I thought it was the other way around but what do I know? At any rate there are advantages and disadvantages to everything and as Martin Luther said, “sin boldly”. Once you make a decision, go for it without looking back. I just hope that this doesn’t turn into another metric versus SAE system again where we’ll have half DC and half AC to contend with. I would need to see overwhelming advantages before I’d go for any switcheroo, at least at the consumer level. It’s bad enough for Europe to be all over the map with their ugly wall outlets without the US going there too. Of course IMHO. Get off my grass and leave me alone.
DC current is great when there is a need for VERY CLEAN power without ripple currents. As for the interchange between types of power, that is interesting. I didn’t realize that part of Japan uses power on the US standard while the other part uses power on the European standard. This happened during the rebuild after WWII. GE and Siemens did it differently. It depends on which part of the country and most of their electronics these days are made smart to use either system. This was never an issue until the 2011 earthquake that damaged many power plants including the Fukushima nuclear complex.
There was a shortage of power throughout the country and but the 60HZ 120V system was more lacking than the 50HZ 240V system. There are interchange stations where one type of power turns a large motor tied directly to a large generator and can convert between the two when needed. The problem was that there weren’t enough of these facilities to perform the conversion being demanded after the earthquake so there was excess power in one system that couldn’t be used in the other.
I also understand that many of the old hydro power plants such as Niagara Falls used to generate 25 cycle power. They actually still do but it was easier to install such a conversion station as described above to convert the 25 cycle power to 60 cycle power instead of completely replacing the generators/turbines. Some of the older pump stations in New Orleans used to use some odd power standard that was no longer in use and this posed an issue during Katrina. So much has changed since then so I don’t know if these still exist or if some type of conversion station has been setup so they can now be used on grid power.
AC vs DC voltage is much like Disc vs Drum brakes, there are benefits and drawbacks to both, I think we will see the return of drum brakes before we see a DC distribution system, transmission yes.
The advantage of AC has always been that it is easy to change the voltage up and down with a transformer; DC requires more equipment and some losses to convert.
That being said, transferring AC power between separate grids requires making sure the phase of the power transmitted matches from the two grids (so that the power from the two grids doesn’t cancel or ring), which is difficult and expensive. This is not a problem for DC, so DC lines are used in cases such as where power is transferred from another grid to increase the capacity of an existing grid, or between countries that use different frequency power.
Capacitance between the AC phases (usually 3 phases are transmitted at once over a line) or between the line and the surrounding soil or water causes losses that are not a problem with DC. Therefore, undersea high voltage lines tend to be DC.
Overall line loss is also lower per 1,000 km, so very long distance transmission lines sometimes use DC.
Just like so many times in the past, I end up learning a whole lot about something I know nothing about. Thanks.
I have heard that once you have the power grid in phase, it tends to naturally stay that way. It is easier for AC generators to become in phase rather than fight each other and conflict.
That’s true, in fact if the prime mover driving the alternator quits, the alternator will keep running in sync with the line frequency and act as a motor driving the dead prime mover.
Throwing an alternator on line is not a simple task, you have to get both the rpm and the phase right before throwing the switch. Sometimes it takes several attempts. You watch an instrument called a synchroscope and when the needle is at zero, you close the breaker, but it’s a moving target and you kind of have to lead it to compensate for the time it takes for the breaker to close.
It’s kind of comparable to putting a non-syncro gearbox in gear without using the clutch and doing it without grinding the gears while the vehicle is in motion.
Back to cars: My parents had a 1969 Pontiac LeMans with the 350 V-8 engine. It had some kind of nylon-plastic timing gears that stripped out. This was a problem with many Pontiacs of that era. The reason given for these nylon-plastic gears was that they ran more quietly than steel timing gears. However, the replacement gears were steel and I couldn’t detect that the steel gears made any more noise.
So Rick, you are saying that the folks that fought having high voltage lines run near their cows had a point? Some claimed they’d get a shock when milking.
