Tesla coil earthing
Gregary Boyles, Fri May 05 2017, 05:30PMWhat is likely to be the effect if I was ti implement a a radial counterpoise ground plain on a circle of artificial grass and connect that ground to a spike in close proximity to a spike coming off my torroid?
Compared to connecting that radial ground plain to a metal spike driven into damp earth to a depth of about 50cm?
Re: Tesla coil earthing
Sulaiman, Sat May 06 2017, 09:53AM
It would behave as if the radials were a real earth provided that the capacitance of the counterpoise radials is many times greater than the topload capacitance.
If the radials capacitance is low it will still work but pri-sec flashovers may occur due to the voltage at the bottom of the secondary.
Sulaiman, Sat May 06 2017, 09:53AM
It would behave as if the radials were a real earth provided that the capacitance of the counterpoise radials is many times greater than the topload capacitance.
If the radials capacitance is low it will still work but pri-sec flashovers may occur due to the voltage at the bottom of the secondary.
Re: Tesla coil earthing
Gregary Boyles, Sun May 07 2017, 03:37AM
I am thinking a more practical way would be to obtain a roll of 1.2m high chicken wire and unroll it to form a cylinder of diameter about 3 times the height of my coil.
This would be far more convenient that trying to flatten chicken wire on the ground or attach lengths of copper wire to a circle of artificial grass.
How would you know if the capacitance of such an arrangement is many times greater than the top load? Not easily I suspect.
Perhaps it is better to connect my cylinder of chicken wire to an earth rod.
Gregary Boyles, Sun May 07 2017, 03:37AM
Sulaiman wrote ...
It would behave as if the radials were a real earth provided that the capacitance of the counterpoise radials is many times greater than the topload capacitance.
If the radials capacitance is low it will still work but pri-sec flashovers may occur due to the voltage at the bottom of the secondary.
It would behave as if the radials were a real earth provided that the capacitance of the counterpoise radials is many times greater than the topload capacitance.
If the radials capacitance is low it will still work but pri-sec flashovers may occur due to the voltage at the bottom of the secondary.
I am thinking a more practical way would be to obtain a roll of 1.2m high chicken wire and unroll it to form a cylinder of diameter about 3 times the height of my coil.
This would be far more convenient that trying to flatten chicken wire on the ground or attach lengths of copper wire to a circle of artificial grass.
How would you know if the capacitance of such an arrangement is many times greater than the top load? Not easily I suspect.
Perhaps it is better to connect my cylinder of chicken wire to an earth rod.
Re: Tesla coil earthing
Dr. Slack, Sun May 07 2017, 05:04AM
do a sketch of what you intend, and stop obsessing about the earth rod. A counterpoise under the coil is perfectly acceptable.
Dr. Slack, Sun May 07 2017, 05:04AM
do a sketch of what you intend, and stop obsessing about the earth rod. A counterpoise under the coil is perfectly acceptable.
Re: Tesla coil earthing
Sulaiman, Sun May 07 2017, 06:50AM
My favourite pseudo-earth was a couple of metres of aluminium cooking foil laid on soil or floor.&
Sulaiman, Sun May 07 2017, 06:50AM
My favourite pseudo-earth was a couple of metres of aluminium cooking foil laid on soil or floor.&
Re: Tesla coil earthing
Gregary Boyles, Sun May 07 2017, 05:46PM
It has not been clear to me at all as to which method is more effective or more appropriate.
Well then from what you have said I have simply cut out some wire mesh to fit over my circle of fake grass.
I will connect the mesh to a vertical steel rod for the streamers to arc across to from my top load.
I will test this setup in this week and post some photos of the results.
Gregary Boyles, Sun May 07 2017, 05:46PM
Dr. Slack wrote ...
do a sketch of what you intend, and stop obsessing about the earth rod. A counterpoise under the coil is perfectly acceptable.
Look I am trying to piece together how exactly to do it properly to get decent arcs from reading what other have done.do a sketch of what you intend, and stop obsessing about the earth rod. A counterpoise under the coil is perfectly acceptable.
It has not been clear to me at all as to which method is more effective or more appropriate.
