How to choose a backup power generator
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1. Rated power and output voltage
When choosing the right generator, you need to be guided by several important aspects. The very first stage before purchasing is calculating the total power of all electrical appliances planned for simultaneous connection. At the same time, it is worth distributing them according to the scale of importance - it is advisable to organize the operation of a refrigerator, hob or gas boiler in the off-season without fail, while you can do without the services of an iron, blender, vacuum cleaner or washing machine for a short time.
The total power of consumers is added up according to the passports of electrical appliances or the power table. Generator manufacturers usually specify two types of power: rated and maximum. Long-term operation of the generator is possible at a load of 30–70% of the rated power. Maximum performance mode can only be maintained for a short period of time, otherwise overload will occur. The practical meaning of this characteristic is to describe the efficiency of the generator when operating with increased starting currents. In some cases, such currents can exceed power consumption by 3 to 7 times. For example, in standard operating mode, a standard non-inverter air conditioner consumes 1 kW, while its starting power is 3.5 kW. Specific electrical equipment has even higher starting currents - a kilowatt well pump can consume up to 5 kW of power in starting mode.
| Power tools | Appliances | ||
|---|---|---|---|
| Consumer | Power, W | Consumer | Power, W |
| Jigsaw | 250-700 | Electric lamps | 5-50 |
| Electric sharpener | 300-1100 | TV | 100-400 |
| Drill | 400-800 | Fridge | 150-600 |
| Electric planer | 400-1000 | Computer | 400-750 |
| Hammer | 600-1400 | Vacuum cleaner | 1000-2000 |
| Grinder | 650-2200 | Hair dryer | 450-2000 |
| Circular Saw | 750-1600 | Iron | 1000-2000 |
| High pressure pump | 2000-2900 | Toaster | 500-1000 |
| Electrical appliances | Coffee maker | 800-1500 | |
| Consumer | Power, W | Oven | 2000-3500 |
| Water pump | 500-900 | Electric kettle | 2000 |
| Electric motors | 550-3000 | Heater | 1000-2000 |
| Fan heater | 750-1700 | Electric stove | 1100-6000 |
| Compressor | 750-2800 | Boiler | 1500-2000 |
| Air conditioner | 1000-3000 | Microwave | 700-1000 |
| A circular saw | 18000-2100 | Washing machine | 1000-2500 |
For normal operation of the generator without overload, it is necessary to take into account the power “in reserve”. To do this, add about 20% more to the resulting amount of power. The reserve will protect against equipment breakdowns, will have a positive effect on fuel consumption and will be life-saving in cases where it is necessary to adjust the operation of additional electrical appliances.
Based on power classes, generators can be divided into several groups:
- up to 3 kW - household generators for a summer house or a small private house; this power is enough to operate lighting, a refrigerator and a small list of vital electrical appliances;
- 3 - 5 kW - the same household generators, providing more comfortable conditions for staying in the house during power outages; will be able to organize the operation of one or two burners of an electric stove, TV and computer;
- 5 - 7 kW - powerful generators for a large house with a boiler, air conditioning, etc.; allow you to quietly survive blackouts and periodically turn on other electrical appliances like a vacuum cleaner; units of this power are also suitable for small offices and small shops;
- from 7 kW and more - this league includes professional-class power plants used in industry, production and during repair and construction work.
If the electrical system of the house is designed for standard 230 V power supply, it is easier to buy a single-phase generator model. Three-phase models with an output voltage of 400 V are designed to ensure the operation of the corresponding equipment. It is important to take into account the number of outlets on board the power plant. In general, “How to connect a generator to the house: through a socket, a switch and an ATS unit” is described in detail in the corresponding article.
In the most popular segment of generators (5 - 6 kW), one 16 A outlet is often installed, or two. Extracting maximum power from one outlet can be problematic. It is optimal to have 2 - 3 outlets at the output. High-power models often have a 7.5 kW and 32 A power outlet, but it is often incompatible with household appliances.
2. Engine and alternator type
For the most part, the range of generators includes not very well-known brands. And equipment from the “sharks of the industry” will cost exorbitant prices. The optimal price/quality ratio are generators with branded engines from venerable manufacturers (Honda, John Deere, Mitsubishi, etc.). A power plant from a little-known brand with a top-end engine is the best choice today.
