nameplate rated current.
- Verify motor parameters by reading the motor nameplate and navigating to parameters E2-01 (Motor Rated Current), E2-02 (Motor Rated Voltage), E2-03 (Motor Rated Frequency), E2-04 (Motor Rated Speed), and E2-05 (Motor Rated Power), correcting any mismatches.
- Check motor cooling by confirming the motor fan is running, air vents are clear, and ambient temperature is within the motor rating, and repair or clean as needed.
- Review thermal protection settings by checking parameter L6-03 (Thermal Overload Time) and L6-02 (Thermal Overload Gain) against the application requirements, adjusting if the settings are too aggressive for the load profile.
- Reset and test by clearing the fault, running the motor under normal load, and monitoring current and temperature over a full cycle to confirm the fault does not return.
Parts Often Needed
| Part | Notes |
|---|---|
| Motor cooling fan | Amazon | Replace if fan blades are damaged or motor is not running; must match motor frame size. |
| Yaskawa A1000 VFD replacement | Amazon | Only if drive hardware is confirmed defective after all parameter and load checks; match horsepower and voltage to application. |
When to Call a Pro
Call a qualified electrician or VFD technician if you are not trained to work with high-voltage three-phase equipment, if the mechanical load inspection reveals complex gearbox or bearing damage requiring disassembly, or if correcting motor parameters and thermal settings does not resolve the fault. VFD programming and load analysis require specialized knowledge of motor control theory and measurement tools. If the fault persists after verifying all settings and the mechanical system is sound, the drive may have a failed current sensor or internal fault requiring factory repair or replacement.
Rough cost: A pro service call runs about $200-800 depending on mechanical repairs or parameter tuning.