and, for low draw AC appliances (i.e., it won't run your microwave, and he wouldn't want to run a 6amp power tool,... but he would be able to plug-in and charge cordless power tools that didn't have car-adapter plugs),... he could just get a cheap lower-end inverter that plugs into one of the cigarette-lighter plugs. such an inverter would only be maybe a hundred bucks.
Well spoken by someone who hasn't checked prices in the last decade. Lighter socket inverters up to 140 watts are typicaly under $30. For $100 you can pick up a 1KW inverter and have enough change to buy a nice dinner. (Check the Costco sales. I picked up a 1 KW unit for $54) A 6 amp power tool is the smaller size of tools I use. I have run a skill saw, microwave oven, vacuum cleaner, blow dryer, and other items on an inverter. You won't run high wattage stuff for long periods of time, but within the KWH capacity of your battery, there is no reason to fix a 3 minute bag of popcorn in the microwave or trim a few 2 X 4's with a skill saw. A 1KW oven for 3 minutes only takes 0.04 KWH.
Watch the sales. I picked up a 2 pack of 75 Watt inverters for $25. That's $12.50 each. I use them with the laptop when riding in a carpool. The inverter is much cheaper than the over $100 12 volt laptop power supply.
Figure a small toaster of 600 watts... at 12 volts that's 50 amps. Assume a 14 volt fully charged battery (generator running maybe) an permitting a 2 volt drop from the shed 50 feet away. That's 100 feet round trip for the conductor. Using ohm's law, 2 volts at 50 amps permits a resistance of 0.04 ohms. Now taking the resistance for 1,000 feet and cutting by 10 to get resistance for 100 feet, a #6 wire at 0.03951 will do the job not counting connectors. That is a 2 Volt X 50 Amp or 100 Watt loss in the wire. That is more loss than the loss of a typical inverter near the battery.
How many watts is the microwave and what is the inverter low voltage shutdown point? My inverter alarms at 12 volts shuts down at 11.5 volts. Please tell me your inverter for the microwave is somewhere near the batteries.
Utility companies have this power thing locked up and are going to be very reluctant to let small producers get in the game. Utility companies should not fear small producers they should embrace them and buy their excess power and resell it at a profit without any over head. The largest source of funds to build the power supply sytem is in the pockets of consumers: let consumers build it.
Most consumers do not have the capacity to meet their own usage, let alone sell any. Many small systems are in the neighborhood of 5-15 KWH/day and a typical family residence is in the 25-40 KWH/day. Either severe effeciency measures are needed, and/or more capacity is needed.
Look at last month's bill. What was your daily KWH usage?
Correct. Small plants have fairly large impedance which limits fault currents. Close to the correct speed is most often defined as within 1 HZ running fast. To prevent phase bounce when the switch is closed, they close the switch as the phase is advancing before it is in phase by about 10 degrees give or take a few. This provides quick phase lock with minimum mechanical bounce and electrical stress.
Voltage regulation (field current) is only used for power factor adjustment as you are not going to drag the grid voltage far. Over excited produces leading power factor (like a capacitor) and tends to increase the voltage and under ecitation produces lagging power factor like a transformer, inductor or induction motor. Power control is controlled by the prime mover throttle only. The voltage regulator (Field current) is not a power adjustment. high power factor is to be avoided as the excess current increases the I squared R loss in the windings. (may overheat it)
To prevent high induced current in the field winding, and to prevent phase bounce, the field winding has shorted turns built into the poles on alternators designed to sync and share a load. Don't try this with a home emergency generator. It will either hunt and bounce, or spike and kill the regulator due to the lack of the shorted turns.
For non-engineers, here is a listing for an alternator with damping windings (shorted field windings); http://www.gensan.info.tr/engparcal.htm "The rotors of alternators are equipped with damping winding as standard for parallel operation and unbalanced loads, having this characteristic allows to run in parallel with other alternators and also with the mains."
It's not pretty (given that alternators want to output three-phase) but it looks possible. I don't think it's a great idea, just tempting because junk alternators are cheap.
It would be really ugly. Learn something about junk alternators. I think you might be speaking a cheap home 60 HZ machine. Most of these are really single phase 120/240 (US market) unless you are speaking of a car alternator which is 3 phase, but it is far from 60 hz for effeciency in size and weight.
First to make it really ugly, the home generator has laminated core on the AC side to reduce the eddy current losses in the core. The Field on the other hand often does not have laminations so eddy currents can provide regulation stability and react to dampen AC current spikes and other transients that would otherwise cause damaging voltage spikes in the field current. The field is often would with some shorted turns so it can sync as an induction motor and pull into sync as a syncronous motor. Putting AC into this Field winding is often impossible as many AC alternators to eliminate wear items are pilot excited to eliminate the brushes. A fixed field on a small pilot alternator provides AC to diodes which then power the main rotating field in the main alternator.
If you are speaking of car alternators, again the field is DC. Most have slip rings to power the rotating field. These instead of having 2 poles on the field, they often have a set of fingers so there is often 14 or more poles. This drives a 3 phase winding which is then rectified into DC. Due to the number of poles and the number of cycles per revolution, you can't just cut the diodes out and expect to obtain anywhere 60 HZ unless you drive it really slow (just over 514 RPM for the 14 pole machine) and get really low voltage and low power as a result. Driving the field with AC won't produce an AC output after the rectifiers. An alternator produces AC with a DC field current until rectified by diodes. (Yes a car alternator does produce AC current in it's windings.)
