Current transformer

Thu Dec 01, 2011 1:23 am   

Would've been nice if I had known a current transformer isn't a very good
transformer. Instead of two terminals, it acts more like a single
terminal, with your poor burden resistor caught in the middle. Ah well,
such is basic research...

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

Thu Dec 01, 2011 2:17 am   

On Wed, 30 Nov 2011 18:23:18 -0600, "Tim Williams"
<tmoranwms_at_charter.net> wrote:


What?

John

Thu Dec 01, 2011 2:26 am   

"John Larkin" <jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote in
message news:ocldd7d2d4f9pqu02ucoqbbqb88i9qa54t_at_4ax.com...

Let me help you....
Here's the Jive Translation:

Would've been supa' fine if ah' had knode some current transfo'ma' isn't
some very baaaad transfo'mer. Ah be baaad... Instead uh two terminals,
it acts mo'e likes some sin'le terminal, wid yo' poo' burden resisto'
caught in de middle. What it is, Mama! Ah sheeit, such be basic
research...

Cheers

Thu Dec 01, 2011 2:34 am   

Tim Williams <tmoranwms_at_charter.net> wrote:

What?

Thu Dec 01, 2011 3:01 am   

"Tim Williams" <tmoranwms_at_charter.net> wrote in message
news:jb6hf9$1rt$1_at_dont-email.me...

All transformers are current transformers, see the Faraday's lows of mutual
induction.
In practice it can be configured in current, voltage or power mode depending
on application.



Mathew Orman

http://www.faster-than-light.us/

Thu Dec 01, 2011 3:03 am   

John Larkin wrote:


His current transformer is out of date...

--
You can't have a sense of humor, if you have no sense.

Thu Dec 01, 2011 3:40 am   

"admformeto" <admformeto_at_onet.eu> wrote in message
news:jb6n5i$u9u$1_at_dont-email.me...

News to Faraday, my transformer doesn't transform. At least, not very
well. At least, not within the first, about a microsecond.

Simple example: go buy a bog standard Triad CT206, it rings like a bell at
a rather low frequency (a MHz or so)!

In fact, I'm pretty sure it's acting as a toroidial resonator, which isn't
much heard of, helical resonators are more common. Same idea, but with
four quadrants.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

Thu Dec 01, 2011 3:56 am   

"Tim Williams" <tmoranwms_at_charter.net> wrote in message
news:jb6pg4$931$1_at_dont-email.me...

Your using it as an air core transformer. Didn't Telsa invent something
similar ;)

Cheers

Thu Dec 01, 2011 4:36 am   

"Martin Riddle" <martin_rid_at_verizon.net> wrote in message
news:jb6qcc$cq8$1_at_dont-email.me...

It sure feels like it, but I'm pretty sure the core is still mu_r >> 100
at whatever resonant frequencies these things are doing it at. I'd call
it a ferrite-loaded helico-toroidial resonator, or something ungainly like
that.

Since L is large, that means F is small (~MHz), and the impedance is
high -- sadly, the Q is also high, so the impedance (ESR, since it's a
series resonant equivalent) at the feedpoint (i.e. burden R) is very low.

It's very interesting to rotate the "primary" around the core and watch
the nodes in the standing wave. I should see about making an air-cored
version, driving it with RF and putting it in a low pressure neon
environment or something.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

Thu Dec 01, 2011 7:11 am   

Tim Williams wrote:

Thu Dec 01, 2011 10:13 am   

On a sunny day (Wed, 30 Nov 2011 20:40:20 -0600) it happened "Tim Williams"
<tmoranwms_at_charter.net> wrote in <jb6pg4$931$1_at_dont-email.me>:


I appreciate your deep knowledge of the subject,
however maybe I should not read about it,
as it makes something that I always perceived as extremely simple,
sooooo complicated.

Current transformer:
current_in / turns_ratio = current_out. (for a low load resistor or short).
current_out x load_resistor = voltage_out.

Of course there are some details,
but those can usually be disregarded as the errors caused by those are very small.
NORMALLY.

One lesson: Do Not Leave Out The Load Resistor, as then
Ze Foltage Kan Beacome Ferry High

Thu Dec 01, 2011 10:13 am   

On a sunny day (Wed, 30 Nov 2011 20:26:34 -0500) it happened "Martin Riddle"
<martin_rid_at_verizon.net> wrote in <jb6l4h$kfg$1_at_dont-email.me>:


LOL

Thu Dec 01, 2011 12:21 pm   

On Dec 1, 4:36 am, "Tim Williams" <tmoran...@charter.net> wrote:

You seem to have failed to take into acount the parallel capacitances
of the windings. No electronic component is pure - in the sense of
presenting only resistive, capacitative or inductive impedance - and
inductors/transformers are more imperfect than most.

--
Bill Sloman, Nijmegen

Thu Dec 01, 2011 1:56 pm   

On Dec 1, 6:11 am, Robert Baer <robertb...@localnet.com> wrote:

maybe he connected the wrong kind of 0 terminal capacitor?


NT

Thu Dec 01, 2011 4:05 pm   

On Wed, 30 Nov 2011 22:11:45 -0800, Robert Baer
<robertbaer_at_localnet.com> wrote:


Some people don't understand that the "burden" resistor value has a
maximum value before a current transformer goes crappy on you.

...Jim Thompson
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