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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: Frank DeWitt on July 31, 2014, 04:06:35 pm

Title: AC-DC Power
Post by: Frank DeWitt on July 31, 2014, 04:06:35 pm
Step one

(http://www.notcot.com/images/2012/06/socket2.jpg)
Title: Re: AC-DC Power
Post by: Stephen Swaffer on July 31, 2014, 05:07:34 pm
As far as homes being wired with DC, not going to happen, even off grid homes are usually wired only with 120v AC now since conversion efficiency has risen to the point where low voltage DC makes no economic sense.

Art

Perhaps-but LED lighting has not been around long enough to impact thinking.  And as Frank points out the USB supply s becoming increasingly common.  Efficiency maybe, but what about economics?  It makes no sense to wire a home with a minimum circuit size of 15 amps when I can light an average floor of a home with 1 to 2 amps.  If the NEC doesn't change, it would be cheaper to wire a home with low voltage wire and buy one power supply vs one for each lamp-maybe 15 or 20?  Might make an electrical inspector cross eyed the first time, but thats OK.
Title: Re: AC-DC Power
Post by: Art Welter on August 02, 2014, 04:56:54 pm
Efficiency maybe, but what about economics?  It makes no sense to wire a home with a minimum circuit size of 15 amps when I can light an average floor of a home with 1 to 2 amps.  If the NEC doesn't change, it would be cheaper to wire a home with low voltage wire and buy one power supply vs one for each lamp-maybe 15 or 20? 
It makes no economic sense to double the wiring in a house, and 12 volt wiring requires large conductors to prevent voltage drop even with relatively low amperage draw.
Title: Re: AC-DC Power
Post by: Frank DeWitt on August 02, 2014, 05:35:00 pm
Step two.  POE   Power over Ethernet

Step three  http://ap.viewsonic.com/in/products/digital-signage/EP1031R.php

Step Four http://www.altinex.com/index.php?q=MUSE

120 VAC 150 watts over CAT5  (sort of)

The Muse products allow users to transmit video, display power, and IR signals up to 300ft (90m) over a single unshielded CAT-6 cable. The Muse is powerful enough to power a 150 watt LCD display up to 300 ft away from a signal and power source. The Muse is fully compliant with HDMI and HDCP standards
Title: Re: AC-DC Power
Post by: Art Welter on August 02, 2014, 06:43:28 pm
Step two.  POE   Power over Ethernet
Step three 
Step Four
120 VAC 150 watts over CAT5  (sort of)
Frank,

Not following what steps 1-4 have to do with the "Best gear to produce a lot of sound without shore power", but using 22 AWG wire to transmit 120 volt power limits the 150 watt to about 100 feet for a 4% drop.

Art
Title: Re: AC-DC Power
Post by: Stephen Swaffer on August 02, 2014, 11:04:48 pm
Debating this here is OT-the market will ultimately settle the debate-personally I think there will be a paradigm shift in the next few years, but I could be very wrong-there are a lot of big corporations with a vested interest in the status quo.

Usually when I wire a home, I do lighting separate anyway.  It takes a lot of wire for switch legs, so I prefer to use 14 awg and 15 amp circuits-but I refuse to use 15 amp receptacle circuits.  Perhaps use LV and save the cost of an arc fault breaker?  LED lighting is available now using addressable switching-120 VAC power to light then a CAT 5 to control it.  This lends itself to automation and occupancy sensing-but the obvious next step is to POE or a similar perhaps for the purpose protocol.  Run an 18 or 16 awg home run to each light, maybe pick up a switch location or several on the home run.  Program everything to work as desired when done-and change at will with a few keystrokes when  (not if) the customer changes their mind.  How many people had cell phones 20 years ago?

I really think the only reason to keep the 120 VAC is the installed base and convenience-and power hungry stuff like AC and appliances.  If we start to see more off the grid solar I would think more LV devices would be available.  For an off the grid portable setup, maximum efficiency would be very important-and a double hit by any loss in an inverter followed by some loss in a PS just creates heat that you have to run a fan to get rid off.

In the short term, it sounds like efficient speakers is the biggest area to gain in right now.
Title: Re: AC-DC Power
Post by: Frank DeWitt on August 02, 2014, 11:20:30 pm
Frank,
, but using 22 AWG wire to transmit 120 volt power limits the 150 watt to about 100 feet for a 4% drop.