So am I.. Are you an apprentice? Google search a reverse current relay. When measuring the phase of the current and voltage forward power is voltage and current in phase up to 90 degrees out of phase depending on power factor. Beyond 90 degrees toward 180 degrees, you are in a reverse current mode feeding power to the source. In a grid tie system, this is normal as you intend to sell power. The industry norm (including driven inducton motors) is to lag the phase. Upon loss of grid, including islanding, the voltage collapses, or you run at a rapidly receeding phase (low frequency) where you relay out for out of tolerance frequency or voltage or both.
They make controllers which monitor the frequency, current and phase just for this application.
Purchase a copy of IEEE Std 1547. It lists the co-gen requirements.
"Cummins peddles cogeneration switchgear for use with their generators and these are based on Basler's cogeneration relay which combines the protective functions that you need. These packages allow you to do both manual and automatic synchronising. Your utility might want to review the schematic diagram and relay features for these cogeneration packages but they are pretty cut and dried. Alledgedly, Basler's relay is smart enough to know when a line is deenergized from the other end when an arcing fault occurs so that the Basler relay will also trip out.
Similarly, inverters for interactive solar generation include a relay that disconnects from the line when there is a power failure and can sense when 1 or more inverters are the sole source of power. Some of this is done with voltage sensing and some of this is done with impedance sensing. That is, the line impedance that a solar inverter sees changes dramatically when the utility opens its circuit breaker or fuse."
The Amperage has changed. Volts times Amps = Watts (ignoring power factor for AC circuits)
A 60 Watt bulb on 120 volts draws a half an amp. A 60 Watt bulb on 12 volts draws 6 amps.
Wire 10X larger" me arse... Arse size has nothing to do with wire size. Physiscs does. 10 X the wire size for 10 X the current with the same voltage drop is what the math does call for. Now with 10 wires instead of 1 dropping that voltage, you now have 10 X the heat loss in the wire.
Do the math before calling someone on the facts. The math is well known and well known.
An inverter is handy only if you can't source a piece of equipment in a 12v model and practically everything can be found in 12v, just look at your nearest marine outfitting shop.
In a recreational boat, most everyting is located within 6 feet of the battery. Hit a vessel over 65 feet and you will find they have very limited 12 volt distribution and all of it is low power.
Most of the parent post is a load of bollocks, and I speak as someone who spent many years in a third world country living in a 12-volt powered house with a kerosene generator and a bank of old car batteries for storage.
Again, very short runs for very small quarters and low power where a single room 12 volt 6 Watt light is the norm and high surge capacity to start a fridge isn't important. Instead of a very expensive RV fridge, we use an effecient full size fridge.
I speak from an 800 Watt solar install running 2 desktop computers, printer, network, the Microwave, a TV, and when overcharged, it picks up the fridge and living room lights. We don't sell surplus power, we use it. Most 3rd world installations live with undersize wire, battery fumes in the room due to lack of safety regulations, and very limited load capacity mostly limited to small incandescent or LED lights.
We have immunity from blackouts, power more stuff as solar provides, cut back and charge from the utility when solar is absent for extended periods (winter) and have backup gas power for the extended winter outage.
Most 3rd world installations are not this complete and are simply a very low power off grid solution for radio and lights and little else.
Care to guess how many MRI units they have? I had a Trachial Diverticulitis. MRI and a modified barium swallow found the cause of my neck swelling and breathing problem. I shudder to think of the free care option in Cuba for this condition. Is it anything other than a pine box? The MRI provided the location, size, and what it was attached to, tangled with, and such. It eliminated a total neck fillet to find it and remove it.
Anyone pushing for free two asprin solutions to a less than simple proceedue scare me. Free medicine puts most people into general pratice with little options for speciallists. Visit a free clinic sometime.
The same would go for the 12 VDC circuits: 5% of 12 V is 0.6 V and not 6 V resulting in the same reduction in DELIVERED power, of course, not power losses---a very important difference!
Correct, but it requires 100 times the wire to provide this low loss at 1/10th the voltage. Instead of using one cord, 100 in parallel or larger equivilant is required. Do the math.
The point often missed is the wire requirement. For a 1,000 Watt microwave oven on 120 volts a 12 AWG wire is fine. At 12 volts for the same voltage drop, use 10 wires in parallel for the same voltage drop but 10 times the loss and a severe brownout. For the same loss 100 12 AWG parallel wires or equivelant needs to be run. The inverter for a house is cheaper than the copper replacement. The bonus is you get to use an existing affordable 120 Volt appliances and wire instead of a non-existant 12 Volt counterpart.
(Perhaps that's why most of the civilized world runs on 400/230 V / 50 Hz )
Higher frequencies require smaller transformers and motors for the same power.. It's why 400 hz is common on aircraft and some marine. The higher frequency does introduce it's own problems for long distance transmission, so 50 or 60 hz is a compromise.
The power supply for your laptop often uses frequencies over 20 KHZ so the transformer can be very small yet handle close to 100 watts.
First off, the lineman will always ground out a medium voltage system prior to doing any work on it. That is the only safe way to work on the system.
Care to back it up? Often they leave the line open becuse the line has a fault somewhere and they impulse the line with a tester to find the short or arcover location. Often they expect the line to be dead while fault testing and can be hurt when someone else unexpectidly energizes the line on them.
