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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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please refresh my memory: what a PFC capacitor does and a real lifeexample of what it means??
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. |
#2
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
On 9/22/19 2:42 PM, KenW wrote:
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.... 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. 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. |
#3
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
On 9/22/19 2:42 PM, KenW wrote:
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.... 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. 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: 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? |
#4
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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.... 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. ** 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 |
#5
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
Larz wrote:
On 9/22/19 2:42 PM, KenW wrote: 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.... 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. 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: 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? Because it does not really matter for lamps that are typically used solitarily or with 2 or 3. It is of course different when hundreds of streetlights have to be powered. |
#6
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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? 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. google mercury lamps to get the figures. They're poor compared to fluorescent, led, sodium or more modern discharge lamps, hence they're obsolete. 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. higher power discharge lamps do tend to be more efficient, but you're stuck with a poor efficiency lamp. Unless you change the lamp for something compatible & a lot more modern. NT |
#7
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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. |
#8
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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 |
#9
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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#10
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
On 9/23/19 10:25 AM, Adrian Caspersz wrote:
On 23/09/2019 14:43, 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. Then you have id :-) *Laughs* You're thinking of that carbuncle on the ass of humanity Arlen Holder. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
#11
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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. |
#12
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
On 9/22/19 11:05 PM, Phil Allison wrote:
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.... 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. ** 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 Ok, I can accept that answer and will try and learn more. |
#13
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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#14
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
On 9/23/19 1:55 PM, Larz wrote:
You know, everytime I post here I am met with sarcasm and other negative commentary.Â* 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.Â* I did have an electric circuits course as part of my major, but that was over 30 years ago and I forgot some things.Â* 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.Â* I much prefer DC, but unfortunately these lamps need AC circuitry. So.... that being said.... I won't bother this patronizing, sarcastic group anymore.Â* 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.Â* Some of you must be college professors because you are a lot like some of the aholes I had. I bid you farewell.Â* My hat is off to you.Â* Whatever floats your boat, but know this: I won't respond nor post any further commentary in this pathetic group.Â* Goodbye. I take some of this back: I will, in the future, respond to those who 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. |
#15
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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. 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 |
#16
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please refresh my memory: what a PFC capacitor does and a real life example of what it means??
In article , elson@pico-
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 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. |
#17
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
On 9/22/2019 2:02 PM, Larz wrote:
On 9/22/19 2:42 PM, KenW wrote: On Sun, 22 Sep 2019 14:30:42 -0400, Larz wrote: I recently installed a mercury vapor light fixture.Â* It is a 125 W lamp with integrated ballast in the housing.Â* 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.Â* Unfortunately, there is no PFC with this yard light, only the bulb and ballast, so I don't think anything can be done. Â* 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.Â* Any ideas as to performance would be welcome.Â* 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. 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: https://www.youtube.com/watch?v=dPFKcUxbNuQ Great refresher!Â* So the capacitor in the mercury vapor circuit should reduce the current if matched correctly.Â* I wonder why there is no such capacitor in my 125 W mercury vapor yard light? 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.electricalengineeringtoo...or-common.html Mikek |
#18
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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.electricalengineeringtoo...or-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 |
#19
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
On 9/23/19 2:47 PM, Jon Elson wrote:
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. 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 Wow, I didn't know this or had forgotten. I am fully used to working 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. |
#20
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
On 9/23/19 3:11 PM, Ralph Mowery wrote:
In article , elson@pico- 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 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. I did all of these AC calculations, but it was at least 20 years ago. 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? |
#21
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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/Kilowa...ebec_meter.JPG The spinning disk will not move unless both current and voltage of the same polarity exist at the same time. ..... Phil |
#22
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
On 9/23/19 10:35 PM, 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/Kilowa...ebec_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. 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. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
#23
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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/Kilowa...ebec_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. **** the hell out of greenish coloured folk nowadays, with their roofs covered in acres of PVs. ..... Phil |
#24
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
#25
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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. Peter Wieck Melrose Park, PA |
#26
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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#27
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please refresh my memory: what a PFC capacitor does and a real life example of what it means??
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#28
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
Ralph Mowery wrote:
--------------------- ** 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 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. ** 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 |
#29
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
On 9/23/2019 10:11 PM, Phil Allison wrote:
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.electricalengineeringtoo...or-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 The reference was to the video where he used an unloaded motor. 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 |
#30
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please refresh my memory: what a PFC capacitor does and a real life example of what it means??
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#31
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
Ralph Mowery wrote:
------------------- 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. 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 |
#32
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please refresh my memory: what a PFC capacitor does and a reallife example of what it means??
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. |
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