Carrier current communication on Low voltage/high current AC

S

Spehro Pefhany

Guest
A little one-off (at the moment) G-job here:

I'm interested in doing carrier current communication over 12VAC
power. Total AC current will probably be in the 10-50A range, and I'd
like to get 4800 or 9600 baud, but less would be acceptable. There
could be a couple hundred feet of wire, and I don't control the source
impedance.

So, a fat choke (or the secondary of a transformer) in series with the
line and couple the carrier in capacitively or inductively?

Looks like there's some advantage in keeping the fundamental frequency
low if this is ever to have to deal with FCC etc. standards.

http://strategis.ic.gc.ca/epic/internet/insmt-gst.nsf/en/sf08216e.html

Maybe the AM IF frequency of 455kHz, making a ceramic filter for the
receiver easy?

Any other suggestions?


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
Hello Spehro,

So, a fat choke (or the secondary of a transformer) in series with the
line and couple the carrier in capacitively or inductively?
Click to expand...
A resonant circuit would make for a smaller device to isolate the RF
path. At 50A a choke can become rather bulky.

Looks like there's some advantage in keeping the fundamental frequency
low if this is ever to have to deal with FCC etc. standards.

http://strategis.ic.gc.ca/epic/internet/insmt-gst.nsf/en/sf08216e.html

Maybe the AM IF frequency of 455kHz, making a ceramic filter for the
receiver easy?
Click to expand...
I would go much lower, below 150kHz, but avoid any Loran ranges. X10
operates on 120kHz and AFAIK they blast several volts onto the mains line.

Any other suggestions?
Click to expand...
Stay away from simple AM on-off protocols. That is one of the downsides
of X10. It should at least be FM or something even more reliable. Your
protocol may have to be fault tolerant against missed or misinterpreted
bits. FEC and all that sort of things.

As to receiver filtering you can't use crystals at 9600bps. But LC is
pretty stable below 150kHz. Another upside of staying under 150kHz is
the abundance of ferrites that are suitable.

Using frequencies that others already have can yield FCC advantages
similar to what FDA 510(k) does in medical: Prior art, less scrutiny.
The downsides may be patent issues and the like.

Regards, Joerg

http://www.analogconsultants.com
 
Spehro Pefhany wrote:
A little one-off (at the moment) G-job here:

I'm interested in doing carrier current communication over 12VAC
power. Total AC current will probably be in the 10-50A range, and I'd
like to get 4800 or 9600 baud, but less would be acceptable. There
could be a couple hundred feet of wire, and I don't control the source
impedance.

So, a fat choke (or the secondary of a transformer) in series with the
line and couple the carrier in capacitively or inductively?

Looks like there's some advantage in keeping the fundamental frequency
low if this is ever to have to deal with FCC etc. standards.

http://strategis.ic.gc.ca/epic/internet/insmt-gst.nsf/en/sf08216e.html

Maybe the AM IF frequency of 455kHz, making a ceramic filter for the
receiver easy?

Any other suggestions?
Click to expand...
Take a look at how X10 stuff works (at the AC voltage zero crossings).
You might be able to adapt some existing chipsets and other hardware.

--
Paul Hovnanian mailto:paul@Hovnanian.com
------------------------------------------------------------------
Hanlon's Razor:
Never attribute to malice that which is adequately explained by
stupidity.
 
Hello Paul,

Take a look at how X10 stuff works (at the AC voltage zero crossings).
You might be able to adapt some existing chipsets and other hardware.
Click to expand...
We have some X10 and I don't find this AM protocol all that reliable. It
is also very slow.

Regards, Joerg

http://www.analogconsultants.com
 
On Wed, 08 Jun 2005 15:42:35 -0400, Spehro Pefhany wrote:

A little one-off (at the moment) G-job here:

I'm interested in doing carrier current communication over 12VAC
power. Total AC current will probably be in the 10-50A range, and I'd
like to get 4800 or 9600 baud, but less would be acceptable. There
could be a couple hundred feet of wire, and I don't control the source
impedance.

So, a fat choke (or the secondary of a transformer) in series with the
line and couple the carrier in capacitively or inductively?

Looks like there's some advantage in keeping the fundamental frequency
low if this is ever to have to deal with FCC etc. standards.

http://strategis.ic.gc.ca/epic/internet/insmt-gst.nsf/en/sf08216e.html

Maybe the AM IF frequency of 455kHz, making a ceramic filter for the
receiver easy?

