An electric generator is a technically complex technique that combines a fuel system with a fast-burning fuel, a mechanical part (internal combustion engine), and an electrical part (alternator /alternator, internal electrics). You can easily make a mistake when choosing a generator. We will help you not to get lost in the variety of selection.
1st mistake. Choose a three-phase 380V generator when there is no need
The most common mistake when choosing a generator is that many sales consultants do not know about. This error occurs because the power supply in houses is three-phase at 380V.
The rule is simple: three-phase generators with a capacity of up to 20 kW are produced exclusively for three-phase electric consumers, for example, industrial furnaces, machine tools, a 380V welding machine, a 380V compressor, and so on. If there are no 380V power consumers, it is not recommended to purchase a three-phase generator, since there will be an interfacial bias, which should not be more than 15%. This can lead to the following results:
- The generator will be constantly switched off, as the automatic protection (circuit breaker) of the generator set will be triggered;
- Overloading can overheat and jam the engine;
- The alternator (alternator) of the generator set may burn out;
- The wiring cables may overheat.
- What then if we buy a 220 V gasoline generator? And how to connect a single-phase generator to a three-phase network?
Connecting electricity generator is really simple
The decision to connect a single-phase generator to a three-phase network at home is not difficult. Mount a three-position switch and make jumpers connecting three phases into one in the position of the network operation from the generator. This method is intended if the generator will be started in manual mode.
If it starts automatically, then it is necessary to purchase a three-phase 380V AVR (automatic reserve input) and switch it with the existing VRSCH (internal switchboard of the house). This should already be done by specialists.
These methods are safe and protect against such negative cases as oncoming voltage and short circuits.
If there are 380 V electrical appliances and they are needed in redundancy, for example, a three-phase pumping station, then a three-phase generator should be selected. Then you need to distribute the loads as evenly as possible between the phases. This will require an assessment and calculations. It is also necessary to carry out the installation, installation, and connection correctly.
2nd mistake. Choose a generator based on incorrectly calculated power
A gasoline generator is a portable power plant, but not a hydroelectric power station. There are two aspects when choosing the right power.
It is impossible to choose a generator with an output power less than or equal to the total power of electrical appliances. Such a choice can lead to engine failure or alternator combustion, since the generator will be overloaded, despite the presence of a circuit breaker. A similar result is likely when electric consumers with an inrush current, for example, pumps, are turned on.
Many customers take 2 kW at home and believe that they can power the whole house, but they do not take into account those aspects that all consumers can turn on at the same time and the generator will not pull them out. As a result, the buyers themselves will have to control the inclusion of electrical appliances.
When choosing, we will help to calculate the power correctly to avoid mistake.
It is not necessary to greatly overestimate the power of the vital. Here are the nuances of choosing a gasoline generator. The buyer sometimes talks about his experience of choosing a model.
Customer calls the store: I need a 10 kW generator.
The seller asks: for what purposes?
Customer: for the reserve of the house. I’ve counted everything. I need exactly this power, so tell me the cost.
Seller: well, the minimum cost of a generator of this power is 2000 EUR.
Customer: and why is it so expensive?
Quick comment on this situation:
Models with 10 kW can cost more. When choosing, the buyer proceeded from the fact that the allowed power that enters the house is 15 kW and the buyer is sure that the reserve should be 10 kW. Now about the nuances: the difference in the cost of generators between 8 and 10 kW can be 80,000 rubles. The first variant has two–cylinder engines, and the second one has single–cylinder engines. Therefore, there is such a difference in cost. 6 kW is enough for many buyers.
The generator should be selected based on the total power of all electric consumers, taking into account the starting loads of each consumer, and increasing this figure by 20-25%. To reserve a house, this figure will often be within 6 kW. This is a universal power at which you can power all household electrical appliances and feel comfortable. The negative reaction to the starting currents of these generators will be minimal.
It is not recommended to calculate the power on their own.
Entrust this to specialists with extensive experience. Our consultations are free for you.
Mistake 3. Choose a generator with a built-in or factory autorun system
In this case, the buyer, as a rule, wants to put the generator on the street or indoors so that the generator starts automatically when the centralized power supply is turned off. Choosing such a generator is a 90% unjustified overpayment for autorun. Other consequences may also occur counter voltage and short circuits. Let’s explain a few reasons why this is so:
As a rule, the factory autorun system is designed for a single-phase 220V network. In the Ukraine, the network is mainly three-phase at 380V. Automation in this case is no longer suitable.
Such generators are made mainly at dubious Chinese factories and quickly fail, as contactors cannot withstand and burn from unstable centralized voltage.
For the generator to start smoothly from the autorun panel, its engine must be located in a warm place, otherwise, the unheated engine will stall when starting. Therefore, it must be placed in a heated room with a specialized installation for the correct operation of the generator (in particular, a forced air inflow and outflow system and a gas exhaust system), or it must be mounted in a specialized insulated container.
For an automatic start system, a specialized adaptation of the engine is required, for example, an automatic engine turnaround system, where special temperature sensors should be installed, as well as an automatic fuel valve should be installed for safety reasons, which will replace the manual fuel tap and other special improvements. In generators with a factory autorun system, such a system is usually not provided, therefore, such a generator will not work correctly and safely.
