On 13/05/2014 11:33, Brian Morrison wrote:
On Tue, 13 May 2014 10:39:24 +0100
Kafkaesque wrote:

It's the DC resistance that limits the primary current once the core
is saturated, not the inductance.

When the core is saturated the effective inductance is zero. Think
about the B-H loop diagram for a transformer.

Which is why it's the resistance which limits the current for the parts
of each half-cycle during which the core is saturated.

On the other hand, the resistance will rise (or even O/C) because the
temperature will rise ... possibly quite rapidly :-)

"Brian Morrison" wrote in message
...

It's the DC resistance that limits the primary current once the core
is saturated, not the inductance.

When the core is saturated the effective inductance is zero. Think
about the B-H loop diagram for a transformer.

You misunderstand.

I was referring to the saturation of the current, which is limited by the
secondary load.

On 13/05/2014 12:23, gareth wrote:
"Brian Morrison" wrote in message
...

It's the DC resistance that limits the primary current once the core
is saturated, not the inductance.

When the core is saturated the effective inductance is zero. Think
about the B-H loop diagram for a transformer.

You misunderstand.

I was referring to the saturation of the current, which is limited by the
secondary load.

Are you referring to saturation of the diodes in the rectifier connected
to the secondary?

Brian,

Hullo?

Are you returning to dispute about that which I said you are in error,
or does it stand that you have been corrected by me (yet again)?

"gareth" wrote in message
...
"Brian Reay" wrote in message
...

Another name for the Magnetic Vector Potential is curl,

That's not correct. Curl is a vector field function applicable to many
things, and you have to have the curl of something.

which is key to understanding it, as there is also a Magnetic Scalar
potential. Confuse the two and you will never understand them.

39


Back the Magnetic Vector Potential under the name of curl. Curl is used
in 3D Vector Calculus (essentially calculus applied to the three
orthogonal components of a vector) and is referred to as a vector
operator. Importantly, it is only applied to rotating vectors

That is very misleading. The flow in a stream has curl when the
middle of the stream flows faster than the edges, but the individual
flow vectors are linear and not rotating.


and, like like all calculus, assumes infinitesimally small changes (in
this case rotation). The curl is found by applying the curl operator, and
it yields a vector represents the instantaneous direction and rate of
change of the Magnetic field.

That is misleading as well. A linear magnetic field moving through
a medium of varying permeability will have a spatial rate of change but
it will not be revealed by curling.


Thus, the Magnetic Vector Potential is a vector which represents the
instantaneous rate of change in the magnetic field.

That is complete nonsense. "Instantaneous" refers to a time element,
whereas curl is a spatial operator.


It is a vector as it has "direction" (as magnetic fields have directions)
and magnitude. It is a rate of change as the curl operator is a
differential operator, applied to the 3 components of rotating vector.


Note: In this context, the rotating vector may be generated by a
sinusoidal current in a coil as identical to one generated by a true
rotating magnetic field


No doubt the OP will criticise the above but that is up to him. It should
have been covered in a telecomms degree. The calculus, although in 3D, is
actually minimal, in that it is applied independently and so is really A
level (or O level for us oldies).


39

Quite a lot of blustering there, OM, but my question related to a visual
representation of the phenomen. Perhaps your much-noted need to
jump in with snide remarks over-rode your technical research via google?

"gareth" wrote in message
...

Also, what of a visualisation of the Magnetic Vector Potential, "A"?


This was something that I puzzled over for years, because in my Uni
textbooks it was introduced out-of-the-blue, but without any preamble
and was therefore difficult to see how it came in (understanding first,
maths second!)

The revelation came, probably about 20 years after studying all that
stuff at Uni, when I was standing close to the platform edge when
a fast train went through, and the dust devils from that passing, as
well as being at ground level, were also in vortices in the air,at which
point it became clear in my mind.

We have many models for what is happening in electrickery, and all
of them are incomplete, or just plain wrong, so it is perhaps surprising
that any tyro can progress!

"Brian Reay" wrote in message
...

I've little doubt this is another of his attempts to start a vehicle for
his abuse.

