Why don't pole transformers that supply your house have resonant caps added on?
ScottH, Thu Mar 16 2017, 01:12PMI learned that resonant caps on a pole pig make the voltage double and compensate for leakage inductance, but if the houses electrical system was designed for such, wouldn't it be more efficient to include a resonant cap on each pole transformer? Will including a PF cap on the primary help correct PF, and the resonant cap boost total power output while using less energy from the substation?
I know that a pole pig has good PF and efficiency, but the PF cap can get the transformer closer to 100% eff. I'm still learning about resonance, and I know resonant caps on a pig make a huge power boost. The resonant caps will be tuned to 60Hz.
Re: Why don't pole transformers that supply your house have resonant caps added on?
Dr. Slack, Thu Mar 16 2017, 05:29PM
There's a big difference between MOTs and pigs, like the shunts introduced into a MOT to raise the leakage inductance, to resonate out some of the doubler rectifier capacitor impedance.
Dr. Slack, Thu Mar 16 2017, 05:29PM
I learned that resonant caps on a pole pig make the voltage double NO and compensate for leakage inductance what little there is on a pig, but if the houses electrical system was designed for such, wouldn't it be more efficient to include a resonant cap on each pole transformer? NO Will including a PF cap on the primary help correct PF Yes, but the primary inductance is so large that the PF hit is minimal, and the resonant cap boost total power output No while using less energy from the substation? No
I know that a pole pig has good PF and efficiency Yay! something right, but the PF cap can get the transformer closer to 100% eff By the sqrt(b'all) at the cost of a cap. I'm still learning about resonance, and I know resonant caps on a pig make a huge power boost Do they? why do you assert this?. The resonant caps will be tuned to 60Hz.
There's a big difference between MOTs and pigs, like the shunts introduced into a MOT to raise the leakage inductance, to resonate out some of the doubler rectifier capacitor impedance.
Re: Why don't pole transformers that supply your house have resonant caps added on?
ScottH, Thu Mar 16 2017, 06:11PM
Ok, I stand corrected
. I have a question though. In a pole pigs case, why do the arcs become longer and brighter when people add a resonant cap to them if it only gives the pig a marginal power boost (hobbyists making arcs, not for industrial use)? Can you please explain what's going on, and how the cap makes the arcs much longer?
I understand how this would apply to Mots and other less efficient transformers, but not to a very efficient pig.
ScottH, Thu Mar 16 2017, 06:11PM
Dr. Slack wrote ...
There's a big difference between MOTs and pigs, like the shunts introduced into a MOT to raise the leakage inductance, to resonate out some of the doubler rectifier capacitor impedance.
I learned that resonant caps on a pole pig make the voltage double NO and compensate for leakage inductance what little there is on a pig, but if the houses electrical system was designed for such, wouldn't it be more efficient to include a resonant cap on each pole transformer? NO Will including a PF cap on the primary help correct PF Yes, but the primary inductance is so large that the PF hit is minimal, and the resonant cap boost total power output No while using less energy from the substation? No
I know that a pole pig has good PF and efficiency Yay! something right, but the PF cap can get the transformer closer to 100% eff By the sqrt(b'all) at the cost of a cap. I'm still learning about resonance, and I know resonant caps on a pig make a huge power boost Do they? why do you assert this?. The resonant caps will be tuned to 60Hz.
There's a big difference between MOTs and pigs, like the shunts introduced into a MOT to raise the leakage inductance, to resonate out some of the doubler rectifier capacitor impedance.
Ok, I stand corrected
. I have a question though. In a pole pigs case, why do the arcs become longer and brighter when people add a resonant cap to them if it only gives the pig a marginal power boost (hobbyists making arcs, not for industrial use)? Can you please explain what's going on, and how the cap makes the arcs much longer?I understand how this would apply to Mots and other less efficient transformers, but not to a very efficient pig.
Re: Why don't pole transformers that supply your house have resonant caps added on?
