Post by KeithL on Jul 20, 2016 9:05:44 GMT -5
I just want to add a few things to this discussion......
1) One other major difference with our SMPS is that it's REGULATED; this means that the rails don't "droop" when you draw a lot of power from them, which reduces interaction between channels, and sometimes gives you other benefits in terms of distortion. (Pretty well all SMPS are regulated - it's sort of inherent in the design. Big linear power supplies, like you find in amplifiers, are almost never regulated - because it increases cost and complexity and reduces efficiency.)
2) Modern fluorescent lights usually have "electronic ballasts", which often include power factor correction, and they're also usually pretty efficient. With older pre-electronic ones, the PF was the least of your problems. With older fluorescent lights, the power rating was for the bulb... not the entire fixture. With incandescent bulbs, the bulb is the only part that uses power, so a 40 watt incandescent lamp really uses 40 watts. However, if you were to look at the actual ratings for a typical "40 watt circular quick-start fluorescent fixture" from 1975 - the kind you probably had in your kitchen - you would find that the entire fixture, including the bulb and ballast, used more like 100 watts - with the extra 60 watts being "burned" as heat by the inefficiency of the starter circuitry and ballast (other parts necessary to fire up a fluorescent bulb). Ones that weren't "quick start" were a lot better - but still pretty bad. And, yes, since it still put out twice as much light as a 100 watt incandescent bulb, you were way ahead overall.... but the "40 watt" rating was very misleading.
3) Unregulated linear power supplies, the kind used in power amps, are actually pretty efficient. Our SMPS is slightly better in that regard, but probably not enough to notice it on your electric bill.
4) And, finally, while it's true that commercial customers usually get some sort of price differential for having a "good" Power Factor, that's generally not true for residential customers. So, while having the majority of their customers in your neighborhood use equipment with good overall PF is nice for your power company, they usually don't reward you personally for your green consideration. Also, things with large motors, like AC units and refrigerators, are the most prone to drawing a lot of power at really odd Power Factors.
5) The main EU limitation regards limiting how much power a device consumes while in Standby (I believe the standard limits that to 1 watt - or maybe 1 VA).
6) If this sort of thing really interests you, then buy yourself a Watt Wizard (a little $20- $30 box that connects between an appliance or power strip and the wall outlet). These typically show Volts, Amps, Watts, VAs, power factor, and can even keep track of how many dollars worth of power your device uses if you set them up right. Of course there are fancy versions that record, and provide graphs, detailed analyses, and probably glossy photos as well...
I"m VERY familiar with PF. Try applying your knowledge of PF to SPEAKERS with huge phase angles. And than factor in that some amps are very POOR when working into such phase angles. This is why I've said
more than once that testing amps into a resistor is not very relavent. I'm being nice, here.
I don't know the exact rules, but the EC is getting REAL picky about PS efficiency. And yes, 100% power draw is probably 'best case' with less of a difference as you draw less power. 'D' amps will have 80%+ efficiency at
full power. this drops as power required also drops. This is Plug to Speaker, which IMO, is the only way that makes sense. These amps have built-in onboard SMPS which probably DO have PFC, as mandated by some of the
markets in which the amp will be sold. Don't forget that when there is NO load on such a PS, it may still draw SOME current. This will be at ZERO % Efficiency.
You can STILL draw max power from a line. The question is DELIVERED or UTILIZED power.
Your 500 watt @0.7pf amp is being BILLED for 500 watts by the power company but USING about 714VA. That's why large factories with LOW PF can receive a supplemental bill. Industrial size PFC is a viable alternative. Your example of using a PF of 0.7 is right at 45 degrees between voltage and current peaks. COS45 = 0.707
I may take the time to MEASURE my ampfliers. If I do, I'll send you a PM with my results.
Can we look at the math a different way? I'm not sure if this works, but here goes.
Let's try a slightly different example: I have a '40 watt' fluorescent tube. When warm the PF is about 0.8 and when cold maybe .75 or even less. An irrelevent point, but something I just noticed.
So, by my METER, it is 0.33amp x 118.6vac = 39v a or about 31 watts. Is that correct? The person who told me about this originally spoke about 'real' and 'apparent' power. The real being WATTS and the APPARENT being VA. The important thing is that the COSINE of the PHASE ANGLE between voltage and current, yields what we are agree is PF. Certain other things can happen, a 'negative' PF and even when voltage leads current or when voltage LAGS current.
