Start / Machinery and application / Machinery cost
Enter the power, how many hours the generator spends in each load band, and the tank. The page calculates the average consumption, the consumption per kWh, how many hours the tank lasts, and the tank size needed for the required autonomy.
Pre-sizing and estimating tool: the results do not replace a design, calculation, or report signed by a qualified professional, nor verification against the applicable standards.
Technical responsibility. This calculator is under verification. The reference values and examples are hypothetical, to illustrate the calculation, and are not technical references. The user is responsible for the data entered, the choice of parameters, and the use of the results, and must validate them with a qualified professional before any decision, purchase, application, or construction work.
Lines: liters per hour from the curve in use and from the published linear model. Points: consumption per kWh.
Operating hours with the tank's usable volume, if the generator always ran at the same load. The dashed line is the desired autonomy.
Drag the controls to simulate data different from what you entered (from 30% less to 30% more) and watch the result change instantly.
Consumption, specific consumption and tank range for loads of 25% to 100% of rated power.
The calculation done in steps, with the values you entered.
Hourly consumption for load factors of 40% to 100%; the highlighted bar is your load.
Diesel cost per hectare for outputs of 6 to 16 ha/h; the highlighted bar is your output.
The calculation memo gathers this page's inputs, results, equations, assumptions, and references, with fields for project, responsible person, and review. The full report also includes the charts and interpretations, in color. In the print window, choose Save as PDF.
The page has two parts. The first, generator set consumption and autonomy, calculates the generator's fuel use from the catalog load curve (or the manufacturer's coefficients), the diesel for the period, the tank range, and the cost per hour and per kWh. The second, Top-up: farm machinery, calculates the hourly fuel use of a tractor, combine or pump engine from power, load factor and specific fuel consumption, and the diesel per hectare based on the operating rate.
The diesel price is a single field, in the first part, and applies to both.
Hypothetical values, to understand the calculation. They are not technical or market references.
Farm machine: 120 kW engine working at 70% of power, with a specific consumption of 0.22 L/kWh. Consumption is 120 × 0.70 × 0.22 = 18.48 L/h. At a rate of 12 ha/h, it is 18.48 ÷ 12 = 1.54 L/ha. At R$ 6.20 per litre, the diesel costs R$ 9.55 per hectare.
Default example generator: 500 kVA with a power factor of 0,8, with a 24 h load profile. Average consumption is 69 L/h, with 106 L/h at full load. A 2,000 L tank with 90% usable lasts about 26 hours of autonomy at average consumption, and the fuel cost comes to about R$ 428 per hour.
At full load (400 kW), a modern generator set uses close to 105 L/h; at 50%, about 57 L/h. The published linear model gives 131 L/h at full load, a more conservative figure.
Divide the usable volume by the average consumption. A 2 000 L tank with 90% usable and an average consumption of 69 L/h lasts about 26 h.
Part of the consumption happens even without load: friction, pumps and fan. At 25% load, a 400 kW set uses 0.34 L/kWh, versus 0.27 L/kWh at 75%.
Multiply the average consumption by 24 and divide by the usable fraction: 69 L/h × 24 ÷ 0.9 = 1 840 L. If the standard requires full load, use 106 L/h: 2 830 L.
Important notice: the Agrocalcs tools make estimates and preliminary sizing based on the data entered and on published engineering methods. They do not replace a design, a calculation report or a report signed by a qualified professional (CREA/ART), nor verification against the applicable technical standards and legislation, such as the Regulatory Standards of the Ministry of Labor. Material and fuel properties vary: check with the manufacturer or with analyses of your process before deciding. By using the site, you agree to the Terms of Use.
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