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Author Topic: Winding a strong electromagnet  (Read 178342 times)

Offline Xaverius

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Re: Winding a strong electromagnet
« Reply #135 on: January 15, 2009, 09:04:47 AM »
I STILL can't get me brain around this - thinking I'm brain damaged!  ???

I have a magnet attached to the end of an electromagnet (EM) with a steel core and pulse the EM with just enough juice to get the magnet to drop off.

Which will require less energy input to get it to drop off?

1) a high permeability core
or
2) a low permeability core

(1-A) the magnet is very strongly attached to the high permeability core and almost all the domains of the core are aligned.  This will require a large input of energy to negate the attraction.  BUT, will the high permeability core more readily 'accept' the flux from the EM pulse meaning it will actually require LESS?

(2-A)  the magnet is attached, but not quite as much as a much smaller % of the domains of the core are aligned, thus less energy input to the EM to get it to drop.  BUT, will the core also be less 'accepting' to the EM pulse so it will require more input?

Or a small size core with a relatively large/strong magnet is going to fully saturate the core, so the high permeability core will require less.
But if the core is large with a relatively small/weak magnet this changes things?

Or what and why?

Tx

For drop off, a high permeability core should require less power input.  The high u core causes a greater ATTRACTION force between it and the PM.  However, the high u core uses a unit of power to produce a greater REPULSION force.

The REPULSION force must be equal to the ATTRACTION force in order to repel the PM.  If the REPULSION is too weak(such as with a low u core) for a unit of power, then the PM will still be ATTRACTED to the core.  Ex.  PM has 2 units of force, core has 1 unit of force, total attraction 3 units.  If PM has 2 units of attraction and core 1 unit of repulsion you still have 1 unit of attraction, 2+-1=1.  Therefore you would need 2 units of power to produce more force(negative) for the low u core to repel the PM.

BTW, the PM will not just drop off, magnets work on an all or nothing basis, the PM and core will repel with rapid speed and distance between them.

Hope this makes sense, the high u core would use less power.

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Re: Winding a strong electromagnet
« Reply #135 on: January 15, 2009, 09:04:47 AM »

Offline tropes

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Re: Winding a strong electromagnet
« Reply #136 on: January 18, 2009, 06:24:01 PM »
For drop off, a high permeability core should require less power input.  The high u core causes a greater ATTRACTION force between it and the PM.  However, the high u core uses a unit of power to produce a greater REPULSION force.

The REPULSION force must be equal to the ATTRACTION force in order to repel the PM.  If the REPULSION is too weak(such as with a low u core) for a unit of power, then the PM will still be ATTRACTED to the core.  Ex.  PM has 2 units of force, core has 1 unit of force, total attraction 3 units.  If PM has 2 units of attraction and core 1 unit of repulsion you still have 1 unit of attraction, 2+-1=1.  Therefore you would need 2 units of power to produce more force(negative) for the low u core to repel the PM.

BTW, the PM will not just drop off, magnets work on an all or nothing basis, the PM and core will repel with rapid speed and distance between them.

Hope this makes sense, the high u core would use less power.
Before building my 4th Sotropa Motor (3/4' neo. magnet pistons), I used this simple apparatus to test the coil, core and voltage requirements:  http://www.youtube.com/watch?v=pNWAlj_lBUk
In my last motor I used an iron pipe as a core. The core diameter is half the magnet diameter and the coil diameter is equal to the magnet diameter. I used 22 gauge wire and added voltage until the coil heated. Removing the BEMF allowed the coil to run cooler. I found that a solid core with no clearance between the core and magnet was impossible to to separate regardless of how much voltage was applied.
Hope this is of some value to those builders.
Tropes

Offline capthook

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Re: Winding a strong electromagnet
« Reply #137 on: February 02, 2009, 04:43:29 AM »
Found this core material study online.

As proper annealing is expensive and difficult to source, especially in small quantitites, the conclusion was that unannealed 'Magnet Iron' was of relative quality compared to expensive annealed Hiperco 50A.

"Magnet iron is recommended for unannealed use"


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Re: Winding a strong electromagnet
« Reply #137 on: February 02, 2009, 04:43:29 AM »
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Offline Ergo

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Re: Winding a strong electromagnet
« Reply #138 on: March 07, 2009, 10:18:51 PM »
All of your calculations and drawings is not valid in your pursuit of
making the strongest electromagnet possible.
The permeability only correlates to a closed magnetc circuit.
You will not see any dfference in magnetic strength when using
advanced core material in an open frame electromagnet.
The tiniest airgap present will deteriorate the properties of the
high efficiency core material. So no gain of strength in this case.

