info
Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss
please refresh my memory: what a PFC capacitor does and a real life example of what it means??
122 views
Skip to first unread message
Larz
Sep 22, 2019, 2:30:46 PM9/22/19
to
I recently installed a mercury vapor light fixture. It is a 125 W lamp
with integrated ballast in the housing. Today, I check the current with
a clamp ammeter on the 120 VAC/ 60 Hz line going into the housing.
After a 10 minute warm up, the current reads approximately 2.3 A AC.
Not being sure, I then wired a series multimeter in line for a moment
and it too read 2.3 A. Unfortunately, there is no PFC with this yard
light, only the bulb and ballast, so I don't think anything can be done.
However....
In another set up I have on the way, there is the 175 W MV bulb, ballast
and the PFC capacitor that will be used with the ballast. Any ideas as
to performance would be welcome. I'm just looking for in general as I
realize we can't get too specific without any more figures, but I'm
really hoping the efficiency is better than with the 125 W set up.
Thank you in advance.
with integrated ballast in the housing. Today, I check the current with
a clamp ammeter on the 120 VAC/ 60 Hz line going into the housing.
After a 10 minute warm up, the current reads approximately 2.3 A AC.
Not being sure, I then wired a series multimeter in line for a moment
and it too read 2.3 A. Unfortunately, there is no PFC with this yard
light, only the bulb and ballast, so I don't think anything can be done.
However....
In another set up I have on the way, there is the 175 W MV bulb, ballast
and the PFC capacitor that will be used with the ballast. Any ideas as
to performance would be welcome. I'm just looking for in general as I
realize we can't get too specific without any more figures, but I'm
really hoping the efficiency is better than with the 125 W set up.
Thank you in advance.
Larz
Sep 22, 2019, 2:50:14 PM9/22/19
to
On 9/22/19 2:42 PM, KenW wrote:
> Since I have no idea about them I searched for > PFC capacitor <
> and there is plenty of information about them which my help you.
>
>
> KenW
>
I was just hoping to cut to the chase with someone using the examples
above. I'm not all that pleased with the lack of efficiency with the
125 W lamp, just wondering if the capacitor would increase efficiency
with the 175 W set up.
At one time, 25+ years ago, in college, we actually had to calculate the
correct capacitor to use in a circuit for PFC, but that's the last time
I did it.
> and there is plenty of information about them which my help you.
>
>
> KenW
>
I was just hoping to cut to the chase with someone using the examples
above. I'm not all that pleased with the lack of efficiency with the
125 W lamp, just wondering if the capacitor would increase efficiency
with the 175 W set up.
At one time, 25+ years ago, in college, we actually had to calculate the
correct capacitor to use in a circuit for PFC, but that's the last time
I did it.
Larz
Sep 22, 2019, 3:02:11 PM9/22/19
to
On 9/22/19 2:42 PM, KenW wrote:
> On Sun, 22 Sep 2019 14:30:42 -0400, Larz <dispc...@nospam.net>
> wrote:
>
> On Sun, 22 Sep 2019 14:30:42 -0400, Larz <dispc...@nospam.net>
> wrote:
>
> Since I have no idea about them I searched for > PFC capacitor <
> and there is plenty of information about them which my help you.
>
>
> KenW
>
Ok, this shows me what happens:
> and there is plenty of information about them which my help you.
>
>
> KenW
>
https://www.youtube.com/watch?v=dPFKcUxbNuQ
Great refresher! So the capacitor in the mercury vapor circuit should
reduce the current if matched correctly. I wonder why there is no such
capacitor in my 125 W mercury vapor yard light?
Phil Allison
Sep 22, 2019, 11:06:02 PM9/22/19
to
Larz wrote:
------------
** You are working under a serious delusion.
PFC caps or circuits have *NO* effect on a device's efficiency.
Power consumption remains exactly the same, with or without.
The sole purpose is to reduce the *current draw* and allow more lights or whatever to be used on the same AC supply circuit.
Current draw that is non-sine wave or not in phase with the voltage is always higher than when it is.
..... Phil
------------
PFC caps or circuits have *NO* effect on a device's efficiency.
Power consumption remains exactly the same, with or without.
The sole purpose is to reduce the *current draw* and allow more lights or whatever to be used on the same AC supply circuit.