Yes I do care to back that up. It is really hard to find a arcing fault on a line with it grounded so you can work on it. It's ungrounded so your test equipment can send a locating signal so you can find where it ends or shorts to earth. Adding your own short to work on the line defeats the test equipment.
Again, do the math. I don't know, like LV lights? What do you think Mr. Wizard?
Let's say you recharge batteries during the day using 6 60 watt panels. Normal for a small installation. Of the day count only 8 hours of overhead sunlight. (average in sunny climates) so you get 360 watts X 8 hours for 2880 watt hours. For the math assume perfect batteries and wire from the panels. (Never true in reality)
Time for evening activities. Kick on the computer for getting online for an hour.. I'll be generous and assume an effecient laptop of 80 watts. The batteries are outside or in the utility room properly enclosed in a ventelated container for safety reasons (normal and required by code in most places) The room is 35 feet from the den. The den is lit with a 14 watt CF lamp. (you can get them in 12V or use an inverter to save lots of money) Do the math and let me know what wire size you need for only a 5% voltage drop from your batteries.. Remeber the round trip is 35 feet X 2. Just for grins you want to fix a bag of microwave popcorn in the same room. The microwave is 1,000 watts. It is only on for 3 minutes for a consumption of of only 0.05 KWH, only a small portion of the stored energy. (microwave use is common on small solar installations).
The laptop drawing 80 watts would draw less than an amp at 120 volts. It would draw 6-2.3 amps on 12 volts. What wire size is needed to keep the voltage drop less than 5% for the 35 foot run from the battery. I'll wait. Copper wire tables are easy to find in a Google search. After you did your homework, get back to me and we will go over the cost of the wire and the cost of a 1500 watt inverter which can run the light, laptop and microwave.
Assume you can get a 12 volt microwave. What wire size is needed for the 35 foot run? I run my microwave 40 feet from the battery. The inverter is within 15 inches and uses a #4 wire. My run to the microwave is 12AWG wire, but at 120 Volt instead of 12 Volt.
A 5% voltage drop at 12 volts is only 0.6 volts. For the laptop's 6-2/3 amps + the 13 watt light at 1.1 amps, the 35 foot run would need to have a resistance less than 0.075 ohms (aproximate).
Using wire 10x the size would work fine because its resistance would be one 1/10 that of the original line. The resulting drop in power would still be 5%
Care to try again? For sake of arguement let's take a 1200 watt load for a 20 amp load at 120 volt for 2400 watts. A 5% voltage drop is 6 volts.
A 2400 watt load on 12 volts is 200 amps.. With a wire 10X the size to handle it, it is still a 6 volt loss.. I'll let you figure out how well the appliance works on half voltage. I run a microwave oven on my inverter. I couldn't get enough power to it from the battery room at 12 vots. This is the reason my inverter low voltage wire is only 30 inches long.
I'll also let you figure out the correct wire size for a 5% voltage drop for the same distance as the original 120 volt circuit. Good luck.
You can try converting parts of your house to 12 or 24 volt, which would negate the need for expensive inverters and whatnot. All you'd need is a simple charging circuit for a battery (could be as simple as a diode) and then feed the 12/24 volt lights straight off it.
This is a common mistake and is only good for very low power stuff. In picking a wire size people often think going from 120 volts to 12 volts only involves the math of supplying a wire 10X larger to handle the current without overheating. In a 120 volt application, you are permitted a 5% voltage drop. This isn't much as 5% of 120 volts is only about 6 volts. No big deal when running a 1200 watt portable hair dryer. If you simply size the wire to now do the same thing on 12 volts, you no longer have a 5% voltage drop. At the same current you still have a 6 volt drop with the 10X larger wire but you now lost 50% of your power in the wire. Take a hint from the pro.. Use an inverter. The 10% the inverter lost is made up by the 45% not lost in the wire. Do the math. Engineer the project.
Either your high draw items (Microwave, toaster, blender, etc) are either within 20 inches of the battery, or you will want an inverter. With an inverter you can use standard appliances. Look for energy effecient ones.
Another item is to ditch the grid tie for small systems. It goes down with the grid providing no security. Put the critical load on an Outback inverter. It was made just for this application. Small solar, battery maitenance, load transfer to and from solar and battery, etc. You don't have a surplus to sell to the utility, so don't connect that way. Use it to supplimant your load and reduce your total load. As a bonus, you don't have to enter a grid tie agreement with the utility where they buy your power whosale and sell it back to you retail.
Disclaimer, I just use it. I am not otherwise involved with this company. The company has grid-tie stuff if you decide you really want it. I don't recommend it except for larger installations. This company has done a great job meeting the market. Their grid tie units are the first that I know of that operate instead of shutting down in the event of a blackout. They solved the number 1 problem with grid tie stuff.. blackouts. http://www.partsonsale.com/outbackgridtie.html
And after a well-deserved spanking, they picked themselves up and bought Hawaii instead.
After Pearl Harbor, they were on the receiving end of 2 special deliveries to their home land.
The RIAA and member labels are next.. They bombed a copyright violator. The PR dammage is severe and the tables are starting to turn since it was way too heavy a stroke. I hope they don't have asbestos on cause the tide has turned.
The won the battle but are losing the battle because of it. They couldn't have done anything better to get a bad PR problem.