But there is still another advantage that not many people know about.
The only really useful advantage of using high tech core material.
Simply the Hysteresis effect.
Hysteresis is the loss on each charge/discharge of the electromagnet.
It takes a certain amount of energy to energise the coil.
But you never get the same amount back as EMF when shut down.
This loss can be minimised by using Hi Tech core material.
When minimising the hysteresis you get rid of the core heating and
you can then run the electromagnet harder without overheating.
But this only matters in a repetitive pulsed state. In static mode
or unfrequently pulsing you can just as well use a regular iron core.

Offline capthook

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Re: Winding a strong electromagnet
« Reply #139 on: March 11, 2009, 04:27:37 PM »
The permeability only correlates to a closed magnetc circuit.
You will not see any dfference in magnetic strength when using
advanced core material in an open frame electromagnet.
The tiniest airgap present will deteriorate the properties of the
high efficiency core material. So no gain of strength in this case.

Do you have any supporting evidence/links?
It would seem contrary to any information I've seen.
Either the domains align more easily due to the molecular structure of the material (high permeability) or they don't (low permeability).  How would the airgap be revelant to this?

- - -
Xaverius-
I did some testing on the 2-strand winding idea to reduce the resistance of the coil and thus increase efficiency/flux.
While this idea may be of benefit when additional power is available, I find it not to be so with a fixed power input.

Testing two identical coils with the only difference being a 1 wire winding vs. a 2 wire winding and a power supply of a 4700 uF capacitor charged to 12V:
The 1 wire was on average 17% more efficient(provided more flux) over varying test conditions/airgaps. 
- - -
Some further updates on materials/annealing:

I've found min. charges of around $250 for hydrogen annealing at 1600F for 2 hours with a 4 hour 100F cooling cycle to be about the norm.  1 provider offered to 'piggyback' on a another order providing time was not an issue (maybe 2 weeks) for $150.

Pure iron (99.95%) @ $90 per inch (OUCH!! $$$)
Iron rod (99.6%) @ $95 per ft.

CMI-C magnet iron 4' for $100 to $250 depending on the providers min. order.

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Re: Winding a strong electromagnet
« Reply #139 on: March 11, 2009, 04:27:37 PM »
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Offline Ergo

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Re: Winding a strong electromagnet
« Reply #140 on: March 12, 2009, 08:34:06 AM »
Do you have any supporting evidence/links?
It would seem contrary to any information I've seen.
Either the domains align more easily due to the molecular structure of the material (high permeability) or they don't (low permeability).  How would the airgap be revelant to this?

Believe it or not but I have studied magnetics for some time now and I can
tell you that I have tested all kind of alloys in a small electromagnet when
trying to optimise its strength.
I have a gauss meter and no matter what I tried I always got the same end
face flux at the same input current.
The fine alloys, (mu metall, MPP, Sendust, Hi Perm oriented Steel) didn't
give any increase in end face flux. I phoned one of the companies and talked
to an engineer on the matter and he told me that any air gap will detoriate
the performance. He also told me about the importance of hysteresis and
why high tech alloys are so good at this compared to solid structures.
He gave me a hint, if I wanted to have an electromagnet that consumed less
current I had to make sure it was bent into a C and the open gap should be
placed tightly against a solid iron return path thick enough to carry all the flux.
In this scenario I would see a drop in current in reaching high flux levels.
But using a Solenoid shape was not an option. The air gap is simply huge.

I have searched internet for a long time but there is no information on this subject.
Either it's burried deep in some heavy science thesis but I believe myself the lack
of infomation is due to lack of interest in this matter. Any involved engineer find
this obvious and there is no literature written on how to optimise a hopeless case.

Edit: I found a new link today. It might provide you with answers but it costs money.
http://www.coursework.info/AS_and_A_Level/Physics/Fields___Forces/_What_effects_the_strength_of_an_electro_L68298.html
« Last Edit: March 12, 2009, 10:39:26 AM by Ergo »

Offline capthook

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Re: Winding a strong electromagnet
« Reply #141 on: April 15, 2009, 08:32:06 AM »
Some interesting information on series vs. parallel windings of an electromagnet.

Conclusion: series (or 1 wire) produces greater or equal magnetism vs. parallel (or multiple wires) windings.