Well then from what you have said I have simply cut out some wire mesh to fit over my circle of fake grass.
I will connect the mesh to a vertical steel rod for the streamers to arc across to from my top load.
I will test this setup in this week and post some photos of the results.
Re: Tesla coil earthing
Gregary Boyles, Mon May 08 2017, 11:46PM
Is this likely to be an adequately large counterpoise ground?
Gregary Boyles, Mon May 08 2017, 11:46PM
Is this likely to be an adequately large counterpoise ground?
Re: Tesla coil earthing
Sulaiman, Tue May 09 2017, 12:14AM
yes
Sulaiman, Tue May 09 2017, 12:14AM
yes
Re: Tesla coil earthing
Gregary Boyles, Tue May 09 2017, 12:22AM
Some one should create a detailed page on this particular aspect of Tesla coils including specifics on areas appropriate to secondary coils sizes, materials, ground rod versus counterpoise pros and cons,......
I have only manged to find bits and pieces and general info on the subject but nothing really that gave me the confidence to say yes I will create my ground that way.
If this sort of earth is appropriate for my tesla coil then what would it take to make this type of earth inappropriate in my situation and an embedded earth rod preferable?
Gregary Boyles, Tue May 09 2017, 12:22AM
Sulaiman wrote ...
yes
yes
Some one should create a detailed page on this particular aspect of Tesla coils including specifics on areas appropriate to secondary coils sizes, materials, ground rod versus counterpoise pros and cons,......
I have only manged to find bits and pieces and general info on the subject but nothing really that gave me the confidence to say yes I will create my ground that way.
If this sort of earth is appropriate for my tesla coil then what would it take to make this type of earth inappropriate in my situation and an embedded earth rod preferable?
Re: Tesla coil earthing
Dr. Slack, Tue May 09 2017, 05:32AM
That counterpoise looks great.
From a connector somewhere on that mesh, run a wire to the bottom of your secondary, or the bottom of the secondary I sense current transformer, and to your TC power supply mains ground. If you are going to operate the TC in that position, then a radial out to your garage door would be good. Are there any other significant areas of conductor that either might get hit by streamers or present a large capacitance to the topload (like steel joists above our head out of shot)? If so, run a radial to them as well.
Thinking about a detailed page, maybe three illustrations would do it. On one extreme, a TC operating in the middle of a field, with secondary bottom connected to the ground. On the other, operating inside a Faraday cage, with secondary bottom connected to the floor of the cage. Then a third showing how any real situation is usually somewhere between the two. But always, the plan is to get the current back from things that are capacitively coupled to the topload back to the secondary bottom terminal, without undue inductance, and without producing inadvertent large voltages between innocent bystander conductors.
Depending on your operating position, the real earth may, or may not be, a conductor that has significant capacitive coupling to the topload. If it is, then connect to it by the shortest means, whether that's an earth spike, or your mains protective earth. If it isn't, then forget about it.
The nice thing about a counterpoise is that it's an organising principle, as much as anything. It's a cheap and easy to provide terminal that does have much coupling to the topload, and it's in the right position to connect with a short wire to the secondary, and back to the TC PSU ground. You'd connect any arc target to it as well. Then having done that, you look around. What else does the topload see? Garage door? Radial to that.
Dr. Slack, Tue May 09 2017, 05:32AM
That counterpoise looks great.
From a connector somewhere on that mesh, run a wire to the bottom of your secondary, or the bottom of the secondary I sense current transformer, and to your TC power supply mains ground. If you are going to operate the TC in that position, then a radial out to your garage door would be good. Are there any other significant areas of conductor that either might get hit by streamers or present a large capacitance to the topload (like steel joists above our head out of shot)? If so, run a radial to them as well.
Thinking about a detailed page, maybe three illustrations would do it. On one extreme, a TC operating in the middle of a field, with secondary bottom connected to the ground. On the other, operating inside a Faraday cage, with secondary bottom connected to the floor of the cage. Then a third showing how any real situation is usually somewhere between the two. But always, the plan is to get the current back from things that are capacitively coupled to the topload back to the secondary bottom terminal, without undue inductance, and without producing inadvertent large voltages between innocent bystander conductors.
