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? If? you look? at the? distorted waveform coming out of the FWB, FWCT, FWD, it typ consists of high, peak pulsed? currents.... when a C filter is used.? ? Like? 15-24A on peaks....and only? 1.5? to? 1.7 msecs in duration? at the bottom....as? seen on a scope.? ?Same deal on both the sec..and pri? of the? plate xfmr.?
To measure primary? AC current on the? plate xfmr,? ?you really require an? TRUE RMS? AC? Ammeter.? ? I hadn't? even thought of that anomaly, when? installing a? 0-150A? panel mount? ? AC? AMMETER.? ?
Did some research, and if using a NON rms ammeter? on the primary of a? single phase plate xfmr...with a FWB / FWD /? FWCT rectifier? and C?? filter, the non rms meter? can indicate as much as 40%? on the low side !
The plan is to compare the panel meter to a Fluke true rms clamp on ac?ammeter.?
Even with all that, you still have the issue of Power factor. True rms??Volts? X? true RMS? amps?=?True??VA power,? not??true?watts.??One of the ham fellows sent me a pix of his? spectrum analyzer display, depicting the odd? harmonics of the? 60 hz input...of a plate xfmr and FWB +? high? C? filter.? ?The? 3rd and also 5th? (180 hz + 300 hz) harmonic is the worse, then the 7/9/11+? drops like a rock.? ? With? full? wave rectification, the harmonics are always odd.? A half wave rectifier produces only even??harmonics.?
What? would be interesting is to measure peak AC current on the pri.? ? ?Then? compare to software results.?
Jim? ?VE7RF
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The garbage coming off the power line, as well as "in house" appliance generated trash doesn't give us much better.? The old Amp meters can give us effective amps based on heat and those don't care what the waveform looks like.
73, Roger (K8RI)
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On 6/12/2019 9:46 AM, jim.thom@... [ham_amplifiers] wrote:
? If? you look? at the? distorted waveform coming out of the FWB, FWCT, FWD, it typ consists of high, peak pulsed? currents.... when a C filter is used.? ? Like 15-24A on peaks....and only? 1.5? to? 1.7 msecs in duration? at the bottom....as? seen on a scope.? ?Same deal on both the sec..and pri? of the? plate xfmr.
To measure primary? AC current on the? plate xfmr, ?you really require an? TRUE RMS? AC? Ammeter.? ? I hadn't? even thought of that anomaly, when? installing a? 0-150A? panel mount? ? AC? AMMETER.
Did some research, and if using a NON rms ammeter on the primary of a? single phase plate xfmr...with a FWB / FWD /? FWCT rectifier? and C ? filter, the non rms meter? can indicate as much as 40%? on the low side !
The plan is to compare the panel meter to a Fluke true rms clamp on ac ammeter.
Even with all that, you still have the issue of Power factor. True rms ?Volts? X? true RMS? amps = True ?VA power,? not true watts. One of the ham fellows sent me a pix of his? spectrum analyzer display, depicting the odd? harmonics of the? 60 hz input...of a plate xfmr and FWB +? high? C? filter.? ?The? 3rd and also 5th (180 hz + 300 hz) harmonic is the worse, then the 7/9/11+? drops like a rock.? ? With? full? wave rectification, the harmonics are always odd.? A half wave rectifier produces only even ?harmonics.
What? would be interesting is to measure peak AC current on the pri. ?Then? compare to software results.
Jim? ?VE7RF
--
Roger (K8RI)
|
<The garbage coming off the power line, as well as "in house" appliance?
<generated trash doesn't give us much better.? The old Amp meters can?
<give us effective amps based on heat and those don't care what the?
<waveform looks like.
<73, Roger (K8RI)
##? apparently, the only type of? AC? AMMETER? ?that? indicates? true? rms? current (regardless of? wave form)? is the Moving Iron type.? ? ?Dunno if my 3 x panel meters? are moving iron? type..or not.? I'll? try and dig up info from the meter? maker.?
##? Mine all use a 5:1? current xfmr torrid....? ?with one conductor? passing through the torroid? hole.? I use a 0-75A? for the? fil of the? 3cx3000a7.? ? ?And a? 0-100? A? ?for the fil of the 3x6? fil.? The 3rd is a 0-150A, used for the pri of the plate xmfr.?
## 2 wires? from current xfmr..... over to the respective panel meter.?
##? I'll? test this all out.? ?Current on both? fi? xfmr? sec? are? resistive of course.? ? Its the plate xfmr pri? ?I'm? concerned about.?
Jim? ?VERF ---In ham_amplifiers@..., <k8ri@...> wrote : The garbage coming off the power line, as well as "in house" appliance
generated trash doesn't give us much better.? The old Amp meters can
give us effective amps based on heat and those don't care what the
waveform looks like.
