Heating grid breaker upgrade

[dm9289]

I asked this question on the NEC forum and got 0 answers I was wondering if you could help

What I have is a metal heating grid system outside a container to melt zinc inside a large metal container (pot)
Current problem is 60 year old GE breaker that looks like switch gear does not open and close properly, old open close window flag gets stuck and one of the ct monitoring coils recently caught fire.

Also I am not sure it is set uo right to begin with so let me post some info

Plant power is 480V ungrounded delta
Feeds to transformer cuts down to 240v 2 wire
600 Breaker/OL feeds 1000KCM thhn wire in conduit to a metal grid no blowers
Breaker has mechanical adjustment wheel adjusted beyond 100% so it dont trip
By current coil measured current is approximately 590 amps.

I am not sure if this needs a breaker OL combo?
Does it requir some form of GFCI protection?
I am not sure if the wire is capable of this current?
Does 125% continuos load apply to wire size 590*125%=737amps? 1000kcm thhn 615amp
I am not sure of heating grid common practice I have been trying to make some sense out 427 I think our pot would be considered a vessel

 

[zog]

Can you post nameplate inof or better yet a photo of the breaker so we have a clue what you are talking about? Lots of conflicting clues in there.

 

[dm9289]

heres the picture

heres the picture

This should clear things up

 

[zog]

Can't see nameplate but looks like an AK-6A-25. We rebuild those all the time and I have about 2,000 spares. Those do require maintenence and an occasional rebuild, which from the sounds of it has never happened.

That trip unit is available with Long time (Overload), Short time, Instantanous, and Ground Fault (Not the same as GFCI) trip functions.

 

[dm9289]

I am wondering if we are using this correctly see questions, and I was wondering about maybe a suggestion for this that is more modern without all the mechanics that are so likely to fail. In the region I am in we get these and larger ones like it "rebuilt" but it seems just like we are chasing different problems with them each time we try to turn them off or on.

 

[zog]

That breakers mechanics are more solid than anything they make now, AK's are one of the few breakers used in nuclear plants safety systems becasue of thier proven relibility. However, there are a ton of shops out there that attempt rebuilds on these that have no idea what they are doing. If you are having issues opening and closing it is related to the operating mechanism and 95% of the time those issues are from improper lubrication. Some places don't fully disassemble the mech (takes about 40 hours) and just clean it, attempt to lubricate, and just end up causing more problems down the road. Looks pretty, works like crap.