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#131
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On Mon, 26 Jul 2004 19:26:02 GMT, kony wrote:
On Mon, 26 Jul 2004 16:42:15 +0100, "Peter Hucker" wrote: On Mon, 26 Jul 2004 15:10:02 GMT, kony wrote: On Mon, 26 Jul 2004 10:17:09 +0100, "Peter Hucker" wrote: It's how americans justify being lazy and fat.. I think I understand. Wasting time on something other than eating can't be good for your health :-) One has to wonder where these stereotypes come from. Considering "1st world" nations, americans work more hours on average than most if not all other nations. Personally, I'd rather be out mowing the lawn for a half hour rather than waiting on hold calling in an RMA. Well, at least after the warmer part of summer is over. I take it you are not overweight? It is a fact that the average american is more overweight than other countries. No, fortunately have been fairly athletic all my life, easier to keep weight off when exercise is on a regular basis... got to keep the feet moving so moss won't grow. Americans may be overweight for many reasons though, including a lot of farm land to produce cheap food, more hours worked = more fast food or higher budget for food, or just the cultural differences in diet. Of course there are some who clearly eat too much and move around too little, but to label a whole nation like that is pointless as it can't be applied to any one person without enough further supporing evidence that country of origin wasn't a relevant detail. There are far more people who are grossly overweight in America than other countries. -- *****TWO BABY CONURES***** 15 parrots and increasing http://www.petersparrots.com 93 silly video clips http://www.insanevideoclips.com 1259 digital photos http://www.petersphotos.com Served from a pentawatercooled dual silent Athlon 2.8 with terrabyte raid With Windows 3.11, we were on the edge of the cliff. With Windows 95, we made a big step forward. |
#132
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On Tue, 27 Jul 2004 06:17:14 +1000, Franc Zabkar wrote:
On Mon, 26 Jul 2004 10:16:34 +0100, "Peter Hucker" put finger to keyboard and composed: Could someone explain "This little ugly thing is the PFC coil, it will be removed due to the fact that it increase power loss and makes a loud humm noise."? I thought PFC was to SAVE power? So I can just remove those things? PFC reduces the peak AC current drawn by your PSU. It does nothing to reduce the *real* metered power consumed by it. Australian domestic consumers pay for real power, ie kW not kVA, so a unity PF appliance will provide no cost benefit to me. The electricity supplier, however, will benefit from the reduced current demand. PFC is particularly important in heavy industry where high peak loadings are penalised with higher tariffs. I'm not sure what you mean with this metering. Are you saying some meters just measure current drawn, then just assume it was all at an average of 240 volts? -- *****TWO BABY CONURES***** 15 parrots and increasing http://www.petersparrots.com 93 silly video clips http://www.insanevideoclips.com 1259 digital photos http://www.petersphotos.com Served from a pentawatercooled dual silent Athlon 2.8 with terrabyte raid "Th on my k yboard has stopp d working" |
#133
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On 27 Jul 2004 02:38:24 -0700, do_not_spam_me wrote:
"Peter Hucker" wrote in message news:opsbql1fpwaiowgp@blue... You have made a mistake. You are assuming I am safe. I don't understand what you mean, but I assume you want to be safe. It's not high on my list of priorities. Until recently I was driving a car at 110mph which had a hole in the floor under the drivers seat. Unlike a dangerous car, a dangerous power supply offers no thrills. So if you want electrical excitement, build a van de Graff generator or (much more potentially lethal) a Jacob's ladder. I don't make the car dangerous for thrills. A 110mph car with a safe seat is just as fun. Q-Tec is one which smoked when I plugged a modem into a 64bit PCI (which it should have worked in - it had the right grooves in the connector). I blame the modem though, as it also blew the 64bit bus on the motherbaord. Nevertheless a PSU should not break due to a short?? Never. Q-tec is so bad that their 500W supplies are made with just sheet aluminum heatsinks and very small transformers, and if a technician was shown the interior of one and wasn't told its power rating, he would probably guess 250W. Haven't Q Technologies sued them yet? -- *****TWO BABY CONURES***** 15 parrots and increasing http://www.petersparrots.com 93 silly video clips http://www.insanevideoclips.com 1259 digital photos http://www.petersphotos.com Served from a pentawatercooled dual silent Athlon 2.8 with terrabyte raid "Th on my k yboard has stopp d working" |
