We (SSC) have been fighting an issue on our EAF for the last few months. Once in a great while a spot on the lower front part of the B-phase current conducting arm electrode holder would become hot and start glowing. This area is made of copper. I have never seen an issue like this and discussed it with many of my contacts. We checked everything we could think of and could not find an issue. Unfortunately the hot spot would occasionally return, requiring EAF power to be switched off resulting in loss of production time.
We decided to change the B-phase current conductive arm last week. We had other reasons for the arm change besides the hot spot issue. Prior to energizing the arm we took meg-ohm readings between the arm and ground and came up with 6 meg-ohms of insulation (which is plenty). We also checked that the new arm was aligned properly on the pitch circle, it was perfect.
The arm is an electrical component of the EAF power delivery system, but the change is more of a mechanical than electrical task. Our guys got it done perfectly. We started the EAF last night with no issues. It is nice to work with competent maintenance. Unfortunately I didn’t take a picture of the arm last night at start up so I can’t post it.