Any other suggestions?
Click to expand...
Just OTTOMH - brute-force baseband (9600 HZ Manchester, DTMF, ?) through a
current transformer?

It's just I'm thinking "modulation", with a transmission line impedance of
0.2 - 1 ohm, 60 HZ "carrier" - or just superimpose your data stream, coded
at your leisure. What kind of noise and crap are we dealing with here?

Good Luck!
Rich
 
On Wed, 08 Jun 2005 15:42:35 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

A little one-off (at the moment) G-job here:

I'm interested in doing carrier current communication over 12VAC
power. Total AC current will probably be in the 10-50A range, and I'd
like to get 4800 or 9600 baud, but less would be acceptable. There
could be a couple hundred feet of wire, and I don't control the source
impedance.

So, a fat choke (or the secondary of a transformer) in series with the
line and couple the carrier in capacitively or inductively?

Looks like there's some advantage in keeping the fundamental frequency
low if this is ever to have to deal with FCC etc. standards.

http://strategis.ic.gc.ca/epic/internet/insmt-gst.nsf/en/sf08216e.html

Maybe the AM IF frequency of 455kHz, making a ceramic filter for the
receiver easy?

Any other suggestions?
Click to expand...

Maybe pass the power wire through a low-mu core and inject the signal
in series, rather than in parallel? Ditto receive end.

If there are any bridge rectifiers in the system, the line parallel
impedance will be modulated by diode conduction!

John
 
In article <g5iea11r8tge2cpf7j0c3ri79h0ls0osip@4ax.com>,
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> wrote:

I'm interested in doing carrier current communication over 12VAC
power. Total AC current will probably be in the 10-50A range, and
I'd like to get 4800 or 9600 baud, but less would be acceptable.
There could be a couple hundred feet of wire, and I don't control
the source impedance.
Click to expand...
Maybe think about transmitting the comms as a common-mode
voltage. The 24Vac system can be connected to Ground at
60Hz (or have stray-C to ground), just devise something
that makes that connection a high impedance at (and above)
the comms carrier frequency.

--
Tony Williams.
 
Tony Williams wrote:
In article <g5iea11r8tge2cpf7j0c3ri79h0ls0osip@4ax.com>,
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> wrote:


I'm interested in doing carrier current communication over 12VAC
power. Total AC current will probably be in the 10-50A range, and
I'd like to get 4800 or 9600 baud, but less would be acceptable.
There could be a couple hundred feet of wire, and I don't control
the source impedance.


Maybe think about transmitting the comms as a common-mode
voltage. The 24Vac system can be connected to Ground at
60Hz (or have stray-C to ground), just devise something
that makes that connection a high impedance at (and above)
the comms carrier frequency.
Click to expand...
That's one of three possibilities of selecting two of three terminals
for the signal transmission , but for some reason it is forbidden for
safety reasons. Also, the current carrier method of inducing a signal
via transformer with secondary in series with line is also rejected-
probably too much bulk required there.
 
On Thu, 09 Jun 2005 12:20:54 GMT, Fred Bloggs <nospam@nospam.com>
wrote:

Tony Williams wrote:
In article <g5iea11r8tge2cpf7j0c3ri79h0ls0osip@4ax.com>,
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> wrote:


I'm interested in doing carrier current communication over 12VAC
power. Total AC current will probably be in the 10-50A range, and
I'd like to get 4800 or 9600 baud, but less would be acceptable.
There could be a couple hundred feet of wire, and I don't control
the source impedance.


Maybe think about transmitting the comms as a common-mode
voltage. The 24Vac system can be connected to Ground at
60Hz (or have stray-C to ground), just devise something
that makes that connection a high impedance at (and above)
the comms carrier frequency.


That's one of three possibilities of selecting two of three terminals
for the signal transmission , but for some reason it is forbidden for
safety reasons. Also, the current carrier method of inducing a signal
via transformer with secondary in series with line is also rejected-
probably too much bulk required there.
Click to expand...

"Is also rejected"? Some sort of Royal decree?

John
 
On Thu, 09 Jun 2005 07:58:10 -0700, the renowned John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
"Is also rejected"? Some sort of Royal decree?

John
Click to expand...
I like it better than that execrable term "deemed".


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
On Thu, 09 Jun 2005 13:01:48 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

On Thu, 09 Jun 2005 07:58:10 -0700, the renowned John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

"Is also rejected"? Some sort of Royal decree?

John

I like it better than that execrable term "deemed".
Click to expand...
The one I hate is "good engineering practice" which usually means "I
always do it that way but can't actually explain why."


