Re: Light Bulbs, Saws, Motors, Circuits and Basic Calculations
- From: "W. Watson" <wolf_tracks@xxxxxxxxxxx>
- Date: Fri, 12 Oct 2007 03:18:27 GMT
Just re-familiarizing myself. After pondering resistive circuits, I started thinking about motors and other devices and how they effect outages and dimming. I think I've gotten as much as I need. If I go deeper, I'd need to go backing to computing impedances, and lots of other stuff that has long since disappeared from my brain. In school, they never really talked much about blowing fuses or overloading circuits in general classes on electricity. Some of that I suppose you learn the hard way, experience.
redbelly wrote:
On Oct 10, 11:34 am, "W. Watson" <wolf_tra...@xxxxxxxxxxx> wrote:I'll buy that, but it's been a very long time since I've heard the the term
back-EMF, which shows how long I've been away from this stuff. If this is
correct, then wouldn't that imply the bulbs in the other part of the
parallel circuit dim,
Probably -- drawing more current would drop the line voltage, it's a
question of by how much and is it noticeable.
and, if the condition remains that the 15 amp fuse
finally blows? I suppose the saw might effectively become an open circuit
under certain conditions, and maybe just die without any effect on the fuse.
The times that I have had a motor stop (on a power drill), and I
applied power for several seconds before realizing I had to stop and
manually un-jam the drill bit, there was a faint burnt odor coming
from the drill. But it continued to work just fine (after clearing
the drill bit).
However, applying power to a stuck motor for a longer time, it could
be a different story.
Just out of curiosity, what are you trying to do? Setting up a
workshop? Or just refamiliarizing yourself with electronics?
Regards,
Mark
Just for kicks I looked back-emf up in Wikipedia.
Back electromotive force is a voltage that occurs in electric motors where
there is relative motion between the armature of the motor and the external
magnetic field. That didn't help me. :-)
redbelly wrote:On Oct 9, 10:31 am, "W. Watson" <wolf_tra...@xxxxxxxxxxx> wrote:--Back to the saw. So when a saw blade gets stuck or hampered, it's resistanceAs I understand it, when a motor is stopped the Back-EMF (the reverse-
(impedance?) decreases?
voltage induced in the coils due to a changing magnetic field) goes to
zero. This increase the net voltage, and hence current, of the motor.
Not sure if I'm 100% accurate on the description, but that's
essentially what's going on.
Mark
I would imagine that if it continues to "be stuck"
then, that it eventually draws more current than can be handled by a 15A fuse.
When the saw draws more current, there will be more voltage drop in--
the wiring, so the lamps will dim slightly.
Wayne Watson (Nevada City, CA)
Web Page: <speckledwithStars.net>
Wayne Watson (Nevada City, CA)
Web Page: <speckledwithStars.net>
--
Wayne Watson (Nevada City, CA)
Web Page: <speckledwithStars.net>
.
- References:
- Light Bulbs, Saws, Motors, Circuits and Basic Calculations
- From: W. Watson
- Re: Light Bulbs, Saws, Motors, Circuits and Basic Calculations
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