Depending on your operating position, the real earth may, or may not be, a conductor that has significant capacitive coupling to the topload. If it is, then connect to it by the shortest means, whether that's an earth spike, or your mains protective earth. If it isn't, then forget about it.
The nice thing about a counterpoise is that it's an organising principle, as much as anything. It's a cheap and easy to provide terminal that does have much coupling to the topload, and it's in the right position to connect with a short wire to the secondary, and back to the TC PSU ground. You'd connect any arc target to it as well. Then having done that, you look around. What else does the topload see? Garage door? Radial to that.
Re: Tesla coil earthing
Gregary Boyles, Tue May 09 2017, 06:38AM
The roof of the garage is consists of steel sheet so I guess that will provide huge capacitance.
The garage door is a steel roller door so I assume you mean a radial connected to the unrolled door......although that is probably small potatoes compared to the area of steel on the roof.
If I set it up in a paddock then I assume I would connect the steel mesh to an earth spike?
Gregary Boyles, Tue May 09 2017, 06:38AM
Dr. Slack wrote ...
That counterpoise looks great.
From a connector somewhere on that mesh, run a wire to the bottom of your secondary, or the bottom of the secondary I sense current transformer, and to your TC power supply mains ground. If you are going to operate the TC in that position, then a radial out to your garage door would be good. Are there any other significant areas of conductor that either might get hit by streamers or present a large capacitance to the topload (like steel joists above our head out of shot)? If so, run a radial to them as well.
Thinking about a detailed page, maybe three illustrations would do it. On one extreme, a TC operating in the middle of a field, with secondary bottom connected to the ground. On the other, operating inside a Faraday cage, with secondary bottom connected to the floor of the cage. Then a third showing how any real situation is usually somewhere between the two. But always, the plan is to get the current back from things that are capacitively coupled to the topload back to the secondary bottom terminal, without undue inductance, and without producing inadvertent large voltages between innocent bystander conductors.
Depending on your operating position, the real earth may, or may not be, a conductor that has significant capacitive coupling to the topload. If it is, then connect to it by the shortest means, whether that's an earth spike, or your mains protective earth. If it isn't, then forget about it.
The nice thing about a counterpoise is that it's an organising principle, as much as anything. It's a cheap and easy to provide terminal that does have much coupling to the topload, and it's in the right position to connect with a short wire to the secondary, and back to the TC PSU ground. You'd connect any arc target to it as well. Then having done that, you look around. What else does the topload see? Garage door? Radial to that.
So you also connect the steel mesh to the mains ground? Is that correct? If so why do you need to do that as well?That counterpoise looks great.
From a connector somewhere on that mesh, run a wire to the bottom of your secondary, or the bottom of the secondary I sense current transformer, and to your TC power supply mains ground. If you are going to operate the TC in that position, then a radial out to your garage door would be good. Are there any other significant areas of conductor that either might get hit by streamers or present a large capacitance to the topload (like steel joists above our head out of shot)? If so, run a radial to them as well.
Thinking about a detailed page, maybe three illustrations would do it. On one extreme, a TC operating in the middle of a field, with secondary bottom connected to the ground. On the other, operating inside a Faraday cage, with secondary bottom connected to the floor of the cage. Then a third showing how any real situation is usually somewhere between the two. But always, the plan is to get the current back from things that are capacitively coupled to the topload back to the secondary bottom terminal, without undue inductance, and without producing inadvertent large voltages between innocent bystander conductors.
Depending on your operating position, the real earth may, or may not be, a conductor that has significant capacitive coupling to the topload. If it is, then connect to it by the shortest means, whether that's an earth spike, or your mains protective earth. If it isn't, then forget about it.
The nice thing about a counterpoise is that it's an organising principle, as much as anything. It's a cheap and easy to provide terminal that does have much coupling to the topload, and it's in the right position to connect with a short wire to the secondary, and back to the TC PSU ground. You'd connect any arc target to it as well. Then having done that, you look around. What else does the topload see? Garage door? Radial to that.
The roof of the garage is consists of steel sheet so I guess that will provide huge capacitance.