#134
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On Tue, 27 Jul 2004 14:05:26 +0100, "Peter Hucker"
put finger to keyboard and composed: On Tue, 27 Jul 2004 06:17:14 +1000, Franc Zabkar wrote: On Mon, 26 Jul 2004 10:16:34 +0100, "Peter Hucker" put finger to keyboard and composed: Could someone explain "This little ugly thing is the PFC coil, it will be removed due to the fact that it increase power loss and makes a loud humm noise."? I thought PFC was to SAVE power? So I can just remove those things? PFC reduces the peak AC current drawn by your PSU. It does nothing to reduce the *real* metered power consumed by it. Australian domestic consumers pay for real power, ie kW not kVA, so a unity PF appliance will provide no cost benefit to me. The electricity supplier, however, will benefit from the reduced current demand. PFC is particularly important in heavy industry where high peak loadings are penalised with higher tariffs. I'm not sure what you mean with this metering. Are you saying some meters just measure current drawn, then just assume it was all at an average of 240 volts? This is how Energy Australia answered a similar question: ================================================== =================== To answer your question, most residential classification customers are metered by a spinning disc [watt]meter, or a basic electronic meter which does not have enough "smarts" in the meter device to enable billing to be carried out at a KVA pricing. Currently small customers are billed on KWh pricing, and KVA Demand pricing usually relates to large commercial and industrial installations where poor power factor may impact upon the EA network, and there may be an economic billing benefit in the customer pricing to ensure that Power factor is closer to Unity. ================================================== =================== - Franc Zabkar -- Please remove one 's' from my address when replying by email. |
#135
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On Wed, 28 Jul 2004 08:20:10 +1000, Franc Zabkar wrote:
On Tue, 27 Jul 2004 14:05:26 +0100, "Peter Hucker" put finger to keyboard and composed: On Tue, 27 Jul 2004 06:17:14 +1000, Franc Zabkar wrote: On Mon, 26 Jul 2004 10:16:34 +0100, "Peter Hucker" put finger to keyboard and composed: Could someone explain "This little ugly thing is the PFC coil, it will be removed due to the fact that it increase power loss and makes a loud humm noise."? I thought PFC was to SAVE power? So I can just remove those things? PFC reduces the peak AC current drawn by your PSU. It does nothing to reduce the *real* metered power consumed by it. Australian domestic consumers pay for real power, ie kW not kVA, so a unity PF appliance will provide no cost benefit to me. The electricity supplier, however, will benefit from the reduced current demand. PFC is particularly important in heavy industry where high peak loadings are penalised with higher tariffs. I'm not sure what you mean with this metering. Are you saying some meters just measure current drawn, then just assume it was all at an average of 240 volts? This is how Energy Australia answered a similar question: ================================================== =================== To answer your question, most residential classification customers are metered by a spinning disc [watt]meter, or a basic electronic meter which does not have enough "smarts" in the meter device to enable billing to be carried out at a KVA pricing. Currently small customers are billed on KWh pricing, and KVA Demand pricing usually relates to large commercial and industrial installations where poor power factor may impact upon the EA network, and there may be an economic billing benefit in the customer pricing to ensure that Power factor is closer to Unity. ================================================== =================== I guess we have the spinning disk in the UK too then. Odd, I was told when studying electronics that the power factor correction in fluourescent ballasts was to save money on the electricity bill! -- *****TWO BABY CONURES***** 15 parrots and increasing http://www.petersparrots.com 93 silly video clips http://www.insanevideoclips.com 1259 digital photos http://www.petersphotos.com Served from a pentawatercooled dual silent Athlon 2.8 with terabyte raid "The world is far too cosy," said God. So he invented Arabs. |
#136
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On Tue, 27 Jul 2004 23:41:23 +0100, "Peter Hucker"
