Info - What is balanced isolated power

[Guest " "]

Define this

"If you have good clean power"

In NYC homes are tipically 15ft apart with anywhere from 15X15 (tipical) to 15X30 (rare)yards. Population density in my comunity is considered light for NYC with half a million folks in a 15 square mile area. Every block has a step down transformer that buzzes at varying levels through out the day. Mine is located 30 feet from my property line. It is about the size of a kitchen grabage can. This particular transformer has been replaced twice in the last seven years. 30 homes share this transformer .

Power right now has to be bumpmed up 8.5 volts at my voltage regulator which is indicating it is adding 8.5 volts of voltage to the incoming power. It typically adds 5 volts - 18 volts. it's always adding something. The voltage regulator works by converting current to voltage. it does this by drawing more power via a change in the windings of a 3000 VA transformer. A CPU monitors the in and out voltage and makes the winding adjustment. By the way, the load on my voltage regulator is only 2.42 amps, and it still has to add 8.5 volts to the incoming power to bring it to normal levels.

The voltage differential right now at my main breakers is 1.1 volts of a difference between the red phase and black phase of the inbound 220. No one is home but me right now. Everything is off in the house except for this computer workstation. A balanced and isolated power transformer connected at 220 will eliminate this differential since the 220 will pass thru the primary winding. In essence my power will improve for devices connected to the balanced and isolated power transformer soley due to be connected to both phases on the 220 as opposed to one or the other of the 120 phase. The 2:1 ratio transformer will bring the 220/230 down to 120. Fully balanced as well.

I thought I was doing a good job running my power thru a voltage regulator (1600 bucks) and a high end line conditioner (1200 bucks) until i did some test using an additional stage involving both isolation and as a seprate test isolation and balanced power. The difference was startling. In reaserching this, it turns out that tbalanced isolated power is a common implementation where the goal of reducing the noise floor exists.

So what is causing these drops and differential voltages, and are we to asume that no harmonisc are bieng generated on the local step down circut by the sources of the power draw?

So now I am rounding up the parts to build a few large capacity black box balanced power units. They will go in-line to the current power path way to my HT equipment, but be the first device before the voltage regulator. I will be running off the 220/230, stepping down to 120 maintaining a totally balanced pathway.

This is a relativly new approach and is increasing popularity in the audio industry. My personal view is that amoung many who do not have power issues, this will be viewed upon as another snake oil offering and classified with other solutions that have merit if you have the problem that is solves and no merit at all if there is nothing broken that needs fixing.

If your happy with your power this may be viewed as a waste of time and money.

If your not happy, the search and projects continue.

[scotrajode]

I think we are talking about two different aspects of "balanced". It is true that two pole residential systems are not balanced because of the split 120 volt circuits. But when you add in the neutral (which brings back the unbalanced load) the total current when reading all three current carrying conductors together with a clamp on ammeter, the total current is 0 amps and therefore is balanced with in the cable and will not induce voltages (although there is no ground wire ran with your service entrance cable to have voltage induced on it anyway. If 0 amps is not read across all 3 conductors, there is a resistive ground fault. The reason that the two poles should try to be as close to balanced as possible, is to minimize voltage drop. I think you know this already, but for example: if you are drawing a total of 200 amps at 120 volts and it is all on one pole, you would read 200 amps on one pole, 200 amps on the neutral, and 0 amps on the other pole. This is a worse case scenario, but you would then read something like 122 volts from one pole to neutral, 112 volts from the other pole to neutral, and 234 volts from pole to pole. Obviously, 112 volts is less than optimal and is also what everything would be running on. In a perfect scenario, there would 100 amps on one pole, 100 amps on the other pole, and zero amps on the neutral. Because there is now half the amperage running through the same length of wire, voltage drop would be cut in half. So there would be 238 volts from pole to pole and 119 volts from each pole to neutral. 119 volts is much better than 112! That is the reason for trying to balance the load.