Art

They use DC and convert it to 120 VAC at the receiving end.  They run the DC using all the conductors in the CAT6 not just a pair.  I was wrong, it is CAT6 not 5,  8  #23 AWG  It is quite clever, safe, and it works.  It is unrelated to the OP but related to the rabbit trail. 
Title: Re: AC-DC Power
Post by: Mike Sokol on August 03, 2014, 12:16:32 pm
Not following what steps 1-4 have to do with the "Best gear to produce a lot of sound without shore power"

I agree, so I've split the topic. AC-DC power is certainly worthy of discussion on this forum, but OT to the original thread about running a PA system "OTG" without house power or a big generator.
Title: Re: AC-DC Power
Post by: Stephen Swaffer on August 04, 2014, 11:18:50 pm
It makes no economic sense to double the wiring in a house, and 12 volt wiring requires large conductors to prevent voltage drop even with relatively low amperage draw.

I would not argue for 12 vdc either.  24 VDC would be more likely to become the standard-it is already the most universal voltage for industrial machine controls, found on machines made in the US, Britain, EU, China,Japan and Korea.  The AC voltages from these areas are all over the map-100, 110, 120, 200, 220, 230 and 240 are all used.

If other voltages are required, DC to DC converters are readily available, essentially switched mode powers supplies without the input rectifier section.   One reason AC distribution has been so common was the best way to change voltages was a transformer-not so much anymore.  The only real question is does it make sense to switch from AC to DC?

Other than the kitchen, major appliances and hair appliances how many rooms in a home really need something that couldn't be done with a power limited 24 VDC circuit?  What about the office?
Title: Re: AC-DC Power
Post by: Scott Holtzman on August 05, 2014, 01:30:14 am
I would not argue for 12 vdc either.  24 VDC would be more likely to become the standard-it is already the most universal voltage for industrial machine controls, found on machines made in the US, Britain, EU, China,Japan and Korea.  The AC voltages from these areas are all over the map-100, 110, 120, 200, 220, 230 and 240 are all used.

If other voltages are required, DC to DC converters are readily available, essentially switched mode powers supplies without the input rectifier section.   One reason AC distribution has been so common was the best way to change voltages was a transformer-not so much anymore.  The only real question is does it make sense to switch from AC to DC?

Other than the kitchen, major appliances and hair appliances how many rooms in a home really need something that couldn't be done with a power limited 24 VDC circuit?  What about the office?

We already have PoE standards now up to 30W with 802.3at and UPoE near or recently ratified.  Let's rally behind the standards UPoE is 60W that should be sufficient for lighting, PC's smaller LCD panels.

Title: Re: AC-DC Power
Post by: Mike Sokol on August 05, 2014, 06:59:22 am
We already have PoE standards now up to 30W with 802.3at and UPoE near or recently ratified.  Let's rally behind the standards UPoE is 60W that should be sufficient for lighting, PC's smaller LCD panels.
Any  PoE infrastructure would also allow device interconnectivity without hogging up with WiFI bandwidth. We're running out of RF space already, and the more appliances and gadgets that go "wireless" the more bandwidth issues we're going to have. We're seeing that already for situations using shared iPads and iPhones for control of small format digital mixers when used with Line6 digital mics. There's only so much spectrum to go around, and just like avoiding RF use for stationary mics, we should try to limit wireless connectivity for stationary gadgets, especially if they need to "plug in" for power anyways.  Have you ever tried to use your Bluetooth headset at a convention along with thousands of other Bluetooth users at the same time in the same space? 
Title: Re: AC-DC Power
Post by: John Roberts {JR} on August 05, 2014, 10:50:36 am
I would not argue for 12 vdc either.  24 VDC would be more likely to become the standard-it is already the most universal voltage for industrial machine controls, found on machines made in the US, Britain, EU, China,Japan and Korea.  The AC voltages from these areas are all over the map-100, 110, 120, 200, 220, 230 and 240 are all used.

If other voltages are required, DC to DC converters are readily available, essentially switched mode powers supplies without the input rectifier section.   One reason AC distribution has been so common was the best way to change voltages was a transformer-not so much anymore.  The only real question is does it make sense to switch from AC to DC?

Other than the kitchen, major appliances and hair appliances how many rooms in a home really need something that couldn't be done with a power limited 24 VDC circuit?  What about the office?

