New member

Re: standby rated gensets working as prime

It all depends on the Engine size and load factor small less than 250KWe, up to 90% of STBY load should have no issues, mid less than 750kWe up to 85% STBY load should have no issues.



Re: standby rated gensets working as prime

[ Edited ]



Below are a few examples of what might occur if a standby generator is used above its classified rating.  


- Engine overheating – Engines used in prime power generator applications typically require a larger cooling capacity to absorb and dissipate the excessive heat.


- Premature engine/component wear – Because of the additional cooling requirements of an engine used in a prime power generator application, excessive heat can and often does impact the life of the engine.


- Alternator winding overheating – Because the generator (alternator) is subject to temperature rise due to continuous flow of current through its windings, prime power generators are typically designed with heavy-duty windings as compared to standby rated generators.


- Depletion of oil viscosity - Shorter oil change intervals – Remember, the oil also acts as a coolant for the engine absorbing excessive heat. Excessive heating of the oil can deplete the properties of the oil causing a drop in oil pressure and possibly premature oil change intervals. Also, in some cases, engines used in standby rated applications may have a smaller capacity oil pan as compared to an engine used in a prime power application. 


Again, these are only a few examples. It’s always recommended you consult with your customer to ensure they understand the consequences of running any generator set above or below its classified rating.






standby rated gensets working as prime

[ Edited ]

As maintenance providers we have found some customers with standby rated gensets but the equipments are working as prime.


I would like to know what are the main issues about this kind of operation and the relation with the maintenance requirements.




Jose Saenz


well using standby set as prime the sets will be due for major replacement of parts earlier than estimated ,as standby rated sets can operate 200hours a year with 100% load in an emergency.