What I am referring is that in a single circuit, the current on the hot equals the current on the neutral but running in opposite directions and both conductors being equal distant from the ground wire, no voltage is induced on the ground wire. That is what I mean by it is balanced. If you look at a piece of cable, you will notice that ground wire is either ran right between the hot and neutral, or as close as possible to equal distant to the current carrying conductors in a multi wire circuit. Multi wire cables are not perfect though. This is why it is best to use a dedicated two wire cable to feed an isolation transformer. it is true that a cable, like CATV will get interference when ran next to a power cable is because the CATV cable is not equal distant from the hot and neutral so the two currents do not cancel each other out and voltage is induced on the CATV cable and you get noise. This is also true between one power cable and another. The heavier the current, the more noise. This why you may see snow on your TV when you run a blender, garbage disposal, or vacuum. The appliance power cable is ran near the TV power cable or CATV cable, or even on the same circuit. Harmonics from the motor load is likely induced through a capacitive effect on the TV system and you get snow. This is can be minimized by a properly grounded system though. Again, this is the need for a separately ran 2 wire dedicated cable to feed an isolation transformer with an isolated ground. This should eliminate the possibility of that problem.

To clarify, a residential service is fed with a single phase, two pole, three wire, 120/240 volt service. Although a two phase system does exist, the phases are 90 degrees out of phase and it is not as practical as a single phase or three phase system. I don't know of an application that it is used in presently, and for all intensive purposes, it does not exist. 2 phase is often misused to describe a residential service, even by some electricians!

220 volts is usually used to describe a piece of equipment that can run on either 208 single phase (commercial) power, or 240 volt single phase (residential). 220v itself is actually not used in this country.

It is true that it is better to step down from the 240 volts to 120 volts to help keep the load balanced in the service. In your case, you say that your load is not balanced. If it is that badly out of balance, it would be better to take your circuit from the pole that has the less load at 120v and just do a 1:1 isolation transformer. This will give you better voltage at your receptacle and also help to balance your electrical service. Well, actually it would be best if you rewired your panel to get it close to balanced and then used a 240v 2:1 step down transformer. That would be optimal.

Again, on an individual circuit, the power is balanced between the hot and neutral. The neutral is just as much a current carrying conductor as the hot is. The neutral is just referenced to ground. Does that make sense?

You said that electricians try to balance the two poles of a residential system. In a perfect world that would be true. Residential construction electricians, for the most part, don't give a crap if the system is balanced or not. They just want to get it done and get out. They are happy if they turn everything on and nothing trips. The electrical engineer tells them what size service is needed for the size house and the equipment in it. A panel schedule is hardly ever engineered and the electricians just hook it up according to their preference. On very rare occasions is it so lopsided that it will cause the main breaker to trip. If it does, they just come out and change a few circuits to bring it a little closer to balanced, but it is still far from optimal.

My main point is that what you are doing is a good thing, but where your ground is referenced (center or end tapped) on your system is meaningless to the quality of your power supply. My guess is that a company wants you to buy their system because it different than other normal isolated power systems because of the center referenced ground. The only draw back is that it is slightly less safe because in the event of a ground fault, you only have 60 volts to ground to push enough current to trip the breaker and prevent electrocution of a fire. I am not saying it is unsafe at all. But ever slightly less safe than a normal grounded system. In short, I am not saying that the center referenced system is not better or worse, but that it simply does not matter to the quality of the power.

I have been involved in the installation of multimillion dollar electrical systems with isolated, dedicated circuits,and isolated grounds feeding ultra clean power to tens of millions of dollars of equipment and center referencing the ground has never been an issue. An even better comparison is that I have installed electrical systems for professional sound systems for auditoriums and such, but they only had several hundred thousand dollars worth of equipment, and the ground reference point is still not an issue. If it had been, I would certainly flip my books back open to rethink my knowledge of electrical theory.

There are systems where the ground reference is an issue, such as hospital operating rooms, and certain industrial applications, but it is still not a power quality issue, but a safety issue.