The garage door is a steel roller door so I assume you mean a radial connected to the unrolled door......although that is probably small potatoes compared to the area of steel on the roof.
If I set it up in a paddock then I assume I would connect the steel mesh to an earth spike?
Re: Tesla coil earthing
Sulaiman, Tue May 09 2017, 09:06AM
As you have a steel roof you may want to consider inverting your TC
use the roof as 'earth'
The downside is access to the primary circuitry,
the upside is ......... a frikin TC in the roof !
(no floorspace consumed, a chandalier of lightning etc.)
(I've not tried, just dreamed)
................................................. ................................................
F or the sake of safety, and academic correctness,
I would connect the earth mat to mains earth and an earth rod and the steel roof ... any exposed conductive surfaces.
This will prevent unexpected large potential differences,
e.g. one foot on the concrete, one on the mat, a streamer hits the roof
... what is the current path without earth bonding / will your testicles survive ?
Sulaiman, Tue May 09 2017, 09:06AM
As you have a steel roof you may want to consider inverting your TC
use the roof as 'earth'
The downside is access to the primary circuitry,
the upside is ......... a frikin TC in the roof !
(no floorspace consumed, a chandalier of lightning etc.)
(I've not tried, just dreamed)
................................................. ................................................
F or the sake of safety, and academic correctness,
I would connect the earth mat to mains earth and an earth rod and the steel roof ... any exposed conductive surfaces.
This will prevent unexpected large potential differences,
e.g. one foot on the concrete, one on the mat, a streamer hits the roof
... what is the current path without earth bonding / will your testicles survive ?
Re: Tesla coil earthing
Gregary Boyles, Tue May 09 2017, 09:23AM
Come to think of it the trailer in the garage is steel to so I could just stick the coil on the trailer and use that rather than the plastic grass and mesh (save these for when I set it up in the driveway).
Can you confirm that I also need to connect all this steel to mains earth as well.
Some people say not to do this as it might induce voltage spikes that may damage household electronics. Others say you need to do this.
Gregary Boyles, Tue May 09 2017, 09:23AM
Sulaiman wrote ...
As you have a steel roof you may want to consider inverting your TC
use the roof as 'earth'
The downside is access to the primary circuitry,
the upside is - a frikin TC in the roof !
(no floorspace consumed, a chandalier of lightning etc.)
(I've not tried, just dreamed)
Well actually the two ends are steel and aluminium roller doors, the roof is steel sheet and one side is steel colorbond.....so I suppose it is close to a faraday cage.As you have a steel roof you may want to consider inverting your TC
use the roof as 'earth'
The downside is access to the primary circuitry,
the upside is - a frikin TC in the roof !
(no floorspace consumed, a chandalier of lightning etc.)
(I've not tried, just dreamed)
Come to think of it the trailer in the garage is steel to so I could just stick the coil on the trailer and use that rather than the plastic grass and mesh (save these for when I set it up in the driveway).
Can you confirm that I also need to connect all this steel to mains earth as well.
Some people say not to do this as it might induce voltage spikes that may damage household electronics. Others say you need to do this.
Re: Tesla coil earthing
Dr. Slack, Tue May 09 2017, 10:16AM
They are already connected to some degree by the capacitance. The question is, do you want to manage that connection, or just let it happen?
The primary is being driven by electronics which are directly coupled (OLTC) or heavily capacitively coupled (if you have an isolation transformer in there) to your mains earth, live and neutral wiring. Consider the secondary bottom terminal (SBT) as your 'star ground', and connect everything to that. However, the distance from the counterpoise to the SBT is pretty small, so it's more convenient to connect to that.
As an exercise in method acting, think of yourself as a piece of charge, leaving the topload in any (or all) directions. What's the first thing you hit? How do you get back to the SBT to complete the circuit? If it involves going through other impedances (a long wire has inductance, an air space between conductors is a capacitor) then it will generate a voltage across that. That's how spikes get into household wiring. Charge lands on a live wire, and if the live has a high impedance to earth at RF, a large voltage is generated live to earth by the RF current flow. That's why (a long time ago, maybe a previous thread) I said have capacitors between live and ground and neutral and ground at your TC power supply. This is to provide a low impedance between these to reduce the voltages launched into the rest of the house wiring.
