Error in measurement with Tektronix Probe 1000:1 ??

[[email protected]]

Hello!
I tried to measure a short high Voltage peak with a little older
Tektronix Probe, Part No. 010-025 on a Tektronix TDS 460 Memory-Scope.
Concretely I wanted to define the ignition voltage of a fluorescent
tube. I guess the voltage is about 1-2 kV (1m length of the tube). I
measured between 7 and 8 kV with the Tektronix Probe (!) and disagreed
with that, because the C_res on the Ballast-Board has a voltage
strength of 1,6 kV and the expected voltage that I got from a gas
discharge graph is about 1 kV/m.

I quantified the divider of the probe with 979:1 on 50 Hz sinus AC,
linear with different voltages between 100 and 400 V which I could set
up on the isolating transformer.

Now the question:
Can somebody help to affirm this variation?
Is there overshoot common because of the short voltage spike?


Thanks for all consideration!

greetings,
Christian

 

[joesmith]

Hi,Christian
The tube is a capacator.
j.

 

[hr(bob) [email protected]]

Hi,Christian
The tube is a capacator.
j.

Mar 9, 10:17 am, [email protected] wrote:








- Show quoted text -

Is it possible that the actual voltage was that high for a short
instant before the arc actually struck? I am guessing that for a 1
meter long fluorescent tube it would be no more than 2 kV at the
most, if the voltage were applied in a slow steadily increasing ramp
up of voltage over a period of several seconds. But, if the striking
voltage was from a step-up transformer, it might be much higher for a
few milliseconds until the arc was fully established.

I am assuming that you used the word "quantified" in the meaning here
in the USA as calibrated or checked or verified the accuracy of the
probe.

H. R.(Bb) Hofmann

 

[Peter Dettmann]

I quantified the divider of the probe with 979:1 on 50 Hz sinus AC,
linear with different voltages between 100 and 400 V which I could set
up on the isolating transformer.

Now the question:
Can somebody help to affirm this variation?
Is there overshoot common because of the short voltage spike?

Well yes there may be a measurement error. But you only refer to a
50Hz test to establish the probe measurement division. It is
essential to properly adjust the compensation elements as described in
the manual. I found that due to most people not having suitable
signal sources, I ended up with the job of calibrating the x1000
probes in my work place. As a minimum look at the waveform on a fast
square wave generator. If that looks ok, your measurement is probably
acceptable.

Peter Dettmann

 

[Jim Yanik]

Is it possible that the actual voltage was that high for a short
instant before the arc actually struck? I am guessing that for a 1
meter long fluorescent tube it would be no more than 2 kV at the
most, if the voltage were applied in a slow steadily increasing ramp
up of voltage over a period of several seconds. But, if the striking
voltage was from a step-up transformer, it might be much higher for a
few milliseconds until the arc was fully established.

I am assuming that you used the word "quantified" in the meaning here
in the USA as calibrated or checked or verified the accuracy of the
probe.

H. R.(Bb) Hofmann

the voltage across the tube is going to increase until the arc establishes
itself and then the voltage will decrease to operating V.

If the probe is a P6015,then the divider should be adjustable.
(and may be adjusted far out on response,too.)

I don't recognize the older TEK p/n.