colin wrote:
"John Popelish" wrote in message
. ..
colin wrote:
(snip)
I have a sheet of magnetic field viewing material that changes color from
green to dark green as it sees field. it is sensitive enough to show the
magnetic strip on the back of a credit card. I wonder what a disc of that
would do in the center of the rotor.
http://cgi.ebay.com/Magnetic-Field-V...mZ160125398593
Much neater than iron filings.
can you cut that stuff ?
I haven't cut mine, but the piece I have looks like it has a
cut edge. It contains some sort of micro capsules, I think.
I've misplaced it at the moment, or I would examine it
more closely.
not sure if its got tiny bubbles with fillings in or the whole sheet is one
space.
It didn't appear to have any sealed edge.
I have tried iron fillings on a plastic tray wich just fitted inside the
stator
however the iron filings congregate between the segment poles and stay
there,
just dancing around a bit. i was exciting it at 12rpm.
gues i need more iron fillings, i just collected a few off the dril stand
and around my vice with a magnet lol.
Ive tested it with the induction rotor, and it does go round,
however ive not been able to get it upto any speed,
with only 12 in each slot im not toooo surprised though,
although this was with 10 amps.
my gues each slot originally had 1000 turns for 250v and was rated at 0.2
amps (6w)
however I was hoping to ascertain if this would work before I spent a few
days
winding about 30 turns onto each coil.
I wound them coils on a former first then squezed them into the slots.
are there any other significant problems associated with running an
induction motor at high speed ?
I think eddy current and hysteresis heating of the stator
laminations are the biggest limitations, after you get past
mechanical resonances it the rotor that make the shaft bend.
I have seen some pretty high speed 2 pole induction motors.
http://scitation.aip.org/getabs/serv...cvips&gifs=yes
http://adsabs.harvard.edu/abs/1991crin.rept.....M
http://stinet.dtic.mil/oai/oai?&verb...er =AD0601968