Yaskawa GA500 fault oH: Heatsink Overheat
Fault oH on a Yaskawa GA500 is Heatsink Overheat: the heatsink temperature exceeded L8-02 [Overheat Alarm Level]. Yaskawa lists high ambient temperature, too heavy a load and a stopped internal cooling fan. The drive stops as set in L8-03 [Overheat Pre-Alarm Selection].
Diagnose this with AI
Try Free Drive Diagnostic Upload a keypad photo, the fault history or a parameter export from your Yaskawa GA500. InduQT compares the evidence and suggests the next useful checks.
When it happens
- Running under heavy load
- Hot weather or poor panel ventilation
- After the drive cooling fan stops
- At high carrier frequency
Likely causes and checks
1Ambient or panel temperature too high
- Points to it
- Trips in summer or after panel changes; other equipment in the panel is hot.
- Check
- Measure the ambient temperature around the drive and improve panel airflow or cooling.
2Internal cooling fan stopped
- Points to it
- Fan not turning or noisy; LT-1 cooling fan maintenance alarm seen earlier.
- Check
- Replace the cooling fan per the manual, then set o4-03 = 0 to reset the fan operation time.
3Load too heavy
- Points to it
- High output current for long periods.
- Check
- Measure output current and decrease the load.
4Carrier frequency high
- Points to it
- C6-02 raised for low motor noise.
- Check
- Decrease C6-02 [Carrier Frequency Selection].
Telling it apart
- oH (fault) uses the user level L8-02. oH1 trips at a fixed level set by the drive model (o2-04) and its auto restart is controlled by L5-08. oH with a flashing ALM LED is the alarm form.
- oH3 and oH4 are motor overheat from a PTC thermistor input, not the drive heatsink.
- V1000 equivalence: the V1000 manual lists oH (temperature above L8-02) and oH1 (heatsink above L8-02 default plus 10 °C) with the same ambient, load and fan causes.
Relevant parameters
| Parameter | Name | Why it matters |
|---|---|---|
| L8-02 | Overheat Alarm Level | Heatsink temperature for oH; default set by drive model. |
| L8-03 | Overheat Pre-Alarm Selection | How the drive stops on oH. |
| C6-02 | Carrier Frequency Selection | Lower carrier frequency reduces drive losses. |
| o4-03 | Fan Operation Time Setting | Reset to 0 after replacing the fan. |
Evidence to collect
- Keypad photo with ALM LED state
- Panel and ambient temperature
- Cooling fan condition and LT-1 history
- Output current trend
- C6-02 and L8-02 settings
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