Input voltage range
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.
Bypass (direct connection)
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.
Output frequency
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.
Redundant sockets
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.
Terminal blocks
The terminals are used to connect wires to the UPS — directly, without using any plugs. For models of relatively low power, such a possibility is not needed, but for powerful devices with at least a few kilowatts (used, in particular, for server cabinets), this connection option often turns out to be optimal, or even the only acceptable one.
A terminal block is a set of several terminals arranged in a row. Note that the number and purpose of such terminals may be different, this point should be clarified according to the official documentation.
Battery(ies) connection to UPS
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.
Total battery capacity
The capacity of the battery installed in the UPS. For models with multiple batteries, this is both the total working capacity and the capacity of each individual battery: the batteries in such devices are usually connected in series, so that their total capacity corresponds to the capacity of each individual cell.
Theoretically, a higher battery capacity means the ability to power loads of a given capacity for longer. However, in fact, this parameter is more of a reference than practically significant. The fact is that the actual amount of energy stored by the battery depends not only on the capacity in amp-hours, but also on the voltage in volts; this voltage is often not specified in the characteristics, despite the fact that for accurate calculations it must be known. So when choosing, you should focus on more "close to life" characteristics — first of all, on the directly claimed operating time in different modes (see above).
Full charge time
The time it takes to fully charge the UPS battery. Note that in this case, this time is calculated according to special rules: not from 0 to 100% of the charge, but from a state in which it is impossible to maintain half the load, up to 90% of the charge. Of course, a full charge will take a little longer. However, this data is closer to practice than the “from 0 to 100%” calculation: the inability to work at half load makes the UPS practically useless, and this condition can be taken as zero, and 90% of the battery is already able to provide a good guarantee in case of a power failure.
External battery connection
Ability
to use an external battery in addition to the UPS's own batteries. Such a battery extends the battery life of the UPS, and its connection is often more convenient than installing additional batteries (for which you have to open the UPS case); on the other hand, the battery makes the device more bulky, because takes up extra space outside.
UPSs with this feature can be supplied with or without internal batteries. Also note that there are models designed to use only external batteries and do not have compartments for internal batteries.