Your garage would be a Faraday cage if the large conductive elements were all connected together securely. So that would be the case if it turns out you have conductive uprights which the roller door and conductive roof are bonded to. A few radials from the SBT to the bottom of those uprights would be more use than a wire out to a ground spike, would have less inductance. That's assuming you're not going to put a spike through the concrete (which is possible, only needs a small hole and a discretely mounted terminal) which would connect to the ground and your uprights in one go. But that spike in the floor is to connect to your uprights and the conductive layer beneath the concrete, not because it is called 'earth'.
There's nothing special about ground, or the earth, it's just a conductor. If it's near, it's relevant. If it's far, then other conductors are more relevant.
Dr. Slack, Tue May 09 2017, 10:16AM
Can you confirm that I also need to connect all this steel to mains earth as well
They are already connected to some degree by the capacitance. The question is, do you want to manage that connection, or just let it happen?
The primary is being driven by electronics which are directly coupled (OLTC) or heavily capacitively coupled (if you have an isolation transformer in there) to your mains earth, live and neutral wiring. Consider the secondary bottom terminal (SBT) as your 'star ground', and connect everything to that. However, the distance from the counterpoise to the SBT is pretty small, so it's more convenient to connect to that.
As an exercise in method acting, think of yourself as a piece of charge, leaving the topload in any (or all) directions. What's the first thing you hit? How do you get back to the SBT to complete the circuit? If it involves going through other impedances (a long wire has inductance, an air space between conductors is a capacitor) then it will generate a voltage across that. That's how spikes get into household wiring. Charge lands on a live wire, and if the live has a high impedance to earth at RF, a large voltage is generated live to earth by the RF current flow. That's why (a long time ago, maybe a previous thread) I said have capacitors between live and ground and neutral and ground at your TC power supply. This is to provide a low impedance between these to reduce the voltages launched into the rest of the house wiring.
Your garage would be a Faraday cage if the large conductive elements were all connected together securely. So that would be the case if it turns out you have conductive uprights which the roller door and conductive roof are bonded to. A few radials from the SBT to the bottom of those uprights would be more use than a wire out to a ground spike, would have less inductance. That's assuming you're not going to put a spike through the concrete (which is possible, only needs a small hole and a discretely mounted terminal) which would connect to the ground and your uprights in one go. But that spike in the floor is to connect to your uprights and the conductive layer beneath the concrete, not because it is called 'earth'.
There's nothing special about ground, or the earth, it's just a conductor. If it's near, it's relevant. If it's far, then other conductors are more relevant.
Re: Tesla coil earthing
Gregary Boyles, Tue May 09 2017, 12:44PM
I am assuming that I would need those capacitors on active and neutral if I was powering the primary from the mains without the transformer?
Out of interest.....what value capacitors would you put on neutral and active?
I am probably a bit safer puting the coil in my metal trailer when it is in the garage actually - further away from the brick wall with the household wiring inside.....inverse square law......
Perhaps I should have done wit it and get some mesh and create a complete faraday cage around it.
The posts in my garage are wood so I would have to run separate radials to the roof, wall and roller doors or else put in a few discrete permanent fence wire connections between the metal roof, wall and roller doors.....and then I would need just one radial to the nearest roller door.
Gregary Boyles, Tue May 09 2017, 12:44PM
Dr. Slack wrote ...
They are already connected to some degree by the capacitance. The question is, do you want to manage that connection, or just let it happen?
The primary is being driven by electronics which are directly coupled (OLTC) or heavily capacitively coupled (if you have an isolation transformer in there) to your mains earth, live and neutral wiring. Consider the secondary bottom terminal (SBT) as your 'star ground', and connect everything to that. However, the distance from the counterpoise to the SBT is pretty small, so it's more convenient to connect to that.