Current draw that is non-sine wave or not in phase with the voltage is always higher than when it is.
..... Phil
Rob
Sep 23, 2019, 4:47:06 AM9/23/19
to
solitarily or with 2 or 3. It is of course different when hundreds
of streetlights have to be powered.
tabb...@gmail.com
Sep 23, 2019, 5:27:39 AM9/23/19
to
On Sunday, 22 September 2019 19:30:46 UTC+1, Larz wrote:
> I recently installed a mercury vapor light fixture. It is a 125 W lamp
> with integrated ballast in the housing. Today, I check the current with
> a clamp ammeter on the 120 VAC/ 60 Hz line going into the housing.
> After a 10 minute warm up, the current reads approximately 2.3 A AC.
> Not being sure, I then wired a series multimeter in line for a moment
> and it too read 2.3 A. Unfortunately, there is no PFC with this yard
> light, only the bulb and ballast, so I don't think anything can be done.
> However....
done about what?
> I recently installed a mercury vapor light fixture. It is a 125 W lamp
> with integrated ballast in the housing. Today, I check the current with
> a clamp ammeter on the 120 VAC/ 60 Hz line going into the housing.
> After a 10 minute warm up, the current reads approximately 2.3 A AC.
> Not being sure, I then wired a series multimeter in line for a moment
> and it too read 2.3 A. Unfortunately, there is no PFC with this yard
> light, only the bulb and ballast, so I don't think anything can be done.
> However....
PFC is normally immaterial in domestic discharge lamps. You're not paying for the reactive current.
> In another set up I have on the way, there is the 175 W MV bulb, ballast
> and the PFC capacitor that will be used with the ballast. Any ideas as
> to performance would be welcome.
> I'm just looking for in general as I
> realize we can't get too specific without any more figures, but I'm
> really hoping the efficiency is better than with the 125 W set up.
>
> Thank you in advance.
NT
Cursitor Doom
Sep 23, 2019, 9:30:30 AM9/23/19
to
On Sun, 22 Sep 2019 15:02:07 -0400, Larz wrote:
>
> Great refresher!
Obviously not *that* great.
> So the capacitor in the mercury vapor circuit should
> reduce the current if matched correctly. I wonder why there is no such
> capacitor in my 125 W mercury vapor yard light?
Oh dear oh dear.
--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.
>
> Great refresher!
Obviously not *that* great.
> So the capacitor in the mercury vapor circuit should
> reduce the current if matched correctly. I wonder why there is no such
> capacitor in my 125 W mercury vapor yard light?
--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.
peterw...@gmail.com
Sep 23, 2019, 9:43:25 AM9/23/19
to
Larz is amongst the Invincibly Ignorant - reminds me of Jimmy Neutron it its own way - might even be the same creature.
Let it be.
Peter Wieck
Melrose Park, PA
Let it be.
Peter Wieck
Melrose Park, PA
Adrian Caspersz
Sep 23, 2019, 11:25:43 AM9/23/19
to
On 23/09/2019 14:43, pf...@aol.com wrote:
> Larz is amongst the Invincibly Ignorant - reminds me of Jimmy Neutron it its own way - might even be the same creature.
>
> Let it be.
>
Wait till it starts posting lots of links and answers its own questions.
> Larz is amongst the Invincibly Ignorant - reminds me of Jimmy Neutron it its own way - might even be the same creature.
>
> Let it be.
>
Then you have id :-)
--
Adrian C
Fox's Mercantile
Sep 23, 2019, 12:03:29 PM9/23/19
to
Holder.
--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com
Larz
Sep 23, 2019, 1:55:22 PM9/23/19
to
You know, everytime I post here I am met with sarcasm and other negative
commentary. I asked a simple question and only two people answered,
appropriately.
You might be surprised what degrees (yes, degrees) I have, but none in
electrical engineering. I did have an electric circuits course as part
of my major, but that was over 30 years ago and I forgot some things. I
never have liked working with AC and maybe, if you do in fact want to
poke fun at my questions as some obviously can't seem to resist for some
odd reason, then credit my lack of AC knowledge as the reason. I much
prefer DC, but unfortunately these lamps need AC circuitry.
