TL;DR
An electrode break stops melting on one phase. Stop the heat, raise the electrodes to the retracted position, and recover the broken stub from the scrap charge before jointing and continuing.
What you might see
- sudden loss of one phase arc current
- broken electrode stub visible in the scrap or bath
- arc control system unable to regulate one electrode
- current imbalance between the three phases
Likely causes
Electrode mechanical stress from a scrap collapse event during the melt
Electrode nipple joint failure from over-tightening or under-tightening during column assembly
Deep boring of the electrode into a compact scrap pile causing bending
Electrode oxidation from excessive oxygen lance use near the electrode
Required tools
- Electrode jointing equipment
- Torque wrench for nipple joint
- Scrap handling crane
- LOTO kit for HV transformer
Safety first
- High-voltage transformer must be isolated and locked out before any person approaches the electrode column or works on the electrode joint.
- Extreme thermal radiation from the open furnace. Aluminized PPE is mandatory.
- Broken electrode stubs in molten steel can cause steam or arc events when touched by the crane or tools. Keep non-essential personnel clear.
Procedure
- 1
Stop the melt immediately when one phase current drops to zero. Raise all electrodes to the fully retracted position.
Warning: Do not enter the furnace bay until the electrodes are fully retracted and the high-voltage transformer is isolated. - 2
Isolate the furnace transformer and lock out the high-voltage circuit.[1]
- 3
Visually inspect the electrode column on the affected phase from the platform. Locate the break position.[1]
- 4
If the broken stub is accessible in the scrap charge, recover it using the scrap handling crane before it is melted in and lost.
- 5
Joint a new electrode segment to the column stub. Ensure the nipple joint is torqued to the specification.
- 6
Lower the electrode to check the new joint position and alignment relative to the other columns.
- 7
Restore power and resume the melt.
Sources
Danieli Danieli Q-One / Digimelter Electric Arc Furnace (EAF) general technical documentation, Danieli
General EAF electrode management and breakage recovery procedures (general)
More guides for Danieli Danieli Q-One / Digimelter
How to detect and manage furnace shell hot spots on a Danieli Q-One / Digimelter EAF
A hot spot on the EAF shell means the refractory lining is thin or damaged at that point. Stop the heat if the shell temperature approaches the critical limit and apply gunning refractory during the next planned stop.
How to detect and respond to water-cooled panel leaks on a Danieli Q-One / Digimelter EAF
Water entering a molten steel bath causes a violent steam explosion. If a panel leak is suspected, stop the heat immediately. Never continue melting with a confirmed water leak into the furnace.
Stop fixing the same fault twice.
Dovient turns guides like this into your team's shared playbook, with AI that catches recurring issues before they break the line.