another quick motor update so there was there were some questions about the
motor and the capacitors and things like that and I did a little brief
exclamation about how the capacitor adds a phase shift to the starting windings
and what I have set up here is my oscilloscope and I have it hooked up to the
motor and I'm going to show on the oscilloscope what the phase shift is and
how you can calculate exactly how many degrees of lead or lag that you have and
from that you can actually adjust your capacitor to get it so it's perfect
at 90 degrees if you want and I already have the motor all hooked up with with
two channels and one channel is the voltage on the incoming voltage and that
which would be the run winding when it's running and the other is hooked up to
the starting winding so it will take a snapshot of the starting winding as it
starts and show us that against the running of the motor or the run winding
all right I'm gonna plug it in there we go
that's a little bit better zoomed in now what we have here are the two sinusoidal
wave's of the motor the one in the middle here I have said
actually I have them set at both the 200 volts range right and that one in the
middle here is the run winding as the motor is running here
the A over here is marked by a this one and was the start sinusoidal wave
and you can see how they're not in line
with one another out there that here this is rising voltage the peak and on
down and then drop it down here you Now here our AC here is 60 cycles and then here
the peak of this one here there's the peak and undoubted peak so that's one
one cycle right
and it all matters it's all a point of reference if you use the running winding
waveform as a reference then the starting winding lagged then it lags the run
winding and then some people will say it leads well if you use this that then
they'll say the running current is leading the starting current so if you
use the start winding as a reference then yes the other current leads
the the thing is is the difference in phase angle between the two waves and we
can move the there's these dashed lines here you'll see these you should be able
to see these dash lines so you'll see these dashed lines here and those are
cursor lines and I'm going to adjust them a little bit here because what we
want to do is we want to measure the difference in time yeah like I said this
is 60 cycles both waves are 60 cycles and the time difference between the
cycles is what we need to check now this meter will give us that right here is
its dT it's the differential time between the two cursors and I'm going to
on both of the rising waveforms okay so the rising wave form of the
rising way from the tide difference from a zero point two zero point here so
let's we're going to adjust this cursor I'm adjusting this cursor over at zero
voltage where it crosses the zero voltage point and then I'm gonna adjust
the other cursor this one here to cross at this waveform right there that's
comes up to be 5.2
5.0 milliseconds between the two okay now we can do a
quick little calculation to determine that that phase shift angle between them
so we'll do a little math so we know it's 60 cycles and I don't have it set
right here most change here for frequency and right here the frequency
is fifty nine point nine eight sixty point zero one it's at 60 cycles for all
intent purposes so go back here to the scope so
a 1 over 60 will give me how many microseconds coming milliseconds it is
anyway 16.6 milliseconds so that's a really is 0.016
now it's 300 the generator whose jiménez generating
this it's 360 degrees there - there for one cycle okay so
360 degrees 16.6 milliseconds and that equals
vehicles 21.6 a degrees per millisecond well our time difference between the two
is five milliseconds so five times twenty one point six eight
because 108 degrees so that's our that's our face our
phase-shift angle is 180 degrees pretty simple and by changing your
capacitance you can adjust that so that the current here the voltage or the
current here is not lagging as much or you might want to like more it all
depends on what you want to do here would what we'd want to reduce it a
little bit so you can change your capacitance to adjust that 108 that's
right in the ballpark it's it's good I'm not going to change
but anyway that this gives you a nice representation to see what's happening
and stuff I could change the scales here
you know you can you can see where how to do something more look the same but
by changing your scales to what you can do is you can actually get a more
accurate number if you want in there and you know move your cursor and we could
zoom in basically we zooming in I'm gonna zoom in
I might be able to get a little more accurate number
yeah 5.12 you know it's gonna change 5.2 milliseconds so it makes it a five-point
to makes it a 112 degrees you know you know or you can even change our scales
and get the waveform so there's steeper
you know where they where they cross and then you're gonna just your cursors
maybe a little bit still where a 5.12 there so it's close enough for what
we're doing we're doing a demonstrating here okay
that's how the motor why the motor starts and how they held this type of
system works alright I hope that everybody helps everybody else II have
an idea with what's happening with their motor it's a pretty good unit i I've had
this one really quite a long time but it's an older unit it's a Fluke 95 scope
here but it works and works good battery's going to get a long time ago
and now I hear what ideas might hit the auto set button here and it kind of sets
up both up and you can see that phase shift between the two so there
all right so I hope that I helped somebody and kind of a cool thing to see
and what catch will catch you next one