Comparison PowerWalker VFI 5000 EVS 5000 VA vs Must EH55-C6KS 6000 VA

In this case, the input voltage range is implied, in which the UPS is able to supply a stable voltage to the load only due to its own regulators, without switching to the battery. For redundant UPSs (see "Type") this range is quite small, approximately 190 to 260 V; for interactive and especially inverter ones, it is much wider. Some UPS models allow you to manually set the input voltage range.

The maximum current drawn by the UPS. In fact, the current reaches its maximum value only when the UPS is operating from the mains with maximum load power and a completely discharged battery. However, when calculating the load on the power grid, this parameter should be taken into account.

The maximum output power supplied by the UPS, in other words, the highest apparent load power allowed for this model.

This indicator is measured in volt-amperes (the general meaning of this unit is the same as that of the watt, and different names are used to separate different types of power). The total power consumption of the load, implied in this case, is the sum of two powers — active and reactive. Active power is actually effective power (it is indicated in watts in the characteristics of electrical appliances). Reactive power is the power wasted by coils and capacitors in AC devices; with numerous coils and/or capacitors, this power can be a fairly significant part of the total energy consumption. Note that for simple tasks, you can use data on effective power (it is often given for UPS — see below); but for accurate electrical calculations it is worth using the full one.

The simplest selection rule for this indicator is: the maximum output power of the UPS in volt-amperes should be at least 1.7 times higher than the total load power in watts. There are also more detailed calculation formulas that take into account the characteristics of different types of load; they can be found in special sources. As for specific values, the most modest modern UPSs give out 700 – 1000 VA, or even less — this is enough to power a PC of average performance; and in the most "heavyweight" models, th...is figure can be 8 – 10 kVA and higher.

The effective output power of the UPS is, in fact, the maximum active power of the load that can be connected to the device.

Active power is consumed directly for the operation of the device; it is expressed in watts. In addition to it, most AC devices also consume reactive power, which is "wasted" (relatively speaking) is spent by coils and capacitors. Apparent power (denoted in volt-amperes) is precisely the sum of active and reactive power; it is this characteristic that should be used in accurate electrical calculations. See "Maximum output power" for details; here we note that when selecting a UPS for a relatively simple application, it is quite possible to use only effective power. This is at least easier than converting the watts claimed in the characteristics of the connected devices into full power volt-amps.

The most modest modern "uninterruptibles" give out less than 500 watts. 501 – 1000 W can be considered an average value, 1.1 – 2 kW is above average, and in the most powerful models this figure exceeds 2 kW and can reach very impressive values (up to 1000 kW or more in some industrial class UPS).

This parameter characterizes the degree of difference between the AC voltage at the output of the UPS and the perfect voltage, the graph of which has the shape of a regular sinusoid. The perfect voltage is so named because it is the most uniform and creates the least unnecessary load on the connected devices. Thus, the distortion of the output voltage is one of the most important parameters that determine the quality of the power received by the load. A distortion level of 0% means that the UPS produces a perfect sine wave, up to 5% — slight sine wave distortion, up to 18% — strong distortion, from 18% to 40% — a trapezoidal signal, more than 40% — a square wave.

Efficiency (coefficient of performance) in the case of a UPS is the ratio of its output power to the power consumed from the network. This is one of the main parameters that determine the overall efficiency of the device: the higher the efficiency, the less energy the UPS wastes (due to heating parts, electromagnetic radiation, etc.). In modern models, the efficiency value can reach 99%.

The absence of a battery in the UPS delivery set - to use such a device for its main purpose, you will have to buy a battery separately. This is associated with additional hassle, but it gives such an important advantage as the ability to independently select the capacity and number of batteries, without relying on the choice of the manufacturer and without the risk of overpaying for an unsuitable option.

Note that only models that do not have internal batteries and are designed for the use of external batteries (see below) can be supplied in such a configuration. These can be both professional inverter models (see "Type") and inexpensive backup models.

Rated voltage of external batteries that can be used in the UPS.

For more information about such batteries, see "External battery connection", here it is worth saying that the voltage of the external battery must correspond to the voltage for which the UPS is designed. If these parameters differ, at best, the UPS simply will not start, and at worst, overloads and even a fire are possible.

In general, the more powerful the UPS, the higher the voltage of the external batteries it is designed for. However, there is no strict rule. Some models even allow for multiple voltage options, such as 96/108/120 V. It is also worth noting that a power source with the required voltage can be assembled from several lower voltage batteries connected in series: for example, 3 batteries of 12 V can be used to achieve 36 V.

It is important to emphasize that the standard voltages for most modern UPS systems are multiples of 12 V. However, car batteries cannot be used in these devices. Despite having identical voltages, car batteries are designed for a fundamentally different mode of operation. Using them in a UPS can result in, at best, improper functioning of the device, and at worst, fires and even explosions.

The lowest current value in Amperes at which the UPS battery can be effectively charged. Note that charging with low currents is considered more gentle and extends the service life of the battery, but this increases the duration of the charging process. The optimal charge current is about 10% of the battery capacity.