As far as power factor goes, 100 is ideal but 85 is not a panic rating. Most commercial buildings have a power factor of less than 85 because of all the motor loads, fluorescent lighting and power supplies. Low power factors is a problem, but if 85 was a panic rating, we would be in midst of a catastrophe.

Its true that power factor is not usually considered a problem in residential, but it can be enough to cause problems with audio equipment.

The capacitor on a residential motor is a start capacitor, not a run capacitor. The capacitor is to give current to the motor during the instant that it is turned on when it is drawing locked rotor current. This current surge can cause nuisance trips, so the capacitor is the cheapest way to solve the problem. Once the motor reaches a certain rpm, the capacitor is switched off. If the motor does not reach that rpm, the capacitor will quickly run out of power and then the motor will start to draw current from the system, which will hopefully trip the breaker before there is a fire, or in a perfect world before the motor burns out. Commercial motors use start windings and run windings instead of a start capacitor. This is a better system, but more expensive.

I am not 100% sure, I would have to do some research to be sure, but to the best of my recollection, harmonics are most prevalent in multiples of three and less prevalent the higher the multiple. If there are 5th and 7th order harmonics are at all a factor, there is some serious problems. Again, I am pretty sure, but not 100%.

Anyway, the isolated power supply is a good thing. I just wanted to clarify some of the information. You may also want to look at the circuit supplying the power supply and make sure it is ran on its own. If you can, you want to run it in MC IG cable. It would also be a good idea to balance the load on your service, if you want an ultra clean power supply.

I will keep tabs to see how your progress goes and what kind of an improvement you get. I think it is a good thing, I do not argue that. I am wondering if it is worth the time and money for the results you get. Of course, that is subjective, and if you are striving for a perfect system, then the answer is a resounding yes!

Scott

[Guest " "]

""I will keep tabs to see how your progress goes and what kind of an improvement you get. I think it is a good thing, I do not argue that. I am wondering if it is worth the time and money for the results you get. Of course, that is subjective, and if you are striving for a perfect system, then the answer is a resounding yes!""

I am going to build three boxes. Two I will use right away. The third won't be needed til spring. My cost per box is 54 bucks for the case with all the outlets, switches, breakers and anywhere between 70 buck to 118 for the transformer. Still deciding which transformer to use. There are product variations that can be compared, but not sure how real world those variations are. Time line to complete the boxes are about two weeks.

If anyone wants to run some spectro test on one of the boxes, I would be intrested in seeing the graphs. Something like a graph that shows line noise of varying types with out the box and some graphs that show what effect the box had. I don't intend to put any filters in the box as this is reportedly not needed and I have filters in devices that will be later in the power path.

I have a graph at work that was posted on another forum which I'll post on monday. The graph showed a before and after. The reported lower noise floor was clearly there. What was odd about the graph was the functional range of the data which suggested the cancellation effect was localized between 60hz and 6KHZ. I found that to be very odd.

As far as the results....it's the kind of thing that would be intresting to demo a klipsch gathering and put the question to the audience.

[scotrajode]

Wholly (not Holy) crap, you do have power problems. 30 is way too many to have on one transformer. I have 4 on mine. The voltage drop is not because of the 2.4 amps you draw on that circuit, but the greatly varying demand you have on the main transformer. Your utility company should split that into at least two, if not three or four transformers. My voltage varies less than 2 volts and never drops below 120 or 240. I highly recommend you balance the poles on your service. That will help a little. Measure all your single pole circuits at varying times and record the current. Then try to balance the load so that the load will be the most balanced most of the time. I would also complain to the power company and try to get your neighbors to complain as well. If you turn off everything in your house and you do not read a bear minimum of 116 volts from each pole to neutral at the very lowest of multiple readings, your utility company is giving you inferior service. That really sucks, you shouldn't have to spend $3000 to try to correct the power companies problems. Good luck and let me know if I can be of any further help.