GrantX, Thu Mar 16 2017, 09:07PM
That's because the pole transformer requires a ballast. If the HV coil was shorted without ballasting, the transformer would attempt to draw a few hundred kVA from the mains. So the 'resonant' setup usually involves a large inductive ballast in series with the mains input, and the capacitor in series with the HV winding. The capacitor is not resonating with the transformers leakage inductance, which is very small.
GrantX, Thu Mar 16 2017, 09:07PM
That's because the pole transformer requires a ballast. If the HV coil was shorted without ballasting, the transformer would attempt to draw a few hundred kVA from the mains. So the 'resonant' setup usually involves a large inductive ballast in series with the mains input, and the capacitor in series with the HV winding. The capacitor is not resonating with the transformers leakage inductance, which is very small.
Re: Why don't pole transformers that supply your house have resonant caps added on?
ScottH, Fri Mar 17 2017, 08:11AM
So what role does the cap play, and how does it boost power so much if it doesn't resonate with anything?
ScottH, Fri Mar 17 2017, 08:11AM
GrantX wrote ...
That's because the pole transformer requires a ballast. If the HV coil was shorted without ballasting, the transformer would attempt to draw a few hundred kVA from the mains. So the 'resonant' setup usually involves a large inductive ballast in series with the mains input, and the capacitor in series with the HV winding. The capacitor is not resonating with the transformers leakage inductance, which is very small.
That's because the pole transformer requires a ballast. If the HV coil was shorted without ballasting, the transformer would attempt to draw a few hundred kVA from the mains. So the 'resonant' setup usually involves a large inductive ballast in series with the mains input, and the capacitor in series with the HV winding. The capacitor is not resonating with the transformers leakage inductance, which is very small.
So what role does the cap play, and how does it boost power so much if it doesn't resonate with anything?
Re: Why don't pole transformers that supply your house have resonant caps added on?
hen918, Fri Mar 17 2017, 08:47AM
The point was that it does resonate with the ballast inductor, cancelling its effects, leaving you with an effectively un-ballasted transformer, from which a greater current can be drawn.
hen918, Fri Mar 17 2017, 08:47AM
ScottH wrote ...
So what role does the cap play, and how does it boost power so much if it doesn't resonate with anything?
GrantX wrote ...
That's because the pole transformer requires a ballast. If the HV coil was shorted without ballasting, the transformer would attempt to draw a few hundred kVA from the mains. So the 'resonant' setup usually involves a large inductive ballast in series with the mains input, and the capacitor in series with the HV winding. The capacitor is not resonating with the transformers leakage inductance, which is very small.
That's because the pole transformer requires a ballast. If the HV coil was shorted without ballasting, the transformer would attempt to draw a few hundred kVA from the mains. So the 'resonant' setup usually involves a large inductive ballast in series with the mains input, and the capacitor in series with the HV winding. The capacitor is not resonating with the transformers leakage inductance, which is very small.
So what role does the cap play, and how does it boost power so much if it doesn't resonate with anything?
The point was that it does resonate with the ballast inductor, cancelling its effects, leaving you with an effectively un-ballasted transformer, from which a greater current can be drawn.
Re: Why don't pole transformers that supply your house have resonant caps added on?
Dr. Slack, Fri Mar 17 2017, 08:53AM
Echoing Grantx's post, link me a video of an arc being drawn from a pig, without any ballast, then with capacitive ballast, and we'll see which is brighter.
There is inherently nothing in a pig that can be resonated. The leakage indutance is minimal, the primary inductance is very large so its admittance is minimal, the secondary inductance is short-circuited by the low impedance grid connected to the primary.
There are two general types of transformer. Ideal transformers, where all parameters are as ideal as economically possible, and non-ideal transformers, where one or more parameters that would be a defect in an ideal transformer is designed up to a specific figure. In a pig, and indeed most power transformers, primary inductance is as near infinity as possible, leakage inductance as close to zero as possible. In a MOT, leakage is added with the magnetic shunts to resonate out some of the doubler capacitor impedance. In a flyback transformer, air-gaps are introduced to reduce primary inductance so more energy can be stored. In an NST, shunts increase the leakage inductance to limit the current delivered into a neon tube.
