i have 350kw old diesel generator and want to calculate the exact consumtionption at various loads.
There is no exact formula. Each engine is unique and the manufacturer has a fuel consumption chart for each engine. It is usually in BTU's per horsepower hour or the metric equivalent. It all has to do with engine efficiency and fuel heating value. See below:
Generator Fuel Consumption Calculator
This can happen due to any number of reasons. 23.4 volt is not a low voltage to start the engine that expects to work on 24 volt. But the battery may not be charged well, even then it shows 23.4 volts, because you are testing it without load. So connect some resistance (that should take same current as the starter motor current) and then check the voltage. If voltage drops to severely,then the battery is discharged or has problems like dry condition, or battery life over etc. If battery is good, then check for any loose connection up to the motor terminals. Other problems could be in the burnt motor or heavy load due to mechanical defect on the IC engine (check whether the diesel engine flywheel can be rotated smoothly- without connecting to motor- but this is possible only in small generators)
You will need the specific fuel consumption of the engine, but it is probably close to 0.5 pounds per HP hour or 250g/KW.h. That is specified for the output shaft power at the operating RPM. It depends whether you have a turbo charger, the fuel a little, the air temperature and barometric pressure. Make sure exhaust and air intakes are not restricted too. You may find for a gen-set that you get a set of curves with the fuel consumption for different KW output. These account for the alternator efficiency already. Contact the engine supplier etc for this info. Use KWh from the generator (volts x amps x time gives KVAh not KWh). The amps might be up to 20% higher, depending on power factor of the load. The reactive part of the load does not need power from the engine. This is why I say to use KWh not KW, as you can use ordinary KWh meters (which ignore the reactive load). Allow for the efficiency of the generator (which varies somewhat, especially at light loads). Let's say 85%. Remember it is exciting the field, so that must be included in the efficiency. Thus if you are using 350KW for one hour, the engine provides 350KWh/0.85 411.8KWh (412KWh). The fuel used is 412KWh x 0.25Kg 103Kg of fuel. Now you need the specific gravity of the fuel you are using. You can call the fuel distributor. Ideally this is corrected for temperature of the fuel with the engine running, remembering the engine heats the fuel in the day tank due to recirculation. Let's assume 0.85 is the SG, so that means 0.85kg/l so 103Kg of fuel is 103/0.85 121 liters. In practice it may be higher, especially if the engine is old and worn. This answer is something like the maximum consumption, full rated output, 121 liters per hour. OR 26.6 imperial gallons or 32 US gallons per hour.
