What do Generator Ratings Mean for You?

CONTINUOUS VS.
PRIMARY VS. STANDBY

What do Generator Ratings Mean for You?

When considering generators, your application is absolutely critical to making the best choice. But not every application calls for the same use rating. In addition to knowing how much power you’ll need (KW Rating), how the load you are powering changes over time and the duration of run time per use are critical considerations. Selecting the wrong type of generator can put you over budget or, even worse, cause your generator to fail (mechanically) when you need it the most. This is summed up in three unique categories:

  • Continuous – Constant power under a constant load
  • Primary – Constant power under a variable load
  • Standby – Temporary power until residential/commercial power can be restored


Generators that are rated for continuous use are designed to supply constant power to a load that is nearly constant. For example, a 400 KW continuous use generator is designed to run continuously to power a 400 KW load. Simple enough right? It’s not as simple as you might think. Many loads are variable, with motors kicking on and off creating a momentary spike in power consumption know as Locked Rotor Amps (LRA). These changes in amp draw may cause power demand to fluctuate from (hypothetically) 150 KW to 380 KW over the course of a day. In an application like this, a Primary generator would be the preferred rating. But what if your load requires between 380 KW and 400 KW all day everyday? That application would be best suited for a generator’s continuous power. Finally, if your load runs for weeks and months at a time on commercial or residential power and is only needed when the power goes out, a back up generator is likely your best option.

Still not sure what the perfect generator for your application looks like?

Call us at 517.706.6464 and one of our skilled product support technicians will give you a free, no obligation quote on the right generator for your home or business.