Comparison Eaton 5E 850I USB 850 VA vs Eaton 5E 650I USB 650 VA

The time required to transfer the load from mains power to battery power. In standby and interactive UPSs (see Type), a short-term power failure occurs at this moment — accordingly, the shorter the time to switch to the battery, the more uniform the power supply is provided by the source during a power failure. Ideally, the switching time for the traditional 50 Hz AC frequency should be less than 5 ms (a quarter of one cycle of the sine wave). With inverter UPSs, the transfer time is, by definition, zero.

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 operating frequency of the alternating current supplied to the input of the UPS — or more precisely, the frequency range of this current in which the device can supply the required power to the load due to its own regulators, without using a battery. When this range is exceeded, the UPS switches to battery mode. The smallest input voltage range is reserved for standby UPSs (see "Type"), the largest for inverter UPSs.

Bypass(by-pass) means such a mode of operation of the UPS, in which power is supplied to the load directly from an external source — the mains, diesel generator, etc. — practically without processing in the UPS itself. This mode can be activated either automatically or manually.

— The automatic bypass is a kind of safety measure. It turns on when the UPS in normal mode cannot supply power to the load — for example, when the UPS is overloaded due to a sharp increase in the power consumption of the load.

— Manual bypass allows you to enable this mode at the request of the user, regardless of the operating parameters. This may be necessary, for example, to hot-swap a battery (see below for details) or to start equipment that has a starting capacity greater than that of the UPS. Technically, it can also play the role of a security measure, but automatic systems are more reliable in this sense.

Some UPSs provide both options for enabling the bypass.

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).

The frequency (frequency range) of the AC voltage output by the UPS. For computer technology, the frequency range of 47-53 Hz is considered normal, although the smaller the deviation from the 50 Hz standard, the better. On the other hand, in some UPS models, this frequency can be automatically synchronized with the frequency of the mains — so the power supplied to the load will not differ regardless of whether the load is powered by the mains or from the battery. In this case, a wider frequency range, on the contrary, is more desirable.

The number of outlets connected to the power reserve(battery) provided in the design of the UPS. In order for the UPS to fulfill its main role (providing a backup power in case of power outages), the corresponding electrical appliances must be connected to these outlets. The sockets have a standard shape and are compatible with the vast majority of popular 230 V plugs.

At a minimum, the UPS has 1 or 2 outlets and, in more advanced ones, there may be 3 or more.