"With a power supply configured as a current source, by setting the current and leaving the voltage free to take any value, the nail's magnetism was lower under parallel connection of the coils."
With a variable current supply, the nail's magnetism was equivalent under both series and parallel.

An interesting .pdf is attached.  The author investigates the early work done on parallel vs. series windings electromagnets.


Free Energy | searching for free energy and discussing free energy

Re: Winding a strong electromagnet
« Reply #141 on: April 15, 2009, 08:32:06 AM »
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Offline tropes

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Re: Winding a strong electromagnet
« Reply #142 on: April 15, 2009, 05:45:56 PM »
Static testing does not give a complete picture. Two things I have found that reduce the amount of current needed to produce an electomagnet. Both involve movement.
1.) As the magnetic piston moves toward the face of the coil, an electric current is induced in the wire. The current induced in the coil wire by the magnet will be of a polarity that repels the magnet. The magnets use the current induced to make the coil core repel the magnetic pistons.

2.) Utilizing CEMF is a method of lowering the overall power consumption required as it collects stored energy from the coils between pulses, and dumps it into a capacitor.

Tropes

Offline Ergo

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Re: Winding a strong electromagnet
« Reply #143 on: May 19, 2009, 10:32:56 AM »
This is why the core material doesn't matter in a solenoid shaped electromagnet regarding flux levels.
It's simply due to the extremely large airgap between the poles and this translates into strong reluctance
in getting magnetised by the applied magnetizing force from the coil.
The reluctance is so strong that it doesn't matter how "easy" the core material is.
The force needed to overcome the large airgap is many times greater than the "magnetizing properties".
The reluctance can only be minimised by decreasing the airgap. And the easiest way is to bend the solenoid
shape into a C where the gap is kept as narrow as possible. And the best performance is obtained when
the C-shape is closed into a toroid shape. This is very easy to magnetise but useless as an electromagnet.

Sorry guys. There is no shortcuts in making a strong electromagnet by using exotic core materials.
But in a pulsed state, preferably at 50Hz or higher, the BEMF at turn off can be recycled at much higher
efficiency than using a regular solid iron core. This is the true benefit of using exotic core materials.
« Last Edit: May 19, 2009, 01:50:01 PM by Ergo »

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Re: Winding a strong electromagnet
« Reply #143 on: May 19, 2009, 10:32:56 AM »
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Offline solinear

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Re: Winding a strong electromagnet
« Reply #144 on: June 25, 2009, 12:25:01 AM »
Ergo is completely correct - once you get a decent core (more than 200-500 permeability rating), the impact of getting higher permeability material is somewhat futile.

The reason why parallel coils are useless is because you end up with identical amp turns/amperage.  If you have a power supply that can handle high amperage, it would be nice for keeping voltage low, but would have zero impact upon wattage used to produce the gauss.  Actually, it would probably be more expensive, in wattage terms, because there will be a small amount of additional resistance created by the leads for each of the separate coils (relatively inconsequential though).

For creating a stronger electromagnet, wrapping your core partially around your magnet will have a much higher impact (think of a putting your electromagnet in a steel can with one side removed - the outside of the steel can would turn into your opposite pole).  Your typical industrial magnets have the can completely around so that both poles are on the same side, creating a magnet that is 3-4 times as strong (if not stronger) with the same number of amp turns.  The closer you can get the two poles together, the stronger the magnetic field will be (in gauss).  For the purposes of attracting or repelling permanent magnets, wrapping your magnet only partially around the coil would likely work best.

A good example would be to look at some industrial magnets, like http://www.magnetechcorp.com/Round.htm .  For that magnet, the outer material is likely some form of iron or steel.  When looking at their opposite pole magnets (they have one listed on their site), they have the same outer shield, but it's made of a non-ferrous material (likely aluminum).  Mattering on your application, you can use a 'U' shape (with one leg of the U having the coil wrapped around it) or an 'E' shape (with the center leg having the coil wrapped around it and the outer legs being the opposite pole as the center).

Offline capthook

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Re: Winding a strong electromagnet
« Reply #145 on: August 29, 2009, 10:54:01 PM »
Testing coil strength for repulsion of a permanent magnet:

Another method for testing coil strength when repulsing a permanent magnet.
A length of wire is stretched taught.  A small permanent magnet is attached to a plastic washer and hung from the wire.  Washer/magnet is then pushed against the coil that is then energized for repulsion and the travel distance is measured.

