Comparison Hitachi E42MC vs Hitachi E40

The rated power of the generator is the highest power supply that the unit is capable of delivering without problems for an unlimited time. In the “weakest” models this figure is less than 1 kW, in the most powerful – 50 – 100 kW or even more ; and generators with welding capabilities (see below) typically have power ratings ranging from 1 – 2 kW to 8 – 10 kW.

The main rule of choice in this case is this: the rated power must not be lower than the total power consumption of the entire connected load. Otherwise, the generator simply will not be able to produce a sufficient amount of energy, or it will work with overloads. However, to determine the minimum required generator power, it is not enough to simply add up the number of watts indicated in the characteristics of each connected device - the calculation method is somewhat more complicated. Firstly, you need to take into account that only the active power of various equipment is usually indicated in watts; In addition, many AC electrical appliances consume reactive power (the "waste" power consumed by coils and capacitors when operating at that power). And the actual load on the generator depends precisely on the total power (active plus reactive), indicated in volt-amperes. There are special coefficients and formulas for its calculation.

...The second nuance is related to the power supply of devices in which the starting power (and, accordingly, the power consumption at the moment of switching on) is significantly higher than the rated one - these are mainly devices with electric motors such as vacuum cleaners, refrigerators, air conditioners, power tools, etc. You can determine the starting power by multiplying the standard power by the so-called starting coefficient. For one type of equipment it is more or less the same - for example, 1.2 - 1.3 for most power tools, 2 for a microwave, 3.5 for an air conditioner, etc.; More detailed data is available in special sources. Starting characteristics of the load are necessary, first of all, to assess the required maximum power of the generator (see below) - however, this power is not always given in the characteristics; often the manufacturer indicates only the rated power of the unit. In such cases, when calculating for equipment with a starting coefficient of more than 1, it is worth using the starting power, and not the rated power.

Also note that if there are several outlets, the specific division of the total power among them may be different. This point should be clarified separately - in particular, for specific types of sockets (for more details, see “230 V sockets”, “400 V sockets”).

The maximum power supply that the generator can provide.

This power is slightly higher than the rated power (see above), but the maximum performance mode can only be maintained for a very short time - otherwise overload occurs. Therefore, the practical meaning of this characteristic is mainly to describe the efficiency of the generator when operating with increased starting currents.

Let us remind you that some types of electrical appliances at the moment of startup consume many times more power (and, accordingly, power) than in normal mode; this is typical mainly for devices with electric motors, such as power tools, refrigerators, etc. However, increased power for such equipment is needed only for a short time; normal operation is restored in just a few seconds. And you can evaluate the starting characteristics by multiplying the rated power by the so-called starting coefficient. For one type of equipment it is more or less the same (1.2 - 1.3 for most power tools, 2 for a microwave, 3.5 for an air conditioner, etc.); More detailed data is available in special sources.

Ideally, the maximum power of the generator should be no lower than the total peak power of the connected load - that is, the starting power of equipment with a starting factor above 1 plus the rated power of all other equipment. This will minimize the likelihood of overloads.

Model name of the engine installed in the generator. Knowing this name, you can, if necessary, find detailed data on the engine and clarify how it meets your requirements. In addition, model data may be needed for some specific tasks, including maintenance and repair.

Note that modern generators are often equipped with branded engines from famous manufacturers: Honda, John Deere, Mitsubishi, Volvo, etc. Such engines are more expensive than similar units from little-known brands, but this is offset by higher quality and/or solid warranty conditions , and in many cases, the ease of finding spare parts and additional documentation (such as manuals for special maintenance and minor repairs).

Fuel consumption of a gasoline or diesel generator, and for combined models — when using gasoline (see "Fuel").

A more powerful engine inevitably means more fuel consumption; however, models with the same engine power may differ in this indicator. In such cases, it is worth considering that a model with a lower flow rate usually costs more, but this difference can quickly pay off, especially with regular use. In addition, knowing the fuel consumption and tank volume, you can determine how long one refueling will last; at the same time, in inverter models at partial load, the actual operating time may be noticeably higher than the theoretical one, see "Alternator" for details.

