Это видео недоступно.
Сожалеем об этом.
💥Ferroresonance💥
HTML-код
- Опубликовано: 29 дек 2020
- This is a ferroresonance generator created by an LC series circuit. This circuit contains non-linear magnetizing inductance which resonates with line shunt capacitance. This simulator was built and tested in lab, under controlled conditions, using a 3 phase delta fed primary transformer trainer bank and 3 - 21 uF capacitors. The capacitors are wired "phase to ground" from source of feed (wye) and the transformers are wired "phase to phase" (delta).
#ferroresonance
Pretty damn cool! I’ve always seen the aftermath. And for every single time, it happened to Delta-delta transformer banks. That’s just from my experience. I’ve seen entire H Racks burn to the ground because of this! Thank you for this demonstration
Happens pretty often to voltage transformers for measuring MV. At 15kV systems we use VTs connected as single phase to ground. When ferro happens, they just cook and eventually short circuit causes them to explode. New systems feature VTs with additional windings/connectors to connect to ferroresonance damping devices.
Amazing! I have rarely seen people explaining such a complex topic in a very succinct way.
@ChristianSugastti Thanks. I appreciate your kind words.
Same here. Fantastic !
I ran across power supplies that used this to stabilize the power of a transformer output. There would be a second coil that just went to a AC cap. The other secondary winding just went to the bridge rectifier. Old school power supply from the 70's.
Incredible job researching and recreating this phenomenon. As far as I can tell not much data collection has been done on this topic, been in the power field for over a decade. And it needs to happen because this will cause XFMRs to blow!
Engineers will grumble when you ask about it 😂. So true!
Great explanation!
Impeccable explanation. Well done! And thanks for your troubles
Excellent. Heard it spoke about on a work call today and it was quickly skipped over. Clearer now.
Glad it helped. Its hard to find people who really understand it, at least in the aspect of utility power transformers. Fascinating subject though.
You Sir, are an Eye opener !
THX so much !
Wow. Very impressive. Thank you!
Impressive, Thank you!
Hey man you have explained it very well. Thank you.
All I saw was a mysterios looking sign at a powerline and now I'm here trying to wrap my head around ferroresonance? Not in a million years!
Great learning opportunity. Thank you kind Sir. it made my day.
Best explanation on whole internet!!!!
Great video 👍
Amazing explanation .. Thanks from Egypt
Great job! It can also be a closed wye delta bank with a floating neutral. Wye being the primary. Or a common core wye wye 3 phase pad mount being fed by urd cable.
Amazing! My research project is on developing a prediction model for ferroresonance in distribution transformers.
Very well explained! Sometimes it will occur when energizing one of the primary windings at the top of the sine wave, like you said it has very low XL or lower impedance which cause the primary to "ring" much like resonant rise used in Tesla Coils.
@AnthonyVolkman Thanks for the positive response. I have a scope image from a P.Q. meter, installed across the primary during the experiment. Interestingly, it showed the V-drop across the transformer as a square wave. The voltage was, as expected, 90* leading. The current through the circuit, however, was sharply spiked at its peak, but otherwise flat for the remainder of the period. It reminded me of an EKG for a heart monitor. Very cool.
Admittedly, no "ferro", but I would guess a tesla "coil" which is really just an air-spaced transformer deliberately driven at resonance is very similar to this effect. if you drive a Tesla Coil out of resonance, you can get a fairly predictable "turns ratio" based output. Once resonance is achieved, things get exciting and the voltage has no (theoretical) limit iIRC.
A difference though, is that the resonance on a Tesla is a function of the capacitance and inductance of the Primary only - if the output coil is loaded, the TC stays in resonance. Yet it seems that with ferroresonance here, the secondary would dampen the effect (or I guess could possibly bring it *into* resonance ????)
Thanks for the video, i didn't know it was an issue with power distribution kit.
Really great lab model there. I have heard in the ferroresonant condition sometimes there is current being pulled from the neutral bus. Besides the phases providing excess excitation current have you tried measuring the neutral side current? I believe Teslas magnifying transmitter worked on a similar principal in which he measured excess energy from ground. This is interesting in those days it was not an electrified world so out on a mountain in Colorado many fewer ground loops.
Yes, the neutrals definitely see current. In the arena of underground electrical distribution (URD), the system neutrals act as the second plate of a cable capacitor (parasitic). This provides the geometry needed to create the LRC series circuit with the source. Kirchhoff's laws should apply. I did not take any measurements around the neutral during this experiment, but I would guess the sum of the magnitudes of current through the neutrals would be the same as that through the primaries.
@@MegavoltHomeschool We were looking for anomalous current derived from this effect, depending on core material this seemed to manifest from time to time beyond the normal capacity of the source/sink. Might be interesting using that choice setup grab some .1ohm resistors and differential probes...