It reminds me of the effect it had on Japan when they won Pearl Harbor in WWII. Right after they won the battle, they realised they woke the sleeping giant.
Maybe they shouldn't triffle in the affairs of dragons as thou are tasty and crunchy when well done. Write this win up as an oops...
Explain how this would work with Vista. Using the default settings that is.
Are you claiming CD and other isertable media is no longer auto-run in Vista? Next time I'm near a Vista machine, I'll have to see if a CD or thumb drive auto-runs... Thanks for the info. I'll be sure to check it out. It's a step in the right direction if true.
Quick Google search.....
Oh, wait nevermind. I found about Vista and auto run here;
Windows Vista by default shows an AutoPlay dialog (right) to ask whether you want to run the AutoRun software.
If you select "Set AutoPlay defaults in Control Panel" then the window below lets you alter the AutoPlay and AutoRun default options.
Weird link.. It has the info on Power Cinema for linux, but no link to the product. Under products and following Power Cinema to the system requirements, you get this;
Operation System: Microsoft Windows XP (Home edition or Professional edition) Microsoft Windows Vista DirectX 9 or above Windows Media Player 9 or above
I've heard rumors of a legal DVD player for Linux, but have not seen it marketed where I could find it. All links for me tend to dead end in the system requirements for Windows * and Direct X.
Laser toner is a cheap black powder. You can buy a refill for about $4.99. Opening the toner equipment for a refill can be tricky, in the case of Lexmark they made it impossible. A new toner costs ~$100
It depends on your selection of printer. My HP Laserjet III is still running. HP no longer makes carts for it. The aftermarket carts are 4/$100 with free shipping. Needless to say, I have no immediate upgrade plans for plain text printing.
What is this DVD support in Windows you're talking about? Last time I installed Windows (XP Home), I had to install more stuff from a CD (PowerDVD?) to get DVDs to play in WMP.
In Windows, a player of some kind is often bundled by the retailer. The bundled player is legal.
In Ubuntu, a player is never bundled and DECSS is most often used with MPlayer or other player in linux and is illegal anywhere the DMCA is king. DECSS is also not in the favor of the DVD consortium and is not an approved licensed player.
"The licensing restrictions on CSS make it impossible to create an open source implementation through official channels, and closed source drivers are unavailable for some operating systems, so some users need DeCSS to watch movies.
Linux can't *ship* the necessary codecs, but they are extremely easy to get installed within the first 5 minutes of using the computer.
Playing DVD's on Ubuntu is illegal in many places due to the DMCA and the use of an unauthorised decoder that breaks the encryption protecting a copyrighted work. So far it hasn't been challanged in court, but it could lead to RIAA style lawsuits. Getting caught is probably the hard part as there is no online presense. Geexbox is the safer option than an installed version because you can rip DVDs with Acidrip which shows intent where Geexbox is a bootable player with no option to save the decoded DVD. As such, it is shown to be a player and not a encrypted DVD ripper. In court, it is still not legal in many places the DMCA is in force.
I'd suggest to you (honestly) - that if all your gf really does is youtube, mail & chat, then she'd be much better off on Ubuntu than windows.
Maybe. Those who use a computer for those tasks often also use it to play music (MP3 Support) and play movies (DVD support) where Microsoft has paid for the privilage to supply the codecs and the Ubuntu distro is lacking.
MP3 support isn't bad, but DVD support comes with dire warnings of DMCA violations and it may be illegal where you live.
Once installed, I like the Ubuntu machine over anything else for playing movies. You put in the DVD and the movie starts.. No previews, no unskippable FBI warning etc. Nice. If I want to watch all the extras, I can watch them later. It's the way a DVD player should work.
If I travel without a laptop, I carry a copy of Geex box. It's a bootable Linux Media player. Nice.
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and, for low draw AC appliances (i.e., it won't run your microwave, and he wouldn't want to run a 6amp power tool, ... but he would be able to plug-in and charge cordless power tools that didn't have car-adapter plugs), ... he could just get a cheap lower-end inverter that plugs into one of the cigarette-lighter plugs. such an inverter would only be maybe a hundred bucks.
Well spoken by someone who hasn't checked prices in the last decade. Lighter socket inverters up to 140 watts are typicaly under $30. For $100 you can pick up a 1KW inverter and have enough change to buy a nice dinner. (Check the Costco sales. I picked up a 1 KW unit for $54) A 6 amp power tool is the smaller size of tools I use. I have run a skill saw, microwave oven, vacuum cleaner, blow dryer, and other items on an inverter. You won't run high wattage stuff for long periods of time, but within the KWH capacity of your battery, there is no reason to fix a 3 minute bag of popcorn in the microwave or trim a few 2 X 4's with a skill saw. A 1KW oven for 3 minutes only takes 0.04 KWH.
A quick Google search quickly brings up a 1 KW inverter for under $100.
http://www.donrowe.com/inverters/inverters.html
The lighter socket stuff for about $30 is here;
http://www.donrowe.com/inverters/150_800_watt.html
Watch the sales. I picked up a 2 pack of 75 Watt inverters for $25. That's $12.50 each. I use them with the laptop when riding in a carpool. The inverter is much cheaper than the over $100 12 volt laptop power supply.
Generator and battery bank were about 50ft away in a separate shed.
Unless the inverter was in the shed next to the battery, I call BS.