Dr. Slack, Fri Mar 17 2017, 08:53AM
Echoing Grantx's post, link me a video of an arc being drawn from a pig, without any ballast, then with capacitive ballast, and we'll see which is brighter.
There is inherently nothing in a pig that can be resonated. The leakage indutance is minimal, the primary inductance is very large so its admittance is minimal, the secondary inductance is short-circuited by the low impedance grid connected to the primary.
There are two general types of transformer. Ideal transformers, where all parameters are as ideal as economically possible, and non-ideal transformers, where one or more parameters that would be a defect in an ideal transformer is designed up to a specific figure. In a pig, and indeed most power transformers, primary inductance is as near infinity as possible, leakage inductance as close to zero as possible. In a MOT, leakage is added with the magnetic shunts to resonate out some of the doubler capacitor impedance. In a flyback transformer, air-gaps are introduced to reduce primary inductance so more energy can be stored. In an NST, shunts increase the leakage inductance to limit the current delivered into a neon tube.
Re: Why don't pole transformers that supply your house have resonant caps added on?
ScottH, Fri Mar 17 2017, 08:55AM
So having the cap is just like hooking up the transformer with no ballast? If that's the case, why not hook up the pig unballasted, and save the cost of an inductor and Hv cap?
ScottH, Fri Mar 17 2017, 08:55AM
hen918 wrote ...
The point was that it does resonate with the ballast inductor, cancelling its effects, leaving you with an effectively un-ballasted transformer, from which a greater current can be drawn.
ScottH wrote ...
So what role does the cap play, and how does it boost power so much if it doesn't resonate with anything?
GrantX wrote ...
That's because the pole transformer requires a ballast. If the HV coil was shorted without ballasting, the transformer would attempt to draw a few hundred kVA from the mains. So the 'resonant' setup usually involves a large inductive ballast in series with the mains input, and the capacitor in series with the HV winding. The capacitor is not resonating with the transformers leakage inductance, which is very small.
That's because the pole transformer requires a ballast. If the HV coil was shorted without ballasting, the transformer would attempt to draw a few hundred kVA from the mains. So the 'resonant' setup usually involves a large inductive ballast in series with the mains input, and the capacitor in series with the HV winding. The capacitor is not resonating with the transformers leakage inductance, which is very small.
So what role does the cap play, and how does it boost power so much if it doesn't resonate with anything?
The point was that it does resonate with the ballast inductor, cancelling its effects, leaving you with an effectively un-ballasted transformer, from which a greater current can be drawn.
So having the cap is just like hooking up the transformer with no ballast? If that's the case, why not hook up the pig unballasted, and save the cost of an inductor and Hv cap?
Re: Why don't pole transformers that supply your house have resonant caps added on?
Dr. Slack, Fri Mar 17 2017, 09:01AM
Yup, you have to look at these sources very carefully to discover exactly what's happening, what's being claimed, what the circuit is etc etc
Dr. Slack, Fri Mar 17 2017, 09:01AM
ScottH wrote ...
So having the cap is just like hooking up the transformer with no ballast? If that's the case, why not hook up the pig unballasted, and save the cost of an inductor and Hv cap?
hen918 wrote ...
The point was that it does resonate with the ballast inductor, cancelling its effects, leaving you with an effectively un-ballasted transformer, from which a greater current can be drawn.
ScottH wrote ...
So what role does the cap play, and how does it boost power so much if it doesn't resonate with anything?
GrantX wrote ...
That's because the pole transformer requires a ballast. If the HV coil was shorted without ballasting, the transformer would attempt to draw a few hundred kVA from the mains. So the 'resonant' setup usually involves a large inductive ballast in series with the mains input, and the capacitor in series with the HV winding. The capacitor is not resonating with the transformers leakage inductance, which is very small.
That's because the pole transformer requires a ballast. If the HV coil was shorted without ballasting, the transformer would attempt to draw a few hundred kVA from the mains. So the 'resonant' setup usually involves a large inductive ballast in series with the mains input, and the capacitor in series with the HV winding. The capacitor is not resonating with the transformers leakage inductance, which is very small.