put finger to keyboard and composed: On Wed, 28 Jul 2004 08:20:10 +1000, Franc Zabkar wrote: On Tue, 27 Jul 2004 14:05:26 +0100, "Peter Hucker" put finger to keyboard and composed: On Tue, 27 Jul 2004 06:17:14 +1000, Franc Zabkar wrote: On Mon, 26 Jul 2004 10:16:34 +0100, "Peter Hucker" put finger to keyboard and composed: Could someone explain "This little ugly thing is the PFC coil, it will be removed due to the fact that it increase power loss and makes a loud humm noise."? I thought PFC was to SAVE power? So I can just remove those things? PFC reduces the peak AC current drawn by your PSU. It does nothing to reduce the *real* metered power consumed by it. Australian domestic consumers pay for real power, ie kW not kVA, so a unity PF appliance will provide no cost benefit to me. The electricity supplier, however, will benefit from the reduced current demand. PFC is particularly important in heavy industry where high peak loadings are penalised with higher tariffs. I'm not sure what you mean with this metering. Are you saying some meters just measure current drawn, then just assume it was all at an average of 240 volts? This is how Energy Australia answered a similar question: ================================================== =================== To answer your question, most residential classification customers are metered by a spinning disc [watt]meter, or a basic electronic meter which does not have enough "smarts" in the meter device to enable billing to be carried out at a KVA pricing. Currently small customers are billed on KWh pricing, and KVA Demand pricing usually relates to large commercial and industrial installations where poor power factor may impact upon the EA network, and there may be an economic billing benefit in the customer pricing to ensure that Power factor is closer to Unity. ================================================== =================== I guess we have the spinning disk in the UK too then. Odd, I was told when studying electronics that the power factor correction in fluourescent ballasts was to save money on the electricity bill! The situation in the UK may be different. Ask your electricity supplier whether you are billed for kVA or kWh. In any case, PFC is now a requirement for the EU. See http://www.seasonic.com/support/a01.jsp "January 2001, European Union have adopted the requirement for new electronic equipment that consumes more than 75 watts to meet the EN 61000-3-2 specification for harmonic content." - Franc Zabkar -- Please remove one 's' from my address when replying by email. |
#137
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On Wed, 28 Jul 2004 17:43:44 +1000, Franc Zabkar wrote:
On Tue, 27 Jul 2004 23:41:23 +0100, "Peter Hucker" put finger to keyboard and composed: On Wed, 28 Jul 2004 08:20:10 +1000, Franc Zabkar wrote: On Tue, 27 Jul 2004 14:05:26 +0100, "Peter Hucker" put finger to keyboard and composed: On Tue, 27 Jul 2004 06:17:14 +1000, Franc Zabkar wrote: On Mon, 26 Jul 2004 10:16:34 +0100, "Peter Hucker" put finger to keyboard and composed: Could someone explain "This little ugly thing is the PFC coil, it will be removed due to the fact that it increase power loss and makes a loud humm noise."? I thought PFC was to SAVE power? So I can just remove those things? PFC reduces the peak AC current drawn by your PSU. It does nothing to reduce the *real* metered power consumed by it. Australian domestic consumers pay for real power, ie kW not kVA, so a unity PF appliance will provide no cost benefit to me. The electricity supplier, however, will benefit from the reduced current demand. PFC is particularly important in heavy industry where high peak loadings are penalised with higher tariffs. I'm not sure what you mean with this metering. Are you saying some meters just measure current drawn, then just assume it was all at an average of 240 volts? This is how Energy Australia answered a similar question: ================================================== =================== To answer your question, most residential classification customers are metered by a spinning disc [watt]meter, or a basic electronic meter which does not have enough "smarts" in the meter device to enable billing to be carried out at a KVA pricing. Currently small customers are billed on KWh pricing, and KVA Demand pricing usually relates to large commercial and industrial installations where poor power factor may impact upon the EA network, and there may be an economic billing benefit in the customer pricing to ensure that Power factor is closer to Unity. ================================================== =================== I guess we have the spinning disk in the UK too then. Odd, I was told when studying electronics that the power factor correction in fluourescent ballasts was to save money on the electricity bill! The situation in the UK may be different. Ask