So.... that being said.... I won't bother this patronizing, sarcastic
group anymore. I must say I have been using Usenet in various
capacities for over 20 years and I have never been meet with conduct
like I'm experiencing here. Some of you must be college professors
because you are a lot like some of the aholes I had.
I bid you farewell. My hat is off to you. Whatever floats your boat,
but know this: I won't respond nor post any further commentary in this
pathetic group. Goodbye.
commentary. I asked a simple question and only two people answered,
appropriately.
You might be surprised what degrees (yes, degrees) I have, but none in
electrical engineering. I did have an electric circuits course as part
of my major, but that was over 30 years ago and I forgot some things. I
never have liked working with AC and maybe, if you do in fact want to
poke fun at my questions as some obviously can't seem to resist for some
odd reason, then credit my lack of AC knowledge as the reason. I much
prefer DC, but unfortunately these lamps need AC circuitry.
So.... that being said.... I won't bother this patronizing, sarcastic
group anymore. I must say I have been using Usenet in various
capacities for over 20 years and I have never been meet with conduct
like I'm experiencing here. Some of you must be college professors
because you are a lot like some of the aholes I had.
I bid you farewell. My hat is off to you. Whatever floats your boat,
but know this: I won't respond nor post any further commentary in this
pathetic group. Goodbye.
Larz
Sep 23, 2019, 1:57:07 PM9/23/19
to
Larz
Sep 23, 2019, 1:57:27 PM9/23/19
to
Larz
Sep 23, 2019, 2:01:01 PM9/23/19
to
responded to me appropriately but as for the rest, you are being
filtered. I won't let the negativity and sarcasm of a few select ruin
it for those who did answer or try to answer appropriately.
Jon Elson
Sep 23, 2019, 2:47:45 PM9/23/19
to
On Sun, 22 Sep 2019 14:30:42 -0400, Larz wrote:
> I recently installed a mercury vapor light fixture. It is a 125 W lamp
> with integrated ballast in the housing. Today, I check the current with
> a clamp ammeter on the 120 VAC/ 60 Hz line going into the housing. After
> a 10 minute warm up, the current reads approximately 2.3 A AC. Not being
> sure, I then wired a series multimeter in line for a moment and it too
> read 2.3 A. Unfortunately, there is no PFC with this yard light, only
> the bulb and ballast, so I don't think anything can be done.
> However....
>
Without a Wattmeter, you have no idea what the actual power draw is.
> I recently installed a mercury vapor light fixture. It is a 125 W lamp
> with integrated ballast in the housing. Today, I check the current with
> a clamp ammeter on the 120 VAC/ 60 Hz line going into the housing. After
> a 10 minute warm up, the current reads approximately 2.3 A AC. Not being
> sure, I then wired a series multimeter in line for a moment and it too
> read 2.3 A. Unfortunately, there is no PFC with this yard light, only
> the bulb and ballast, so I don't think anything can be done.
> However....
>
Some of that 2.3 A is reactive current, at 90 degrees to the voltage, and
you are not billed for that. Measuring the current and voltage
separately, you only get the VA (volts * amps) which is NOT the power in
Watts.
Jon
Ralph Mowery
Sep 23, 2019, 3:11:24 PM9/23/19
to
In article <f8ydnTnWzv3UjhTA...@giganews.com>, elson@pico-
systems.com says...
or amps can lead if there is any reactance in the circuit. I have an
inline power meter that shows voltage, current, and power (watts )_ A
heater element will show about the same watts as the voltage times the
courrent. A load with a large transformer in it will show a much
differant V times A than the watt meter. I understand it doing that,
but not how the power company realy charges for the power.
systems.com says...
>
> Without a Wattmeter, you have no idea what the actual power draw is.
> Some of that 2.3 A is reactive current, at 90 degrees to the voltage, and
> you are not billed for that. Measuring the current and voltage
> separately, you only get the VA (volts * amps) which is NOT the power in
> Watts
>
I never could get it in my head about AC power either. I know how volts
> Without a Wattmeter, you have no idea what the actual power draw is.