In generators, the alternator is directly responsible for generating electricity, converting mechanical energy into electrical energy. There are the following common types of alternators:
- Synchronous - the rotation of the movable rotor in their design coincides with the rotation of the magnetic field of the stator (fixed part). Generators with such an alternator cope well not only with active, but also with reactive loads - for a short period of time they are capable of delivering a power that is several times higher than the rated one. This ensures the required starting power for the reactive load (refrigerator or air conditioner compressor, well pump motor, etc.). In addition, the design of models with a synchronous alternator necessarily has an auto-voltage regulator, which smoothes out differences in “voltage” when connecting energy-hungry consumers (for example, an electric kettle). The only thing is that alternators of this type are sensitive to short circuits and long-term overloads.
- Inverter ones are essentially the same synchronous alternators, but with the introduction of an additional electronic unit (inverter) into the circuit, which provides double power conversion: from alternating to direct and then again to alternating. Models with an inverter alternator produce a stable output voltage, are able to regulate engine operation depending on the connected load, and in general they are more compact, quieter and less wasteful in terms of fuel consumption. The vast majority of inverter generators have relatively low power (up to 3 - 4 kW).
At the same time, there is a small caste of models with an asynchronous alternator, where the rotor, when rotating, is somewhat ahead of the movement of the magnetic field. They are not widely used because they do not tolerate reactive loads well, and the voltage and frequency of the output power in such generators directly depend on engine speed.
Regardless of the type, an attribute of advanced generator models is the copper alternator winding. The winding made of copper conductors heats up less and withstands temperature changes and vibration loads. However, such pleasure will not come cheap.
3. Gasoline generators
Gasoline generators are the most widely used. They have proven themselves to be excellent backup or emergency power sources. The advantages of gas generators are obvious. In particular, these are the low cost of starting capital investments, relatively low noise levels, small dimensions and weight, and high mobility. In addition, at sub-zero air temperatures, gasoline-powered generators are easier to start.
Disadvantages of gasoline power plants: high fuel consumption, which negatively affects the cost of electricity produced, short service life, inability to work for a long time without a “smoke break.” For every 5 - 8 hours of electricity generation, they need to allocate at least an hour of rest. And at 100 percent load, the time of continuous operation can be significantly reduced - up to half an hour.
Standing apart from the line of gas generators are the on top-mentioned inverter models, which are ideal for powering highly sensitive electronic equipment. Such equipment produces “pure” voltage without drops and surges; consumers can be safely connected to it directly - using a voltage stabilizer. And thanks to their compact dimensions and light weight, “inverter engines” are suitable for use during travel and forays into nature.
when relaxing in nature, away from electrical civilization.
To perform welding work, specialized welding generators with the ability to connect electrodes directly to a power plant are displayed on store shelves.
4. Answers to frequently asked questions about gas generators
How to start a gasoline generator correctly?
Gasoline generators with a mechanical starting system for the power unit are started by the starter starting cord. It is necessary to pull it towards you until pronounced resistance appears, then sharply pull the handle in one movement to the end and smoothly release it. If the engine does not start the first time, the procedure must be repeated.
A gasoline generator with an electric starter is started using a special button on the control panel or by turning the key, like in a car. You will need to check in advance that the polarity on the battery is correct and that the terminals are securely seated.
Gasoline generators with automatic reserve switch on immediately after the electronic control unit on board receives a signal about the lack of power from the main power supply. When the light supply is restored, self-starting generators usually turn off on their own.
and automatically switch the load to the generator when there are interruptions in the light supply.
What is the fuel consumption of gasoline generators?
On average, gasoline generators consume about 350 ml of fuel per 1 kW of generated electricity for one hour. Consumption strongly depends on the load on the power plant - clogged filters and low-grade gasoline can lead to increased fuel consumption. It is extremely important to perform timely maintenance of generator components and change the oil on time. More on this below.
How to care for a gasoline generator?
The key to long and uninterrupted service of any gas generator is systematic maintenance. During maintenance, check the oil level, condition of filters and spark plugs. During the “break-in” period, these manipulations must be performed after approximately 20 operating hours. In the future, the generator will need to be serviced every 50–100 hours - specific terms for replacing consumables are regulated in the instructions for each device.