Scott

[Guest " "]

"The voltage drop is not because of the 2.4 amps you draw on that circuit, but the greatly varying demand you have on the main transformer"

Yeah I know. Power issues seem independent of whats going on in my house.

Right now it's 115.3 on one phase and 114.4 on the other, so my AVS is adding 4.6 volts.

I think I am more concerned with the imperfections that are being delivered along with the power I recieve, generated by the neighborhood appliances on the community transformer as they try to out surge each other.

My take power issues are probally more common than folks realize.

[Jim E]

"If you have good clean power" by my definition was spelled out. Speakerfritz, I am not trying to cast doubt on your post. I am sure you are sincere. Quite the opposite, I've seen people go to many extremes in the quest of better audio. The cost for these extremes can be staggering and often lead to marginal improvement if any. I am only suggesting an alternative that could work for perhaps 95% of the people with similar problems. I live in Southern California and if you watch the news, each summer we have electrical power shortages and sometimes they shut-off entire areas to prevent total failure. I don't live in NYC and your location may need additional gadgetry to reach your goal. I must say that adding a single phase 220/230 stepdown or isolation transformer will not rid you of local power fluctuation. Fortunately most modern audio equipment is designed to operate within the estimated voltage range in the real world. It is interesting to note in the early days of commercial audio much of the equipment was DC and battery powered systems were very common. Maybe they had it right the first time.

I'll try again to explain and elaborate.

Home runs to the mains panel, the lines should not be shared by items that can generate spikes or have high in-rush current on startup. For example thyristor type dimmer and speed modules (aka diac/triac or scr light dimmers/motor speed controlers) can introduce noise into the line not only through the "Hot" but any shared neutrals as well. This can happen even when they are designed as a zero-crossing device. High in-rush and current hogs will cause dropout or low current conditions for other equipment on the same line.

Have dedicated neutrals and grounds for each circuit. Adding an "earth" or technical ground can help. It could save you and your stuff in an electrical storm as well.

Balance the electrical load in your panel. If you are not an electrician don't even think about doing the work yourself. This will never be precise as many items that draw current are not used all the time.

It is beneficial to operate all of your audio and video equipment on the same leg or phase of the power panel. This applies to single connected systems. If you have multiple systems within your home they can be on the other phase for balancing purposes.

I have one question for you. What is it that you are hearing that is causing you all this grief? If your surroundings in NY are as you stated, you must have spent a fortune to get you listening area so quiet. The noise floor on CD is very low (unless you count poor recordings as part of the noise).

FYI, some power companies will install (on a temporary basis) a digital powerline monitor to assist in finding supply issues. These can track and record typical problems for say a week. As you said, they have replaced the transformer several times. There may be other issues that have not been addressed.

[scotrajode]

Yup, they all compound on each other. I live in the suburbs, so I may be shielded. Although the commercial buildings I work in (Washington DC) are not underpowered. That is certainly a metro area. I don't know how the residential service is though. I'll bet your voltage drops below 110 when it is hot and everyone's air conditioner is running. Under voltage causes many more problems with equipment that minor over voltage (124v or so). Under voltage will even cause your amp to clip prematurely. That should not be a usual problem with Klipsch speakers though. If you can't get the power company to correct the problem, you may want to look into installing an isolation transformer for your house with voltage correction taps. Maybe to pricey, but it would isolate your house from everyone else and you should be able to set your whole house voltage to run between 124 and 116. In either case, in addition to doing the pole balancing, turn your main breaker off and make sure ALL the connections in you panel are snug. Just be aware that the feed wires coming in are still hot, and will make a nice explosion if you short them. If you have electrically insulated tools, and are comfortable with it, you should also check the connection on your incoming wires. If I think of anything else, I will let you know.