John
 
On Thu, 09 Jun 2005 18:49:52 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Thu, 09 Jun 2005 13:01:48 -0400, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

On Thu, 09 Jun 2005 07:58:10 -0700, the renowned John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

"Is also rejected"? Some sort of Royal decree?

John

I like it better than that execrable term "deemed".



The one I hate is "good engineering practice" which usually means "I
always do it that way but can't actually explain why."


John
Click to expand...
I use the term "good engineering practice" to indicate to the client
that, if they'd done it my way, they wouldn't be in ka-ka-land right
now ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
On Thu, 09 Jun 2005 19:03:45 -0700, Jim Thompson
<thegreatone@example.com> wrote:

On Thu, 09 Jun 2005 18:49:52 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Thu, 09 Jun 2005 13:01:48 -0400, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

On Thu, 09 Jun 2005 07:58:10 -0700, the renowned John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

"Is also rejected"? Some sort of Royal decree?

John

I like it better than that execrable term "deemed".



The one I hate is "good engineering practice" which usually means "I
always do it that way but can't actually explain why."


John

I use the term "good engineering practice" to indicate to the client
that, if they'd done it my way, they wouldn't be in ka-ka-land right
now ;-)

...Jim Thompson
Click to expand...
I should have added... I told a client more than two weeks ago, "your
design failed because....".

They vehemently denied it could happen, that I was totally wrong, how
could I be so wrong, all their simulations showed it was stable, etc.

Guess who's kissing my ass today ?:)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
On Thu, 09 Jun 2005 18:49:52 -0700, the renowned John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Thu, 09 Jun 2005 13:01:48 -0400, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

On Thu, 09 Jun 2005 07:58:10 -0700, the renowned John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

"Is also rejected"? Some sort of Royal decree?

John

I like it better than that execrable term "deemed".



The one I hate is "good engineering practice" which usually means "I
always do it that way but can't actually explain why."
John
Click to expand...
Or they just don't like the looks of something innovative, therefore
it doesn't conform to "good engineering practice".


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
Jim Thompson wrote:
On Thu, 09 Jun 2005 19:03:45 -0700, Jim Thompson
thegreatone@example.com> wrote:


On Thu, 09 Jun 2005 18:49:52 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:


On Thu, 09 Jun 2005 13:01:48 -0400, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:


On Thu, 09 Jun 2005 07:58:10 -0700, the renowned John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

"Is also rejected"? Some sort of Royal decree?

John

I like it better than that execrable term "deemed".



The one I hate is "good engineering practice" which usually means "I
always do it that way but can't actually explain why."


John

I use the term "good engineering practice" to indicate to the client
that, if they'd done it my way, they wouldn't be in ka-ka-land right
now ;-)

...Jim Thompson


I should have added... I told a client more than two weeks ago, "your
design failed because....".

They vehemently denied it could happen, that I was totally wrong, how
could I be so wrong, all their simulations showed it was stable, etc.

Guess who's kissing my ass today ?:)

...Jim Thompson
Click to expand...
Ya gotta love it when that happens. I love that Gore Vidal quote - "It
is not enough to succeed, others must fail"

Cheers
Terry
 
Tony Williams wrote:
In article <42A83423.1040507@nospam.com>,
Fred Bloggs <nospam@nospam.com> wrote:


Tony Williams wrote:

Maybe think about transmitting the comms as a common-mode
voltage....etc.


That's one of three possibilities of selecting two of three
terminals for the signal transmission , but for some reason it
is forbidden for safety reasons............


Pity. Common-mode signalling would probably be the
easier to implement.


........Also, the current carrier method of inducing a signal via
transformer with secondary in series with line is also rejected-
probably too much bulk required there.


An inductor at each end of the line might be used to raise
the impedance at the carrier frequency. This would allow
capacitively-coupled differential signalling.

* L1 50A,60Hz * L2
+-----/////---+--------->--------+--/////----+
60Hz supply ----- | | ----- Load
+-----/////-------+----------+------/////----+
* | | | | *
C1=== | | ===C2
| | | |
Tx Rx

Perhaps look for inductors from switchers, in the range
20-50uH at 50Adc polarisation. Use Speff's 455KHz
carrier frequency.
Click to expand...
Now that looks darn near perfect....
 