@mkjekyll I did look at the waveforms for both voltage and current at the primary winding, during the experiment. This was done with a Fluke 43B. it showed the voltage almost a squarewave, with very steep dv/dt at the polarity reversals... like alternating sugar loafs. The current was sawtooth but with large gaps between polarity reversals, like a shark in need of dental work. But it too had very steep di/dt. P.F. was 0 because the voltage and current waveforms, although very odd looking in geometry, were exactly 90* shifted apart. The interesting thing was that using a normal meter was almost useless , as the waveforms were both very non-sinusoidal. So the take away, if there is one, is to say that accurate measurements of either V or I would be somewhat tricky. Might need Fourier analysis... which is still just a little beyond my skill set.
@@MegavoltHomeschool Could check the gauss of the field see how it compares to normal mode, might shake a magnet in your hand... If you like send me a note at gee mail same name, some info I don't have permission to post publicly. Mick
haha well that's awesome! You should connect a PQ analyzer and see what harmonics you're getting, etc
@DavidVerzwyvelt I looked at the VA waveforms with a Fluke. Interestingly, it showed the voltage across the primary of the trans as very flat on the peaks with sharp dV/dt between (semi square wave). The current showed exactly the opposite. It was very quiet during most of the cycle, interrupted by sharp saw tooth peaks. It was also exactly 90* out of phase with the voltage, as would be expected. But a very cool experiment for sure. :-)
@@MegavoltHomeschools it coz the 90 deg phase change of the added cap changes the change in rate of current through the transformer... Nd if resonant of transformer helps create additional current Nd voltage what's the damage as additional transformer can b used to step it down from the resonant transformer for additional power
Could we make ferroresonace test for CVT in routine test with application of voltage on the secondary side ?
I have thought that the reason for this/that is...... the last magnetic state/position/angle the inductor/transformer was left with when switched OFF....... that magnetic back EMI is what is presented to the new switch closures and phase of the instantly introduced voltage.
Believe I’ve seen it once in 15 years. Blew a lightning arrestor.
Teslas car ran on ferroresonance. He intentionally built an asymmetrical transformer to operate in this manor. Your right, "science" cant or wont explain it therefore it dosent exist. Great work!
This is derived from the either.
One question so basically can we say that in times of clearing SLG fault there is possibility of observing this phemnomena?
By SLG do you mean single phase to ground? That would be true, in my opinion. Especially if there were any levels of unloaded inductive reactance present within the circuit.
@@MegavoltHomeschool yeah thanks mate.
Could I ask how you built your transformers? Also, could this phenomenon be replicated with a wye primary and a delta secondary? I would love to show this to my students. Thanks!
I built the bank using small, dry-core, multi tap transformers. They are set inside the tanks and being driven with 120/208. They will provide 120/240/208 (depending on how they are wired). From my limited understanding of ferroresonance, the condition needs an LC series circuit to be established, with respect to neutral/ground. Because of this, it is very difficult to create a ferroresonant condition by wiring the high sides of the pigs in wye. Wye creates a low impedance path between the transformer inductance and ground, rather than another phase. This neutral/ground relationship is in parallel to the cable capacitance. So the inductive current is not required to flow through cable capacitance to get back to the source. By wiring the high sides in delta, however, the current has the option to do just that. However, if the secondaries were wired delta, like you mentioned, then it might be possible to create a ferroresonant effect with backfeed, when the primaries are isolated. Would be a good experiment. 🙂
Ahh! Gotcha. I forgot to mention we typically float the neutral in wye/delta so as not to create an Open Delta situation if we lost a power leg. So, it would have to be an ungrounded wye primary to create that situation. I’ll be looking at finding those capacitors and hope to replicate what you did. Awesome stuff!
@stephenlock6542 yes, you have a point! If the neutral is isolated (H0) then there could conceivably be a resonant circuit created through the primary coils of the transformer and the cable capacitance. Hadn't looked at it that way before. 👍
Where can I get one of your amazing transformers
The transformers are homemade. Various parts from around the shop were used to construct the tanks and bushings. The cores are made from old isolation transformers, originally used for street lighting. They have multiple tap arrangements which allow for proper voltage transformation. High sides are usually fed 120 wye. This produces 120/208/240 out the bottom. If the high sides are fed 208 delta, however, then everything out the bottom has the same ratios but get boosted by √3 ---> 208/360/416. Although not standard, those voltages can still be used to provide demonstrations for load balancing exercises, etc.
Megavolt homeschool. Would you be able to contact me about this? We have this issue on our grid here in Virginia and I'm trying to figure out how to fix the problem
...and then you find out that the Germans had built a voltage stabilizer out of it.
It's strange engineers mostly don't understand the principles (including the math) behind ferroresonance. Simple understanding of capacitance, inductance, and lenz's law is all that's needed to understand FR. This is an educational failure on the engineer's part.
Chaos theory? Ghost phenomena? Really?