This is the key technology difference between now and then... Transformers and AC distribution facilitated reasonably low tech and robust voltage shifting first up for transmission with less losses then down for use. Now we have high frequency switching regulators that can do the voltage shifting at higher frequency using smaller magnetics.

It isn't hard to imagine more DC distribution in homes and smart power conversion could probably work with whatever it gets, making it better for wind or solar power that varies all over the place.

That said I expect there to be a lot of inertia resisting wholesale change to DC, so DC power and AC power may coexist for some time, perhaps with bridges between the two system so either one could support the other as needed..

JR
Title: Re: AC-DC Power
Post by: Cailen Waddell on August 05, 2014, 11:19:47 am

This is the key technology difference between now and then... Transformers and AC distribution facilitated reasonably low tech and robust voltage shifting first up for transmission with less losses then down for use. Now we have high frequency switching regulators that can do the voltage shifting at higher frequency using smaller magnetics.

It isn't hard to imagine more DC distribution in homes and smart power conversion could probably work with whatever it gets, making it better for wind or solar power that varies all over the place.

That said I expect there to be a lot of inertia resisting wholesale change to DC, so DC power and AC power may coexist for some time, perhaps with bridges between the two system so either one could support the other as needed..

JR

This is an interesting topic for me, my landscape lights are 12v LEDs, my undercounted lights in the kitchen, I'm about to put in some lights for our art in the living room....

I have considered a relay, deep cycle marine battery and central 12v pwm dimmer in my house...  Everything can run off of low voltage security wire.   When the power goes out - our lights will stay on.
Title: Re: AC-DC Power
Post by: John Roberts {JR} on August 05, 2014, 11:36:57 am
This is an interesting topic for me, my landscape lights are 12v LEDs, my undercounted lights in the kitchen, I'm about to put in some lights for our art in the living room....

I have considered a relay, deep cycle marine battery and central 12v pwm dimmer in my house...  Everything can run off of low voltage security wire.   When the power goes out - our lights will stay on.

Just because it's only 12v do not treat it too casually, it can still start fires.

JR
Title: Re: AC-DC Power
Post by: Scott Holtzman on August 05, 2014, 12:15:36 pm
Just because it's only 12v do not treat it too casually, it can still start fires.

JR

Amen, it also needs heavier wire to avoid voltage drop.   I am going to stay the PoE bandwagon.  It has current limiting, device negotiation etc.  Small DC-DC converts are pennies and very efficient.  Adding a PoE port to a device just for power would not be difficult.

It's already been pointed out that RF is a last resort if a wired connection is available.

Title: Re: AC-DC Power
Post by: Mike Sokol on August 05, 2014, 02:04:45 pm
It's already been pointed out that RF is a last resort if a wired connection is available.

Does anyone make a little 12-volt dimmer or on/off controller that can listen to IP control on a CAT-5 PoE cable? That way you could simply do home runs of CAT-5 to centrally located routers with PoE output. Run heavy wire to the PoE routers for the 12 volts, then standard CAT-5/6 cabling to power and control things such as under cabinet lighting, ceiling lights, in-wall speakers, security cameras, etc... Seems like a no-brainer to me since once you set up the local IP communication and a WAN link you could control anything you like with a smart phone from anywhere in the world.
Title: Re: AC-DC Power
Post by: Steve M Smith on August 05, 2014, 02:11:26 pm
There could be a good case for a 24v or 48v supply for domestic lighting.  The current compact fluorescent bulbs are, in my opinion, just an interim technology until LEDs get better and/or more affordable.

The company I work for makes flexible flat panels with light guides and reflectors on them which are used for domestic and architectural lighting by this company: http://designledproducts.com/

There are some clever tricks you can do with LEDs to control the spread of light and I think that LEDs are the future of domestic lighting.  Having access to a suitable DC supply would certainly make a lot of sense compared with the other option of a small power supply for each light fixture.  It especially makes sense for the flat lighting panels I posted a link to as they would remain flat, requiring just a connection to the DC supply (switched, obviously!).


