Part Loading Generators

How the Inoplex Cogen Generator
fixes this issue

What’s the problem? Its easy and feels “safe” to choose a generator a little bigger than you really need as opposed to buying one that may be too small. You need one that is powerful enough to cope with that hot weather and still produce the power you need (thermal de-ratings) as well as cope with your largest electrical motor being switched on and the block or step load that this adds to the generator. So to play it safe we install a generator that is bigger than we generally need. This then means the generator runs turned down from its rated power.

The issue with Traditional Generators

Traditional generator engines are often designed to optimally run at full load. This is where they will perform “best” and the performance data is often provided. Synchronous, or fixed speed generators, decrease efficiency, fuel economy and emissions when they are run at part load, and in the scenario above where an oversized generator is installed, this will be almost all the time!

More than the reduced efficiency, which costs you some extra fuel which you probably can live with, running the engine at part load also accelerates harmful wear and tear on the engine:

• The engine runs cool causing the piston rings, the piston itself and the cylinder to not dilate enough to ensure a good seal and as a result the oil reaches the combustion cylinders and is expelled through the exhaust valves as a smoke.
• Exhaust gases blow by the cylinder rings into the engine crankcase potentially causing further oily emissions from the engine through crank case emissions. If these emissions are drawn back into the engine to burn as part of a crank case ventilation system, this oil can harm the turbocharger and foul the spark plugs, oxygen sensor and foul/block a catalytic converter.
• Cause excessive deposits of carbon residue of the surfaces of the valves, valve seats, pistons and exhaust manifold.
• Cause excessive wear on the turbocharger and oil leaks within the body of the turbocharger.
• The engine runs at lower temperature with fuel being partially burn, causing exhaust smoke and high hydrocarbon emissions.

If the engine is still serviceable, the generator can be connected to a larger electrical load, such as a load bank, and run at full load to burn the oily residues from the bore and partly restore the engine condition. However, ongoing operation at part load will reduce the life expectancy of your assets.

How our competitors generally deal with part load issues

The conventional approach is to not run generators below 30% of their rated capacity for any significant length of time. This is easy for an engine manufacture to write but it may just not be practical. If you are running a generator as a back up power supply and your site loads vary up and down, then you may have no option but to run at low loads. Some competitors add an electrical load bank, yes more cost, that is switched on to create higher electrical demand when the site demand is decreased, just so the engine can work harder (yes, and burn more fuel than is needed, and yes, more of your cash going up the exhaust pipe for no benefit to you).  However, there is another option.

How the Inoplex Cogen Generator deals with this

This is where the variable speed and power electronics featured in the Inoplex Cogen Generator really demonstrate their technical and engineering superiority. Our CHP Engines turn down their target speed and at the lower speed target, still run flat out, under heavily loaded conditions maintaining (actually enhancing) efficiency and service life. For example, we if have a 66 KW generator, producing this rated power at 2200 rpm, this same engine will produce 33 KW at around 1100 rpm working hard with the throttle wide open. If your site load drops further, then this generator will still produce 23 KW at 750 rpm and still be running at full load, all be it at a reduced speed. This allows a 66% turn down from full power without losses in efficiency of harming the engine life expectancy. The inverter generators can still turn down further from 23 kw at 750 rpm to just 100w to power up just one light bulb, all without harming engine life as the variable valve timing is used to adjust the amount of air and fuel the engine draws in.

The variable speed engine combined with power electronics and variable valve timing helps you to select the correct size cogen generator for your next project. They can run from full load to just a few watts with maximum efficiency without the fear of harming engine life.  Perfect for many applications where the electrical load varies considerably. 

So reduce the risk for your next project and specify an Inoplex Cogen Generator.