The volume of the fuel tank installed in the generator.

Knowing the fuel consumption (see above) and the capacity of the tank, you can calculate the operating time on one gas station (if it is not indicated in the specifications). However, a more capacious tank is also more bulky. Therefore, manufacturers choose tanks based on the general level and "voracity" of the generator — in order to provide an acceptable operating time without a significant increase in size and weight. So in general, this parameter is more of a reference than practically significant.

As for the numbers, in low-power models, tanks are installed for 5 – 10 liters, or even less ; in heavy professional equipment, this figure can exceed 50 liters.

The time during which the generator is guaranteed to operate without interruption.

This parameter is indicated exclusively for liquid fuel models with a built-in tank, and according to the simplest formula: tank capacity divided by fuel consumption. However, in some models, data may be provided for a certain load level (which is specified in the notes); at a higher or lower load, the operating time will be shorter or longer, respectively. As for specific numbers, in most modern generators the operating time is up to 8 hours - this is quite enough for backup power and occasional use. More reputable models are capable of working for 8 – 12 hours, and an indicator of 13 hours and above is typical mainly for professional solutions.

We also note that, theoretically, many generators can be refueled without shutting down, but in practice it is better to take breaks and not exceed the stated time of continuous operation - this will avoid overheating and increased wear.

The level of protection provided by the generator housing — namely, the degree of protection of the “hardware” from dust, moisture and foreign objects. It is designated by the IP standard with two numbers, one of which corresponds to protection against solid objects and dust, the second — from moisture, for example, IP24.

According to the level of dust protection (first digit) in modern generators, the following values \u200b\u200bare found:

2 — protection against objects with a diameter of more than 12.5 mm (fingers, etc.);
3 — from objects larger than 2.5 mm (most instruments);
4 — from objects more than 1 mm (almost all tools, most wires);
5 — dustproof (full protection against contact; dust can penetrate inside, but does not affect the operation of the device).

Water protection levels can be as follows:

1 — protection against vertically falling drops of water;
2 — from water drops with a deviation of up to 15 ° from the vertical axis of the device (rain);
3 — from water drops with a deviation of up to 60 ° from the vertical axis of the device (rain with wind);
4 — against splashes from any direction (rain with strong wind);


In general, for indoor use, this indicator does not play a key role, but on the street and in similar conditions (for example, at a construction site), you should make sure that the selected generator is sufficiently protected — or else take additional protection measures.

The noise level produced by the generator during normal operation. The less noise the unit makes, the more comfortable it is to use, the closer it can be placed to people, but the higher its price, all other things being equal.

It is also worth considering that generators with internal combustion engines are, in principle, quite noisy equipment. So, even the “quiest” units produce up to 70 dB - this is the volume of conversation in tones from medium to high. Accordingly, it is recommended to install the device remotely from the place of use. At the same time, we note that the noise level is not directly related to power: for example, among units with 80 dB or more, there are both heavy and relatively low-power models.

The total weight of the unit - as a rule, excluding fuel; The full fill weight can be easily determined by knowing the tank capacity.

In general, more powerful generators inevitably turn out to be heavier, but models with similar characteristics can differ noticeably in weight. When assessing these differences and generally choosing an option based on weight, it is worth taking into account the specific application of the generator. So, if the device will often be moved from place to place - for example, when used “on the road” - it may be worth paying attention to lighter units that are more convenient to transport. However, it is worth considering that the downside of a lightweight design is often an increased cost or a reduced degree of protection. But for stationary use, you can not pay much attention to this parameter - or even the opposite: choose a heavier (and, as a rule, more advanced and functional) option.

Regarding specific numbers, it is worth noting that modern generators in general are quite massive. So, a small weight for such equipment is considered not only up to 20 kg, but even 20 – 30 kg ; Many units weigh 150–200 kg, or even more, and the weight of stationary industrial models is already measured in tons.