We had other misc small appliances, (toaster, blender, hot-wire foam/glass cutter, soldering iron, inverter-powered microwave, fans etc).
These items blender, toaster, microwave, simply can't be powered by a battery 50 feet away on any normal size wire.
Just for grins use this copper wire table;
http://www.powerstream.com/Wire_Size.htm
Figure a small toaster of 600 watts... at 12 volts that's 50 amps. Assume a 14 volt fully charged battery (generator running maybe) an permitting a 2 volt drop from the shed 50 feet away. That's 100 feet round trip for the conductor. Using ohm's law, 2 volts at 50 amps permits a resistance of 0.04 ohms. Now taking the resistance for 1,000 feet and cutting by 10 to get resistance for 100 feet, a #6 wire at 0.03951 will do the job not counting connectors. That is a 2 Volt X 50 Amp or 100 Watt loss in the wire. That is more loss than the loss of a typical inverter near the battery.
How many watts is the microwave and what is the inverter low voltage shutdown point? My inverter alarms at 12 volts shuts down at 11.5 volts. Please tell me your inverter for the microwave is somewhere near the batteries.
Utility companies have this power thing locked up and are going to be very reluctant to let small producers get in the game. Utility companies should not fear small producers they should embrace them and buy their excess power and resell it at a profit without any over head. The largest source of funds to build the power supply sytem is in the pockets of consumers: let consumers build it.
Most consumers do not have the capacity to meet their own usage, let alone sell any. Many small systems are in the neighborhood of 5-15 KWH/day and a typical family residence is in the 25-40 KWH/day. Either severe effeciency measures are needed, and/or more capacity is needed.
Look at last month's bill. What was your daily KWH usage?
Apparently, some imprecision is tolerable.
Correct. Small plants have fairly large impedance which limits fault currents. Close to the correct speed is most often defined as within 1 HZ running fast. To prevent phase bounce when the switch is closed, they close the switch as the phase is advancing before it is in phase by about 10 degrees give or take a few. This provides quick phase lock with minimum mechanical bounce and electrical stress.
Voltage regulation (field current) is only used for power factor adjustment as you are not going to drag the grid voltage far. Over excited produces leading power factor (like a capacitor) and tends to increase the voltage and under ecitation produces lagging power factor like a transformer, inductor or induction motor. Power control is controlled by the prime mover throttle only. The voltage regulator (Field current) is not a power adjustment. high power factor is to be avoided as the excess current increases the I squared R loss in the windings. (may overheat it)
To prevent high induced current in the field winding, and to prevent phase bounce, the field winding has shorted turns built into the poles on alternators designed to sync and share a load. Don't try this with a home emergency generator. It will either hunt and bounce, or spike and kill the regulator due to the lack of the shorted turns.
The nitty gritty for engineers is here;
http://books.google.com/books?id=WHAEAAAAMAAJ&pg=PA59&lpg=PA59&dq=alternator+damping+winding&source=web&ots=o4mYJrn7Iv&sig=H9cnWa4hXTYP5CtOuCIKIx4Emos&hl=en#PPA72,M1
For non-engineers, here is a listing for an alternator with damping windings (shorted field windings);
http://www.gensan.info.tr/engparcal.htm
"The rotors of alternators are equipped with damping winding as standard for parallel operation and unbalanced loads, having this characteristic allows to run in parallel with other alternators and also with the mains."
It's not pretty (given that alternators want to output three-phase) but it looks possible. I don't think it's a great idea, just tempting because junk alternators are cheap.
It would be really ugly. Learn something about junk alternators. I think you might be speaking a cheap home 60 HZ machine. Most of these are really single phase 120/240 (US market) unless you are speaking of a car alternator which is 3 phase, but it is far from 60 hz for effeciency in size and weight.
First to make it really ugly, the home generator has laminated core on the AC side to reduce the eddy current losses in the core. The Field on the other hand often does not have laminations so eddy currents can provide regulation stability and react to dampen AC current spikes and other transients that would otherwise cause damaging voltage spikes in the field current. The field is often would with some shorted turns so it can sync as an induction motor and pull into sync as a syncronous motor. Putting AC into this Field winding is often impossible as many AC alternators to eliminate wear items are pilot excited to eliminate the brushes. A fixed field on a small pilot alternator provides AC to diodes which then power the main rotating field in the main alternator.
If you are speaking of car alternators, again the field is DC. Most have slip rings to power the rotating field. These instead of having 2 poles on the field, they often have a set of fingers so there is often 14 or more poles. This drives a 3 phase winding which is then rectified into DC. Due to the number of poles and the number of cycles per revolution, you can't just cut the diodes out and expect to obtain anywhere 60 HZ unless you drive it really slow (just over 514 RPM for the 14 pole machine) and get really low voltage and low power as a result. Driving the field with AC won't produce an AC output after the rectifiers. An alternator produces AC with a DC field current until rectified by diodes. (Yes a car alternator does produce AC current in it's windings.)
http://www.alternatorparts.com/understanding_alternators.htm
I am a CET!
So am I.. Are you an apprentice? Google search a reverse current relay. When measuring the phase of the current and voltage forward power is voltage and current in phase up to 90 degrees out of phase depending on power factor. Beyond 90 degrees toward 180 degrees, you are in a reverse current mode feeding power to the source. In a grid tie system, this is normal as you intend to sell power. The industry norm (including driven inducton motors) is to lag the phase. Upon loss of grid, including islanding, the voltage collapses, or you run at a rapidly receeding phase (low frequency) where you relay out for out of tolerance frequency or voltage or both.
