{"id":32322,"date":"2019-10-15T09:55:39","date_gmt":"2019-10-15T07:55:39","guid":{"rendered":"https:\/\/nueva.genesalenergy.com\/la-importancia-del-perfil-de-carga-y-consumo-de-un-grupo-electrogeno\/"},"modified":"2025-10-20T13:27:40","modified_gmt":"2025-10-20T11:27:40","slug":"load-profiles-generators","status":"publish","type":"post","link":"https:\/\/genesalenergy.com\/en\/communication\/articles\/load-profiles-generators\/","title":{"rendered":"Generator load profile and step load explained"},"content":{"rendered":"

\"Technical<\/h2>\n

Knowing the type of loads a generator must power is essential to calculate its required power correctly.<\/h2>\n

The load profile and the step load \u2014the initial load applied at start-up\u2014 are key factors in generator sizing. Power demand is not static; it fluctuates depending on the equipment and conditions, and ignoring these variations can lead to overloads, inefficiencies, or equipment failure.<\/p>\n

The power that a generator set manages isn\u2019t an absolute and static value. Its level tends to fluctuate according to certain factors and processes, and it does so differently in each type of unit.<\/p>\n

For this reason, calculating the power a generator set needs to function is not a simple operation. Different variables must be taken into account which, if not considered, can cause serious issues in our installation.<\/p>\n

For instance, an overload in any of the phases can cause overheating and voltage imbalances. This can cause damage both in the generator set and the equipment connected to it.<\/p>\n

Start-up: the first step load<\/b><\/h2>\n

The generator set is going to be limited during its start-up by what is called the <\/span>first step load<\/span><\/i>, that is: the total transient load that the genset is initially capable of enduring until reaching its stable regime with some transient variations in voltage and frequency.<\/span><\/p>\n

This is why it\u2019s important to verify the characteristics in the nameplates of the equipment connected to the generator set, and to be aware of the <\/span>possible transient effects which they may suffer during its start-up processes<\/b>.\u00a0<\/span><\/p>\n

Certain equipment such as pumps or motors with variable drives, for instance, may increase their current temporarily during commissioning.\u00a0<\/span><\/p>\n

Likewise, elements such as UPS\u2019s (uninterruptable power supplies) can cause harmonic distortions which must be contemplated in our calculations.<\/span><\/p>\n

Which parameters affect the dimensioning of loads?\u00a0<\/b><\/h2>\n
    \n
  1. The first parameter to contemplate is the <\/span>type of load<\/b>. As we\u2019ve pointed out, some units experience transient increases in current during start-up. With this in mind, we\u2019ll pay special attention to the following loads:<\/span><\/li>\n<\/ol>\n
      \n
    • Uninterruptable power supplies (UPS). The alternator\u2019s rated power is oversized depending on the installation.\u00a0\u00a0<\/span><\/li>\n
    • Big motor loads. They can increase starting power to up to 6 times the power, depending on the type of start-up.\u00a0\u00a0<\/span><\/li>\n
    • Lighting loads (with special attention to sodium vapour lighting and metal halides).\u00a0<\/span><\/li>\n
    • Systems with Variable Frequency Drives (VFD). These can cause an oversizing from 40 to 100%.\u00a0<\/span><\/li>\n
    • Other loads which are especially sensitive to transients and voltage and frequency variations.\u00a0<\/span><\/li>\n<\/ul>\n
        \n
      1. Another factor we must keep in mind is the <\/span>type of start-up of the motor<\/b> in question. This is due to the fact that each type of starter requires a specific starting current, which must be higher than the unit\u2019s rated current. Thus, we find that:<\/span><\/li>\n<\/ol>\n
          \n
        • Electric motors with star-delta starting: <\/b>its \u201cstarting current\u201d will be equal to three times the rated or operating current.<\/span>\u00a0<\/b><\/li>\n
        • Direct starting motors:<\/b> demand 6 times nominal current.\u00a0<\/span><\/li>\n
        • Starter motors with variable frequency drives:<\/b> special attention must be payed to its technical sheet as normally the ramp and increase in speed is configurable.\u00a0<\/span><\/li>\n<\/ul>\n

          Other important aspects to consider for genset load calculation<\/b><\/h2>\n

          To finish carrying out this entire calculation of power with maximum precision, other variables must be kept in mind such as:\u00a0<\/span><\/p>\n

            \n
          • Power factor during start-up.<\/span><\/li>\n
          • Starter power.<\/span><\/li>\n
          • Rated power factor.<\/span><\/li>\n
          • Rated power<\/span><\/li>\n
          • Efficiency<\/span><\/li>\n
          • Number of start-ups<\/span><\/li>\n<\/ul>\n

            Ultimately, we must be extremely rigorous in this calculation. To avoid any surprises, it\u2019s vital to know the type of load we\u2019re dealing with as well as its behaviour. All, with the <\/span>objective of the generator set always powering a balanced load, without generating unexpected peaks<\/b>.<\/span><\/p>\n

             <\/p>\n\n