73, Roger (K8RI)
On 6/12/2019 9:46 AM, jim.thom@... [ham_amplifiers] wrote:
>
> ? If? you look? at the? distorted waveform coming out of the FWB,
> FWCT, FWD, it typ consists of high, peak pulsed? currents.... when a C
> filter is used.? ? Like 15-24A on peaks....and only? 1.5? to? 1.7
> msecs in duration? at the bottom....as? seen on a scope.? ?Same deal
> on both the sec..and pri? of the? plate xfmr.
>
>
> To measure primary? AC current on the? plate xfmr, ?you really require
> an? TRUE RMS? AC? Ammeter.? ? I hadn't? even thought of that anomaly,
> when? installing a? 0-150A? panel mount? ? AC? AMMETER.
>
>
> Did some research, and if using a NON rms ammeter on the primary of a?
> single phase plate xfmr...with a FWB / FWD /? FWCT rectifier? and C ?
> filter, the non rms meter? can indicate as much as 40%? on the low side !
>
>
> The plan is to compare the panel meter to a Fluke true rms clamp on ac
> ammeter.
>
>
> Even with all that, you still have the issue of Power factor. True rms
> ?Volts? X? true RMS? amps = True ?VA power,? not true watts. One of
> the ham fellows sent me a pix of his? spectrum analyzer display,
> depicting the odd? harmonics of the? 60 hz input...of a plate xfmr and
> FWB +? high? C? filter.? ?The? 3rd and also 5th (180 hz + 300 hz)
> harmonic is the worse, then the 7/9/11+? drops like a rock.? ? With?
> full? wave rectification, the harmonics are always odd.? A half wave
> rectifier produces only even ?harmonics.
>
>
> What? would be interesting is to measure peak AC current on the pri.
> ?Then? compare to software results.
>
>
> Jim? ?VE7RF
>
>
--
Roger (K8RI)
|
A few years back, on some FB group I belonged to at the time, I
forget which, somebody posted a picture of a large industrial
transformer, I'll guess it was maybe 10' square and 8' tall, I
really don't remember, but YUGE compared to a residential pole
pig. It was old, and had definite discoloration of the paint in
some areas, not in others.
I didn't follow his point of posting, so I asked him why an old
xfmr would discolor in some areas, not in others, and many years
after installation. He said that, being in an industrial area,
there were lots of machines using solid-state switching at high
power levels, creating all sorts of transients and weird currents
that the design of the old xfrm never anticipated.
Obviously, some of that garbage would escape back out into the
neighborhood HV lines. And back into our homes. So, yeah, no. Not
gonna be easy to get the RMS value of garbage.
73
Randy
KZ4RV
On 6/13/2019 4:10 AM, 'Roger (K8RI)'
k8ri@... [ham_amplifiers] wrote:
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Show quoted text
??
The garbage coming off the power line, as well as "in
house" appliance
generated trash doesn't give us much better.?? The old Amp
meters can
give us effective amps based on heat and those don't care
what the
waveform looks like.
73, Roger (K8RI)
|
A thermocouple meter will measure true RMS regardless of the waveform. Old school stuff. ?
toggle quoted message
Show quoted text
On Jun 12, 2019, at 9:46 AM, jim.thom@... [ham_amplifiers] < ham_amplifiers@...> wrote:
?
? If? you look? at the? distorted waveform coming out of the FWB, FWCT, FWD, it typ consists of high, peak pulsed? currents.... when a C filter is used.? ? Like? 15-24A on peaks....and only? 1.5? to? 1.7 msecs in duration? at the bottom....as? seen on a scope.? ?Same deal on both the sec..and pri? of the? plate xfmr.?
To measure primary? AC current on the? plate xfmr,? ?you really require an? TRUE RMS? AC? Ammeter.? ? I hadn't? even thought of that anomaly, when? installing a? 0-150A? panel mount? ? AC? AMMETER.? ?
Did some research, and if using a NON rms ammeter? on the primary of a? single phase plate xfmr...with a FWB / FWD /? FWCT rectifier? and C?? filter, the non rms meter? can indicate as much as 40%? on the low side !
The plan is to compare the panel meter to a Fluke true rms clamp on ac?ammeter.?
Even with all that, you still have the issue of Power factor. True rms??Volts? X? true RMS? amps?=?True??VA power,? not??true?watts.??One of the ham fellows sent me a pix of his? spectrum analyzer display, depicting the odd!
? harmonics of the? 60 hz input...of a plate xfmr and FWB +? high? C? filter.? ?The? 3rd and also 5th? (180 hz + 300 hz) harmonic is the worse, then the 7/9/11+? drops like a rock.? ? With? full? wave rectification, the harmonics are always odd.? A half wave rectifier produces only even??harmonics.?
