I told you already - or at least hinted - that I started a new “career” in light machine building. A little heavier than making clocks but nothing above what our 400 V three-phase 16 A fuses can handle.
I always wanted a motor test bench. There are few around. From schools, mostly and with mechanical scales, like the ones you found at the butcher’s shop. And, of course, with DC motors and in some cases with an electric brake, even.
Big, heavy and no way you can have a look at unbalanced (negative sequence) grid, starting transients, EDM and many other things where myths more than facts seem to prevail. The efficieny of the European IE3 and IE4 motors are also interesting to have a deeper look into. Not to mention EDM (bearing electric erosion) oils film break-through at different speeds and temperatures. And probably a lot of other things that I haven’t tought much about and will pop up once I get started.
Low cost - use scrap.
Machining limits are:
Band saw up to around 4 or 5 inches (100 - 125 mm) steel and sigma c:a 70 um. Nice little Chinese guy.
Lathe with milling attachment and possible to run pieces up to around 100 mm diameter and 250 mm long. Works best on bronze and alu but can handle steel if you are careful and have hours to spend.
A little DC welder that I am a bit afraid of. Done some “Scrap Art” but nothing serious yet.
Just started. Finished a sturdy frame (buiilt with Al extrusions from a baldachin(?) that isn¨t needed any more, Some 20x20 mm square tube and some “self-made” nuts, screws and bolts.
Speed measurement. No Probs - done that most of my life - anything will work. From DC tachs via encoders and reciprocal measurements with simple pic-up.
Torque measurement. Pressductor/Torductor (ABB) but on a smaller scale, Strain Gauge perhaps but with a twist. One of the Amazon pressure transducers may also work - but not sure if I can get one working well in this application. This part is the real challenge. So far…
Time-wise, I am not in a hurry. The only guy getting impatiant is me, myself and Skogsgurra.
Unbalanced grid Will use either a Variac or a Squariac for one phase.
Harmonics and interharmonics A phase-locked power amplifier with suitable software and a 24 V secondary winding for up to around 10% THD. Need three amplifiers for that - could be costly - will scavenge the nearby scrap yard for som boomers (no, not that)
Power measurement Standard procedure - will use what I have available - and that is a lot.
Other ‘lectric’ measurements Also standard procedure.
Comments and suggestions are welcome (as Bob Pease used to say).