John Larkin wrote:
On Thu, 09 Jun 2005 12:20:54 GMT, Fred Bloggs <nospam@nospam.com
wrote:



Tony Williams wrote:

In article <g5iea11r8tge2cpf7j0c3ri79h0ls0osip@4ax.com>,
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> wrote:



I'm interested in doing carrier current communication over 12VAC
power. Total AC current will probably be in the 10-50A range, and
I'd like to get 4800 or 9600 baud, but less would be acceptable.
There could be a couple hundred feet of wire, and I don't control
the source impedance.


Maybe think about transmitting the comms as a common-mode
voltage. The 24Vac system can be connected to Ground at
60Hz (or have stray-C to ground), just devise something
that makes that connection a high impedance at (and above)
the comms carrier frequency.


That's one of three possibilities of selecting two of three terminals
for the signal transmission , but for some reason it is forbidden for
safety reasons. Also, the current carrier method of inducing a signal
via transformer with secondary in series with line is also rejected-
probably too much bulk required there.



"Is also rejected"? Some sort of Royal decree?

John
Click to expand...
Your series inductive coupling requires you to break the high power
utility circuit, you do not need to break the circuit to install a shunt
source and the components do not have to be rated to withstand 10KA
surges and whatnots. ASK is the last kind of modulation anyone would
want to use. A high frequency trap driving a comparator/limiter
combination into his 455KHz resonator for gain/slope detection of an FSK
signal in MARK-NULL-SPACE format is much more impervious to
interference- there should be more than a few reference designs he can use.
 
Tony Williams wrote:

[...]

An inductor at each end of the line might be used to raise
the impedance at the carrier frequency. This would allow
capacitively-coupled differential signalling.

* L1 50A,60Hz * L2
+-----/////---+--------->--------+--/////----+
60Hz supply ----- | | ----- Load
+-----/////-------+----------+------/////----+
* | | | | *
C1=== | | ===C2
| | | |
Tx Rx

Perhaps look for inductors from switchers, in the range
20-50uH at 50Adc polarisation. Use Speff's 455KHz
carrier frequency.

Tony Williams.
Click to expand...
How about using the GND and Neutral? No series inductors needed, and
no line voltage to worry about.

The GND and neutral are joined at the source, so the driver has to
deliver current into a short circuit. A few dozen feet of wire will
give enough impedance to develop a useful signal.

Hot +-------------------- Black ------------------+

60Hz supply Load

+-------------+------ White -----+------------+
| |
GND +-------------|---+-- Green -+---|------------+
| | | |
C1=== | | ===C2
| | | |
Tx Rx

Carrier current often uses wideband FM to reduce noise. The
frequencies may be around 300KHz or so.

In fact, now that I think of it, I may have a use for this. Thanks!

Mike Monett
 
In article <42A9736A.594B@spam.com>,
Mike Monett <no@spam.com> wrote:

The GND and neutral are joined at the source, so the driver
has to deliver current into a short circuit. A few dozen feet
of wire will give enough impedance to develop a useful signal.

Hot +-------------------- Black ------------------+

60Hz supply Load

+-------------+------ White -----+------------+
| |
GND +-------------|---+-- Green -+---|------------+
| | | |
C1=== | | ===C2
| | | |
Tx Rx
Click to expand...
I think that is a variation of the common-mode
signalling that has already been mentioned Mike.

Hot +-------------------- Black ------------------+

60Hz supply Load
L1 L2
+------///----+------ White -----+------///---+
|? | | |?
GND +-------------|---+-- Green -+---|------------+
| | | |
C1=== | | ===C2
| | | |
Tx Rx

L1 and L2 are still handy additions because they isolate
the comms-driven section of line, away from any Grounding
that may happen at either end.

--
Tony Williams.
 
On Fri, 10 Jun 2005 09:43:49 +0100, the renowned Tony Williams
<tonyw@ledelec.demon.co.uk> wrote:

An inductor at each end of the line might be used to raise
the impedance at the carrier frequency. This would allow
capacitively-coupled differential signalling.

* L1 50A,60Hz * L2
+-----/////---+--------->--------+--/////----+
60Hz supply ----- | | ----- Load
+-----/////-------+----------+------/////----+
* | | | | *
C1=== | | ===C2
| | | |
Tx Rx

Perhaps look for inductors from switchers, in the range
20-50uH at 50Adc polarisation. Use Speff's 455KHz
carrier frequency.
Click to expand...
That should work nicely, of course one of the advantages of getting
the frequency up is to use a smaller inductor. It's almost into
reasonable air-core range, which could be helpful at one end.

I keep thinking I'm missing some obvious possibility with those
chokes, but maybe not.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top