> Some of that 2.3 A is reactive current, at 90 degrees to the voltage, and
> you are not billed for that. Measuring the current and voltage
> separately, you only get the VA (volts * amps) which is NOT the power in
> Watts
>
or amps can lead if there is any reactance in the circuit. I have an
inline power meter that shows voltage, current, and power (watts )_ A
heater element will show about the same watts as the voltage times the
courrent. A load with a large transformer in it will show a much
differant V times A than the watt meter. I understand it doing that,
but not how the power company realy charges for the power.
amdx
Sep 23, 2019, 3:18:18 PM9/23/19
to
0.15 with no-load, and 0.7 to 0.85 with a load.
> https://www.electricalengineeringtoolbox.com/2016/12/typical-power-factors-for-common.html
Mikek
Phil Allison
Sep 23, 2019, 11:11:46 PM9/23/19
to
amdx dickhead wrote:
--------------------
>
>
> Kind of interesting, this website shows an electric motor has a PF of
> 0.15 with no-load, and 0.7 to 0.85 with a load.
>
https://www.electricalengineeringtoolbox.com/2016/12/typical-power-factors-for-common.html
---------------------------------------------------
** Fraid the info is so minimal, it's highly misleading.
Motors used in domestic appliances like washers and fridges operate on full or near full load at all times - so have good PFs.
What they might do off load is not important, as it is very rare.
In any case, the current draw and power consumed off load is much lower.
.... Phil
--------------------
>
>
> Kind of interesting, this website shows an electric motor has a PF of
> 0.15 with no-load, and 0.7 to 0.85 with a load.
>
https://www.electricalengineeringtoolbox.com/2016/12/typical-power-factors-for-common.html
** Fraid the info is so minimal, it's highly misleading.
Motors used in domestic appliances like washers and fridges operate on full or near full load at all times - so have good PFs.
What they might do off load is not important, as it is very rare.
In any case, the current draw and power consumed off load is much lower.
.... Phil
Larz
Sep 23, 2019, 11:12:25 PM9/23/19
to
with DC, seldom AC I see digital plug in wattmeters on Amazon in the
$10-15. Would something like those be satisfactory? I really would
like to find out the true wattage.
Larz
Sep 23, 2019, 11:17:30 PM9/23/19
to
I've mainly worked with DC since that time & I've always found DC a lot
simpler. Speaking of which, I understand there's actually a way to run
these MV bulbs from DC. I wonder if it's like is done with certain
x-ray tubes and just using a diode to convert to DC, or more elaborate?
Phil Allison
Sep 23, 2019, 11:35:18 PM9/23/19
to
Ralph Mowery wrote:
-----------------------
> I understand it doing that,
> but not how the power company realy charges for the power.
>
** They use *wattmeters* that accumulate so becoming "Watt-hour" meters.
Customers get charged for the actual energy used, not merely current over time.
The ones where I live look much like this:
https://en.wikipedia.org/wiki/Kilowatt_hour#/media/File:Hydro_quebec_meter.JPG
The spinning disk will not move unless both current and voltage of the same polarity exist at the same time.
.... Phil
-----------------------
> I understand it doing that,
> but not how the power company realy charges for the power.
>
Customers get charged for the actual energy used, not merely current over time.
The ones where I live look much like this:
https://en.wikipedia.org/wiki/Kilowatt_hour#/media/File:Hydro_quebec_meter.JPG
The spinning disk will not move unless both current and voltage of the same polarity exist at the same time.
.... Phil
Fox's Mercantile
Sep 24, 2019, 8:01:06 AM9/24/19
to
On 9/23/19 10:35 PM, Phil Allison wrote:
> ** They use*wattmeters* that accumulate so becoming
friend, The house had a single 120 vac feed, not the more
common 120/120 240 vac feed. So his 1 KW Heathkit amplifier
would draw a LOT of current.
I picked up a power company power factor correction
capacitor. Heh, when we put that across the line, the watt
meter would come to a complete halt.
Watt hour meters will read, properly, with an r+j impedance
load. They get confused with an r-j impedance.
> ** They use*wattmeters* that accumulate so becoming
> "Watt-hour" meters.
>
> Customers get charged for the actual energy used, not
> merely current over time.
>
> The ones where I live look much like this:
>
> https://en.wikipedia.org/wiki/Kilowatt_hour#/media/File:Hydro_quebec_meter.JPG
>
> The spinning disk will not move unless both current and
> voltage of the same polarity exist at the same time.