So what role does the cap play, and how does it boost power so much if it doesn't resonate with anything?
The point was that it does resonate with the ballast inductor, cancelling its effects, leaving you with an effectively un-ballasted transformer, from which a greater current can be drawn.
So having the cap is just like hooking up the transformer with no ballast? If that's the case, why not hook up the pig unballasted, and save the cost of an inductor and Hv cap?
Yup, you have to look at these sources very carefully to discover exactly what's happening, what's being claimed, what the circuit is etc etc
Re: Why don't pole transformers that supply your house have resonant caps added on?
ScottH, Fri Mar 17 2017, 11:21AM
Read the videos description. This is the ArcZilla guys explanation.
Another video with a description on how someone else has it wired
What is your take on this, Dr. Slack? Is this setup the same (power wise) but more efficient than running it unballasted?
ScottH, Fri Mar 17 2017, 11:21AM
Dr. Slack wrote ...
Yup, you have to look at these sources very carefully to discover exactly what's happening, what's being claimed, what the circuit is etc etc
Yup, you have to look at these sources very carefully to discover exactly what's happening, what's being claimed, what the circuit is etc etc
Read the videos description. This is the ArcZilla guys explanation.Another video with a description on how someone else has it wired
What is your take on this, Dr. Slack? Is this setup the same (power wise) but more efficient than running it unballasted?
Re: Why don't pole transformers that supply your house have resonant caps added on?
Dr. Slack, Fri Mar 17 2017, 03:07PM
There's not enough in the description in the first link to tell what else the guy has got in the circuit other than the pig, the capacitor, and a 'homebuilt ballast', which could be anything.
In the second link, the description specifies two Lincoln welder transformers in parallel as the ballast. The point about a welding transformer is that it has a large, and controllable (to set the current), leakage inductance, to provide series current limiting to stabilise the negative resistance of the welding arc.
So yes, the series capacitor is resonating out some of the ballast's series inductance. If you have an inductive ballast that cannot be set low enough, then resonating out some of it is a way to set the effective inductance even lower, that would be one valid reason for using a cap.
A problem with using a cap in series to resonate a series inductance is that the overall series impedance drops, so you'll get more current for any given voltage. However, the capacitor and inductor still have their original impedances, so what this means is that the voltage across each increases (the 'resonant rise') to force more current through each. This increase in voltage can be very profound if you do hit actual resonance, and can over-volt the cap. I notice they're using a 100kV cap in both videos, so there should be some margin to allow it to survive.
Just because there's a cap in there doesn't mean it's resonated out all of the ballast inductance. Indeed, if it had, the pig would blow the supply breakers, so this is not equivalent to 'running unballasted'. A useful experiment would be to measure the input current to the pig (you know, measurement rather than guesswork, the thing that scientists do when they want to actually understand something) for different settings of the ballast (one, two in parallel, series) with and without series caps, then we would have a correspondance between current consumption and arc appearance that could be judged.
So why didn't he simply ballast to the current he wanted? Who knows, you ask him. Perhaps he thought (like some people do) that resonance always leads to MOAR POWA, and tried it, without understanding what it was doing. Perhaps he had a 100kV Maxwell and wanted to show it off in a video, I would if I had!
Putting the resonant components either side of a transformer can be self-defeating because transformer saturation will prevent any significant resonant rise.
In any case, fewest series components carrying the current will result in the best efficiency.
Dr. Slack, Fri Mar 17 2017, 03:07PM
There's not enough in the description in the first link to tell what else the guy has got in the circuit other than the pig, the capacitor, and a 'homebuilt ballast', which could be anything.
In the second link, the description specifies two Lincoln welder transformers in parallel as the ballast. The point about a welding transformer is that it has a large, and controllable (to set the current), leakage inductance, to provide series current limiting to stabilise the negative resistance of the welding arc.
