▲ 841 r/submechanophobia
Two wrecks and it’s getting dark
I hate the thought of being near this in the darkness of night. Theres probably 200ft worth of half a ship lurking under that water.
u/RotarySam27 — 4 days ago
Step-up transformer soft starter
Mains supply of 24KVA max (single phase 240V on a 100A main fuse).
I may be trying to use a 240V to 415V step up transformer rated for 20KVA in a rotary phase converter project.
Doing the maths, under normal load conditions, i will be safely within my 100A supply with some room to spare. Loads will be solely induction motors in manual machines tools. Lots of motor fwd/rev off/on conditions but i don’t believe its an issue for my supply once it is all running.
The issue is the initial inrush magnetising current when first powering up such a transformer. I believe it is 50/50 if the main fuse will blow, which I can’t have happen. I sometimes use 300A oil cooled stick welder that is rated for 15KVA, it blows D rated MCBs like they are nothing, it takes a few clicks of the brakers to get it to stay on, but once on, it doesn’t trip when in use. I reckon i will be pushing my luck with 20KVA.
What device do i look for in this specific case? How are these current limiting devices or soft starters rated or sized? It’s for 240V operation obviously but do i look for something that limits it to 80A - near the transformer primarily current at full load? Is it more? Or less? I assume I cant exceed 100A in any case. I also see these things rated in watts, mostly nowhere near the current i expect too, some at 16A or 32A. I have been looking into making my own but then again there’s very little information or examples out there of someone doing it for inspiration. I would just be using a resistor bank and time delay bypass but it would be tricky to experiment with, as getting it wrong may mean my distribution supplier coming out to change the main fuse.
Anyone worked with these or ever tried a diy method?
u/RotarySam27 — 1 month ago
▲ 312 r/RX8
Body refurb update
Back again with a quick update and better pictures of the underside of the rx. I put a couple more coats of paint on and went to it with some seam seal. It is more of a function over form job here, it is going to be coated with stonechip tomorrow so it will all be hidden. The sealer i am using is Sika 221 polyurethane.
On taking this all back to metal, a significant amount of all these little holes and slots in the body were covered with some sticky tape that would remind you of emery cloth (without the abrasive of course) and i couldn’t find an alternative so i went with aluminium foil instead. I have left some holes uncovered so i can use a cavity injection gun and really get in there, then plug whatever is left with rubber grommets. I have added some aluminium rivnuts in the rails and sills so i can later fasten a new custom aluminium belly pan.
Heat shield around the gearbox and cat tunnel will go on tomorrow and i will stone chip it.
u/RotarySam27 — 3 months ago