Back in Manhattan Beach, California, while living with a
>
> Customers get charged for the actual energy used, not
> merely current over time.
>
> The ones where I live look much like this:
>
> https://en.wikipedia.org/wiki/Kilowatt_hour#/media/File:Hydro_quebec_meter.JPG
>
> The spinning disk will not move unless both current and
> voltage of the same polarity exist at the same time.
friend, The house had a single 120 vac feed, not the more
common 120/120 240 vac feed. So his 1 KW Heathkit amplifier
would draw a LOT of current.
I picked up a power company power factor correction
capacitor. Heh, when we put that across the line, the watt
meter would come to a complete halt.
Watt hour meters will read, properly, with an r+j impedance
load. They get confused with an r-j impedance.
Phil Allison
Sep 24, 2019, 8:18:03 AM9/24/19
to
Fox's Mercantile wrote:
----------------------
> Phil Allison wrote:
>
> > ** They use*wattmeters* that accumulate so becoming
> > "Watt-hour" meters.
> >
> > Customers get charged for the actual energy used, not
> > merely current over time.
> >
> > The ones where I live look much like this:
> >
> > https://en.wikipedia.org/wiki/Kilowatt_hour#/media/File:Hydro_quebec_meter.JPG
> >
> > The spinning disk will not move unless both current and
> > voltage of the same polarity exist at the same time.
>
>
> Back in Manhattan Beach, California, while living with a
> friend, The house had a single 120 vac feed, not the more
> common 120/120 240 vac feed. So his 1 KW Heathkit amplifier
> would draw a LOT of current.
>
** Heathkit ? 1kW ??
FYI, there is ZERO phase angle between the V and I drawn by an amplifier.
> I picked up a power company power factor correction
> capacitor. Heh, when we put that across the line, the watt
> meter would come to a complete halt.
>
> Watt hour meters will read, properly, with an r+j impedance
> load. They get confused with an r-j impedance.
>
** Hope that is not some weed induced hallucination form the late 1960s...
The only thought I have that connects is the power company, aware such shenanigans sometime went on, fitted a device to PREVENT the watt-hour meter ever going backwards. Easy enough to do, in the reduction gear chain for eg.
Piss the hell out of greenish coloured folk nowadays, with their roofs covered in acres of PVs.
.... Phil
----------------------
> Phil Allison wrote:
>
> > ** They use*wattmeters* that accumulate so becoming
> > "Watt-hour" meters.
> >
> > Customers get charged for the actual energy used, not
> > merely current over time.
> >
> > The ones where I live look much like this:
> >
> > https://en.wikipedia.org/wiki/Kilowatt_hour#/media/File:Hydro_quebec_meter.JPG
> >
> > The spinning disk will not move unless both current and
> > voltage of the same polarity exist at the same time.
>
>
> Back in Manhattan Beach, California, while living with a
> friend, The house had a single 120 vac feed, not the more
> common 120/120 240 vac feed. So his 1 KW Heathkit amplifier
> would draw a LOT of current.
>
FYI, there is ZERO phase angle between the V and I drawn by an amplifier.
> I picked up a power company power factor correction
> capacitor. Heh, when we put that across the line, the watt
> meter would come to a complete halt.
>
> Watt hour meters will read, properly, with an r+j impedance
> load. They get confused with an r-j impedance.
>
The only thought I have that connects is the power company, aware such shenanigans sometime went on, fitted a device to PREVENT the watt-hour meter ever going backwards. Easy enough to do, in the reduction gear chain for eg.
Piss the hell out of greenish coloured folk nowadays, with their roofs covered in acres of PVs.
.... Phil
Fox's Mercantile
Sep 24, 2019, 8:38:08 AM9/24/19
to
On 9/24/19 7:18 AM, Phil Allison wrote:
> ** Hope that is not some weed induced hallucination
> form the late 1960s...
Nope, never did weed or any other drugs.
> ** Hope that is not some weed induced hallucination
> form the late 1960s...
peterw...@gmail.com
Sep 24, 2019, 8:44:02 AM9/24/19
to
There are several Heath amps that put very nearly 1 kw on the outlet. The AA1640 comes right to mind, as it, in mono, makes 800 watts into 4 ohms. circuit losses of 200 watts or so does not seem unlikely.
