Tag: building the new generator

Making slow progress

I haven’t posted in some time as I’ve not made much progress on finishing the electronic system for the new prototype. Life, with all its complications, has interfered and between maintaining my house and property added to some health issues that involved a hospital stay, I haven’t spent much time in my shop. To be honest, as that the last prototype didn’t show even the smallest hint of working, it made it hard for me to maintain my enthusiasm.

However, it setting up the new system I’ve re-examined everything and made more careful measurements. There is a real possibility I didn’t have the phasing correct in my last attempt, and as it blew up after running for less than a minute, I never did get the chance to do anything beyond one quick look.

Phasing is critical, but it’s very hard to get right. Remember, I need to make sure the field coil’s expanding magnetic field is in phase with the increasing current flow in the core. And the only way I have of achieving this is with an oscilloscope looking at voltage changes at various points in the wiring. If I measure the voltage at wrong point or the wrong way, then it can look in phase but isn’t.

When I duplicated my previous wiring, but changed the way I measured things, I got this:

Scope

If these two signals were in phase, their peaks and valleys would appear lined up vertically. As you can see the top signal is following the bottom waveform by almost 90°.  Which means the magnetic field and the current weren’t working together.

I’m not sure this was happening in the prototype that blew up, but as I never got a chance to experiment, it remains a possibility. Getting the phasing right makes all the difference, so I’ll take my time before heating up the new prototype.

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Insulating for 750°C

Here’s the hot box sitting on firebricks. To the left you can see one of the metal sides with exit holes drilled for the wires.

Before start

In a previous post I showed the lid I’d made for the hot box. I’ll put it in place after I’ve gotten most of the insulation around the sides.

Two Sides

Above I show two of the sides in place. These are the sides where most of the wires emerge, so I’m installing them first. As the sides are rather flimsy, I’m using those wooden braces at the top to hold them in place while I work. Later they’ll be removed.

In the next picture I show how the insulation fits between the hot box and the metal sides.

Part insulated

And:

box with sides

Above, the back side is just propped into place, so I can make sure everything is going to mate up. When it came time to secure the sides together I used a strap to hold them while I screwed the corner braces on.

Installing the sides

In this next picture you can see how the various wires come out of the core, pass through the hot box and finally out of the metal sides.

Core wires out

In this picture you can see most of the insulation in place. At this point I installed the hot box lid and added the insulation all the way to the top of the outer container.

Hot zone in its insulation

Once fully stuffed with insulation, I made a metal lid. It’s removable as I will want to take it off after doing a run, or the hot box will take days to cool down.

Ready for lid

Yes, now that it is finished, it really looks like a big white box.

Compteted insulation

Electronic controls.

I’ve been rebuilding my electronic control assembly. I need two current sources, one for the core and one for the coil. In addition, I need to monitor both the input and output. I’m relying on two oscilloscopes to detect any change.The idea is simple but changes will be difficult to detect. As I’ve not included any cooling system in this prototype, my intention is to discover if iron’s Curie Point can be changed by applying electrical stress in those few degrees before the core becomes completely non-magnetic.

Most probably, this should be noticeable by a change in the current used to energize the coil. When the core is below its Curie Point, it behaves as an iron-core inductor. When it is close to its Curie Point, it acts more like an air-core inductor and draws additional current. (After compensating for the increased resistance of the copper wire at those higher temperatures.)

If all works out like I hope, when the core’s temperature is around 690-750°C sending a bias current through the core will have the effect of increasing the coil’s inductance and be noticeable by a drop in the current draw.  When the bias current stops, the current should once again increase.

This is not an especially elegant test of the theory. I’m simply hoping to get enough positive data to make more intense studies worthwhile. Working with mild steel’s lower permittivity and over-high Curie Point has proved to be next to impossible. But without some indication the Curie Point can be changed by electrical stress, the research necessary to produce a high permittivity, low Curie Point core metal just isn’t going to happen.

Here is the main control table:

Control table

I’m running the coil at 120V 60Hz AC from the wall outlet. The core can be energized by either 24V or 13V AC transformers. There’s a reversing switch to invert the phasing.  The meters and oscilloscopes should tell me what the current is doing.

Here is a closer look:

The table

The back of the control table looks rather confusing, but it’s all wired point-to-point so if I didn’t make any errors, it’s good to go.

Back of controls

As the core resistance will change significantly once it’s up to temperature, I need to use ballast resistors for testing and making the initial measurements. At room temperature the core has a resistance of 0.4 ohms, so these resistors are necessary to keep the current under control. They might get hot, so I’m using that cooling-fan tower I made previously to keep them cool.

Balast resistors

The generator unit isn’t connected at this time. (I still have to apply its final insulation.) But this is its connection point plus a monitoring panel for observing the output of a secondary winding. The yellow and black input wires are for energizing the core and coil respectively. The two plug and switch boxes are for the heaters. There are two 120V heaters and one 240V heater down the center of the core.

This is as far as I can go until the insulation around the core unit is finished.

Magnetic Domains.

This is a quick rundown on magnetic domains—part of my overview of the basic science behind the ferromagnetic generator.

Any ferromagnetic material, like iron, contains tiny magnetic domains. These are areas where all the atoms in the sample have undergone exchange coupling so their individual magnetic fields can act as single larger magnet. These places can be visually seen (under a microscope) by allowing a colloidal suspension of iron particles to settle on the specimen’s surface. The domain boundaries leak a little magnetic flux which attracts the particles of iron. The result reveals the pattern of the domains.  Normally, each domain measures around a tenth of a millimeter across

Domains are created by the exchange forces created when the kinetic energy required to move an electron to an upper free band is less than allowing two electrons to enter into a parallel orientation. Basically, that says a few metals will arrange their inner shell electrons so not every electron’s magnetic field cancels another’s out.

Normally, electrons exist in pairs with their spins opposed, so each has its magnetic pole neutralized by its mate.  Remember, an electron is a spinning electric charge, and whenever a charge moves, it creates a magnetic field. If we simplify and imagine electrons as spinning tops, it would look something like this:

The green lines represent the magnetic flux. You can see how the flux would not travel very far.

But in the ferromagnetic materials, like iron, the 3d electron lacks a mate in its shell. When that happens its field will reach out into space.

If the inter-atomic distance is correct, the atoms can arrange themselves so that exchange coupling between these unpaired electrons in neighboring atoms takes place and their fields add together.

Now if all the atoms in a sample were linked into the same magnetic orientation, they would generate a powerful external field which would extend far beyond the sample. In nature a lower energy state is preferred, so domains are formed to keep the magnetic lines of force as short as possible. (A lower energy state.)

Although each small domain is a magnet, within the matrix the domains arrange themselves so that overall, an unmagnetized ferromagnetic sample shows no external magnetic field. In pure iron, because of its crystal lattice, there are six possible orientations a domain can assume. Inside a domain all of the atoms are linked and their total magnetic field points in the same direction. But, just a short tenth of a millimeter away there are another bunch of atoms all lined up and pointing their field in a different direction. Like good neighbors they establish a boundary between them. And that boundary is called a domain wall and this is the place that attracts those particles of iron.  At room temperature, the boundaries’ thickness is around 1000 atomic diameters. As a sample is heated, the boundaries’ width expands.

When a sample’s temperature reaches its Curie Point, you could say the boundaries have become so wide they start to touch each other and the domains have disappeared.

This is one reason why I believe the ferromagnetic generator should operate best a few degrees below the sample’s Curie point. It needs those boundaries and the remaining still-linked exchange forces to react to the external electronic stress necessary to change the Curie Point.