They make controllers which monitor the frequency, current and phase just for this application.
Purchase a copy of IEEE Std 1547. It lists the co-gen requirements.
"Cummins peddles cogeneration switchgear for use with their generators and these are based on Basler's cogeneration relay which combines the protective functions that you need. These packages allow you to do both manual and automatic synchronising. Your utility might want to review the schematic diagram and relay features for these cogeneration packages but they are pretty cut and dried. Alledgedly, Basler's relay is smart enough to know when a line is deenergized from the other end when an arcing fault occurs so that the Basler relay will also trip out.
Similarly, inverters for interactive solar generation include a relay that disconnects from the line when there is a power failure and can sense when 1 or more inverters are the sole source of power. Some of this is done with voltage sensing and some of this is done with impedance sensing. That is, the line impedance that a solar inverter sees changes dramatically when the utility opens its circuit breaker or fuse."
From;
http://www.eng-tips.com/viewthread.cfm?qid=145806&page=1
the wattage hasn't changed!
The Amperage has changed. Volts times Amps = Watts (ignoring power factor for AC circuits)
A 60 Watt bulb on 120 volts draws a half an amp. A 60 Watt bulb on 12 volts draws 6 amps.
Wire 10X larger" me arse... Arse size has nothing to do with wire size. Physiscs does. 10 X the wire size for 10 X the current with the same voltage drop is what the math does call for. Now with 10 wires instead of 1 dropping that voltage, you now have 10 X the heat loss in the wire.
Do the math before calling someone on the facts. The math is well known and well known.
An inverter is handy only if you can't source a piece of equipment in a 12v model and practically everything can be found in 12v, just look at your nearest marine outfitting shop.
In a recreational boat, most everyting is located within 6 feet of the battery. Hit a vessel over 65 feet and you will find they have very limited 12 volt distribution and all of it is low power.
Most of the parent post is a load of bollocks, and I speak as someone who spent many years in a third world country living in a 12-volt powered house with a kerosene generator and a bank of old car batteries for storage.
Again, very short runs for very small quarters and low power where a single room 12 volt 6 Watt light is the norm and high surge capacity to start a fridge isn't important. Instead of a very expensive RV fridge, we use an effecient full size fridge.
I speak from an 800 Watt solar install running 2 desktop computers, printer, network, the Microwave, a TV, and when overcharged, it picks up the fridge and living room lights. We don't sell surplus power, we use it. Most 3rd world installations live with undersize wire, battery fumes in the room due to lack of safety regulations, and very limited load capacity mostly limited to small incandescent or LED lights.
We have immunity from blackouts, power more stuff as solar provides, cut back and charge from the utility when solar is absent for extended periods (winter) and have backup gas power for the extended winter outage.
Most 3rd world installations are not this complete and are simply a very low power off grid solution for radio and lights and little else.
they have free health care!
They have very limited free health care!
There fixed it for you.
Care to guess how many MRI units they have? I had a Trachial Diverticulitis. MRI and a modified barium swallow found the cause of my neck swelling and breathing problem. I shudder to think of the free care option in Cuba for this condition. Is it anything other than a pine box? The MRI provided the location, size, and what it was attached to, tangled with, and such. It eliminated a total neck fillet to find it and remove it.
Anyone pushing for free two asprin solutions to a less than simple proceedue scare me.
Free medicine puts most people into general pratice with little options for speciallists. Visit a free clinic sometime.
The same would go for the 12 VDC circuits: 5% of 12 V is 0.6 V and not 6 V resulting in the same reduction in DELIVERED power, of course, not power losses---a very important difference!
Correct, but it requires 100 times the wire to provide this low loss at 1/10th the voltage. Instead of using one cord, 100 in parallel or larger equivilant is required. Do the math.
The point often missed is the wire requirement. For a 1,000 Watt microwave oven on 120 volts a 12 AWG wire is fine. At 12 volts for the same voltage drop, use 10 wires in parallel for the same voltage drop but 10 times the loss and a severe brownout. For the same loss 100 12 AWG parallel wires or equivelant needs to be run. The inverter for a house is cheaper than the copper replacement. The bonus is you get to use an existing affordable 120 Volt appliances and wire instead of a non-existant 12 Volt counterpart.
(Perhaps that's why most of the civilized world runs on 400/230 V / 50 Hz )
Higher frequencies require smaller transformers and motors for the same power.. It's why 400 hz is common on aircraft and some marine. The higher frequency does introduce it's own problems for long distance transmission, so 50 or 60 hz is a compromise.
The power supply for your laptop often uses frequencies over 20 KHZ so the transformer can be very small yet handle close to 100 watts.
First off, the lineman will always ground out a medium voltage system prior to doing any work on it. That is the only safe way to work on the system.
Care to back it up? Often they leave the line open becuse the line has a fault somewhere and they impulse the line with a tester to find the short or arcover location. Often they expect the line to be dead while fault testing and can be hurt when someone else unexpectidly energizes the line on them.