My Harman Kardon Citation 16 draws close to 12 amps @ 120 VAC at full load, making 1,440 watts. Not that it has ever been driven to that extreme - but it is just possible.
Dynaco 416, Phase Linear 700, Crown CE1000. There are a good many brute-force amps out there, not accounting for quality, just force.
My Harman Kardon Citation 16 draws close to 12 amps @ 120 VAC at full load, making 1,440 watts. Not that it has ever been driven to that extreme - but it is just possible.
Dynaco 416, Phase Linear 700, Crown CE1000. There are a good many brute-force amps out there, not accounting for quality, just force.
Fox's Mercantile
Sep 24, 2019, 9:20:28 AM9/24/19
to
On 9/24/19 7:43 AM, pf...@aol.com wrote:
> There are several Heath amps that put very nearly 1 kw on the outlet.
This was an Amateur Radio RF amplifier.
> There are several Heath amps that put very nearly 1 kw on the outlet.
3.5 to 30 MHz.
SB-200
<http://www.n2ckh.com/FORSALE/AMPLIFIERS/SB200/sb-200_front.gif>
Ralph Mowery
Sep 24, 2019, 1:13:28 PM9/24/19
to
In article <f7c85242-eb1c-4e21...@googlegroups.com>,
palli...@gmail.com says...
tubes in my Sb-200 amp. I wanted to see how efficient the amp was.
I had an el cheepo China meter that showed Volts, amps, watts. The
volts did check with my Fluke meter.
With a bathroom heater the watts and V times A were vey close maybe
because of the very small fan motor. When hooked to my amp and loaded
to 600 to 700 watts RF out the watts and V times A were way off. One
showed maybe 80 to 90 $ different depending on the loading. I took that
to be the inductance of the transformer causing that.
I don't know enough AC theory to explain it if there is not more than a
ZERO phase angle.
palli...@gmail.com says...
>
> ** Heathkit ? 1kW ??
>
> FYI, there is ZERO phase angle between the V and I drawn by an amplifier.
>
>
>
I don't know how accurate it was, but a few years ago I replaced the
> ** Heathkit ? 1kW ??
>
> FYI, there is ZERO phase angle between the V and I drawn by an amplifier.
>
>
>
tubes in my Sb-200 amp. I wanted to see how efficient the amp was.
I had an el cheepo China meter that showed Volts, amps, watts. The
volts did check with my Fluke meter.
With a bathroom heater the watts and V times A were vey close maybe
because of the very small fan motor. When hooked to my amp and loaded
to 600 to 700 watts RF out the watts and V times A were way off. One
showed maybe 80 to 90 $ different depending on the loading. I took that
to be the inductance of the transformer causing that.
I don't know enough AC theory to explain it if there is not more than a
ZERO phase angle.
Phil Allison
Sep 25, 2019, 7:29:43 AM9/25/19
to
Ralph Mowery wrote:
---------------------
** The PF of general electronic load is about 0.5 to 0.65.
But that has NOTHING to do with transformer inductance ( a myth) or phase angle and cannot be fixed with a capacitor across the supply.
It has everything to do with the current wave be made up of pulses ( at double the supply frequency ) and so not being a sine wave.
The "true rms" value of a pulsed current is higher than a comparable steady sine current.
.... Phil
---------------------
But that has NOTHING to do with transformer inductance ( a myth) or phase angle and cannot be fixed with a capacitor across the supply.
It has everything to do with the current wave be made up of pulses ( at double the supply frequency ) and so not being a sine wave.
The "true rms" value of a pulsed current is higher than a comparable steady sine current.
.... Phil
amdx
Sep 25, 2019, 9:19:10 AM9/25/19
to
Then as you say, "current draw and power consumed off load is much
lower". So how often do you run a motor unloaded and is it worth the
cost of PFC.
How often does a factory run a motor unloaded?
Mikek
Ralph Mowery
Sep 25, 2019, 12:47:19 PM9/25/19
to
In article <16a879a4-381c-4f70...@googlegroups.com>,
palli...@gmail.com says...
I do understand the part about a 'true rms' not being the same as what
most simple meters show when calibrated for a sine wave and not all
kinds of non sine waves.
Just faulty thinking about the inductance of a transformer.
palli...@gmail.com says...
