Calculator
Click here for more Electrical Calculators
Diesel generators (DG sets) are commonly used to provide power backup in factories, hospitals, construction locations & remote areas.
Understanding the relationship between the following is essential for managing operating expenses and performance:
- Apparent Power (KVA)
- Active Power (kW)
- Load %
- Fuel consumption
- Cost per kWh.
This post leads you through a typical Diesel Generator Calculator Sheet, explaining its formulae & analyze and providing an example for determining load kW, kVA, efficiency and cost-effectiveness.
Apparent Power (S)
The overall power output of a generator is measured in kVA (kilo Volt-Amperes). It incorporates both actual and reactive power.
Power Factor (cos φ)
The ratio between active power (kW) and perceived power (kVA). Usually, diesel generators typically have a rating of 0.8.
Active Power P (kW) = Apparent Power S (kVA) x Power Factor (Cos φ)
Load Percentage (%)
This value provides a measure of the percentage of the generator’s rated power that it is now operating at:
Load (kVA) = Apparent Power × Load %
Load (kW) = Active Power × Load %
Fuel Consumption
Fuel consumption denotes the amount of diesel that is consumed in one hour, often by:
- Liters/hour (l/h)
- Liters/kVAh
- Liters/kWh
Cost of Energy Generation
This is the cost of generating 1 kWh with diesel.
Cost per kWh = (Fuel consumption in liters/hour x Cost per liter) / Load in kW
PCI (Low Heating Value)
The PCI (Power Calorific Index) determines the energy in diesel fuel that is generally:
PCI ≈ 9.8 kWh/liter
Yield of the Engine
It demonstrates how effectively the diesel engine transforms fuel into electrical energy.
Energy Yield = (kWh output)/(Fuel input in liters x PCI)
Important Recommendations
- In addition to having a reduced cost per kWh, efficient generators have a lower liters per kWh.
- The efficiency of a DG can be improved by operating it at 75–80% load.
- Both the cost of fuel and the yield of the engine have a substantial impact on operational expenses.
- Before making a purchase or getting your generator serviced, you may utilize this calculator to compare it to another generator.
Solved Example
A diesel generator rated at 100 kVA has a power factor of 0.8 & runs at 75% load. Diesel costs ₹100 per liter and is consumed at a rate of 20 liters per hour.
Calculate:
- Active power output (kW)
- Actual power output at 75% load in kW
- Fuel usage per unit of electricity generated (L/kWh)
- Cost of generating one unit of electricity (in ₹/kWh)
Solution
Step-1: Active Power
P = 100 × 0.8 = 80 kW
Step-2: Load Power
Load kW = 80 × 0.75 = 60 kW
Step-3: Fuel Consumption per kWh
Fuel/kWh = 20 ÷ 60 = 0.33 liters/kWh
Step-4: Cost per kWh
Cost/kWh = 0.33 × ₹100 = ₹33/kWh
Calculator for Diesel Generators that performs the following:
- Calculations of power (in kilowatts from kilovolts),
- The use of fuel based on load,
- The cost per kilowatt-hour &
- Comparative effectiveness of a number of different generator models.
Additionally, it provides:
- Use of gasoline on a daily basis,
- Obtainable potential energy from the fuel &
- Overall cost for each day.
A diesel generator’s operational efficiency depends on its power rating and fuel consumption/energy cost.
Users may optimize generator utilize, budget fuel prices, and compare models using an Excel-based calculator. Optimize efficiency by monitoring power factor, load percentage & daily usage.