So yes, the series capacitor is resonating out some of the ballast's series inductance. If you have an inductive ballast that cannot be set low enough, then resonating out some of it is a way to set the effective inductance even lower, that would be one valid reason for using a cap.
A problem with using a cap in series to resonate a series inductance is that the overall series impedance drops, so you'll get more current for any given voltage. However, the capacitor and inductor still have their original impedances, so what this means is that the voltage across each increases (the 'resonant rise') to force more current through each. This increase in voltage can be very profound if you do hit actual resonance, and can over-volt the cap. I notice they're using a 100kV cap in both videos, so there should be some margin to allow it to survive.
Just because there's a cap in there doesn't mean it's resonated out all of the ballast inductance. Indeed, if it had, the pig would blow the supply breakers, so this is not equivalent to 'running unballasted'. A useful experiment would be to measure the input current to the pig (you know, measurement rather than guesswork, the thing that scientists do when they want to actually understand something) for different settings of the ballast (one, two in parallel, series) with and without series caps, then we would have a correspondance between current consumption and arc appearance that could be judged.
So why didn't he simply ballast to the current he wanted? Who knows, you ask him. Perhaps he thought (like some people do) that resonance always leads to MOAR POWA, and tried it, without understanding what it was doing. Perhaps he had a 100kV Maxwell and wanted to show it off in a video, I would if I had!
Putting the resonant components either side of a transformer can be self-defeating because transformer saturation will prevent any significant resonant rise.
In any case, fewest series components carrying the current will result in the best efficiency.
Re: Why don't pole transformers that supply your house have resonant caps added on?
ScottH, Fri Mar 17 2017, 07:32PM
In the resonant cap setup vs no caps, why does this happen?:
"Through a homebuilt ballast control panel setup, this setup draws upwards of 150 amps at 240 volts input when the arc is "streched out" near the top of the rails! Without the resonant capacitors in series with the transformers' output, the max current is drawn when the arc starts at the bottom of the rails but gradually decreases until the arc extinguishes at the upper end of the rails."
Does this have something to do with the phase of current and voltage?
I also read that resonance with the inductor and capacitor (secondary side inductor) also "feed" each other a bit, and while boosting secondary voltage/power, require less current flow pulled from the primary coil when the arc starts. This might explain why my MOTS draw less current from the wall with resonant caps alone in series with my secondary coil (no PF cap included). Less current being drawn from the primary would mean less eddy currents/core saturation after the secondary's resonance kicks in, so the MOTS heat up considerably less (I have observed much less heating of my MOTS in this case)--even though output arcs are still boosted significantly. Is this true?
If the voltage of the ballast increases due to resonance, how would that affect the input mains power source?
ScottH, Fri Mar 17 2017, 07:32PM
Dr. Slack wrote ...
There's not enough in the description in the first link to tell what else the guy has got in the circuit other than the pig, the capacitor, and a 'homebuilt ballast', which could be anything.
In the second link, the description specifies two Lincoln welder transformers in parallel as the ballast. The point about a welding transformer is that it has a large, and controllable (to set the current), leakage inductance, to provide series current limiting to stabilise the negative resistance of the welding arc.
So yes, the series capacitor is resonating out some of the ballast's series inductance. If you have an inductive ballast that cannot be set low enough, then resonating out some of it is a way to set the effective inductance even lower, that would be one valid reason for using a cap.
A problem with using a cap in series to resonate a series inductance is that the overall series impedance drops, so you'll get more current for any given voltage. However, the capacitor and inductor still have their original impedances, so what this means is that the voltage across each increases (the 'resonant rise') to force more current through each. This increase in voltage can be very profound if you do hit actual resonance, and can over-volt the cap. I notice they're using a 100kV cap in both videos, so there should be some margin to allow it to survive.
Just because there's a cap in there doesn't mean it's resonated out all of the ballast inductance. Indeed, if it had, the pig would blow the supply breakers, so this is not equivalent to 'running unballasted'. A useful experiment would be to measure the input current to the pig (you know, measurement rather than guesswork, the thing that scientists do when they want to actually understand something) for different settings of the ballast (one, two in parallel, series) with and without series caps, then we would have a correspondance between current consumption and arc appearance that could be judged.
