** Two pics of scope screens for SED

Same 23 watt CFL used in each case for current trace.

Normal AC supply versus pure sine wave supply.

Voltage trace = 100 V per div

Current trace =120 mA per div



...... Phil

On Wed, 18 Mar 2009 19:25:35 +1100, "Phil Allison"
wrote:



** Two pics of scope screens for SED

Same 23 watt CFL used in each case for current trace.

Normal AC supply versus pure sine wave supply.

Voltage trace = 100 V per div

Current trace =120 mA per div



..... Phil






Pretty nice if all that is needed to excite the gas are the peaks.

You mention units per division, but no divisions are visible.

Looks like the cut-off source makes light with less power.

What brands of lamp?

"Mr.Eko"

** Two pics of scope screens for SED

Same 23 watt CFL used in each case for current trace.

Pretty nice if all that is needed to excite the gas are the peaks.


** So you have no idea what a " CFL " is ?


You mention units per division, but no divisions are visible.


** Yes they are.

**** off - IMBECILE

On Wed, 18 Mar 2009 20:11:06 +1100, "Phil Allison"
wrote:


"Mr.Eko"

** Two pics of scope screens for SED

Same 23 watt CFL used in each case for current trace.

Pretty nice if all that is needed to excite the gas are the peaks.


** So you have no idea what a " CFL " is ?


You mention units per division, but no divisions are visible.


** Yes they are.

**** off - IMBECILE

You couldn't get any worse, idiot.

Yes, I know what the device under discussion is, and it is YOU that is
the imbecile.

Mainly because you wouldn't know how to respond to anyone if you tried.
You are sub-human scum.

Even Roy and Proteus are better than a dope like you, Phil.

And no, you do not have the brains many here tout you as having. The
main reason being your abject inability to make a proper response.

You take idiocy to an all time new low. I hope you feel good about
yourself. You really are a sad case.


All the blank lines after the CRAP you post is another reason that you
are stupid.

In article ,
"Phil Allison" wrote:

Same 23 watt CFL used in each case for current trace.

Normal AC supply versus pure sine wave supply.

Voltage trace = 100 V per div

Current trace =120 mA per div



..... Phil

What is your 'normal' supply? If it does this on ‰ 0.5 A it's got
some problems. The tail on the current wave is LT 0.1 A

The last time I saw a 'flat' topped AC supply wave, it was
because the experimenter had set the wrong range on the recording
device and the wave was clipped.

Also, could it be that your normal supply has a heavy 3rd
harmonic load? (I retired before harmonics on the neutral became
an issue so I've never seen this type of distortion from a wall
outlet but I imagine that it could exist somewhere.)

--
Fred Lotte

Phil Allison wrote:

** Two pics of scope screens for SED

Same 23 watt CFL used in each case for current trace.

Normal AC supply versus pure sine wave supply.

You've got a serious case of 'flat topping' there. What's the THD ?

Graham

On Wed, 18 Mar 2009 19:25:35 +1100, Phil Allison wrote:

** Two pics of scope screens for SED

Same 23 watt CFL used in each case for current trace.

Normal AC supply versus pure sine wave supply.

Voltage trace = 100 V per div

Current trace =120 mA per div



How did you get the clean AC, Phil? I'm assuming that the blip on the
voltage waveform where the CFL fires is because the supply isn't of a low
enough impedance, so is it from the output of an amplifier, stepped up
through a step-up transformer?

Your mains supply looks rubbish! Are you on the end of a long feed?

Nice pics, by the way.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.

"mick"
Phil Allison wrote:

** Two pics of scope screens for SED

Same 23 watt CFL used in each case for current trace.

Normal AC supply versus pure sine wave supply.

Voltage trace = 100 V per div

Current trace =120 mA per div



How did you get the clean AC, Phil? I'm assuming that the blip on the
voltage waveform where the CFL fires is because the supply isn't of a low
enough impedance, so is it from the output of an amplifier, stepped up
through a step-up transformer?


** Yep.

I used a 600 watt mosfet amp driving a 300VA toroidal in reverse, fed from
my bench sine generator set to 50 Hz.


Your mains supply looks rubbish!


** Fraid the same wave shape is almost universal.

Ever checked your local AC power voltage wave shape ?


Are you on the end of a long feed?


** In the heart of Sydney's inner suburbs.



....... Phil

On Thu, 19 Mar 2009 20:07:16 +1100, "Phil Allison"
wrote:


"mick"
Phil Allison wrote:

** Two pics of scope screens for SED

Same 23 watt CFL used in each case for current trace.

Normal AC supply versus pure sine wave supply.

Voltage trace = 100 V per div

Current trace =120 mA per div



How did you get the clean AC, Phil? I'm assuming that the blip on the
voltage waveform where the CFL fires is because the supply isn't of a low
enough impedance, so is it from the output of an amplifier, stepped up
through a step-up transformer?


** Yep.

I used a 600 watt mosfet amp driving a 300VA toroidal in reverse, fed from
my bench sine generator set to 50 Hz.


Your mains supply looks rubbish!


** Fraid the same wave shape is almost universal.

Ever checked your local AC power voltage wave shape ?


Are you on the end of a long feed?


** In the heart of Sydney's inner suburbs.



...... Phil


Same bulb, but I'd bet that your "pure sine wave" drive actually
consumes more power.

On Thu, 19 Mar 2009 20:07:16 +1100, "Phil Allison"
wrote:


"mick"
Phil Allison wrote:

** Two pics of scope screens for SED

Same 23 watt CFL used in each case for current trace.