One of the tests was to determine the difference in winding a coil with 1 wire vs. 2-in-hand (parallel / half the resistance).
It has been proposed that 2-in-hand will outperform as there is half the resistance, thus 2x the amps.

Results: Avg. of 10 tests on each with 9V battery.

Coil 1: 20.4"
1/2"diameter core / #22 wire / 2 1/4"L x 1 1/4" OD diameter coil / 2.85 ohms

Coil 2: 18.7" : 20.5" equalized to coil 1 (1.3ohms x 2= 2.6 ohms : 2.85/2.6 = 9.6% : 18.7" x 1.096 = 20.5")
same as coil 1 but with 2-in-hand / 1.3 ohms

Coil 3: 15.5" : 17.7" equalized to coil 1 (2.85/2.5 = 14% : 15.5" x 1.14 = 17.67")
3/8" diameter core / same as coil 1 / 2.5 ohms


Conclusions:
When results are equalized for small variations in winding accuracy, coil 1 and coil 2 provide identical results.  This is a 3rd set of test data (2 methods/results reported previously) that shows no additional benefit of coil strength by winding with multiple wires.

Coil 1, with the larger diameter core, shows a 15% increase over coil 3.

Further tests with larger diameter cores to come.

Free Energy | searching for free energy and discussing free energy

Re: Winding a strong electromagnet
« Reply #145 on: August 29, 2009, 10:54:01 PM »
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Offline capthook

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Re: Winding a strong electromagnet
« Reply #146 on: September 02, 2009, 01:27:58 AM »
How to wind a coil with a larger diameter core?

Attached pictures show a 1-1/4" diameter 1018 core ready for winding.

Winding with an electric drill is much faster, easier and winds a neater coil than trying to do by hand.  But a large diameter core won't fit into the drill chuck.

The extra prep work is worth it - especially having to wind 4 coils.

How do YOU wind your large diameter coils?

Offline ltseung888

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Re: Winding a strong electromagnet
« Reply #147 on: August 22, 2015, 03:59:06 AM »
I would like to get the highest repulsion between two iron-core coils to demonstrate possible overunity.  The technique is to compare the jumping height of a coil (Output potential energy) with the Input Electrical Energy (via a DSO).

The Coils can have a hole in the middle and the jumping restricted by a non-magnetic rod.

Any useful advice?  Thank you.

More information in:
http://overunity.com/15077/ufo-propu-engine-closed-loop/new/#new

Lawrence Tseung

Offline ltseung888

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Re: Winding a strong electromagnet
« Reply #148 on: August 22, 2015, 09:38:29 PM »
If the magnetic strength is dependent on NI where N is the number of turns and I is the current, the chance of getting Output Potential Energy greater than Input Electrical Energy is high.  COP > 1.

The number of turns N is the key factor.

Ferromagnetic core can produce 2,000 times the magnetic strength of air-core. 

The Input Electric Energy to the air-core and the iron-core can be approximately the same but the magnetic strength can be 2,000 times different.

It is obvious that the Input Electrical Energy is not the only source of energy to repel the magnet.  Magnetic energy is lead-out via alignment of the "tiny magnets" inside the ferromagnetic core.
« Last Edit: August 23, 2015, 12:07:32 AM by ltseung888 »

Offline ltseung888

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Re: Winding a strong electromagnet
« Reply #149 on: August 23, 2015, 12:23:50 AM »
If the magnetic strength is dependent on NI where N is the number of turns and I is the current, the chance of getting Output Potential Energy greater than Input Electrical Energy is high.  COP > 1.

The number of turns N is the key factor.

Ferromagnetic core can produce 2,000 times the magnetic strength of air-core. 

The Input Electric Energy to the air-core and the iron-core can be approximately the same but the magnetic strength can be 2,000 times different.

It is obvious that the Input Electrical Energy is not the only source of energy to repel the magnet.  Magnetic energy is lead-out via alignment of the "tiny magnets" inside the ferromagnetic core.

The Output Potential Energy/Input Electrical Energy (COP) is greater than 1.  This is theoretically predicted.  It will be confirmed by Hong Kong University or other top academic institutions.

If COP is greater than 1 in the straight line case, it will also be greater than 1 in the circular motion case.

Thus the 225HP Pulse Motor, the Laing Car, the QMOGENs, the Witts Generators are all theoretically possible.

The Chinese and USA Military Establishments have lead-out energy flying saucers.  Will they disclose such top secret?  What can we do to get them disclose such secrets to benefit the World?

 

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