So why didn't he simply ballast to the current he wanted? Who knows, you ask him. Perhaps he thought (like some people do) that resonance always leads to MOAR POWA, and tried it, without understanding what it was doing. Perhaps he had a 100kV Maxwell and wanted to show it off in a video, I would if I had!
Putting the resonant components either side of a transformer can be self-defeating because transformer saturation will prevent any significant resonant rise.
In any case, fewest series components carrying the current will result in the best efficiency.
There's not enough in the description in the first link to tell what else the guy has got in the circuit other than the pig, the capacitor, and a 'homebuilt ballast', which could be anything.
In the second link, the description specifies two Lincoln welder transformers in parallel as the ballast. The point about a welding transformer is that it has a large, and controllable (to set the current), leakage inductance, to provide series current limiting to stabilise the negative resistance of the welding arc.
So yes, the series capacitor is resonating out some of the ballast's series inductance. If you have an inductive ballast that cannot be set low enough, then resonating out some of it is a way to set the effective inductance even lower, that would be one valid reason for using a cap.
A problem with using a cap in series to resonate a series inductance is that the overall series impedance drops, so you'll get more current for any given voltage. However, the capacitor and inductor still have their original impedances, so what this means is that the voltage across each increases (the 'resonant rise') to force more current through each. This increase in voltage can be very profound if you do hit actual resonance, and can over-volt the cap. I notice they're using a 100kV cap in both videos, so there should be some margin to allow it to survive.
Just because there's a cap in there doesn't mean it's resonated out all of the ballast inductance. Indeed, if it had, the pig would blow the supply breakers, so this is not equivalent to 'running unballasted'. A useful experiment would be to measure the input current to the pig (you know, measurement rather than guesswork, the thing that scientists do when they want to actually understand something) for different settings of the ballast (one, two in parallel, series) with and without series caps, then we would have a correspondance between current consumption and arc appearance that could be judged.
So why didn't he simply ballast to the current he wanted? Who knows, you ask him. Perhaps he thought (like some people do) that resonance always leads to MOAR POWA, and tried it, without understanding what it was doing. Perhaps he had a 100kV Maxwell and wanted to show it off in a video, I would if I had!
Putting the resonant components either side of a transformer can be self-defeating because transformer saturation will prevent any significant resonant rise.
In any case, fewest series components carrying the current will result in the best efficiency.
In the resonant cap setup vs no caps, why does this happen?:
"Through a homebuilt ballast control panel setup, this setup draws upwards of 150 amps at 240 volts input when the arc is "streched out" near the top of the rails! Without the resonant capacitors in series with the transformers' output, the max current is drawn when the arc starts at the bottom of the rails but gradually decreases until the arc extinguishes at the upper end of the rails."
Does this have something to do with the phase of current and voltage?
I also read that resonance with the inductor and capacitor (secondary side inductor) also "feed" each other a bit, and while boosting secondary voltage/power, require less current flow pulled from the primary coil when the arc starts. This might explain why my MOTS draw less current from the wall with resonant caps alone in series with my secondary coil (no PF cap included). Less current being drawn from the primary would mean less eddy currents/core saturation after the secondary's resonance kicks in, so the MOTS heat up considerably less (I have observed much less heating of my MOTS in this case)--even though output arcs are still boosted significantly. Is this true?
However, the capacitor and inductor still have their original impedances, so what this means is that the voltage across each increases (the 'resonant rise') to force more current through each. This increase in voltage can be very profound if you do hit actual resonance, and can over-volt the cap. I notice they're using a 100kV cap in both videos, so there should be some margin to allow it to survive.
If the voltage of the ballast increases due to resonance, how would that affect the input mains power source?
Re: Why don't pole transformers that supply your house have resonant caps added on?
johnf, Sat Mar 18 2017, 07:33PM
Scotth
Its about time you did this for yourself with LTspice it is free.
continually asking the same questions in differing ways is tiresome.