I came upon this when reading about speakers storing energy and just how BAD a load most are, treating the amp as a power supply and the speaker as a load. My Christmas Wish would be for amp manufacturers and Speaker builders to have a little chat.
1) One other major difference with our SMPS is that it's REGULATED; this means that the rails don't "droop" when you draw a lot of power from them, which reduces interaction between channels, and sometimes gives you other benefits in terms of distortion. (Pretty well all SMPS are regulated - it's sort of inherent in the design. Big linear power supplies, like you find in amplifiers, are almost never regulated - because it increases cost and complexity and reduces efficiency.)
2) Modern fluorescent lights usually have "electronic ballasts", which often include power factor correction, and they're also usually pretty efficient. With older pre-electronic ones, the PF was the least of your problems. With older fluorescent lights, the power rating was for the bulb... not the entire fixture. With incandescent bulbs, the bulb is the only part that uses power, so a 40 watt incandescent lamp really uses 40 watts. However, if you were to look at the actual ratings for a typical "40 watt circular quick-start fluorescent fixture" from 1975 - the kind you probably had in your kitchen - you would find that the entire fixture, including the bulb and ballast, used more like 100 watts - with the extra 60 watts being "burned" as heat by the inefficiency of the starter circuitry and ballast (other parts necessary to fire up a fluorescent bulb). Ones that weren't "quick start" were a lot better - but still pretty bad. And, yes, since it still put out twice as much light as a 100 watt incandescent bulb, you were way ahead overall.... but the "40 watt" rating was very misleading.
3) Unregulated linear power supplies, the kind used in power amps, are actually pretty efficient. Our SMPS is slightly better in that regard, but probably not enough to notice it on your electric bill.
4) And, finally, while it's true that commercial customers usually get some sort of price differential for having a "good" Power Factor, that's generally not true for residential customers. So, while having the majority of their customers in your neighborhood use equipment with good overall PF is nice for your power company, they usually don't reward you personally for your green consideration. Also, things with large motors, like AC units and refrigerators, are the most prone to drawing a lot of power at really odd Power Factors.
5) The main EU limitation regards limiting how much power a device consumes while in Standby (I believe the standard limits that to 1 watt - or maybe 1 VA).
6) If this sort of thing really interests you, then buy yourself a Watt Wizard (a little $20- $30 box that connects between an appliance or power strip and the wall outlet). These typically show Volts, Amps, Watts, VAs, power factor, and can even keep track of how many dollars worth of power your device uses if you set them up right. Of course there are fancy versions that record, and provide graphs, detailed analyses, and probably glossy photos as well...
more than once that testing amps into a resistor is not very relavent. I'm being nice, here.
I don't know the exact rules, but the EC is getting REAL picky about PS efficiency. And yes, 100% power draw is probably 'best case' with less of a difference as you draw less power. 'D' amps will have 80%+ efficiency at
full power. this drops as power required also drops. This is Plug to Speaker, which IMO, is the only way that makes sense. These amps have built-in onboard SMPS which probably DO have PFC, as mandated by some of the
markets in which the amp will be sold. Don't forget that when there is NO load on such a PS, it may still draw SOME current. This will be at ZERO % Efficiency.
You can STILL draw max power from a line. The question is DELIVERED or UTILIZED power.
Your 500 watt @0.7pf amp is being BILLED for 500 watts by the power company but USING about 714VA. That's why large factories with LOW PF can receive a supplemental bill. Industrial size PFC is a viable alternative. Your example of using a PF of 0.7 is right at 45 degrees between voltage and current peaks. COS45 = 0.707
I may take the time to MEASURE my ampfliers. If I do, I'll send you a PM with my results.
Can we look at the math a different way? I'm not sure if this works, but here goes.
Let's try a slightly different example: I have a '40 watt' fluorescent tube. When warm the PF is about 0.8 and when cold maybe .75 or even less. An irrelevent point, but something I just noticed.
So, by my METER, it is 0.33amp x 118.6vac = 39v a or about 31 watts. Is that correct? The person who told me about this originally spoke about 'real' and 'apparent' power. The real being WATTS and the APPARENT being VA. The important thing is that the COSINE of the PHASE ANGLE between voltage and current, yields what we are agree is PF. Certain other things can happen, a 'negative' PF and even when voltage leads current or when voltage LAGS current.
I came upon this when reading about speakers storing energy and just how BAD a load most are, treating the amp as a power supply and the speaker as a load. My Christmas Wish would be for amp manufacturers and Speaker builders to have a little chat.