your electricity supplier whether you are billed for kVA or kWh. I'd get a dumb blonde telephone answerer who hasn't a clue what I am on about. In any case, PFC is now a requirement for the EU. See http://www.seasonic.com/support/a01.jsp "January 2001, European Union have adopted the requirement for new electronic equipment that consumes more than 75 watts to meet the EN 61000-3-2 specification for harmonic content." It's bad for the power supply company? **** that, I'd prefer not to be throwing away money with the heat off the bloody thing. So, if I remember correctly from earlier in the thread - PC PSUs without PFC draw more current at lower voltage in the cycle? And a simple transformer + rectifier + capacitor would draw more at the higher voltages, so don't they even out? -- *****TWO BABY CONURES***** 15 parrots and increasing http://www.petersparrots.com 93 silly video clips http://www.insanevideoclips.com 1259 digital photos http://www.petersphotos.com Served from a pentawatercooled dual silent Athlon 2.8 with terabyte raid Do infants have as much fun in their infancy as adults do in adultery? |
#138
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On Wed, 28 Jul 2004 09:18:39 +0100, "Peter Hucker"
put finger to keyboard and composed: So, if I remember correctly from earlier in the thread - PC PSUs without PFC draw more current at lower voltage in the cycle? And a simple transformer + rectifier + capacitor would draw more at the higher voltages, so don't they even out? The way that the concept of PF is taught leads to the prevailing misconception that there must be phase angle between current and voltage peaks for a non-unity PF to exist. I regret that I also perpetuated this misconception in an earlier thread in a.c.h.h until I was finally shown the error of my ways in aus.electronics. Let me now explain this concept as best as I can. Traditionally PF is analysed for passive linear "sinusoidal" loads such as the following (R/C = resistor/capacitor). Iin - |----|-----| o | Ic | Ir Vac C | R | o | v | v |----|-----| Let's assume that the magnitudes of Ic and Ir are equal. As ideal capacitors dissipate no power, the real power dissipated by this RC load is V x Ir. The reactive power is V x Ic. Ir is in phase with Vac, whereas Ic leads Vac by 90 degrees. The current, Iin, drawn from the mains is Ir x sqrt(2). The PF is given by (Vac x Iin) / (Vac x Ir) = 0.707. In this special case, the PF is equal to the phase angle between Vac and Iin, namely 45 degrees. As you can see, the current drawn from the mains is about 40% higher than that drawn by the *real* load. One could bring the PF of this load closer to unity by adding a parallel PFC inductance, L, whose reactance is equal to C at mains frequency. Iin - |----|-----|-----| o | Ic | Ir | Il Vac C | R | L | o | v | v | v |----|-----|-----| As Il is 180 deg out of phase with Ic, the two components cancel each other, leaving Iin = Ir. Hence PF = 1. Note that an ideal inductor dissipates no power. As you have seen, PF in the traditional linear case is directly related to phase angles. This is not true for non-linear active loads such as PSUs. A non-PFC PSU draws current from the mains only when the main filter capacitor is being charged, and that is just before the voltage peak of each half cycle. Traditional analysis of the simple transformer + rectifier + capacitor circuit has the shape of this current pulse as "triangular" with a vertical leading edge and sinusoidal falling edge. In reality it is more like a narrow rectangle with rounded edges. See fig 2 in this Vicor app note: http://www.vicr.com/documents/applic...active-pfc.pdf For simplicity, let's assume that the pulse has a 20% duty cycle, that it is rectangular, and that it is centred on the voltage peak. Now Vin (rms) x Iin (rms) = Vac x Ipeak x sqrt(0.2). Real power = Vac (peak) x Ipeak x 0.2 = Vac x sqrt(2) x Ipeak x 0.2 PF = real power / Vin (rms) x Iin (rms) = sqrt(10) x 0.2 = 0.63 Hence we have shown that a non-unity PF can exist even in cases where the phase angle between current and voltage peaks is zero. An active PFC circuit works by monitoring the current in the load and then drawing additional current from the mains so that the overall current draw approaches that of an in-phase sinusoid. - Franc Zabkar -- Please remove one 's' from my address when replying by email. |
#139
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On Thu, 29 Jul 2004 07:11:19 +1000, Franc Zabkar
put finger to keyboard and composed: The PF is given by (Vac x Iin) / (Vac x Ir) Oops, that should be PF = (Vac x Ir) / (Vac x Iin). - Franc Zabkar -- Please remove one 's' from my address when replying by email. |
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