The arc furnace

No fuel, no pressure, no explosion risk: the arc furnace simply melts pure ore with electricity. In return it wants the power exactly when it needs it – and if the grid does not give it, it calls it a day.

What it can do#

The arc furnace (StructureArcFurnace) takes ore in slot 0 and outputs ingots in slot 1. It melts one piece of ore after the other. The game's recipe data give per piece:

So a stack of 50 iron ore needs 50 seconds and 10,000 J. It cannot do alloys – for those you still need the furnace with gas.

Readable are On, Power, Activate, Reagents, RecipeHash, ImportCount, ExportCount and both slots. Idle exists as well, but on the arc furnace the game never changes the value: it is always 1, whether the furnace smelts or not.

Activate: every stack needs a start#

On 1 alone smelts nothing. The furnace only begins when Activate goes to 1 – by hand with the button on the device or from the chip. Then it smelts the whole stack from slot 0, piece by piece. When the stack is through, it sets Activate back to 0 by itself and outputs the ingots. The next stack needs Activate 1 again.

lbns tmp ARC HASH("Lichtbogen") 0 Occupied Average
and tmp tmp power
and tmp tmp free
seqz ok act
and tmp tmp ok
beqz tmp count
sbn ARC HASH("Lichtbogen") Activate START
count:

So the chip only writes Activate when ore is waiting, the furnace is on and released and no stack is running. That also makes Activate your “smelting right now” signal.

Planning the power demand#

This is where the trap lies. Before every piece the furnace checks whether the grid still has enough power left for that piece. If it is not enough – or it has no power at all –, it switches itself off: On jumps to 0, and it stays off until someone switches it on again.

The chip takes care of that. It releases the furnace by battery level, with hysteresis:

sgt tmp level OFF
and free free tmp
sgt tmp level ON
or free free tmp
sbn ARC HASH("Lichtbogen") On free

Because the chip writes On every tick, it switches the furnace back on by itself after a self shutdown – but only when the battery really has enough. The aborted stack is then restarted by Activate.

Throughput#

ExportCount counts how often the furnace has output something. That is not the number of ingots but the number of outputs: an ore stack can come out as one ingot stack. For real piece counts you count in storage tomorrow.