Calculating the power and capacity of a diesel generator—or performing accurate diesel generator sizing—is one of the most critical steps in designing standby and prime power systems. At Rastak Power Industries, our team provides free consultation for all customers and projects based on years of technical knowledge and practical experience. Choosing the right generator capacity increases efficiency, reduces maintenance costs, and optimizes fuel consumption.
This article explains how to size a diesel generator and includes power conversion tables to assist engineers and users.
1. Determining the Required Electrical Load
Before selecting a generator, you must first calculate the total electrical load.
This involves estimating the power consumption of all devices and equipment that will be powered by the generator.
2. Identifying the Type of Load
Electrical loads generally fall into three main categories:
Resistive Loads: such as incandescent lamps and heating elements.
Inductive Loads: such as motors, transformers, and air conditioning systems.
Capacitive Loads: such as certain types of switch-mode power supplies.
Note: Inductive loads have high starting currents and therefore require generators with higher capacities.
3. Power Factor (PF)
Generators are typically designed with a power factor of 0.8.
To calculate the real power, use the following formula:
KW = KVA * PF
4. Choosing the Right Diesel Generator
When selecting a diesel generator, consider the following factors:
Environmental conditions: temperature, altitude, and humidity
Application type: standby, prime, or continuous operation
Overload requirements: some equipment may require temporary overload capability
Power Conversion Tables
1. kVA to kW and Amperes Conversion
| Amp (400V-3P) | Amp (230V-1P) | kW (PF=0.8) | kVA |
|---|---|---|---|
| 14.4 | 43.5 | 8 | 10 |
| 28.9 | 87 | 16 | 20 |
| 72.3 | 217.5 | 40 | 50 |
| 144.6 | 435 | 80 | 100 |
| 289.2 | 870 | 160 | 200 |
| 723 | 2175 | 400 | 500 |
2. Kilowatt to Horsepower (HP) Conversion
Horsepower is a common unit for describing the power of generator engines.
Use the following formula to convert:
HP= KW * 1.341
| HP | KW |
|---|---|
| 13.41 | 10 |
| 26.82 | 20 |
| 67.05 | 50 |
| 134.1 | 100 |
| 268.2 | 200 |
| 670.5 | 500 |
3. Watt to Ampere Conversion
To convert power (W) to current (A), use the formula:
A= W/V
| Current (A) at 400V | Current (A) at 230V | Power (W) |
|---|---|---|
| 2.5 | 4.35 | 1,000 |
| 12.5 | 21.7 | 5,000 |
| 25 | 43.5 | 10,000 |
| 125 | 217.4 | 50,000 |
Conclusion
Proper sizing of a diesel generator requires a detailed analysis of load demand, equipment type, environmental conditions, and applicable standards.
Using power conversion tables helps engineers and technicians make accurate generator selections.
At Rastak Power Industries, our experienced technical experts are always ready to provide consultation and support to ensure you select the most efficient and reliable diesel generator for your application.
