"Clean" Power Systems

[BigJ]

I was talking to a guy today and he was getting into what he called clean power systems. The most obvious thing I was familiar with were electrical pieces that have isolated grounds, like hospital grade receptacles. Beyond the isolated grounds, I have no idea what he meant by clean power systems. Did not get a chance to talk to my buddy who is an electrician.

Few questions for those knowledgeable of such systems.

What classifies electrical devices as being "clean"?
What do you have to do (installation wise) to setup a clean system/circuits?
What are the real advantages of having such a system?
Why would you actually use these in a residential installation? I know some audiophiles will use hospital grade receptacles, but what benefit is there for the average home user?

And no, I'm not googling it.

 

[frostedflakes]

Probably referring to power factor, I suck at explaining it so Wiki or Google it (I believe in you, give it a shot).

Power factor correction (PFC) is becoming common on some higher-power consumer products (PC power supplies for example). For residences having a low PF isn't a huge issue as we are charged for actual power, which is the same no matter what the PF. Industry is charged for apparent power, though, so it is beneficial for them to increase PF. Larger facilities will implement a circuit similar to the small one on a power supply, but it will be on a much larger scale and in-line with where the AC goes into the building. The circuit will consist of inductive or capacitative loads to force the voltage and current waveforms back into phase, resulting in a high PF (the closer to 1.0 the better).

 

[Aluvus]

If you had Googled it, you would have found a bunch of links about solar, wind, and similarly "clean" power generation technologies.

 

[jagec]

I'm guessing it refers to power supplies and distribution that induce no noise on the circuit. Given that every single electrical appliance you have in your house is able to take a shocking amount of noise without compromising performance, and that utility power is fairly clean already, there are no benefits to your average home user.

 

[BigJ]

Originally posted by: Aluvus
If you had Googled it, you would have found a bunch of links about solar, wind, and similarly "clean" power generation technologies.

Laziness pays off!

 

[BrownTown]

"Clean" means that you have all the energy in the 60Hz sine wave and not in a bunch of higher order harmonics. If you have alto of energy at a much higher frequency then you can get all types of problems. I guess it could also refer to DC power to, again the point is to have a constant DC value and not alot of ripple in the power supply. There are tons of things that are commonly done to accomplish this. For example I am designing a PCB right now and the number of bypass and filter capacitors is huge. Every IC needs a bypass capacitor, and you need filter capacitors all over the place to and at the power supply etc.

So basically "clean" means that all the energy is where it is "suppsoed" to be, in an AC system it might mean say 120V 60Hz EXACTLY, and in a DC system +5V EXACTLY.

 

[Rubycon]

Lack of ripple = clean.

 

[JohnCU]

Originally posted by: BrownTown
"Clean" means that you have all the energy in the 60Hz sine wave and not in a bunch of higher order harmonics. If you have alto of energy at a much higher frequency then you can get all types of problems. I guess it could also refer to DC power to, again the point is to have a constant DC value and not alot of ripple in the power supply. There are tons of things that are commonly done to accomplish this. For example I am designing a PCB right now and the number of bypass and filter capacitors is huge. Every IC needs a bypass capacitor, and you need filter capacitors all over the place to and at the power supply etc.

So basically "clean" means that all the energy is where it is "suppsoed" to be, in an AC system it might mean say 120V 60Hz EXACTLY, and in a DC system +5V EXACTLY.

ehh 59.98 Hz will work

 

[BigJ]

Now that we've established what clean power is (thank you all), what is having isolated grounds going to accomplish in regards to making sure that the line stays clean?

Just noise reduction?

Also, jagec, thanks for answering the other questions. I did talk with the guy briefly about what clean power was so I did have some idea, but I figured along the lines of what you said. That home appliances probably have a great amount of tolerance (otherwise you'd see people coming in with problems all the time) and that there was no real use for it in your average home. Although I do like the orange color of the receptacles.

 

[Rubycon]

Originally posted by: JohnCU

ehh 59.98 Hz will work

So will 50Hz.

That brings up an interesting thing. Back in May I was fooling around with a large audio amplifier and decided to see what things would do with different frequencies. The output of the amplifier was connected to a socket. and different things were plugged into this socket.

A power drill had no issues with running on lower frequencies. At higher frequencies (we tried 400Hz which is common in aviation systems) the motor turned with far less torque and was singing loudly. The sparks on the commutator looked more plasma-like too. (almost fire coming off the brushes!)

At 20Hz it was very "bumpy". A 20Hz square wave made it vibrate violently and smoke starting coming out of the vents.

A vacuum cleaner had different results except it did not run at 400Hz at all. 400Hz square wave power made it emit a squeal that could awaken the dead!

A fluorescent light (electronic ballast) was tried and had no problem with 50/60Hz power. Square waves made it noticeably dimmer. 400Hz made it pop. 20Hz caused it to sputter like a blown lamp.

Finally I tried rap music and the drill was acting in a hilarious manner. Imagine if a power tool could take cocaine...

:laugh:

 

[BrownTown]

Well I am no expert on isolated grounds, but I'm pretty sure it has to do with reducing crosstalk on different systems. Like we were saying before, even if something is assumed to be +5V (or in this case GND = 0V) that isn't always true, if you are dumping alot of power into the ground then the voltage will rise above 0V (it might be 0V back at some transformer, but there due to the resistance of the lines at the remote ground it will vary based on the amount of current in the ground circuit). Because of this if you have a piece of equipment that you want to have very "clean" power you might isolate its ground from the rest of the equipment. Certain things like large motors have high inrush currents which will screw up the power quality when they switch on and off, you want to isolate the sensitive equipment from these disturbances so you use an isolated ground.

Does that sound right to anyone with more knowledge?

EDIT: the above post provides some nice examples of why you want clean power unless you want your appliances to be on cocaine. Also worth pointing out that electronics (like say your computer chips) are not nearly as forgiving. If you put unexpected voltages and frequencies on them the magic smoke is sure to escape and never come backs.