in addition to improved line transient protection, your balanced AC supply line offers increased common mode noise rejection over the traditional unbalanced commercial power source. A possible downside may be an increased supply line impedance: associated with dynamic headroom constraints.
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Some gear has polarity sensitive filtering in it and going to a balanced AC system may negate many of the specific design attributes of such a design. Contact the manufacturers of the gear that you are running and discuss it with them before going any further. Anything less could be experimenting at your cost. Sean
Hi Sean it appears that Luke already has his balanced power setup in place; BTW isn't your own AC supplied via a balancing transformer? I recall your traveling to (Ohio was it?) a couple of years ago due to a bargain find on 2kva transformers. Wish that I had been working at the time but I was off for a year updating my data networking education; otherwise I would have liked to try one! So Luke if your reserach dictates that you'd be better off without then please do let me know...
"it's definatly a safer system as you would not get shocked unless you touched both legs at the same time."
Not if you wired the secondary of the xfmr correctly. The center point of the xfmr should be bonded to the main service grounding electrode system. Thus this is a grounded conductor. This is also the point in which the equipment grounds of this new AC derived system will tie to. You will have 60V to ground from either one of the two hot conductors of the 120V system.
What type of receptacles did you use? Isolated grounding type?
The grounding system i am using is a common all across system, so the primary and the secondary ground is the same, with normal outlet ground, i am having trouble with ac noise, on my sub (sunfire) it has a humm without any inputs attached, the grounding system may be the reason for it.
heres a pick for one of the transformers i am using, wich is dedicated to my sunfire sub, as it draws up to 2700 watts of ac power:
The input has been config for 240v in as thats what my apc runs on, and output taps 5 and 8, this system was made to be tough,mainly becaus of the sunfire high current draw.
Thank you for your help, i will keep posting on this thread as we discuss this matter,
"in addition to improved line transient protection, your balanced AC supply line offers increased common mode noise rejection over the traditional unbalanced commercial power source."
Could you please explain in more detail.....
This being the unbalanced.
A single phase isolation transformer with one of the two secondary output leads bonded to ground. Thus one grounded conductor and one ungrounded conductor, 120V.
This being the balanced.
A single phase isolation transformer with a center tap secondary winding 60/120V,
60V-0-60V. The center tap being bonded to ground. Two 120V ungrounded conductors with a reference voltage potential to ground of 60V each.
Some of the Sunfire subs are notorious for being noisy. You should contact Sunfire about this problem and discuss it directly with them.
As to the isolation transformer pictured, it looks WAY too small to pass 2000 KVA with low distortion. Then again, it is hard to judge how big the core actually is going by that picture, as there are only the wires and heads of the bolts holding it together to gauge the physical features by. This wouldn't introduce hum into the sub at idle, but it could introduce other distortions at higher power demands. Sean
"The input has been config for 240v in as thats what my apc runs on, and output taps 5 and 8, this system was made to be tough,mainly becaus of the sunfire high current draw."
"taps 5 and 8" >>> #5 = 0, #8 = 115V output.
"The input has been config for 240v"
Then #2 & #3 tied together? With the 240V supply connected to terms #1 & #4?
Agreed more than likely xfmr is to small.
Max safe load of xfmr 2000 x 80% = 1600VA
Check the output voltage of the xfmr with the load connected. The load being the Sub
The Sunfire amps are quite efficient by design, so they don't pull much current at idle or even during normal use. The only time that they really pull BIG power is when you're throttling the volume with heavy bass passages. As such, the small core Iso transformer wouldn't be causing the hum at idle, which is what Luke has alluded to. Sean
The APC is the battery backup, 7500 va model, it operates at 208/240 1 ph, i have it set to 240 in and out, and have to use a TX on the output to achieve 120, as you cannot split the 240 on the output of the APC of course, the transformer is rated at 2kva or 2,000 Va, at the current tap im running, the sunfire does humm at idle, but less than say 5db, so its just barly noticable, but lowd enough to keep it from going to stanby on the auto power off, when i plug it directly into the wall the humm seams less, and enough to let it go to standby when not in use, and of course the noise test is done without the low level input connected, and connected sounds the same.
