I thought I might have seen one posted in the "all out assault" page here once...It seems like a good idea to me. I wish I had the means...
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I've got a 5KVA GE step-down wired for balanced AC output (derate by half) feeding two amps of 500W draw each. The idea is to isolate, so a single household one defeats some of the purpose, but not entirely. 10KVA, single phase transformers are rare and about 200lbs. Most that size are 3-phase.
Noticed a 5KVA Sola MCR on Ebay that does regulation and harmonic filtering but you have to be careful not to exceed the rating of these type, even more so than "regular" ones. Haven't heard of anyone doing a center tap on these, probably because of the price.
There are many benefits to proper selection and installation of iso transformers in your system. Besides reducing noise and creating a blacker background, I have found they eliminate grounding issues and the need for any further PCs, and make the system much less sensistive to cable/wire swapping.
See my system page below and the pictures and diagrams.
Here are some keys: Balanced configuration is OK but not necessary. Iso must be iron core (the heavier the better), and rated 2-3 times your peak power demand. Follow electrical codes for a subpanel and grounding.
A very nice installation. I tip my hat to you.
The 'archtecture' page on Zargon's system displays very clearly the guidelines that are spelled out in the Topaz (Square-D) documentation. The only variation that I can see is that Topaz states that (if possible) it is preferable (regarding the downstream ISOs) to place them as close as possible to the load component.
For a look at another system that utilizes a configuration in line with what you described, look at:
Lak uses double 5KVA ISOs (one per 120V leg) feeding his sub-panel.
You might find it helpful to search old threads on this subject. Though he does not post anymore, the past expert on this subject was 'Sean', who was a strong advocate of multiple ISO combined both downstream and upstream of a sub-panel. Sean was also an outspoken advocate of putting further isolation circuitry in the 'bells' of the ISOs.
I am using multiple small ISOs (just like the single that Zargon uses to feed his CD). I have found that some components really shine when placed behind an ISO, and some do not seem to care.
If you can swing the power company to do a three phase install on your home, you get your own dedicated 15 KVA transformer and (if lucky) you will be the only one in the neighborhood on the transformer.
I did this, took a lot of time with a TXU supervisor and I had to "prove" I needed it. In my case the photo studio on the back of my home. Probably a big stereo with multiple breakers might convince them too.
While you're at it, the 750 Amp trans socket meter base is a huge upgrade over conventional power meters and as a bonus, there is no provision for trans socket to be digital (at least not in my market).
Jeffcott, if by "downstream iso", I assume you are referring to the small 125va iso on the CD dedicated line. That iso, while next to the subpanel and large iso, is only 15 ft. from the CD player. Note that I mounted it at right angles to the main iso to minimize any cross coupling. I have tried the small iso in the room on the CD, and tried it as presently mounted, and could not perceive any difference. Note also that the class D amps in each speaker are on dedicated lines but not through the main iso.
Yes, that is what I was trying to communicate. I hope that you understand that I meant absolutely no disrespect by quoting what the documentation says. I can think of a thousand reasons why an ISO might very well not be the most desirable component in a living environment. Like I tried to say, NICE install.
No disrespect taken. My comments were mearly directed at trying to pass what I learned when experimenting with the small iso location.
WRT to the desirability of having an iso in the living environment, while the small iso is virtually inaudible and only slightly warm to the touch, the large iso can easily be heard from several feet away, and is quite warm to the touch. Hence, I decided to locate both isos on the block wall just outside the audio room.
I have been using balanced ISOs in my living environment for the past 5 years; currently 1 x 2kVA Equi=Tech Q type and 2 x 250VA in a single chassis. I recently completed a rebuild in a taller chassis, to add the second 250VA transformer. The large iso has an oversized core, is very immune to saturation from DC on the power line, and as a result, runs quietly. I've tried other isos that were very noisy.
Current setup: http://img.villagephotos.com/p/2003-5/191557/2083672
Past versions: http://img.villagephotos.com/p/2003-5/191557/1741050
It must cost you guys $50.00 plus a month just to turn these transformers on. I tryed a tranny from GE, just to power up the coils it pulled 5 amp for a 5KVA 208vac to 110vac stepdown center tap balanced transformer. I was told by GE that the amp draw is normal, too much cost for me. I even tryed to use a starter for on off cotrol but the breaker tripped on inrush at times.
I picked up a line reactor that I am going to try soon to clean up my power. They work on VFD's to stop dirty power for getting to it or from it.
I prefer real woman myself anyway. LOL.
Ngjockey, actually it's a 25KVA transformer but I didn't notice I typed the numeral wrong until later in the thread.
I'm the only one in the neighborhood on the service, so it's more than enough.
We have gas HVAC and gas water heater but in Texas the killer is summer heat and associated AC cost. I installed a commercial 3 phase AC (8 tons) and it really did help cut the electric bill.