How To Sizing a Diesel Generator?

Diesel Generator software can be very complex, involving many different website particular components to be considered. This report presents a simple guide to sizing a diesel generator. It assumes a basic knowledge of electricity calculations.

Diesel Generator sizing involves calculating the next load factors:

1. The constant load functioning at any given time

2. Derating factors

3. Transient performance

4. Non-Linear Loads

The size needed will be dependent on the most demand from one of the above-mentioned load factors. We’ll now expand on each one. Browse for searching more about  Diesel generator (which is also known as ” เรียกค้น เพื่อค้นหาข้อมูลเพิ่มเติมเกี่ยวกับเครื่องกำเนิดไฟฟ้าดีเซล”  the  Thai language ).


· Calculate the total kVA for all motors and machines that will be working at one time

· Calculate the total kVA for all heating/air conditioning that will be operating at a single time

· Calculate the total kVA for all lighting that will be working at a single time

The run kVA (VA) equals the amount of the maximum potential load requirement at once.


Common de-rate components are:

· Altitude

· Ambient temperature

· Dust

· Humidity

· Power Factor

Each diesel generator will have their own de-rate characteristics to every product, hence their technical information must be known. If more than one de-rate applies the multipliers become cumulative.

When de-rates employ the continuous rating of the generator is reduced by the multiplier.


When a motor begins its first kVA (begin kVA) is bigger than its run kVA. This happens because of initial inrush current required to start the motor. The skVA can be many times the rkVA causing an initial bigger load demand and consequent voltage dip in the terminals.

Generally speaking, a voltage dip greater than 25% may cause the generator to stall/shutdown, hence becoming an important element to take into account. Generators have specific starting voltage characteristics that have to be considered.

Various starting methods are used in software to decrease the skVA.Each will have their own performance characteristics and will provide their beginning impact. Technical information can be obtained from the producers.

Motors which come online at different phases, calculations are based on the greatest possible demand scenario. When There’s More than 1 motor starting concurrently the complete skVA is the amount of all the motors skVA


Non-linear loads (NLL) are described as electric gear that draws nonsinusoidal current from the supply source (diesel generator) causing harmonics in the current waveform, which then causes distortion in the voltage waveform. Current distortion (ID) is a function of the amount pulses. The level of distortion can lead to instability in the heap’s control generators and system excitation system.

For a diesel generator to have the ability to limit the voltage distortion (VD) that the alternator has to have a sub-transient reactance (X”d) in a degree (lower the better) that allows for this.

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