What? would be interesting is to measure peak AC current on the pri.? ? ?Then? compare to software results.?
Jim? ?VE7RF
|
What precision do you want?
For what you probably want, I would think a true RMS volt meter of a known accuracy within a couple % and a known resistance should suffice as measuring the calibration, but.the problem with true RMS volt meters is how do they handle a not so clean wave form.
The problem with the moving vane current meters, as I understand it, is accuracy and I believe they are also the cheapest
I don't know where they stand as far as repeatability.
I use a 3KVA line conditioner that develops a clean and regulated, true sin wave for the 120 VAC stuff in the shack. (2 computers and two transceivers) They could be calibrated against a precision Power Supply or in series with a precision A meter using clean DC.
OTOH I don't remember any inexpensive way to measure how well they do against a ratty RMS wave form.
It's been a very long time since I did measurements traceable to the NBS
After 33 years I'm not sure if I can remember how I did all of that.
73, Roger (K8RI)
toggle quoted message
Show quoted text
On 6/13/2019 9:52 AM, jim.thom@... [ham_amplifiers] wrote:
<The garbage coming off the power line, as well as "in house" appliance
<generated trash doesn't give us much better.? The old Amp meters can
<give us effective amps based on heat and those don't care what the
<waveform looks like.
<73, Roger (K8RI)
##? apparently, the only type of? AC? AMMETER? ?that? indicates? true rms? current (regardless of? wave form)? is the Moving Iron type.? ? ?Dunno if my 3 x panel meters? are moving iron? type..or not.? I'll? try and dig up info from the meter? maker.
##? Mine all use a 5:1? current xfmr torrid....? ?with one conductor passing through the torroid? hole.
I use a 0-75A? for the? fil of the? 3cx3000a7.? ? ?And a? 0-100? A? ?for the fil of the 3x6? fil.? The 3rd is a 0-150A,
used for the pri of the plate xmfr.
## 2 wires? from current xfmr..... over to the respective panel meter.
##? I'll? test this all out.? ?Current on both? fi? xfmr? sec? are resistive of course.? ? Its the plate xfmr pri? ?I'm concerned about.
Jim? ?VERF
---In ham_amplifiers@..., <k8ri@...> wrote :
The garbage coming off the power line, as well as "in house" appliance
generated trash doesn't give us much better.? The old Amp meters can
give us effective amps based on heat and those don't care what the
waveform looks like.
73, Roger (K8RI)
On 6/12/2019 9:46 AM, jim.thom@... <mailto:jim.thom@...>
[ham_amplifiers] wrote:
>
> ? If? you look? at the? distorted waveform coming out of the FWB,
> FWCT, FWD, it typ consists of high, peak pulsed? currents....
when a C
> filter is used.? ? Like 15-24A on peaks....and only? 1.5? to? 1.7
> msecs in duration? at the bottom....as? seen on a scope.? ?Same
deal
> on both the sec..and pri? of the? plate xfmr.
>
>
> To measure primary? AC current on the? plate xfmr, ?you really
require
> an? TRUE RMS? AC? Ammeter.? ? I hadn't? even thought of that
anomaly,
> when? installing a? 0-150A? panel mount? ? AC AMMETER.
>
>
> Did some research, and if using a NON rms ammeter on the primary
of a
> single phase plate xfmr...with a FWB / FWD / FWCT rectifier? and C
> filter, the non rms meter? can indicate as much as 40%? on the
low side !
>
>
> The plan is to compare the panel meter to a Fluke true rms clamp
on ac
> ammeter.
>
>
> Even with all that, you still have the issue of Power factor.
True rms
> ?Volts? X? true RMS? amps = True ?VA power, not true watts. One of
> the ham fellows sent me a pix of his? spectrum analyzer display,
> depicting the odd? harmonics of the? 60 hz input...of a plate
xfmr and
> FWB +? high? C? filter.? ?The? 3rd and also 5th (180 hz + 300 hz)
> harmonic is the worse, then the 7/9/11+? drops like a rock.? ? With
> full? wave rectification, the harmonics are always odd.? A half
wave
> rectifier produces only even ?harmonics.
>
>
> What? would be interesting is to measure peak AC current on the
pri.
> ?Then? compare to software results.
>
>
> Jim? ?VE7RF
>
>
--
Roger (K8RI)
--
Roger (K8RI)
|
Trus? rms? voltmeters work really good with? ratty waveforms.? ?They will handle anything you throw at em...including? sawtooth, square waves, and loads of harmonics.??
True? rms? ac? ammeters, good ones, have? 1%? accuracy? > 100Amps.......and? 2% accuracy? for? <100 Amps. I still have not heard? back? from Wilbac..who makes my various panel meters.?
Jim? ?VE7RF.? ??
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