4th mistake. To choose an inverter generator for household needs
Most often, in the manufacturers’ service centers, it is the inverter gasoline generators that are under repair.
These are generators with an inverter board for double current conversion: from DC to AC. The electric current passes through the inverter rectifier, resulting in an almost perfect AC sine wave.
You can use such generators only where the load is always linear and uniform: lighting, electronics, kettle, and so on. For these reasons, as well as due to their low noise, compactness, mobility, and low weight, they are well suited for camping, hunting, fishing, and other outdoor activities where there is no centralized power supply.
However, these generators are not suitable for household needs, as they do not tolerate voltage surges, for example, from such electrical appliances as a refrigerator or a pump. The fact is that they have a fragile and unreliable electronic board, which fails very quickly during power surges.
Fifth mistake. Is not to choose a budget generator, but at the lowest cost
Let’s make a reservation right away that in our assortment there are decent budget solutions for many practical situations. But about everything in order.
Buyers often turn to the desire to buy an inexpensive gasoline generator, since electricity is not turned off often, so the electric generator will rarely turn on.
Let’s clarify the following: all gasoline generators serve only as a backup power source. A 6 kW generator from a well–known Japanese or European manufacturer for more than 130,000 or other models worth within 40,000 rubles. These are gasoline backup power generators, and they cannot work for a long time.
At the same time, a well-known Japanese or European brand with its design quality, guaranteed copper winding, high-quality metal, and ignition system will start up without problems and work “like clockwork”, then a generator from another manufacturer may be difficult to start when it has been idle for a long time and suddenly needed. There is also a high probability of its failure during operation, because the cheaper the equipment, the more savings on the quality of the material of all parts and assemblies. However, the main risk is ignition during operation, which can lead to a fire on its site, since one of the main “diseases” of cheap generators is a leak of the fuel tank and fuel tap.
The solution to the problems is the purchase of a generator from well-known Japanese or European manufacturers or decent, time-tested, low-cost gasoline generators with the best “price/quality” indicators. Such models are manufactured at world-famous industrial plants.
Mistake No. 6 To choose a portable diesel electric generator with an air-cooled engine for household needs
Disadvantages of a generator with an air-cooled diesel engine:
- It starts badly at low temperatures and it is very difficult to find solutions to eliminate this problem, unlike gasoline and gas carburetor generators, where there are ways to start the engine at the lowest temperatures;
- It cannot work for a long time at low load, the engine needs to be loaded by at least 25%, otherwise, it will lead to its coking and repair. This is the specificity of all diesel engines. In everyday life, it happens that the generator provides power, for example, only lighting, especially when the generator is installed with an automatic start. Therefore, you do not properly control the minimum load;
- The noise from the engine is very high, many times more than that of gasoline and gas generators;
- Heavy and not mobile;
- Since diesel is a seasonal fuel, it must be changed at least 2 times a year;
- The cost is more expensive than gasoline generators;
What to know more about diesel generator
Many buyers who want to choose a diesel generator for domestic use, contact us assuming that:
A diesel engine has a larger motor/resource than a gasoline engine. This is true, but keep in mind that it is not much more. In addition, it is not quite correct to count the moto/backup power supply resource, because it is usually considered when the generator is running for several hours every day.
It has lower fuel consumption. Yes, but again irrelevant. The generator will not pay off due to the difference in the price of fuel. Diesel fuel sometimes costs more than gasoline.
If you use backup diesel generators, then it is with a liquid (water) cooling engine in a casing with an engine heating system. This is a different level of equipment and, accordingly, the cost.
We emphasize that we are talking about the use of portable diesel generators with an air-cooled engine for household needs, for example, in a private house.
At the same time, these generators are more suitable for construction work than gasoline ones.
#7 Choose a gas-gasoline generator instead of a gas one
These generators are initially with gasoline engines on which a gas gearbox (“frog”) is mounted.
Here we will talk about security. Such generators are produced only by Chinese factories with cheap components, and their gas gearbox is of dubious quality. Also, often, there is a conventional fuel tap, instead of a safe fuel valve. With such a system, a gas leak may occur.
Many mistakenly believe that this generator can be connected to a centralized gas pipeline. This is a misconception because due to low gas pressure, the gearbox can not cope and the system does not work.
If it is a gas generator that is needed, it should work exclusively on gas. There are not so many manufacturers, but there are decent ones among them. Such generators can operate from both liquefied gas (propane/butane) and centralized mainline (methane). They cost more. Our engineers will help you with the optimal choice.
Mistake #8 to choose gasoline generators with a two-stroke engine
For an alternating voltage of 220 or 380 V with a frequency of 50 Hz to be produced at the output of the alternator/alternator, the engine must unwind the generator armature at constant speeds, usually 3000 or 1500 rpm and if a four–stroke engine copes with this task properly, then a two-stroke engine is very bad, because it is very difficult to adjust constant revolutions due to jumps at two cycles. Therefore, for these generators, the voltmeter needle jumps a lot, which means that it is dangerous to connect most electric consumers to such a generator since they can burn out or fail. In addition, these generators can produce no more than 650 watts.
So apart from lighting, you will not connect anything else to it.
We hope that now you know really well how to avoid mistake choosing the electric generator. If you would like to know more, check out more interesting articles in our blog