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ARSG drive motor - was: [TCML] July 4th and why not to be in a hurry
Hi Bart,
My motor is a Star Track 2.5 HP variable speed,
treadmill duty DC motor. It has a rated armature
voltage of 130 volts, a rated armeture amperage
of 17.5 amps, and will trun 3500 RPM, per the
label. I would assume that it would only draw
the rated amperage when it is loaded at its rated
HP output as it doesn't seem to draw near that
much current just turning the 11.5" x 1/2" thick
G-10 rotary disc with the (8) 3/8" diameter x
1 3/4" long flying tungsten electrodes, even at
3000 RPM, though I've never actually measured
it with an ammeter. As I said before, I run 0 - 120
volts to it via a 7.5 amp, 120 volt variac, then run
this variable voltage through a FWB rectifier.
I also place a 400 VDC, 3900 uFd 'lytic cap in
parallel with the rectified input to the motor. Not
really sure that this cap is necessary but I thought
that it may smooth out the ripple a bit. I usually run
it with the variac set bewtween 75 and 80 on the
0 - 100 dial but it is neat to be able to adjust the
BPS rate while the coil is firing and to note the
different tone of the output sparks.
David
----- Original Message -----
From: "bartb" <bartb@xxxxxxxxxxxxxxxx>
Hi David,
I figured you were doing something like that with the motor (due to
statements of 300+ bps). Sure, a DC motor will do just fine. What type
of HP is the motor (if you know)? As Adam so well listed, there are a
lot of bells and whistles. If we wanted, the potentiometer can be put
away and a 16 position switch could be used to run at 16 different
predefined speeds. I did this early on, but didn't like it. The pot and
ability to vary the bps make a difference in control. If your using
variable speeds, I know you realize this as well (I have no doubt).
Take care,
Bart
David Rieben wrote:
Phillip, Bart,
sniperz:
----- Original Message ----- From: "bartb" <bartb@xxxxxxxxxxxxxxxx>
Hi Phillip,
The VFD receives 1 phase 240V power and outputs 3-phase 230V power to
the motor. The frequency is changed which changes the speed of the
motor. It all built in to the VFD. I simply use a small
potentiometer mounted on the control panel to vary the analog signal
and the drive takes this information and vary's the frequency
accordingly. The PLC is the brains, but it's mainly for errors. The
main reason I use it is that if the VFD gets an error of any type,
the motor will either stop within 5 seconds or freewheel to a stop.
The VFD outputs an error signal which I feed into the PLC. If there
are any errors, it will shut down the main contactor to the coil.
While I was at it, I threw in a deadman switch (low level signal),
enable key, etc.
Adam Minchey also runs 3-phase via VFD on his coils. One could also
use a DC motor and simply vary the voltage for bps control.
Yep, I use a permanent magnet DC treadmill drive motor powered through
a variac and a FWB rectifier, which pretty
much gives an infinite range of speed control. Not quite as many
"bells and whistles" as is available with a VFD drive system
but never the less, it still gets the job done ;^)
Take care,
Bart
David
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