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Diesel generators are the most common source of power for remote locations because they are reliable and relatively efficient compared to other internal combustion engines.

Some details on diesel generators, terminology, factors to consider, and recommended features.

The diesel generator sets for this sample project are sized for 30kw continuous/baseload, or 38kw prime power. The Control System will automatically start a second generator if the first generator reaches 80% of its capacity, synchronize and operate them in parallel. When the load drops below 70% of the single genset capacity it will automatically unload and cool down the second genset. If the running generator shuts down due to a fault the second generator will automatically start and carry the load; if possible (in the case of a critical warning, like high water temperature or low coolant) the load will be transferred automatically before shut down.

We prefer to purchase gensets built to specification from Martin Machinery rather than package sets from, for example, Cummins Power, Caterpillar, etc. The primary reason is that we can specify the size of generator end separately from the engine size, resulting in a better match for long-life. Most packaged power sets size the generator end for at least 80°C rise at rated power, which can result in a generator that is as hot as 130°C (266°F)! Standby power generators frequently operate at even higher temperatures.

First, this is very wasteful of energy that could be doing useful work like operating your computer or lights. Second, this shortens the life of the generator end considerably. Time and temperature are the two primary factors governing the life of a generator - the higher the temperature, the shorter the life. If you intend to use your generator for a decade or more (and given the initial expense, why wouldn't you?), it is worth oversizing the generator end by as much as 30-40%. This results in cooler operation. There is no real downside to oversizing beyond the additional initial cost. Martin Machinery normally does this for prime power gensets and can advise on the best options for your application.

However, oversizing an engine so that it ends up loaded to less than 30% rated output for more than 80% of the time can also result in shorter engine life. “Wet stacking”, where unburned fuel starts showing up in the exhaust as a tar-like residue, is one problem. This is usually cured by operating the engine at 50% or more load for three or more hours continuously. More seriously, if the injectors become fouled with unburned fuel, you will get poor economy because the diesel fuel fails to be atomized properly, and then drips down the cylinder walls, contaminating the oil and reducing the lubrication of the piston rings. This could require an overhaul at far fewer hours than you should normally be able to expect, and at worst could damage the crankshaft, which is the most expensive part of the engine to replace – and the most difficult to transport.

For very detailed information on sizing and installing generators, see Cummins Power Application Engineering Manual for Liquid-Cooled Generators(PDF),


  • John Deere 4045D
  • Widely used in agriculture for power and water pumping
  • Can be rebuilt/overhauled to original factory specification as often as required (typically every 15,000 hours of prime power operation)
  • Engine Sensors
    • Water Temperature Sender (provides temperature indication & warning)
    • Water Temperature Switch (shutdown for high temperature)
    • Low coolant switch
    • Oil Pressure Sender
    • Oil Pressure Switch
    • Oil Level switch
    • Air Filter Indicator Switch (signals when to change air filter)
  • Fuel Filter/Water Separator


  • Marathon Electric Mariner1) in double-delta for single phase operation with PMG2) and Digital AVR3)
    • Rated 77kw 3-phase, 38kw (50%) single phase at 220v, 50Hz
    • Compare with dedicated single-phase model 431PSL6224 Performance Data
    • Note: generator windings in high humidity or tropical environments can experience insulation failure in just two or three years due to absorption of moisture in the windings. The Mariner model somewhat helps to prevent this; for the best protection, see the article on generator heaters.

The gensets can be built to order by Martin Machinery. Contact them for a quote and if you want to make changes from the standard design (generator size, engine size, model, features, etc.).

for tropical/high humidity locations
Permanent Magnet Generator
Automatic Voltage Regulator
ge/start.txt · Last modified: 2022/10/11 09:27 by