Yes I do care to back that up. It is really hard to find a arcing fault on a line with it grounded so you can work on it. It's ungrounded so your test equipment can send a locating signal so you can find where it ends or shorts to earth. Adding your own short to work on the line defeats the test equipment.
http://www.wipo.int/pctdb/en/wo.jsp?IA=WO1997042514&WO=1997042514&DISPLAY=DESC
http://www.nettechdi.com/cable_pipe_locators1.htm
http://www.nettechdi.com/locators/8869rf_cable_pipe.htm
http://www.indiansources.com/mksystems.htm
Again, do the math.
I don't know, like LV lights? What do you think Mr. Wizard?
Let's say you recharge batteries during the day using 6 60 watt panels. Normal for a small installation. Of the day count only 8 hours of overhead sunlight. (average in sunny climates) so you get 360 watts X 8 hours for 2880 watt hours. For the math assume perfect batteries and wire from the panels. (Never true in reality)
Time for evening activities. Kick on the computer for getting online for an hour.. I'll be generous and assume an effecient laptop of 80 watts. The batteries are outside or in the utility room properly enclosed in a ventelated container for safety reasons (normal and required by code in most places) The room is 35 feet from the den. The den is lit with a 14 watt CF lamp. (you can get them in 12V or use an inverter to save lots of money) Do the math and let me know what wire size you need for only a 5% voltage drop from your batteries.. Remeber the round trip is 35 feet X 2. Just for grins you want to fix a bag of microwave popcorn in the same room. The microwave is 1,000 watts. It is only on for 3 minutes for a consumption of of only 0.05 KWH, only a small portion of the stored energy. (microwave use is common on small solar installations).
The laptop drawing 80 watts would draw less than an amp at 120 volts. It would draw 6-2.3 amps on 12 volts. What wire size is needed to keep the voltage drop less than 5% for the 35 foot run from the battery. I'll wait. Copper wire tables are easy to find in a Google search. After you did your homework, get back to me and we will go over the cost of the wire and the cost of a 1500 watt inverter which can run the light, laptop and microwave.
Assume you can get a 12 volt microwave. What wire size is needed for the 35 foot run? I run my microwave 40 feet from the battery. The inverter is within 15 inches and uses a #4 wire. My run to the microwave is 12AWG wire, but at 120 Volt instead of 12 Volt.
A 5% voltage drop at 12 volts is only 0.6 volts. For the laptop's 6-2/3 amps + the 13 watt light at 1.1 amps, the 35 foot run would need to have a resistance less than 0.075 ohms (aproximate).
Now do the same thing for a 1,000 watt microwave.
Do the math. I'd love to see your numbers..
WTF?!? The current is higher yes, but the voltage is commensurately lower, the wattage hasn't changed!
You are indeed correct. The WTF that you missed is a 6 volt drop at 120 volts is a 5 volt drop to 115 volts.
A 6 volt drop from 12 volts is a half voltage severe brownout. That is what you missed.
Using wire 10x the size would work fine because its resistance would be one 1/10 that of the original line. The resulting drop in power would still be 5%
Care to try again? For sake of arguement let's take a 1200 watt load for a 20 amp load at 120 volt for 2400 watts. A 5% voltage drop is 6 volts.
A 2400 watt load on 12 volts is 200 amps.. With a wire 10X the size to handle it, it is still a 6 volt loss.. I'll let you figure out how well the appliance works on half voltage. I run a microwave oven on my inverter. I couldn't get enough power to it from the battery room at 12 vots. This is the reason my inverter low voltage wire is only 30 inches long.
I'll also let you figure out the correct wire size for a 5% voltage drop for the same distance as the original 120 volt circuit. Good luck.
You can try converting parts of your house to 12 or 24 volt, which would negate the need for expensive inverters and whatnot. All you'd need is a simple charging circuit for a battery (could be as simple as a diode) and then feed the 12/24 volt lights straight off it.
This is a common mistake and is only good for very low power stuff. In picking a wire size people often think going from 120 volts to 12 volts only involves the math of supplying a wire 10X larger to handle the current without overheating. In a 120 volt application, you are permitted a 5% voltage drop. This isn't much as 5% of 120 volts is only about 6 volts. No big deal when running a 1200 watt portable hair dryer. If you simply size the wire to now do the same thing on 12 volts, you no longer have a 5% voltage drop. At the same current you still have a 6 volt drop with the 10X larger wire but you now lost 50% of your power in the wire. Take a hint from the pro.. Use an inverter. The 10% the inverter lost is made up by the 45% not lost in the wire. Do the math. Engineer the project.
Either your high draw items (Microwave, toaster, blender, etc) are either within 20 inches of the battery, or you will want an inverter. With an inverter you can use standard appliances. Look for energy effecient ones.
Another item is to ditch the grid tie for small systems. It goes down with the grid providing no security. Put the critical load on an Outback inverter. It was made just for this application. Small solar, battery maitenance, load transfer to and from solar and battery, etc. You don't have a surplus to sell to the utility, so don't connect that way. Use it to supplimant your load and reduce your total load. As a bonus, you don't have to enter a grid tie agreement with the utility where they buy your power whosale and sell it back to you retail.
Find Outback stuff here;
http://www.outbackpower.com/
Disclaimer, I just use it. I am not otherwise involved with this company. The company has grid-tie stuff if you decide you really want it. I don't recommend it except for larger installations. This company has done a great job meeting the market. Their grid tie units are the first that I know of that operate instead of shutting down in the event of a blackout. They solved the number 1 problem with grid tie stuff.. blackouts.
http://www.partsonsale.com/outbackgridtie.html
And after a well-deserved spanking, they picked themselves up and bought Hawaii instead.