By doing it yourself in a simulator you only get virtual smoke. When you fully understand what you are doing in the virtual world it is time for real experiments to validate what your virtual world is saying to you
johnf, Sat Mar 18 2017, 07:33PM
Scotth
Its about time you did this for yourself with LTspice it is free.
continually asking the same questions in differing ways is tiresome.
By doing it yourself in a simulator you only get virtual smoke. When you fully understand what you are doing in the virtual world it is time for real experiments to validate what your virtual world is saying to you
Re: Why don't pole transformers that supply your house have resonant caps added on?
Dr. Slack, Sun Mar 19 2017, 10:27AM
Scotth, that's a good suggestion from johnf.
There's nothing like playing with a few ideal components and tracing out the waveforms to get to understand what's going on.
There are a couple of problems with simulating this sort of thing in Spice however. Ideal transformers are easy to do, transformers with saturation are possible, but trickier. For the moment, stick to ideal transformers. Secondly, modelling an arc in full, with the temperature modulated conductivity, is not really possible. Just model it as a resistor, and use a wide range of values to see the range of things that can happen. But you don't need to model either transformers or arcs to see how resonance with Ls and Cs works.
Dr. Slack, Sun Mar 19 2017, 10:27AM
Scotth, that's a good suggestion from johnf.
There's nothing like playing with a few ideal components and tracing out the waveforms to get to understand what's going on.
There are a couple of problems with simulating this sort of thing in Spice however. Ideal transformers are easy to do, transformers with saturation are possible, but trickier. For the moment, stick to ideal transformers. Secondly, modelling an arc in full, with the temperature modulated conductivity, is not really possible. Just model it as a resistor, and use a wide range of values to see the range of things that can happen. But you don't need to model either transformers or arcs to see how resonance with Ls and Cs works.
Re: Why don't pole transformers that supply your house have resonant caps added on?
ScottH, Sun Mar 19 2017, 02:00PM
I'm still trying to get the hang of LTSpice, but its interesting. Can you explain to me why the arc pulls the most power (from the mains) when the arc is at the top of Jacobs Ladder (transformer pulls more power when the arc gets longer) when the resonant cap is introduced on the secondary; and why the arc pulls the most power at the bottom of the Ladder (pulls less power as the arc gets longer) without the cap?
I believe it pulls the same amps from the mains either way, just opposite of the arc lengths with/without cap on secondary. Thanks.
ScottH, Sun Mar 19 2017, 02:00PM
Dr. Slack wrote ...
Scotth, that's a good suggestion from johnf.
There's nothing like playing with a few ideal components and tracing out the waveforms to get to understand what's going on.
There are a couple of problems with simulating this sort of thing in Spice however. Ideal transformers are easy to do, transformers with saturation are possible, but trickier. For the moment, stick to ideal transformers. Secondly, modelling an arc in full, with the temperature modulated conductivity, is not really possible. Just model it as a resistor, and use a wide range of values to see the range of things that can happen. But you don't need to model either transformers or arcs to see how resonance with Ls and Cs works.
Scotth, that's a good suggestion from johnf.
There's nothing like playing with a few ideal components and tracing out the waveforms to get to understand what's going on.
There are a couple of problems with simulating this sort of thing in Spice however. Ideal transformers are easy to do, transformers with saturation are possible, but trickier. For the moment, stick to ideal transformers. Secondly, modelling an arc in full, with the temperature modulated conductivity, is not really possible. Just model it as a resistor, and use a wide range of values to see the range of things that can happen. But you don't need to model either transformers or arcs to see how resonance with Ls and Cs works.
I'm still trying to get the hang of LTSpice, but its interesting. Can you explain to me why the arc pulls the most power (from the mains) when the arc is at the top of Jacobs Ladder (transformer pulls more power when the arc gets longer) when the resonant cap is introduced on the secondary; and why the arc pulls the most power at the bottom of the Ladder (pulls less power as the arc gets longer) without the cap?
I believe it pulls the same amps from the mains either way, just opposite of the arc lengths with/without cap on secondary. Thanks.
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