Mitsubishi Electric MELSERVO-J4 (MR-J4) alarm AL.33: Overvoltage
Alarm AL.33 on a Mitsubishi MR-J4 servo amplifier is Overvoltage: the bus voltage exceeded the prescribed value (400 V DC for the 200 V class, 800 V DC for the 400 V class, 400 V DC for the 100 V class).
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When it happens
- During deceleration, as the motor regenerates
- On vertical axes while lowering
- At any time if the input supply is too high
Reading the subset
| Subset | What it tells you |
|---|---|
| 33.1 | Main circuit voltage error. |
Likely causes and checks
1Regenerative option set incorrectly
- Points to it
- After commissioning or a resistor change.
- Check
- Check the regenerative resistor (regenerative option) and the [Pr. PA02] setting.
2Regenerative option not connected or open circuit
- Points to it
- Option fitted but stays cold; resistance abnormal.
- Check
- Check the connection and measure the resistance of the built-in resistor or regenerative option.
3Regeneration capacity insufficient
- Points to it
- Alarm stops when the deceleration time constant is lengthened.
- Check
- Set a longer deceleration time constant and check repeatability; if that cures it, fit a (larger) regenerative option.
4Input supply voltage too high
- Points to it
- Alarm without motion or on gentle stops.
- Check
- Measure the input voltage: above 264 V AC (200 V class) or 528 V AC (400 V class) is over the limit.
5Noise or surroundings
- Points to it
- All else checks good.
- Check
- Check noise and ambient temperature and take countermeasures.
Telling it apart
- Alarm only during deceleration points to regeneration; alarm at standstill points to the supply.
- AL.30 (Regenerative error) means the regenerative circuit is overloaded or faulty; AL.33 means the bus voltage itself went too high. Warning AL.E0 (Excessive regeneration warning) comes before AL.30.
Relevant parameters
| Parameter | Name | Why it matters |
|---|---|---|
| PA02 | Regenerative option | Must match the fitted regenerative option. |
Evidence to collect
- Alarm history with AL.33 and any AL.E0/AL.30
- Deceleration time constant
- [Pr. PA02] setting and regenerative option model
- Measured input voltage
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