Delta · MS300Fault Code LvWarning
Delta MS300 — Lv DC Bus Undervoltage
Occurs when the DC bus drops below the lower limit. Supply sag, phase loss or capacitor ageing are triggers.
Updated: 2026-07-05
Symptoms
- Lv on power-up / load
- Frequent trips during supply fluctuations
- Sudden stop under load
Probable Causes
- Supply voltage sag
- Input phase loss
- Ageing of DC-bus capacitors
Checkpoints
- Measure supply under load
- Verify input phases
- Assess capacitor condition
Solution
If mains is healthy, aged capacitors collapse the bus; the board is repaired by recapping.
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