After Pearl Harbor, they were on the receiving end of 2 special deliveries to their home land.
The RIAA and member labels are next.. They bombed a copyright violator. The PR dammage is severe and the tables are starting to turn since it was way too heavy a stroke. I hope they don't have asbestos on cause the tide has turned.
I agree. It needs to be placed in the same status as 10. and 192.168. That should fix it.
They did win one, didn't they?
The won the battle but are losing the battle because of it. They couldn't have done anything better to get a bad PR problem.
It reminds me of the effect it had on Japan when they won Pearl Harbor in WWII. Right after they won the battle, they realised they woke the sleeping giant.
Maybe they shouldn't triffle in the affairs of dragons as thou are tasty and crunchy when well done. Write this win up as an oops...
They're already selling these online. Just check the box next to "I certify I'm a cop. Seriously, I am." and it's all yours for $19.95.
Obvious fake. The article stated these were free to law inforcement.
Explain how this would work with Vista. Using the default settings that is.
Are you claiming CD and other isertable media is no longer auto-run in Vista? Next time I'm near a Vista machine, I'll have to see if a CD or thumb drive auto-runs... Thanks for the info. I'll be sure to check it out. It's a step in the right direction if true.
Quick Google search.....
Oh, wait nevermind. I found about Vista and auto run here;
Windows Vista by default shows an AutoPlay dialog (right) to ask whether you want to run the AutoRun software.
If you select "Set AutoPlay defaults in Control Panel" then the window below lets you alter the AutoPlay and AutoRun default options.
http://www.phdcc.com/shellrun/autorun.htm
All the guy has to do that has physical access to your machine is OK a dialog box. Yea, that will stop them dead in their tracks.... End sarcasm..
Weird link.. It has the info on Power Cinema for linux, but no link to the product. Under products and following Power Cinema to the system requirements, you get this;
Operation System:
Microsoft Windows XP (Home edition or Professional edition)
Microsoft Windows Vista
DirectX 9 or above
Windows Media Player 9 or above
How do you find the Linux one? The link;
http://www.cyberlink.com/english/products/powercinema/pcm-linux/pcmlinuxgpl.jsp
appears to be only a GPL license page for the GPL portions of the product. Is there really a Cyberlink Cinema product for Linux and how do you find it?
I've heard rumors of a legal DVD player for Linux, but have not seen it marketed where I could find it. All links for me tend to dead end in the system requirements for Windows * and Direct X.
Laser toner is a cheap black powder. You can buy a refill for about $4.99. Opening the toner equipment for a refill can be tricky, in the case of Lexmark they made it impossible. A new toner costs ~$100
It depends on your selection of printer. My HP Laserjet III is still running. HP no longer makes carts for it. The aftermarket carts are 4/$100 with free shipping. Needless to say, I have no immediate upgrade plans for plain text printing.
What is this DVD support in Windows you're talking about? Last time I installed Windows (XP Home), I had to install more stuff from a CD (PowerDVD?) to get DVDs to play in WMP.
In Windows, a player of some kind is often bundled by the retailer. The bundled player is legal.
In Ubuntu, a player is never bundled and DECSS is most often used with MPlayer or other player in linux and is illegal anywhere the DMCA is king. DECSS is also not in the favor of the DVD consortium and is not an approved licensed player.
http://en.wikipedia.org/wiki/DVD_Forum
"The licensing restrictions on CSS make it impossible to create an open source implementation through official channels, and closed source drivers are unavailable for some operating systems, so some users need DeCSS to watch movies.
http://en.wikipedia.org/wiki/DeCSS
Linux can't *ship* the necessary codecs, but they are extremely easy to get installed within the first 5 minutes of using the computer.
Playing DVD's on Ubuntu is illegal in many places due to the DMCA and the use of an unauthorised decoder that breaks the encryption protecting a copyrighted work. So far it hasn't been challanged in court, but it could lead to RIAA style lawsuits. Getting caught is probably the hard part as there is no online presense. Geexbox is the safer option than an installed version because you can rip DVDs with Acidrip which shows intent where Geexbox is a bootable player with no option to save the decoded DVD. As such, it is shown to be a player and not a encrypted DVD ripper. In court, it is still not legal in many places the DMCA is in force.
Pick up a copy here;
http://geexbox.org/en/downloads.html
I use it on Winows boxes where the built in player is hosed. Boot it, use it, give a copy to the owner. It shows many Windows users that Linux works.
I'd suggest to you (honestly) - that if all your gf really does is youtube, mail & chat, then she'd be much better off on Ubuntu than windows.
Maybe. Those who use a computer for those tasks often also use it to play music (MP3 Support) and play movies (DVD support) where Microsoft has paid for the privilage to supply the codecs and the Ubuntu distro is lacking.
MP3 support isn't bad, but DVD support comes with dire warnings of DMCA violations and it may be illegal where you live.
Once installed, I like the Ubuntu machine over anything else for playing movies. You put in the DVD and the movie starts.. No previews, no unskippable FBI warning etc. Nice. If I want to watch all the extras, I can watch them later. It's the way a DVD player should work.
If I travel without a laptop, I carry a copy of Geex box. It's a bootable Linux Media player. Nice.