How to size a Diesel Generator

When calculating How to size a Diesel Generator, consider the following points:-

Firstly, calculate the maximum peak load that you want to supply with Diesel Generator Power.
Secondly, is this for emergency power or is it for Prime Power?
Prime Power means in place of Mains GRID Power.
Standby diesel generators are used for emergency power during a MAINS power outage.
Make sure the Diesel Generator power rating can also handle battery charging at Diesel Generator start.

Diesel Generator CalculationsDiesel-Generator-How-to-Size

Take into account that all generators can support 65% of their capacity upon startup.
As well as this, take into account the power factor is 0.8. This applies to all diesel generators.
Therefore, never undersize a generator

Calculate how many hours you wish the Diesel Generator to run (at least 8- 12 hours running time).
Then choose what size fuel tank you require.
Ensure the diesel fuel is double skinned and bunded.
NEVER allow the genes to run out of fuel.
NEVER allow the generator is use the  fuel at the bottom of the tank as there will be residue sediment there.

To calculate the size a Diesel Generator download our Power Calculator app from the Apple App Store for free – Click Here to download.

How to size a Diesel Generator Example

This example presents how to calculate the Diesel Generator Size.

The rated power Pn (kVA) of a Generator is the maximum output power given an output power factor of 0.8.
It is necessary to calculate the corresponding input power to determine the Diesel Generator power rating

Therefore a Diesel GENERATOR of  100 kVA  supplies the load with a maximum output power of 100 x 0.75 = 75 kW

How to explain Diesel Generator Power Factor

Diesel Generators have a power factor of around 0.75-0.8
Gas Generators have a power factor of around 0.50
LPG Generators have a power factor of around 0.45

Another helpful example

If the increase is 18% (value supplied by the manufacturer), the necessary input power is Pe = 80 x 1.18 = 94.4 kW.

Therefore the Diesel Generator must be sized to supply power Pg.
Such that, if the input power factor is 0.8, then Pg > 94.4 / 0.8 = 118 kVA.

In this case, where both the input and output power factors are equal to 0.8,
it is possible to calculate the result as 100kVA x 1.18 = 118 kVA

To calculate the size a Diesel Generator download our Power Calculator app from the Apple App Store for free – Click Here to download.

Behaviour of a Diesel Generator with harmonics

Diesel Generators are designed to supply linear loads.
Should you notice the  presence of harmonics it’s necessary to take action to ensure compatibility.
Otherwise, there will be possible repercussions down stream on the Diesel Generator and its Power Control.

 

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