Hi Dick,
I am pretty new at doing/trying these things here, so I will answer the
best I can. Still learning.
"Caution using clamp-on current meters as they are highly inductive. Please
watch out for loose connections and inductive kickback. Do you know how much
phase shift you are getting through the internal circuit? This may be
modifying your screen waveform. If you are very careful, I would recommend a
series current shunt at the lowest potential point with respect to ground.
And float your meter if necessary."
I do not know how much phase shift.
This scope current clamp is also battery powered. And my scope is battery
powered.
"Some Tektronix probes are prone to overheat when measuring continuous high
voltage - I have toasted two 35 kV probes with my little 811A VTTC. Have you
considered building a bi-filar (non-inductive) probe of Nichrome wire (high
side) and koolohm (N.I.) low side resistor."
No, I have not yet.
The probe I have is a P6015.
I am attaching a couple of screenshots of the PDF file I have of it. My
probe is currently at the shop at my place. Not with me at my Father's shop
currently. One is a picture of it from the manual. Then the other is a
chart of duty cycles that I think you are talking about. My probe is filled
with the fluid.
I only did long enough to get what I wanted.
Peak voltage unloaded was approx. 6KV peak and then dropped to approx.
4.5KV peak when the coil "fired" pulling a heavy load. Pretty much as
expected, from what I have read elsewhere. What I found interesting was
"seeing" what it shows afterwards the coil has fired, showing the unloaded
voltage "climbing" back up.
Probe pic and chart:
https://photos.app.goo.gl/uMJc7emHEe5hWTCh9
A last big quote here:
"Back a few years when I was impulse testing UHV insulators, we used the
original Tektronix 507 Dual Beam Oscilloscope. We experienced oscillations
in the input amplifier circuits which appeared as oscillating time (negative
time) during the rise of the voltage rise for each impulse. The fix was to
remove the input amplifiers completely and directly connect the incoming
signal to the vertical plates of the 507 scope. The images were captured
single-trace on high speed Polaroid flatpack film. A pair of 1000 mm
(40-inch) spheres were used to calibrate the total measurement for a
uni-potential pulse from a 5000 kV Marx generator. {
https://www.google.com/maps/@41.0378424,-81.7583024,52m/data=!3m1!1e3 }
--------- note: be sure that your scope is reading the true risetime of the
voltage waveform!
Rule of thumb - you need at least 1 ft of clearance for every 100 kV (peak)
of arc potential with a nominal 1 kv/uSec rise time. Faster risetime has a
higher breakdown voltage, where slower risetime has a lower breakdown
voltage. Ref-IEEE-4. "
I want to say just WOW!!! Very big stuff on that compound. I have looked
out of curiosity zooming in and out of the satellite imagine link you
provided. Can see also all kinds of very large interesting things. Looks to
be large corona rings on several things also. Even though I know huge,
still hard to comprehend the full scale of this all.
Really neat. Quite the research compound.
Chris Reeland
Ladd Illinois USA
Sent from my LG V20
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