>
> But that has NOTHING to do with transformer inductance ( a myth) or phase angle and cannot be fixed with a capacitor across the supply.
>
> It has everything to do with the current wave be made up of pulses ( at double the supply frequency ) and so not being a sine wave.
>
> The "true rms" value of a pulsed current is higher than a comparable steady sine current.
>
>
>
Ok I can see that , The meters are not really showing what is going on.
> But that has NOTHING to do with transformer inductance ( a myth) or phase angle and cannot be fixed with a capacitor across the supply.
>
> It has everything to do with the current wave be made up of pulses ( at double the supply frequency ) and so not being a sine wave.
>
> The "true rms" value of a pulsed current is higher than a comparable steady sine current.
>
>
>
I do understand the part about a 'true rms' not being the same as what
most simple meters show when calibrated for a sine wave and not all
kinds of non sine waves.
Just faulty thinking about the inductance of a transformer.
Phil Allison
Sep 25, 2019, 7:51:16 PM9/25/19
to
Ralph Mowery wrote:
-------------------
FYI: VA = rms Voltage times rms Current.
and PF = true power / VA
For example,
a true rms clamp mater allows a sparkie to measure the VA of a load but he would need a "watt-meter" to find the true power.
Plug-in meters that do both cost very little nowadays.
.... Phil
-------------------
>
> >
> > But that has NOTHING to do with transformer inductance ( a myth) or phase angle and cannot be fixed with a capacitor across the supply.
> >
> > It has everything to do with the current wave be made up of pulses ( at double the supply frequency ) and so not being a sine wave.
> >
> > The "true rms" value of a pulsed current is higher than a comparable steady sine current.
> >
> >
> >
>
> Ok I can see that , The meters are not really showing what is going on.
> I do understand the part about a 'true rms' not being the same as what
> most simple meters show when calibrated for a sine wave and not all
> kinds of non sine waves.
>
> Just faulty thinking about the inductance of a transformer.
>
** The simple mistake that most folk make is not knowing the definition of VA and hence the meaning of Power Factor.
> >
> > But that has NOTHING to do with transformer inductance ( a myth) or phase angle and cannot be fixed with a capacitor across the supply.
> >
> > It has everything to do with the current wave be made up of pulses ( at double the supply frequency ) and so not being a sine wave.
> >
> > The "true rms" value of a pulsed current is higher than a comparable steady sine current.
> >
> >
> >
>
> Ok I can see that , The meters are not really showing what is going on.
> I do understand the part about a 'true rms' not being the same as what
> most simple meters show when calibrated for a sine wave and not all
> kinds of non sine waves.
>
> Just faulty thinking about the inductance of a transformer.
>
FYI: VA = rms Voltage times rms Current.
and PF = true power / VA
For example,
a true rms clamp mater allows a sparkie to measure the VA of a load but he would need a "watt-meter" to find the true power.
Plug-in meters that do both cost very little nowadays.
.... Phil
Larz
Sep 28, 2019, 5:36:53 PM9/28/19
to
Ok, so I picked up a Kuman Electricity Usage Monitor. For anyone not
familiar, it shows KW used, current V and I, some other things like a
cost calculation, etc. I plugged the 175 W mercury lamp into it and
here are the figures I got after letting the system run for 8 hours, 35 min:
1.77 Kwh
209.8 W
0.19 cost
2.018 A
0.84 pfc
So, inputting my Kwh rate beforehand, it's showing ~19 cents per 8 hour
period.
I have no idea if these figures are correct and probably won't until the
electric bill arrives and/or I ever came across a scope. The device had
good ratings and most folks seemed satisfied, which was the main reason
I purchased it.
familiar, it shows KW used, current V and I, some other things like a
cost calculation, etc. I plugged the 175 W mercury lamp into it and
here are the figures I got after letting the system run for 8 hours, 35 min:
1.77 Kwh
209.8 W
0.19 cost
2.018 A
0.84 pfc
So, inputting my Kwh rate beforehand, it's showing ~19 cents per 8 hour
period.
I have no idea if these figures are correct and probably won't until the
electric bill arrives and/or I ever came across a scope. The device had
good ratings and most folks seemed satisfied, which was the main reason
I purchased it.
0 new messages