TinMan Generator Research Moderated Topic

[Void]

Hi Tinman. Regarding arcing between the commutator and brushes, this is my understanding of it, although I may not have
everything exactly 100% correct, this should be the general idea.

You have two different types of arcing. You can have arcing in air due to high voltage causing ionization breakdown of the air across a fixed
gap which causes current to flow through the ionized air where there previously was no current flow. This type of arcing in air requires a
high voltage to initiate the air ionization and the subsequent arcing and current discharges.

Another type of arcing such as seen between electric motor commutators and brushes and on breaking relay contacts is sometimes called
breaking arcing. This is where you have a current flowing in a wire or coil and you then start separating the contacts in the wire. If the current is
of high enough magnitude, you will see arcing in the gap as the wire contacts are separated. The cause of this type of arcing is still
the same, ionization of the air. When you start to break an existing current flow by starting to separate contacts, there is enough energy in the
electron current flow to ionize the air in the very narrow air gap that starts to form between the contacts when you first start separating
the contacts. As the gap between the contacts (commutator and brush in this case) continues to widen, the current flowing though
the tiny initial gap in the air continues to ionize more air molecules/atoms and the arc grows bigger until the energy driving the current
dissipates, as in the case of a collapsing magnetic field around a coil, to a low enough point that it can no longer sustain the arc, or the
gap becomes too wide to allow the arcing to continue any further. It is still arcing due to air ionization. I believe it is able to ionize the air
at a much lower voltage than for the first type of arcing because the air gap starts out very tiny between the contacts and you already have
an electron current flow between the contacts which helps to get the ionization started as the narrow air gap starts to form. 

When the commutator and brushes heat up, they heat up the air around them, and air at a higher termperature breaks down into ionization easier
due to the molecules and atoms in the air having more energy, and thus more motion and higher energy collisions.

In the case of where you are breaking contact in a high current coil circuit, you may not see a very high voltage spike because the current
never really fully breaks abruptly. You go from current flowing through the touching contacts to about the same current continuing to flow
as the contacts start to seperate and acring starts in the air, and then the current drops off gradually as the gap continues to widen and as
the energy in the coil continues to diissipate through the arc. If the arcing is initiated by fairly high current, the arc can be quite hot and can
speed up the breakdown of the metals in the commutator and brushes, and you may see glowing bits of metal as little pieces of metal
break off. The high current arcing is what is making the little bits of metal glow however. The one exception might be where you have
badly scored or chipped brushes and commutators and maybe misaligned brushes and the friction and impacts between the rough surfaces
may cause excessive heating in the metals and maybe metal sparking as little pieces heat up and break off, but that would be a problem due
to damaged or warped or a misaligned commutators and brushes. You could maybe have both this type of sparking and arcing going on in
this case.
All the best...

[gotoluc]

In the video below,you can actually see these particles still burning away between the commutator segments long after that segment has passed by the brush. You will also note that the arcing takes place exactly as the brush shorts each coil.

Luc
You were wondering why one brush gets hot,while the other stays cool. Well the answer is in the video-can you spot it?-which brush is doing almost all the arcing?-->which brush is the one shorting the coils first-which brush is the leading brush.

https://www.youtube.com/watch?v=gc4l1eooPKM

So my best guess is, even though the brushes look to be in alignment it would only take a very small variation for one brush to lead.

Would you say I understand correctly?

Thanks for sharing

Luc

[Jimboot]

So my best guess is, even though the brushes look to be in alignment it would only take a very small variation for one brush to lead.

Would you say I understand correctly?

Thanks for sharing

Luc

Or does it change with polarity?

[seychelles]

NOBODY TOLD ME IT WAS GOING TO BE THAT HARD. ANYWAY MY SMALL
CONTRIBUTION..FORGIVE ME CAP NAZIES. 
https://www.youtube.com/watch?v=rz0wPIhGFk8&amp=&feature=youtube_gdata_player

[tinman]

So my best guess is, even though the brushes look to be in alignment it would only take a very small variation for one brush to lead.

Would you say I understand correctly?

Thanks for sharing

Luc

A number of things can cause one brush to get hotter than the other,but yes,that is one of those reasons.