Steve.
Title: Re: AC-DC Power
Post by: Scott Holtzman on August 05, 2014, 02:37:05 pm
Does anyone make a little 12-volt dimmer or on/off controller that can listen to IP control on a CAT-5 PoE cable? That way you could simply do home runs of CAT-5 to centrally located routers with PoE output. Run heavy wire to the PoE routers for the 12 volts, then standard CAT-5/6 cabling to power and control things such as under cabinet lighting, ceiling lights, in-wall speakers, security cameras, etc... Seems like a no-brainer to me since once you set up the local IP communication and a WAN link you could control anything you like with a smart phone from anywhere in the world.

PoE switches, especially a 24 port unit with a 600 or 1000 watt total capacity needs a -48vdc rail. 
Title: Re: AC-DC Power
Post by: Stephen Swaffer on August 05, 2014, 09:40:21 pm
Exhibit A: 12 VDC current limiter.

Seriously though, voltage drop is determined by current draw.  (Which is proportionately larger for lower voltage for the same watts than higher voltage).  We had some 24 VDC powered carts on rails where I used to work.  Someone had wired them with 2/0 weld cable because they were DC running off deep cycle batteries that looked like car batteries.  FLA for motors?  25 amps-easily handed by #10 AWG.  4 10 watt cans for a room is 40 watts or roughly 3.5 amps at 12 VDC which can use wire several sizes smaller than the minimum the NEC allows to be run for 120 VAC circuits.

Another plus to DC supply-DC dimming should be a lot less electrically noisy.  Mechanical DC switches are noisier and harder to design well-but solid state switching for DC is a natural.

But then, what would Mike do without ground loops and AC hum to chase down?
Title: Re: AC-DC Power
Post by: Mike Sokol on August 05, 2014, 10:15:15 pm
But then, what would Mike do without ground loops and AC hum to chase down?

What??? Say it's not so.... :o
Title: Re: AC-DC Power
Post by: John Roberts {JR} on August 06, 2014, 10:57:26 am


Another plus to DC supply-DC dimming should be a lot less electrically noisy.  Mechanical DC switches are noisier and harder to design well-but solid state switching for DC is a natural.

But then, what would Mike do without ground loops and AC hum to chase down?
I am not so sure that DC dimming is so quiet. To do it efficiently involve PWM not unlike AC lamp dimmers but running at a much higher frequency. Arguably the higher frequency dimming could be easier to filter out but still must be managed.

Dimming that does not involve switching would involve active pass devices to scrub off voltage, and those pass elements would dissipate heat and waste power.

In fact while not cheap some recording studios use variacs (variable transformers) to dim lights efficiently and quietly.   

JR
Title: Re: AC-DC Power
Post by: Stephen Swaffer on August 08, 2014, 10:51:25 pm
 To be totally "outside the box", I suppose one could avoid non-linear loads in AC-DC conversion by using something similar to a rotary phase converter-an AC motor driving a DC generator.  Though I imagine efficiency would take a pretty good hit.

On the larger wire for 12 VDC thought.  Obviously it takes 10 times the current at 12 VDC to convey the same energy as 120 VAC rms.  Right now, LEDs are averaging roughly 1/7th of the energy for the same lumens as incandescent lamps or metal halides (a rough approximation from recommendations I am getting on application).  So a fully loaded circuit might take a little larger wire to run LEDs on the lower voltage vs incandescents on the higher voltage.

I was told yesterday by my supplier that current LEDs are running about 100 lumens/watt.  A major manufacturer has a prototype ready to field test that is doing 200 lumens/watt and another in the lab that is showing 303 lumens/watt. Supposedly the theory said 300 lumens/watt was the limit.  If there is substance to this information, then we still have a ways to go before the potential for LED technology is reached. So the question becomes-invest now or wait 6 months?
Title: Re: AC-DC Power
Post by: Frank DeWitt on August 09, 2014, 03:14:32 pm
  So the question becomes-invest now or wait 6 months?

I think this is a eternal question on every subject.  Christ, wife, car guitar mixer LED Lights.

If you need it invest now  (Everyone needs Christ)
If you don't, wait 6 months
Title: Re: AC-DC Power
Post by: Jonathan Johnson on August 11, 2014, 01:42:43 am
A major manufacturer has a prototype ready to field test that is doing 200 lumens/watt and another in the lab that is showing 303 lumens/watt. Supposedly the theory said 300 lumens/watt was the limit.
Seems to me that the theoretical limit would be when all of the energy used is transformed into visible light, resulting in no heating of the element or supporting electronics. I don't know how many lumens/watt that would be.