And a gasoline generator is like a car that needs to drive. And if electrical power rarely goes out, it is advisable to start the power plant at least once a quarter and let it run for 15 - 20 minutes so that it remains in good condition.
What kind of oil is poured into a gasoline generator?
Semi-synthetic oils 10W-30 and 10W-40 are optimal for gasoline generators. Changing the lubricant has a certain interval, which is specified for each generator in the data sheet. For proper operation of the power plant, it is important to periodically check the oil level, for which a special dipstick is introduced into the design of the power unit - the “minimum” and “maximum” lines are indicated on it. If the level is low, it is recommended to add oil before starting the engine.
5. Diesel generators
Diesel fuel generators are designed for long-term non-stop operation, often in non-stop mode. They are distinguished by economical consumption of diesel fuel, reliable and trouble-free operation. Another characteristic factor for diesel electric generators is resistance to high loads. Continuous operation of units on diesel fuel is possible for 10 hours or longer (some models can easily be “taken out” for more than a day). The specific duration of non-stop operation is usually prescribed in the accompanying technical documentation for the generator.
Pros and cons of diesel generators
Diesel generators consume on average 250 ml of fuel per 1 kW of electricity produced in 1 hour, i.e. a good third less than gasoline models. At the same time, they are characterized by durability and long service life. The disadvantages of diesel fuel generators include their high cost and sensitivity to low temperatures - in cold weather they will require special seasonal diesel fuel with antifreeze additives.
Mobile and stationary solutions
As a rule, heavy diesel generators are assembled on a chassis and are often placed on wheels for ease of transportation to the location. Professional models are installed permanently - they are usually used in production and construction as permanent sources of electricity. Such units cost several times more than gasoline ones, but they benefit from a much longer service life and fuel economy, which pays off in the long run.
Diesel Generator Maintenance
Compliance with the maintenance schedule for diesel generators guarantees their long service life and trouble-free operation. Checking components and replacing consumables in equipment of constantly operating power plants should be carried out approximately every 100 operating hours. For installations that operate in backup mode, scheduled maintenance is tied to a certain period of time, but is performed at least once a year. During rare power outages, it is advisable to start the diesel generator at least once a quarter so that it remains viable.
6. Gas generators and hybrids
Gas-powered generators are characterized by low fuel consumption, a small amount of harmful emissions and low noise levels. On the other hand, using gas as a fuel is associated with certain difficulties: it is necessary to connect the power plant to the gas main or regularly replace special cylinders, and the fuel system of gas generators is especially sensitive to leaks.
Purpose of gas generators
There are not many portable models for gas fuel, and most gas-powered generators are stationary high-power devices. Thus, industrial models of gas generators with liquid cooling can be used continuously for 100 hours or more, household models with classic air cooling - 5 - 8 hours (like their gasoline counterparts).
Mobile dual-fuel generators that run primarily on gas and gasoline are designed for domestic use. They can generate electricity using two types of fuel, and there is no need to turn off the generator when switching modes. Mixed units are quite economical and provide room for maneuver if one type of fuel runs out.
Pros and cons of gas generators
The main advantage of gas generators is the low cost of generating 1 kW/h of electricity compared to other options for autonomous power plants. In addition, gas units produce fewer harmful emissions into the atmosphere and are the quietest.
When installing and connecting a gas generator to a centralized gas main, it is advisable to contact specialists from the nearest regional gas supply office. Otherwise, you will have to constantly refill the cylinder with compressed gas, which is not always convenient or easy. The operation of cylinders is always associated with certain risks due to the possibility of gas leaks.
7. Additional functions and features
Hour meter
Additional attachments make the standby generator more convenient to use. For example, an hour meter that shows the “mileage” of the engine since it was first turned on will be useful. Based on the data from it, you can plan routine maintenance; this parameter will also be important when purchasing a used generator.
Built-in voltmeter
The power voltage at the output of the power plant is often shown by the built-in voltmeter. It helps control the operating mode and reduces the risk that the load will be subject to unacceptable voltage.
12V connectors
The 12V output from the generator provides DC power for charging car batteries. And you can charge portable gadgets from the USB port equipped with individual generator models.
Fuel level indicator and soundproofing casing
An important role in the arsenal of generators is played by the fuel level indicator and the sound insulation casing, which helps muffle the noise from the operation of the power plant.
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