From: "Terrell W. Fritz"
Date: Sat, 12 Oct 2002 17:31:04 -0600
Subject: Re: [TSSP] Top Voltage
Hi All, I hooked up the OLTC with the Pearson current probe measuring secondary base current and the TEKP5202 differential probe looking across the primary caps. The new differential probe was costly at $550 (factory refurbished and caled sales demo) but I really like it!!! It makes checking things on my OLTC so easy!! First, I confirmed that when the coil does breakout, it is indeed at the medium size sphere on the top and nowhere else. It is... I found that the coil does not discharge completely with a 53uS dwell: http://hot-streamer.com/temp/OLTC10-12-01.gif The top yellow wave form is base current but the detail is lost here with such a long time scale. But the bottom primary cap voltage shows that the coil is going from about 300 Volts to 200 volts. If I expand the time scale we see: http://hot-streamer.com/temp/OLTC10-12-02.gif The yellow base current scale is accurate BTW... So it looks like this 1Hz single shot mode and the 52uS dwell don't really match well. So I turned the dwell knob to 500uS to really drain the system: http://hot-streamer.com/temp/OLTC10-12-03.gif First I was stunned at how many primary to secondary notches I was getting!! Note - need to check Q again... Now more energy should be getting to the top terminal and all. However, the breakouts were just as rare!! Nothing really seems to have changed as far as breakout "quality"... 300Volts firing voltage and 3 amps peak secondary base current.... I must wonder if the odd things we see are well known. I used to work on 340kV power lines (60HZ) that were about 1 inch in diameter... I never saw any "breakout" from them....???? Hmmmm, There must be some great truth there we are missing!!! That always confused me and I never found the answer to that one over the years... Realizing that this was getting complex. I tried something else... I tested the Q of the coil at 100,150, 200, 250, and 300 firing volts. The scope pictures of each range are at: http://hot-streamer.com/temp/OLTC10-12-04.gif http://hot-streamer.com/temp/OLTC10-12-05.gif http://hot-streamer.com/temp/OLTC10-12-06.gif http://hot-streamer.com/temp/OLTC10-12-07.gif http://hot-streamer.com/temp/OLTC10-12-08.gif I was fine adjusting the yellow (secondary base current) to get a good signal for TCMA thus the odd volts per division numbers. The blue is the primary cap voltage. The cheap meter and the TEKP5202 disagreed a little on the primary cap voltage. The cheap meter also kept locking up... I used the cheap meter readings here but I bet the TEK probe was far more accurate... TCMA may have been a little confused due to the problem Paul mentioned earlier. It has some trouble finding all the modes but here are the results: 100 Firing Volts PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL 1 37.154 (0.01%,4Hz) 93.74 (0.99%, 0.9) 0.0dB 2 113.836 (0.01%,13Hz) 44.40 (13.28%, 5.9) -26.6dB 3 171.901 (0.01%,20Hz) 36.22 (13.28%, 4.8) -30.0dB 4 225.143 (0.01%,26Hz) 49.17 (26.56%,13.1) -30.8dB 5 225.553 (0.01%,26Hz) 44.42 (26.56%,11.8) -30.5dB 150 Firing volts PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL 1 37.162 (0.01%,4Hz) 92.77 (1.17%, 1.1) 0.0dB 2 113.880 (0.01%,13Hz) 42.82 (15.79%, 6.8) -26.8dB 3 171.564 (0.01%,20Hz) 34.94 (13.28%, 4.6) -30.7dB 4 74.005 (0.01%,9Hz) 2000.00 (100.00%,2000.0) -47.5dB 5 225.570 (0.01%,26Hz) 44.69 (22.33%,10.0) -31.1dB 6 225.585 (0.01%,26Hz) 44.61 (22.33%,10.0) -31.0dB 200 Firing Volts PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL 1 37.160 (0.01%,4Hz) 92.13 (1.17%, 1.1) 0.0dB 2 113.870 (0.01%,13Hz) 41.07 (18.78%, 7.7) -27.0dB 3 73.862 (0.01%,8Hz) 2000.00 (100.00%,2000.0) -47.7dB 4 225.661 (0.01%,26Hz) 44.18 (26.56%,11.7) -31.6dB 5 225.681 (0.01%,26Hz) 44.15 (26.56%,11.7) -31.5dB 6 171.720 (0.01%,19Hz) 30.68 (18.78%, 5.8) -31.0dB 250 firing volts PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL 1 37.160 (0.01%,4Hz) 91.03 (1.17%, 1.1) 0.0dB 2 113.907 (0.01%,13Hz) 39.86 (18.78%, 7.5) -26.9dB 300 Firing Volts PK FREQ kHz (Error +/-) Q FACTOR (Error +/-) LEVEL 1 37.158 (0.01%,4Hz) 89.92 (1.40%, 1.3) 0.0dB 2 113.963 (0.01%,13Hz) 40.46 (15.79%, 6.4) -25.9dB The CSV files for each are at: http://hot-streamer.com/temp/OLTC10-12-01.CSV http://hot-streamer.com/temp/OLTC10-12-02.CSV http://hot-streamer.com/temp/OLTC10-12-03.CSV http://hot-streamer.com/temp/OLTC10-12-04.CSV http://hot-streamer.com/temp/OLTC10-12-05.CSV Of course, the running Q now is about 94 :-)))) I have no idea why.... At 250 volts I (the scope) took 64 readings and there were 4 breakouts. At 300 volts there were 6 breakouts. I did note that the breakouts seem to occur soon after the coil was turned on and then stopped. After the 300 volt run, I "wandered" around in there feeling the coil and surroundings for residual charge. I could detect nothing. I am not a sensitive electrometer or anything, but I sure didn't feel any hair standing on edge stuff... So, probably more questions than answers here ;-))) Cheers, Terry
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.