Scott

[Guest " "]

Home runs to the mains panel, the lines should not be shared by items that can generate spikes or have high in-rush current on startup. For example thyristor type dimmer and speed modules (aka diac/triac or scr light dimmers/motor speed controlers) can introduce noise into the line not only through the "Hot" but any shared neutrals as well. This can happen even when they are designed as a zero-crossing device. High in-rush and current hogs will cause dropout or low current conditions for other equipment on the same line.

Have dedicated neutrals and grounds for each circuit. Adding an "earth" or technical ground can help. It could save you and your stuff in an electrical storm as well.

Balance the electrical load in your panel. If you are not an electrician don't even think about doing the work yourself. This will never be precise as many items that draw current are not used all the time.

It is beneficial to operate all of your audio and video equipment on the same leg or phase of the power panel. This applies to single connected systems. If you have multiple systems within your home they can be on the other phase for balancing purposes.

The above is a pretty good start for a useful checklist.

[scotrajode]

Jim,

You sound like you have a good grasp of electrical theory. Do you work in the electrical field or did you learn on your own? I do have a question about one of your statements though. What do you mean by "Have dedicated neutrals and grounds for each circuit. Adding an "earth" or technical ground can help. It could save you and your stuff in an electrical storm as well." Your original grounds should already be bonded to earth at your main bonding jumper. Are you referring to a separate isolated ground? I may not understand what you are saying.

Scott

[Guest " "]

I took the "Have dedicated neutrals and grounds for each circuit" and "earth or technical ground" as two seperate levels of implementation initally since you could put in a "technical ground" with out having isolated grounds for each circut.

Here is a pretty good link on installing technical grounds.

http://www.equitech.com/support/techgrnd.html

I have always enjoyed reading this discussion about isolated grounds.

http://www.mikeholt.com/technical.php?id=powerquality/unformatted/8-3-99&type=u&title=Power%20Quality%20Article

[Duke Spinner]

S.F. ...!!!

what ever are you doing on the Mike Holt forums .....???

that's just for us Sparkies ......[8-|]

[Guest " "]

Duke Spinner

My younger brother is a sparky. He used to watch over my shoulder during the early 70's and ask what was I doing when ever he saw electrical tools being hauled out.

He has since traveled down the industrial electrician path and when he comes over, tells me stories about what his newbies do and don't do.

If I don't keep my self abreast of "sparky" talk, he will have to endure discussions about the audio industry, information management, aircraft or auto mechanics, or worst of all, the challenges of rasing teenagers.

[scotrajode]

The electrical code requires that the equipment grounds, grounding electrode conductor, supplemental ground, and neutral all be bonded at the main bonding jumper located in either the separately derived service (transformer) or the first disconnecting means (the main disconnect). In residential service, the main bonding jumper is always the ground bar in the main panel. The grounding electrode conductor and the supplemental ground is what electrically bonds the ground to earth and gives a consistent ground reference point. In commercial power, and isolated ground connects to the ground prong of the receptacle, is isolated from any metal boxes, yokes, conduit, or mc and passes through any sub panels via an isolated ground bar, which is electrically isolated from the equipment ground bar and does not connect to ground until it reaches the main bonding jumper. The equipment grounding conductor then grounds all the stuff that the isolated ground is isolated from. This will reduced noise caused by other equipment.

However, in residential power, the boxes are usually plastic, the wire is ran in romex, not MC or conduit, and there is usually no sub panels. This only leaves one other thing to be grounded. The yoke of receptacle. The yoke is the last place a ground interference comes from. That being said, if you run a dedicated 2 wire from the receptacle to the panel with a plastic outlet box for the receptacle, you essentially have an isolated ground. If you can run MC, it will shield the circuit from outside interference. Then you would want to ground the MC and metal box separate from the equipment. Then you would need two grounds i.e. MC IG. Either way, all the grounds would still be connected to the ground bar in the panel. Again, this is for a residential application only.

