How to dimension a power generator? Check it out here

It is impossible to describe the feeling that we are surprised by a sudden lack of electricity in the middle of work or household chores. Have you ever imagined what your life would be like if you no longer depended on these eventualities? Is it possible? For this, a specialist is always recommended, who will check your real demand, the cabling and the security of the installation and the system. We just want to make you more familiar with the subject, and prepared to give the right answers, which will assist in a better dimensioning.

How to choose a power generator?

The market has the most varied brands and capacities of generators, which vary due to the voltage generated (110v, 220v, 380v), type of phase (three-phase/single-phase), maximum and nominal powers, type of start (electric/manual), powered by diesel or gasoline, portable or fixed , etc.

You will have to carefully analyze the type of generator you will buy, so that you are sure that it will serve you in the best possible way. For example, diesel generators are ideal for higher power, generally more robust and require less maintenance. On the other hand, Westinghouse iGen4500 inverter generator (gasoline generator) is easier to operate, lighter and ideal for smaller power outputs.

Important data

Good sizing is essential for the proper functioning of the energy generator. If undersized, it can cause excessive smoke and excessive consumption of lubricating oil, while if oversized it causes overheating and constant shutdowns. The ideal working range is between 30% and 70% of its nominal capacity. It is very important that you have the following data in hand at the time of purchase so that you make the most of the equipment’s characteristics –

  • What are the types of load prevalent in the location (induction motors, lighting, etc.),
  • Physical characteristics of the location (internal or external area, high temperature, etc.),
  • What is the usage regime (emergency or frequent use, how many hours a day).

In addition to these, to calculate the dimensioning, you will have to check the plates of the equipment that will be connected by the generator. The data on the operating and peak power of these devices is very important, as well as the electric current and operating voltage. On the nameplate, we get the power information in W (Watt).

If it is a resistive equipment (lamps, shower, heaters, television), this is the value you will use. If it is inductive equipment, which has a motor, you will have to multiply this value four times. This is due to the peak energy that these devices need when starting.

Calculation for dimensioning the power generator

For consideration in the calculation, the power values ​​in W will be used, which can be verified on the equipment plates. For resistive equipment, the peak and nominal values ​​are the same. For equipment with inductive characteristics, we will simplify the peak load to 4 times the nominal load. For a clearer understanding, here’s an example, home emergency generator –

  • 1 Electric heater x 2,000W = 2,000W normal use
  • 6 Fluorescent lamps 60 W = 360W normal use
  • 1 Computer = 300W normal use
  • 1 Refrigerator = 300W normal use
  • 1 computer store = 800W
  • 1 Motor 1CV = 750W normal use/3000W peak use
  • Total = 4,510 W/6,760 at peak


Another important point is which equipment to use for the calculation. If the user is looking for an emergency generator, it would be interesting not to consider equipment such as air conditioning, shower, electric heaters, which have a very high power. Another very important data to take into account at the time of purchase is the autonomy of work. Autonomy is related to the capacity of the reservoir and the time in which it is able to work with this reserve.