Just wanted to vent a bit

I have this colossal, prehistoric, power-hungry compressor in my workshop. It came with the building when I bought it eight years ago, probably as some kind of practical joke from the universe. And when I say large, I don’t mean "a bit hefty" — I mean 22kW / 30hp of ‘call the utility company before you start it’. Two tanks, each about a meter long, hooked up to 3-phase power like it’s running a small submarine.

Now, motors this size typically have a Wye-Delta starter to avoid dimming the lights for a 3-block radius every time they fire up. But for the past year, this ancient beast has been acting like a stubborn teenager. Sometimes it works, sometimes it just sits there sulking. The control box? Well, it was probably cutting-edge when the Berlin Wall was still standing. Flat-head screws everywhere (because, apparently, Phillips heads hadn’t made it to this corner of the world yet) and an absolute rat’s nest of black wires. Because color-coding is for cowards.

Suspecting a dead contactor or two, I decided it was time to upgrade. Could I find replacements? Of course not. The labels were more faded than my will to live at this point. So I ordered a shiny new Wye-Delta controller while I was in China — 1/5th of the price quoted in Australia for something rated way higher than necessary, because overkill is the only kill I trust these days.

Yesterday morning, I get a message: Delivery this afternoon. Excellent. So I dive into the old control box like a caffeinated raccoon, only to find Problem #1: the motor is only connected with three wires. Now, for those playing at home, a Wye-Delta setup should have six. I crawl under the compressor (through piles of what can only be described as workshop archaeology) and discover the motor’s hard-wired in Delta. Meaning the Wye-Delta control box has been doing sweet F-all this whole time, acting as an overpriced light switch.

Fine. Whatever. I bypass the (probably fried) contactors, wire the motor straight to mains, hit the switch… Bzzzz… hummm… nothing. Okay. Belts off to remove load. Bzzz… hummm… still nothing. At this point, I’m ready to list the entire workshop on Facebook Marketplace out of spite.

But wait — I remember the previous owner left a “newly refurbished” spare motor buried somewhere. Of course it’s under a decade’s worth of other junk. After twisting my back in six different directions and moving stuff that probably should have been thrown out in 2019, I finally drag the 70kg lump out. Wire it up, press start… Bzzz… humm… ARE. YOU. KIDDING. ME.

It’s at this point, after losing two litres of sweat and a chunk of my sanity, I finally think to check the mains voltage. And what do I find? Between L1 and L2 — a healthy 380V. Between L1 and L3? 24 volts. TWENTY-FOUR.

Turns out all this grief was because one of my phases dropped out. The mains line I had replaced a couple years ago because it was “old and unreliable” decided it was time for a little performance art.

So yeah — moral of the story: before you start tearing your whole workshop apart and questioning your life choices, maybe test the power first.

Anyway, have a great day. I’m going to go lie down and question the last decade of my existence.

Geland, call yourself lucky that the thermal safety switch was adjusted fine, if not you would have burned the motor when trying to start on 2 phases only.


And as always the rule still counts: 15 minutes of thinking/planning can save you hours or even days of work...

not that I'm that good in planning, but I learned to know Murphy...

Leland,
You didn't write the how to rope a deer speil from a few years ago did you.
Sorry to say I haven't laughed so hard since I read that.
Experience, that thing you get 5 mins after you needed it.
Well at least you've achieved some exercise and started a much needed clean up.