BTW, I may be wrong, but I don't think they make a two ground conductor romex cable, if you wanted to ground your yoke separately. If you really wanted to ground it separately, you could use a 3 wire and tape the red wire with green tape and a yellow stripe and connect that to the ground prong of an isolated receptacle. Then connect the bare ground to the yoke. This would require an isolated grounding receptacle with two grounding terminals. They are usually self grounding yokes to a metal box, and the equipment ground is then connected to the metal box.

In short, a dedicated circuit in Romex will essentially give an isolated ground. For a further level of protection, run a dedicated circuit in MC IG.

Scott

[scotrajode]

Heck, have your brother look over your electrical system for you the next time he drops by. He should certainly be able to help you tighten it up, and then you can add your isolation transformer from there. That is about the best you can do. Although I do commercial power and he does industrial, the installations are usually different, but the theory is always the same

Scott

[scotrajode]

Duke, anything you can add to this subject?

Scott

[Guest " "]

FYI, I have BX or Armor Clad (AC) wiring through out.

The 3 wire plus tape method you discribe is a common approach for either converting a 120 outlet ran with BX/3 to 220 or for converting a standard outlet wiring scheme to an isolated ground scheme.

The overview of isolated grounds using romex would be correct if you used a 3-wire scheme and both the neutral and the lines ground fell within the overview provided in your first paragraph.

But, if you were converting to a hard wired isolated balanced power scheme, there would no longer be a neutral as it would be one of the 60 volt phases and the ground would return back to the service box as discribed in your first paragraph. The center tap of the balanced transformer would also be grounded as discribed in your first paragraph. There is a diagram of the wiring topology used in hard wired balanced isolated power earlier in this thread.

[Duke Spinner]

Naaah ...Scott

we already been around that Isolated Ground thing....quite a bit here

some terms ...like Grounding Electrode Conductor...

slide right on by .....

[Guest " "]

This is from earlier in the thread.

 

[scotrajode]

I forgot, I have heard they used the better wiring methods in New York, inclusive of the residences. Just so we are on the same page, BX uses the armor and a small piece of wire as the ground. AC uses an insulated green wire as the equipment ground. If you have both, I would think that if you can find a circuit that uses AC cable near your audio system, you may be able to isolate the circuit and use ground as an isolated ground and then the armor to ground the box back to the panel. You will have to make sure the connections are tight on the armor. That is somewhat of a gray area as far as code goes, some inspectors allow it on low amperage circuits, and some won't allow it at all. But still if it is feasible, I would pull a new MC IG. Worst case, if all you can find is a BX cable near your system you could make it dedicated for your system, you just won't be able to have an isolated ground. Anyway, sounds like you have a pretty good idea of what to do. I am interested to see your results. Still a shame you have to go through all this though.

Scott

BTW, just to clarify, I was talking about wiring for bringing the power to your isolation transformer, the diagram is for after the transformer with a center referenced ground.

[Jim E]

Scott,

I am in the motion picture industry here in Hollywood. Specifically I engineer and install film and digital projection systems and their related sound systems. In short, I've got the best job possible because I work with what I enjoy. I've been an IATSE union member for 35 years and I'm still learning.

What I meant by dedicated neutrals and grounds is that many times I have found some people including electricians will install one (sometimes oversized) neutral for two or three circuits and a single ground. By electrical code this is basically correct if you are dealing with 3 phase. When dealing with multiple same phase circuits, sharing a neutral is obviously not a good practice. Properly wired the neutral has the same load as the hot. As far as grounds are concerned, you are correct that they should be already bonded somewhere in the panel. Again many electricians believe the condiut will suffice for a ground. While the conduit will provide some shock safety, it often corrodes at couplings and doesn't do much until a full short occurs welding the joint. A solid ground is needed for electronics. I prefer and specify separate and sometimes isolated grounds in any installation. Poor grounds are often hard to locate and often overlooked. A separate grounding rod into the earth can be prudent as electricity will most always take the path of least resistance. Depending on your location it should be deep enough to hit moist earth to be effective.

Hey! You guys think I'm being too "Old School"?