Of course if you decide to use a balanced power unit, all this is of no concern.
AC cord polarity?? Does it matter???????
I've just noticed that from experimenting with preterminated factory builty cords that not all companies use the same polarities. Even with two stock cords, one from USA made in China and one from China made in China for USA the polarity of the cords are reversed. All my Synergistic cords are one way, my Electraglide is the other way and other cords from different manufacturers are different. The poles are reveresed from one cord to the next. Now I'm really confused to the polarisation issue as if different companies use one polarity and other companies use the reversepolarites, then it's a guess wether or not one system is in the right polarity or if just certain components are properly polaroized. It appears that in the US made cords I've noticed both direct and reverse polarity in cords. The Asian made cords are different depending on company as well. Does this then mean that polarity has no issue and it doesn't matter? Is there no right or wrong way to polarize a components ac? The cords in my system are giving half my components one direction of ac polarisation and the other half are in reverse.Perhaps it doesn't matter? I'm confused again!!!!
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>>"Of course if you decide to use a balanced power unit, all this is of no concern."<< [Nsgarch] >>>>> Maybe, True if all the audio equipment connected by ics is pluged into the same balanced power unit. ========== Nsgarch, What is your thoughts of feeding a balanced power unit from 120V? Jmho, I believe there would be better isolation if a balanced power unit was feed by 240 volt. Here is some reading material. Make note of how the utility companies bond the high voltage neutral and all the secondary neutrals together at every utility transformer. This can't be good for AC noise.... http://www.mikeholt.com/documents/strayvoltage/pdf/DangersofStrayVoltageandCurrent.pdf Jmo it appears to me the only way to get total AC isolation is with an isolation transformer fed from 240 volt. Jim |
Nsgarch, I am not sure..... >>"Of course if you decide to use a balanced power unit, all this is of no concern."<< [Nsgarch] >>>>> >>'Maybe, True if all the audio equipment connected by ics is pluged into the same balanced power unit."<< [jea48] >>>>>>>>> After thinking about the balanced 120V (60V-0V-60V) system I am not sure one would not be in the same boat. It's those darn ICs that connect the audio equipment together. Two hot 120 volt conductors. I will call them L1 and L2, 120V. A power transformer, for say, a power amp. It is nothing more than an isolation transformer. It has a winding polarity relationship between the primary and secondary windings. For sake of argument lets label the primary leads H1 and H2. The secondary leads X1 and X2. If the manufacture of the transformer labeled the leads correctly, H1 polarity match is X1 and H2 polarity match is X2. Connect the audio power transformer primary to the 120V power from the balanced power unit. (L1 to H1) (L2 to H2). If all the audio equipment power transformers are wired the same the the secondary AC polarities will be the same and so the DC power supplies. (Providing a primary winding polarity to power supply polarity were correct to start with) What happens if one of the audio equipment power transformer's primary connections is reversed? (L1 to H2) (L2 to H1) Any thoughts?? |
Jea, a 240V line is inherently "balanced". Its ground and neutral are the same (center) conductor, with a potential of +120v on one side and -120V on the other (which reverses every 60 sec. of course.) BTW, I don't believe European 240V power is configured this way (at the outlet), but somebody correct me if this is wrong. Now to get balanced 120V is a whole 'nuther matter. First you get a great big toroidal transformer and feed it 120V +/_ into one tap and zero volts (neutral) into the other. In a second, identical winding, you take the power out at 60V +/_ tap and 60V -/+ tap and feed one to each blade of the AC plug. To keep the drama queens at U/L happy, you create an artificial ground/neutral for the center ground pin of the plug/receptacle. This is done through some kind of circuitry which U/L is willing to certify provides shock protection ;~)) but it's not an "earth" ground. If your equipment circuit designer or assembler has been less than attentive as you postulate, then balanced power will save his/her ass because both primary leads are being fed equal (60V) voltage in a "push-pull" arrangement around (or across) an "imaginary" ground (rather than the normal zero volts in one lead and plus-or-minus 120V in the other.) So in the balanced-power-fed component, circuit polarity relative to ground disappears along with any polarity mismatches in the wiring. |
>>" a 240V line is inherently "balanced". Its ground and neutral are the same (center) conductor, with a potential of +120v on one side and -120V on the other"<< >>>>>>>>>>>>> Correct. The utility transformer's secondary windings are configured as a split phase winding exactly a balanced power system. 120V-0V-120V. The center point of the two connected secondary windings is bonded, connected to earth ground. Just like the 60V-0V-60V system. If all the loads connected to the 120V-0V-120V utility transformer were all 240V loads it would work exactly like the 60V-0V-60V balanced system. Here is one for you. For a single phase/split phase utility transformer where 120 volts loads are exactly balanced across the two mains, zerro amperes will travel back on the neutral conductor to the source, the transformer. Example 30 amps of connected 120 volt load from L1 to neutral, and 30 amps of connected 120 volt load from L2 to neutral. The connected 120V loads from L1 to neutral will be in series with the connected 120V loads from L2 to neutral. Only the unbalanced 120V loads travel back on the neutral conductor to the source, utility transformer. http://www.ibiblio.org/obp/electricCircuits/AC/AC_10.html#xtocid269100 |
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