Re: ASYNC RSG RPM

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

HI Steve,
          An idea which has a wide range of applicability (and which, 
as usual, I haven't got around to trying to my eternal lament) is to 
use an optical fibre to safely couple an optical signal to some well 
shielded electronics located a safe distance away from the doings.
A number of uses for coupled optics have suggested themselves (Terry 
already makes excellent use of one for V measurements): monitoring 
gap position and using the gap generated light to shut a switchmode 
cap charger down for the duration of primary dwell being among them.
 
     What exactly are you interested in observing - gap electrode 
position vs mains waveform or something else?

Regards,
Malcolm
 
On 29 Jul 01, at 22:27, Tesla list wrote:

> Original poster: "S & J Young by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<youngs-at-konnections-dot-net>
> 
> Hi all,
> 
> Just wondering if some of you have good ideas for monitoring async RPM of a
> RSG while the TC is operating.  Specifically, a direct readout, not syncing
> a strobe light.
> 
> The electrical environment around a RSG is truly horrible, and I suspect
> most electronics will fail or not operate correctly.  Currently, I just
> monitor the AC voltage to the drive motor and compare it to a calibration
> chart of RPM measurements made with no HV to the TC.  OK, but is there a
> better, more accurate way?
> 
> One idea is to couple a bicycle generator to the RSG shaft.  The bike
> generator is a low impedance AC generator which could drive a frequency
> meter.  But the connecting wires would be a good antenna, and I fear the
> freq meter would get zapped.
> 
> Another idea is to sense the current pulses in a gap lead, something like a
> clamp-on ammeter.  But again, I fear the common mode pickup of the
> connecting cable will destroy the readout electronics.
> 
> Focus the light from a gap via lens to a distant photo pickup?  Junkyard
> speedometer?  Use some sort of battery powered sensor (e.g. Hall effect) to
> drive a fiber optic connection to the freq meter?
> 
> Any ideas out there?
> 
> Thanks in advance,
> --Steve
> 
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