but i am bonding the ground to everything, from the chasis, to the transformer casing, to the outlet it self on both pri and sec sides, and did run a #1Odd welding cable to bond directly to grounding rod, and this still made no diff, i am moving next week to an apt. and will re-evaluate the system then, i will then do tests to see if this setup does endeed kill the dynamics of the systms sound, as that is what i heard you get with a lot of power filters, as right now this is basically what the service goes through before it hits my equipment:
240V main service into home into primary filter which consists of 1 large inductor filter per phase, then a high energy surge protector, then a small filter cap to ground per phase, after that it runs though the main panel to a dedicated 30 amp 240v circuit upstairs into the "APC" (battery backup) in that it filters the power again, with numerous Torrid filters and filter caps, then it drives the power through SCR's to process the frequency and voltage, (no normal bypass as some battery backups do) then it leavs the APC and goes into my home brew dist block, (the large grey thing next to the apc in the pictures i have up)there it runs though the isolation/step down transformer, then it pases through the EMI/RFI filter (both legs), then to the outlet. and meanwhile the same ground on everything, everywhere.
What is the output voltage of the xfmr with the load connected to it? Is the Sub the only load connected to this xfmr?
Any type of filtering on the output of the xfmr? Did you ground one leg of the output of the xfmr? Creating a grounded conductor. I hope so, for safety. If not try that and see if it makes any difference. On your duplex outlets the silver color term is for the grounded conductor as you know. Just for the heck of it make the grounded conductor term #5 of the secondary on the xfmr. Basically you have created a new AC electrical power system and as such you need to make it a 120V grounded AC system. That is why one output lead of the xfmr is bonded to earth ground. This new ground point you have created is also where the equipment grounds of the receptacles will connect to. If you have a metallic main incoming water line this is were I would go to for the earth ground. Is the plug on the Sub a 3wire grounding type?
Home brew unit
Sure looks like a lot going on in there.
I just now noticed you summitted a second post I will need some time to digest it. Especially the grounding system and ground rod.
Where do you live?
Im in independence, Missouri, about 30 miles east of KC.
I had never thought to gound the #5 terminal,but maybee the #0 or the 0Volt tap,i figured it would short the primary, but i will fuse it low and try it, then that would eliminate the 60/60. but i do run the power after the transformer through the EMI/RFI filter, before it hits the outlet.
And this is just for the sub, i still have one other dual coil transformer im using for the rest of the equipment, but the output on both seam to be a little high, around 126 at low to no load, im not sure what the tube stuff likes best, im sure the sub wont mind.
I have a currently unused variac installed and "was" using it to drop output to around 115, for the amp,tv,xbox etc.
"Im in independence, Missouri, about 30 miles east of KC."
From your picture I figured you lived in the midwest, USA. The mahogany woodwork and sprayed on lacquer finish is typical for homes in the 60s,70s, and 80s, in the midwest.
You had me confused for a while when you mentioned the electrical service in you home being 240V. Now I know you meant 120/240V.
"I had never thought to ground the #5 terminal,but maybee the #0 or the 0Volt tap,i figured it would short the primary, but i will fuse it low and try it, then that would eliminate the 60/60."
This is an isolation xfmr. The primary and secondary are not connected electrically. Where as on the other hand, autotransformers are.
Before you do anything in regard to grounding term #5 on the secondary of the xfmr please explain to me your statement about "60/60". I fail to see it, as for the secondary of the xfmr we have been discussing. All I see is a 120 volt floating secondary with no reference to ground.
"60/60 otherwords 60 volts to ground on each leg, but 120 between both legs, as in no neutral, just 60/60 and common ground."
The output of your isol xfmr is only 115V if you are using the common term #5 and the tap term #8. The secondary on the xfmr in your picture is a multi tap winding with #5 being one end of the winding and #11 being the other. 170V potential between term#5 and #11.Various taps in between.
A split phase, center tap, winding would be a winding with, say, 120V measured across the total winding and 60V measured from either to the center tap. The center tap is bonded to earth ground. This new grounded point is were any equipment grounds of connected loads would connect to.
Here is some great reading material for you.