Normal AC supply versus pure sine wave supply.

Voltage trace = 100 V per div

Current trace =120 mA per div



How did you get the clean AC, Phil? I'm assuming that the blip on the
voltage waveform where the CFL fires is because the supply isn't of a low
enough impedance, so is it from the output of an amplifier, stepped up
through a step-up transformer?


** Yep.

I used a 600 watt mosfet amp driving a 300VA toroidal in reverse, fed from
my bench sine generator set to 50 Hz.


Your mains supply looks rubbish!


** Fraid the same wave shape is almost universal.

Ever checked your local AC power voltage wave shape ?


Are you on the end of a long feed?


** In the heart of Sydney's inner suburbs.



...... Phil



I dont know a lot about transmission line theory, not have i put a lot
of thought to it, but why is it so bad?

On Thu, 19 Mar 2009 20:07:16 +1100, Phil Allison wrote:

snip

** Fraid the same wave shape is almost universal.

Ever checked your local AC power voltage wave shape ?



I just had a look now (2PM on Thursday here, so mostly businesses on the
mains). Our waveshape at the moment is fairly clean. Some flat-topping
and, perhaps, a bit more triangular than sine! Probably a *bit* better
than yours was at the time though.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.

On Thu, 19 Mar 2009 14:16:29 GMT, mick wrote:

On Thu, 19 Mar 2009 20:07:16 +1100, Phil Allison wrote:

snip

** Fraid the same wave shape is almost universal.

Ever checked your local AC power voltage wave shape ?



I just had a look now (2PM on Thursday here, so mostly businesses on the
mains). Our waveshape at the moment is fairly clean. Some flat-topping
and, perhaps, a bit more triangular than sine! Probably a *bit* better
than yours was at the time though.

I'd love to see some grid waveforms from around the world.

Here are 4, all from around the Puget Sound area.

There's quite a bit of variation for a relatively small geographic area.

Phil Allison wrote:

"mick"
Phil Allison wrote:

** Two pics of scope screens for SED

Same 23 watt CFL used in each case for current trace.

Normal AC supply versus pure sine wave supply.

Voltage trace = 100 V per div

Current trace =120 mA per div


How did you get the clean AC, Phil? I'm assuming that the blip on the
voltage waveform where the CFL fires is because the supply isn't of a low
enough impedance, so is it from the output of an amplifier, stepped up
through a step-up transformer?

** Yep.

I used a 600 watt mosfet amp driving a 300VA toroidal in reverse, fed from
my bench sine generator set to 50 Hz.

Almost exactly what I did for *measuring* harmonics on EUT.


Your mains supply looks rubbish!

** Fraid the same wave shape is almost universal.

Ever checked your local AC power voltage wave shape ?

I certainly have. It's not as bad as that. Do you have a THD figure ?

Graham

The Real Andy wrote:

I dont know a lot about transmission line theory, not have i put a lot
of thought to it, but why is it so bad?

It's nothing to do with transmission line theory. It's the combination of supply
source impedance and non-linear loads like capacitor input filter DC supplies.
The current is drawn only over somewhere between (typically) 2 and 3.5 ms of a
10 ms 1/2 cycle. The effect is called 'flat-topping'.

EN61000-3-2 addresses it and much new equipment must correct for the harmonic
content of the current it draws, slightly erroneously usually called PFC (power
factor correction ).

Graham

The Phantom wrote:

On Thu, 19 Mar 2009 14:16:29 GMT, mick wrote:
On Thu, 19 Mar 2009 20:07:16 +1100, Phil Allison wrote:

** Fraid the same wave shape is almost universal.

Ever checked your local AC power voltage wave shape ?

I just had a look now (2PM on Thursday here, so mostly businesses on the
mains). Our waveshape at the moment is fairly clean. Some flat-topping
and, perhaps, a bit more triangular than sine! Probably a *bit* better
than yours was at the time though.

I'd love to see some grid waveforms from around the world.

Here are 4, all from around the Puget Sound area.

There's quite a bit of variation for a relatively small geographic area.

Number 1 looks very clean but there's some strange waveform distortion in
there. 3 and 4 are more typical of what I'd expect to see widely..

Graham

"The Phantom" wrote in message
...
On Thu, 19 Mar 2009 14:16:29 GMT, mick wrote:

On Thu, 19 Mar 2009 20:07:16 +1100, Phil Allison wrote:

snip

** Fraid the same wave shape is almost universal.

Ever checked your local AC power voltage wave shape ?



I just had a look now (2PM on Thursday here, so mostly businesses on the
mains). Our waveshape at the moment is fairly clean. Some flat-topping
and, perhaps, a bit more triangular than sine! Probably a *bit* better
than yours was at the time though.

I'd love to see some grid waveforms from around the world.

Here are 4, all from around the Puget Sound area.

There's quite a bit of variation for a relatively small geographic area.




Pic from a couple of years ago. Still same 5 minutes ago.
NB: your Pics #3 and #4, look to have that characteristic non linear
crossover distortion seen at the secondaries of low voltage step down
transformers ??.

"john jardine"


NB: your Pics #3 and #4, look to have that characteristic non linear
crossover distortion seen at the secondaries of low voltage step down
transformers ??.


** Entirely due to magnetising current peaks in the primary occurring 90
degrees later than the voltage peaks.

These current peaks briefly drop the effective primary voltage and create
the waveform distortion seen at the secondary.

The effect is pretty much limited to small e-core jobs - less than 50VA.



...... Phil