Being as I know you’re from my state, there’s a pedestrian bridge in Maple Grove over 81 where in the right weather conditions your scalp will tingle because of the power lines passing so (relatively) close overhead.
I now seem to also remember a certain GM engine from the 1980’s that used plastic/nylon timing sprockets that didn’t hold up so well. I never messed around with one of these but it might have been the Quad 4.
I believe that modern engines are migrating to a sprayed steel piston liner. So most engine blocks are aluminum for weight reasons. These historically has steel liners that are both boreable and replaceable for engine rebuild. The new design is some sort of “flame sprayed” liner that will make the engine blocks one time use and non rebuildable. I would imagine this is being used in small engines that have a engineered short life.
The vega had silicon lined cylinder walls. You couldn’t reline them, but you could bore them out a little and put in steels sleeves. Actually made the Vega engine very reliable
The S2000 and later generations of Prelude had fiber-reinforced metal linings. You score those things, you’d better hope someone in your town has the equipment and knowhow to hone them or your engine just became a big paperweight.
Had a friend who needed this done on his S2000 - it ended up being cheaper to source another engine than to have a shop do the work.
More common is cast-in-place liners, either wet or dry. Usually wet, i.e. in contact with the coolant. Some can be overbored a small amount, None can be replaced if cast-in-place. Some aluminum blocks (since the 70’s!) have Nikasil or Alusil (and other trade names) coated aluminum bores. Can be overbored with a method developed by Sunnen and GM for the Vega. These are commonly used by Mercedes, Porsche and BMW although BMW gave it up because of damage from higher sulfur in US fuels. That problem and BMW’s use of aluminum bores is fixed now. Ford used an aluminum block with a plasma spray surface for the bores on a Shelby Mustang starting in 2011.
So, no, this isn’t used on cheap cars with short lives.
I understand a similar process is used on most small engines. Commercial grade units still use cast iron for better wear characteristics and seem to usually advertise this clearly on the outside of the unit in writing. Of course small engines tend to be abuse and neglected more, plus many are air cooled so the oil may thin more at high temps.
Kawasaki has been using this process on a lot of their motorcycle engines. The cylinder surface is so hard that it just doesn’t wear. If a two stroke moto-cross race bike seizes a piston, you just put in a new piston and remove the smeared aluminum from the piston off the cylinder wall with muriatic acid and go back and race.
My Kawasaki ZRX1200R had this cylinder technology and it rolled over the odometer and still was not burning any oil. I never had to top off the oil between oil changes.
Bodes well for my Kawasaki Concours with the de-tuned Ninja 1000 engine, I’d say. A friend owned a Concours with 93,000 miles that used virtually no oil and rode pretty much like my far lower mileage bike.
I saw reference to the plastic deck on the mowers. This is actually a very high strength impact resistant plastic that doesn’t rust so is a good use of plastic in mowers. I don’t know if the Honda Harmony uses the GCV or the GXV engine but I suspect it is the GX series which is the more commercial grade line.
I was recently at Lowes looking at some push mowers. They only have a few models left since it is getting to be the end of the season. All but one had the “never needs on oil change” engine. I told them this would never work with the way I mowed. They asked if I did commercial work. I said no but I own a farm so the same difference. They told me the warranty might not apply to me if I use it more than a certain amount. There is nothing stopping you from changing the oil. You have to turn the thing over which is best done when you are low or out of gas. On the other hand, I was great about changing the oil on the one with a plastic camshaft and it didn’t really get me anything.
Maybe this makes sense? One can certainly understand, I think, that General Motors wouldn’t want Ford to get its “proprietary and confidential” airbag information so that Ford could produce cars that kill and maim as few people as General Motors cars do and vice versa, If it got into the wrong hands, this information could save lives. Hence, perhaps, its treatment as a trade secret rather than a patent. Trade secrets hide information whereas patents make it available to everyone so that the world can learn.
A detailed, clear explanation of the operation of “adjustable” airbag inflators is not easy to find. However, just such an explanation can be found in U. S. patent number 5,664,802. Good patent attorneys are skillful.