As an exercise in method acting, think of yourself as a piece of charge, leaving the topload in any (or all) directions. What's the first thing you hit? How do you get back to the SBT to complete the circuit? If it involves going through other impedances (a long wire has inductance, an air space between conductors is a capacitor) then it will generate a voltage across that. That's how spikes get into household wiring. Charge lands on a live wire, and if the live has a high impedance to earth at RF, a large voltage is generated live to earth by the RF current flow. That's why (a long time ago, maybe a previous thread) I said have capacitors between live and ground and neutral and ground at your TC power supply. This is to provide a low impedance between these to reduce the voltages launched into the rest of the house wiring.
Your garage would be a Faraday cage if the large conductive elements were all connected together securely. So that would be the case if it turns out you have conductive uprights which the roller door and conductive roof are bonded to. A few radials from the SBT to the bottom of those uprights would be more use than a wire out to a ground spike, would have less inductance. That's assuming you're not going to put a spike through the concrete (which is possible, only needs a small hole and a discretely mounted terminal) which would connect to the ground and your uprights in one go. But that spike in the floor is to connect to your uprights and the conductive layer beneath the concrete, not because it is called 'earth'.
There's nothing special about ground, or the earth, it's just a conductor. If it's near, it's relevant. If it's far, then other conductors are more relevant.
I am powering the primary via a transformer - the 3 x MOT device sitting on the saw horses behind the coil and wire mesh. Can you confirm that I also need to connect all this steel to mains earth as well
They are already connected to some degree by the capacitance. The question is, do you want to manage that connection, or just let it happen?
The primary is being driven by electronics which are directly coupled (OLTC) or heavily capacitively coupled (if you have an isolation transformer in there) to your mains earth, live and neutral wiring. Consider the secondary bottom terminal (SBT) as your 'star ground', and connect everything to that. However, the distance from the counterpoise to the SBT is pretty small, so it's more convenient to connect to that.
As an exercise in method acting, think of yourself as a piece of charge, leaving the topload in any (or all) directions. What's the first thing you hit? How do you get back to the SBT to complete the circuit? If it involves going through other impedances (a long wire has inductance, an air space between conductors is a capacitor) then it will generate a voltage across that. That's how spikes get into household wiring. Charge lands on a live wire, and if the live has a high impedance to earth at RF, a large voltage is generated live to earth by the RF current flow. That's why (a long time ago, maybe a previous thread) I said have capacitors between live and ground and neutral and ground at your TC power supply. This is to provide a low impedance between these to reduce the voltages launched into the rest of the house wiring.
Your garage would be a Faraday cage if the large conductive elements were all connected together securely. So that would be the case if it turns out you have conductive uprights which the roller door and conductive roof are bonded to. A few radials from the SBT to the bottom of those uprights would be more use than a wire out to a ground spike, would have less inductance. That's assuming you're not going to put a spike through the concrete (which is possible, only needs a small hole and a discretely mounted terminal) which would connect to the ground and your uprights in one go. But that spike in the floor is to connect to your uprights and the conductive layer beneath the concrete, not because it is called 'earth'.
There's nothing special about ground, or the earth, it's just a conductor. If it's near, it's relevant. If it's far, then other conductors are more relevant.
I am assuming that I would need those capacitors on active and neutral if I was powering the primary from the mains without the transformer?
Out of interest.....what value capacitors would you put on neutral and active?
I am probably a bit safer puting the coil in my metal trailer when it is in the garage actually - further away from the brick wall with the household wiring inside.....inverse square law......
Perhaps I should have done wit it and get some mesh and create a complete faraday cage around it.
The posts in my garage are wood so I would have to run separate radials to the roof, wall and roller doors or else put in a few discrete permanent fence wire connections between the metal roof, wall and roller doors.....and then I would need just one radial to the nearest roller door.
Re: Tesla coil earthing
Gregary Boyles, Wed May 10 2017, 02:06PM
By the way, I have electrically connected the roof and back wall of my garage to the two metal roller doors in the photo above. So I need only run 1 radial to the nearest roller door.
Can't wait to try it out with my MOT power supply.
Gregary Boyles, Wed May 10 2017, 02:06PM
By the way, I have electrically connected the roof and back wall of my garage to the two metal roller doors in the photo above. So I need only run 1 radial to the nearest roller door.
Can't wait to try it out with my MOT power supply.
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