I know nothing about Lister-Petter except what I found on the web today.
e.g.
web page 1
web page 2
web page 3
A google newsgroup search for Lister-Petter shows most comments on the companies generators are from the UK. What is the parts availability in Ohio?
The Lister-Petter engine is 1800 RPM which is good for a long life. The life of a slow speed diesel will be better (for long engine life) than the life of a high speed (3600 RPM) diesel engine, which in turn is better than a 1800 RPM gasoline engine and on down to a 3600 RPM gasoline engine. I see that Lister-Petter has a long history of making marine diesel engines (good again).
I still have problems with the claim of 12,000 to 30,000 hours between overhauls. 30,000 hours is 1250 days or 3 and a half years of near continuous operation. I am skeptical of this. I don't have experience with any motor with this kind of life, or with a slow speed diesel engine. Since I don't have direct experience with this type engine I compare it to something I am familiar with, a car engine. Using the car analogy, at 50 Miles an hour this would be 1,500,000 miles. This is possible for a rare exceptional car engine, exceptionably well maintained, but not for an average figure. Second what are they claiming with the range 12,000 or 30,000? That is an extremely large range, more than a factor of two. I would read that as the lower figure, the minimum they claim for their generator. A failure at 12,001 hour would meet the published specs. So the lower figure is all they are really claiming. (Still seems high to me but it is closer to reality.)
With all the moving parts in the diesel engine these numbers just 'feel' too high. We start off with the injection pump, a mechanical high pressure pump which must spray fuel into the cylinder at maximum compression. We have many bearings (on the crankshaft, the cam shaft, both ends of the connecting rod, cam shaft ...). Sliding friction between the piston rings and cylinder walls, in the valve guides ...). There are things that can just break or burn, valve guides, lubrication passages to clog, timing belts to slip or break, gear teeth to break, ... There are just too many places with metal rubbing on metal for nothing to get out of spec in 10,000 to 30,000 hours. The only way I see to spec a MTBO this long is to define a very lose fit, much loser than new, as acceptable, and hope that nothing actually breaks or burns.
(Please anyone am I am off base here?)
There are generator technologies with the potential for extremely long life. The Capstone MicroTurbine
microturbine.com is capable of a MTBO and MTBF exceeding 100,000 hours. It uses a small turbine engine with air bearings so it has one moving part, and no metal to metal friction. The first scheduled maintenance is at 8000 hours, an air filter change. At 30 KW and up it is above the power range we have talked about. The price is above the price range we are talking about by an order of magnitude. (I did see one Capstone on
ebay last year, new, never uncrated, with no reserve, no bids, a starting price of $9,000, and the auction about to end. At the time I considered getting it as the ultimate back up generator for my house (or to resell for a big profit) but ended up decided that it just sounded too good to be true, and there was no time to check out the seller. )
If forced to come up with an explanation for the price of the Miller welder/generators, I would explain that the welder price situation is the way it is because the market for Generators has been separate from the market for Engine driven welders with auxiliary power output. The prices have been set, over a long time, based on competitive pressures within their own markets. The prices tell us that the Welder market has been more competitive, keeping the prices down, and demanding high reliability. Miller (given the generators page on their web site) has realized that there is an opportunity to sell to the other market is now actively attempting to sell into the generator market. Miller is limited by its distribution system, most generator purchasers still do not think to check Miller before buying, and the retail level in Millers distribution chain, welding stores are not exactly pushing for new markets, or friendly to anyone walking in the store who will not buy 1000 pounds of electrode a month.
In addition, the Miller units have a big disadvantage for most users of portable generators, weight. The Bobcat and Trailblazer weigh about 600 pounds and the trailblazer pro weighs over 900 pounds. This would not matter to you, you are comparing it to a stationary generator (among others). But someone looking at a PORTABLE generator will compare the Miller to a Honda or even a Northstar 6000 Watt generator at about 300 pounds. Even a 10.5 KW Commercial duty Honda gasoline generator only weighs 400 pounds.
If it will be moved by hand 600 pounds 'is' (seems to be) at least 4 times as heavy as 300 pounds. (On the other hand there is Mashburn's law of quality: Shipping weight is a direct measure of quality when comparing two items of the same type. Heavy items are better with bigger beefy parts, therefore higher weight in the item. Light precision items benefit from big beefy shipping containers, therefore more weight in the packaging materials.)
Three phase power is a whole other can of worms.
There is no 2 phase power system in common use. Single phase power is two legs (wires) of the three phase power. Adding one wire gives us three phase. Think of the phase as the voltage difference between each pair of wires. Three wires A B and C give us phases AB AC and BC. A single phase service is only one of the pairs, any one one of the pairs. Presumably the other two pairs provide electrical power to others with single phase service to balance the load to the generator. In addition to the two (single phase) or three hot wires (three phase) there is a ground. The phase of the 60 Hz voltage on each of the three wires is phase shifted by 120 degrees relative to the other two wires. (360 degrees being one complete cycle of the sine wave.)
Basically you would already know if you needed three phase. Power distribution, industrial equipment, and big motors are three phase. Three phase motors are usually more efficient and split the power required over the three input wires. This lowers the current flowing through each wire and therefore the size needed for each conductor. Three phase motors can be reversed trivially, with a simple switch, by exchanging any two of the 3 input power wires.
In the US household power is single phase with a center tapped ground. The distribution system is three phase. The two hot legs give 240 volts between each other and 120 volts from each hot leg to ground. At the service entry (and only at the service entry) the household Neutral is bonded to ground. The Neutral serves as the return for 120 Volt power. In The US both 240 and 480 volt three Phase power is used, depending on the requirements and availability. The three phase can be converted between 240 Volts and 480 volts by three phase transformers. (I will stop here and not get into the differences between delta and wye ('Y') three phase. Believe me, you do not want to know.)
In the US most residential areas are not wired to provide three phase power. (My next door neighbor considered building a pole barn for his woodworking business but found that he would have to pay for something like many miles of power line to get three phase power. The cost would have been far more than the pole barn.)
You would need 3 phase power if you were planning to have large electric motors over about 8 horsepower (real horsepower not Sears horsepower). In a workshop this would typically be on serious metalworking or woodworking machines. A Bridgeport mill could have either a single or three phase motor while a bigger vertical mill will almost always have a three phase motor.
Hobbyists and small shops which do not have a three phase feed from the power company and have (smallish) tools which require three phase can generate the three phase power for specific tools with a phase converter. A simple phase converter is just a three phase electric motor driven with the two hot legs from the power company acting as a generator to generate the missing leg (this works with some inefficiency). A far more complex technique is a VFD (Variable Frequency Drive), this is a more modern solution. A VFD is a solid state device which produces true three phase at a selected frequency. By changing the frequency 'slightly' from 60 Hz the speed of the motor can be changed. (The speed of a three phase motor is determined by the frequency of the power.) In general terms the machines which would need three phase would need more than 7 to 10 KW of power, more than can be powered by the generators we are talking about. (A 10 HP motor can use 47 KW to start and 11 KW to run. A 5 HP motor can require 23KW and 7KW.)
One of the Miller Gasoline welder/generators offers 480 Volt three phase power output, but at 9.5 KW output its not big enough to start the really interesting machines. (Eastec is coming up in May, so I will get to see some of the big stuff soon.)