39, OM.

Why are you so opposed to every attempt of mine to foment discussion
on technical matters in the amateur radio NG, and thereby restore to
prominence
the other great tradition of amateur radio, that of international
gentlemanliness?

What have you got against open technical discussion?

So far, the only abuse is that quoted above, and it has come from your own
keyboard, and your own keyboard alone.

What is it that has you contributing so much bile and bitterness into these
NG?

You repeatedly lay that sort of accusation at the door of other
contributors,
but invariably it is from you that unpleasantness originates, as quoted
above.

Well Brian, OM, point out the technical errors
in what I have replied to you. It would be a far better
approach than resorting to infantile sneers such as you do below?

(It is not a good example of public debate for the schoolchildren
under your care when you resort to abusive remarks after you
have been challenged in debate.)

"Brian Reay" wrote in message
...

I see he is also disputing KFK's /BM's inputs.

39

No, I'm not. What Brian said is true, but it is not to what
I was referring. Perhaps, once again, you urge to rush in
with infantile remarks has over-ridden your comprehension
of what you read?

You have to ask yourself why he thinks those with successful careers in
engineering (despite his totally false and malicious claims) are wrong and
he is always right.

23

We are not the ones with an "interesting" history of complaining about
employers etc.

39

An attempt to start Big K saga mk2.

7

Clearly he isn't getting enough attention in other areas.

39

"Brian Reay" wrote in message
...

You have to ask yourself why he thinks those with successful careers in
engineering are wrong and he is always right.

What a peculiar thing to say?

Are you suggesting that at times that you post things that you think to be
wrong?

But I think that you're on a very sticky wicket by referring
to "those with successful careers in engineering ", after Stan G4EGH
described you in floods of tears down the phone to him after you
were terminated only a very few weeks after changing jobs.

What happened there, OM?

On Tue, 13 May 2014 15:46:48 +0100, "gareth"
wrote:

"Brian Reay" wrote in message
...

You have to ask yourself why he thinks those with successful careers in
engineering are wrong and he is always right.

What a peculiar thing to say?

Are you suggesting that at times that you post things that you think to be
wrong?

But I think that you're on a very sticky wicket by referring
to "those with successful careers in engineering ", after Stan G4EGH
described you in floods of tears down the phone to him after you
were terminated only a very few weeks after changing jobs.

What happened there, OM?

That's an interesting point Gareth, why exactly would some-one who had
such a successful career, take up teaching? Indeed he is so desperate
to attempt to feel superior that he spends half the night researching
the Royal Logistic Corps in order to attempt to another poster wrong!

"Rambo" wrote in message
...
On Tue, 13 May 2014 15:46:48 +0100, "gareth"
wrote:

"Brian Reay" wrote in message
...

You have to ask yourself why he thinks those with successful careers in
engineering are wrong and he is always right.

What a peculiar thing to say?

Are you suggesting that at times that you post things that you think to be
wrong?

But I think that you're on a very sticky wicket by referring
to "those with successful careers in engineering ", after Stan G4EGH
described you in floods of tears down the phone to him after you
were terminated only a very few weeks after changing jobs.

What happened there, OM?

That's an interesting point Gareth, why exactly would some-one who had
such a successful career, take up teaching? Indeed he is so desperate
to attempt to feel superior that he spends half the night researching
the Royal Logistic Corps in order to attempt to another poster wrong!

The vocation of teaching is an indicator of a noble profession, but only
when
undertaken from graduation.

Those who "decide" to take up teaching at the age of 45 because their
"successful career" has been terminated and they cannot get another
job are just despicable.

When someone who _BOASTS_ of two degrees, one in electronics and the
other in mathematics talks such arrant nonsense about vector field theory
and makes false claims that the vector magnetic potential is a curl***** and
all is accompanied by gratuitous snide remarks, one
is forced to call into question exactly what nonsense he teaches and
whether or not he should be allowed to continue in a classroom?

The magnetic vector potential, A, is not a curl; however, the
magnetic field B comes from curl A.

(EOE, it is 20 years since Ii last looked at all this)