The use of an electric generator in a home, office or small industry is a great advantage, especially in those moments when the standard electrical power supply is not available.
Electric generators come in different models and designs, which can complicate the job of selecting the most appropriate one, if the criteria and aspects that must be taken into account are not known, in addition to clearly knowing their correct operation.
The Electric generators They are classified by the ISO, as of:
- Emergency Auxiliary Power
- Auxiliary Power
- Main Power
- Continuous power
The Electric generators for homes, industries or small businesses are the Electric generators emergency auxiliary power, also known as Electric generators for emergency or in Stand By mode. These are the generators They are used for very short use, with a maximum use time of 50-200 hours. They can be fueled by gasoline and handle low or medium loads, that is, they do not require feeding many equipment.
Aspects to consider for the proper selection of an electric generator for home, office or small business
When selecting a Electric generatorWhether for use in a home, office, or small industry, there are several things to consider when choosing the right equipment.
The Electric generators with low or medium loads, they can run on diesel, gas or gasoline. Diesel is more economical, and is ideal if a generator of continuous use, for several days or months. It should be noted that diesel generates smoke and noise.
The generators that run on gasoline, are ideal for periods of work of 4 to 6 hours.
For their part, Electric generators that run on gas do not generate noise, and are safe. If they are fixed generators they can be connected to the gas network, if they are portable they can work with a cylinder.
Fixed or Portable
The Electric generators Fixed are the right choice, if continuous service is required. They can also be used in Stand By mode, during sporadic power outages, to power a considerable number of appliances.
These generators They have a very large electrical load and a transfer switch, to feed the electrical network of the place. Without the presence of this device, the Electric generator directly to the home or office.
For their part, portable generators they are for small loads, between approximately 1000 – 3500 W. They are perfect to be transported by hand, or with the use of wheels. This type of generators are the indicated selection, if it is required to use them in different places.
2 or 4 times
The Electric generators 2 strokes produce much more noise, but consume less fuel, are cheaper and provide greater autonomy.
The generators 4-stroke are quieter and more expensive. However, they have a longer service life.
Inverter or AVR technology
This is a very important aspect to consider, since this technology allows a Electric generator behave stably and avoid fluctuations in electrical voltage, which could cause damage to electrical appliances.
This is the main aspect to take into account. Power is calculated by adding the power of all appliances that will use the energy provided by the Electric generator.
To carry out this calculation, a differentiation must be made between the two types of existing power:
- Power based on resistance: this is the power required by standard devices such as bulbs or spotlights, heaters, toasters, irons, among others, for its operation and is the one that is indicated on each device.
- Inductive power: this is the power required by appliances with rotary motors, such as refrigerators or refrigerators, washing machines, pumps, etc., for the moment of start-up. In some cases the necessary power is up to 4 times the nominal power of use. So the calculation of this power must be different.
Depending on the type of starting of the device, the inductive power varies:
- Direct Start (DOL): the nominal power is multiplied 6 times.
- Star Delta (ET) start: the nominal power is multiplied 3 times.
- Soft Starter or Variable Frequency Drive (VF): the nominal power is multiplied 2.5 times.
We will use a simple example to explain in detail, the calculation of the power that needs to be covered with the Electric generator.
Example: suppose that we need to provide the power to allow the operation of the following devices:
5 Lamps each 75W = 375 W
1 Refrigerator = 575 W x 3 (due to inductive power) = 1725 W
1 Water pump (1HP) = 745 wx 3 (due to inductive power) = 2235 w
1 TV = 65 W
The sum of the power required by the appliances is 4400 W.
This value is divided by 1000 to obtain the result in Kw: 4400/1000 = 4.40 Kw.
To obtain the required KVA, divide the Kw by the cosine of Phi: 4.40 / 0.8 (Cosine Phi (F)) = 5.5 KVA
Once the final value has been obtained, it is advisable to increase it by 20% as a safety margin and for other applications: 5.5 + 20% = 6.6 KVA
In conclusion, an electric generator covering 6.6 KVA would be required, which would be covered by the 7.5 KVA models available in the market.
The following tables indicate the power values (based on resistance and inductive) calculated for some devices.
Below are the values of both powers, according to the HP of each device.
Tips for the correct use of an electric generator at home, office or small business
- Be sure to read and follow the manufacturer’s instructions
- The Electric generators They are internal combustion engines, so they emit exhaust gases. That is why places with good ventilation, dry and dust-free must be installed.
- A minimum margin of 20% must be left over the required power calculated for the generator. This will prevent the generator from working at 100% capacity.
- Store fuel in a safe place.
- Do not touch the Electric generator while in operation, this may cause a burn.
- A ground connection must be installed at the Electric generatorwhenever possible.
Taking into account the aspects described in this article, you can select the Electric generator suitable to your needs.