To determine how much power your generator set needs, you must know not only the nominal power of the equipment that will operate at the same time, but also the peak power consumption, especially at start-up. For example, an electric motor can consume up to three times its nominal power at start-up. The generator set must be able to provide the peak power consumed by all the equipment that needs to start at the same time. For resistive equipment (lighting, television, small electrical appliances, etc.), a safety factor of 30% must be added when determining the power of the generator set. For inductive equipment (i.e. electric motors), their nominal power must be multiplied by 3 to take into account peak consumption.
For generator sets that deliver a three-phase power supply, the power is indicated in kilo-volt-amperes (kVA): this is referred to as the apparent power. For the ones that supply direct current or single-phase power, the power is indicated in kW: this is referred to as active power.
The difference between kVA and kW comes from the phase shift between each phase. This phase shift is called cos φ (cosine phi). To obtain the active power of a generator set whose apparent power and cos φ you know, multiply these two values, for example: 1 kVA x 0.8 = 800 W (as a general rule, the cos φ of generator sets is 0.8).
Generally, generator set manufacturers indicate the continuous power and the maximum power that corresponds with an overload of about 20% of the continuous power for a limited time.
I was never aware that there are many different options to outdoor generators for us to choose from and one of the best ways to choose which is the best is by knowing how much horsepower we need. My wife is planning to install a patio in the garden with fairy lights and she needs an outdoor generator to operate it. I will bring her to a local shop and speak with an experienced professional to identify which generator suits her best.
The other day while my family and I were out having dinner, I overheard the restaurant manager looking for a commercial generator to have installed for the restaurant in case of a power disrupt. I appreciate that this post pointed out it is important to confirm how much power the generator needs before purchasing it as it impacts the generator’s efficiency. If I happen to walk past the restaurant later this week, I will relay this information to the manager.
I like how you mentioned that it is important to consider the power that a generator can give. My uncle mentioned to me last night that he is planning to have a generator installed in their home for emergency electricity supply and asked if I have any idea what is the best option to do. Thanks to this informative article and I’ll be sure to tell him that they can consult a well-known generator installation service as they can answer all their inquiries and will provide good-quality service.