Form factor
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Standard (Tower). UPS designed for floor mounting or placement on any suitable horizontal surface. This “installation” is extremely simple, and it is suitable even for the most powerful and heaviest devices, and therefore most modern uninterruptible power supplies (of all categories) are made in the usual Tower form factor. They are supposed to be placed vertically.
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Rack. Models for installation in telecommunication racks. Most of these uninterruptible power supplies belong to the professional equipment segment, designed to power servers and other similar electronics (which are also often mounted in a similar way). The most common standard of racks is 19", however there are other options, so it would not hurt to check the compatibility of the UPS with a specific rack separately. We also note that models of this type are often equipped with legs that allow you to place the device on the floor “sideways” or in a vertical position. Display (if available) in such models may have a rotating design for ease of reading parameters in both positions.
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Wall-mounted. Uninterruptible power supplies, primarily designed for wall mounting. Wall hanging may be the best option in tight spaces. However, such an installation is not the only option - many devices can optionally be installed on the floor. Also note that wall-mounted UPSs are often used for heat
...ing boilers. The main disadvantage of this form factor is the need to drill into the walls to install an uninterruptible power supply.
- Flat. UPS, structurally assembled in a low, flat housing. As a rule, this form factor allows for several options for installing equipment: the uninterruptible power supply can be installed horizontally or vertically. However, it is the horizontal method of installing the UPS that predominates. In fact, everything depends on the location of the uninterruptible power supply and its dimensions - it would not hurt to clarify this point separately.
— Extension cord. Uninterruptible power supplies that resemble an extension cord in appearance. Structurally, such UPSs consist of a set of sockets in one housing, with the sockets located on the top platform of the uninterruptible power supply. Often, the housing of such UPSs is provided with holes or fasteners for wall mounting.Input voltage
The input voltage for which the UPS is designed. This parameter practically also determines the type of network — different voltages correspond to a different number of phases:
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1 phase (230 V). Connection to ordinary household networks of the 230 V standard. It is these networks that are used by most devices powered by uninterruptible power supplies: computers, video and audio equipment, gas boilers, air conditioners, medical equipment, etc. Therefore, the vast majority of modern UPSs are designed specifically for 230 V. At the same time, relatively low-power models can work directly from the outlet, but for devices with a high maximum output power — from 3.5 kVA — a special connection format (directly to the shield) may be required.
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3 phases (400 V). Connection to three-phase networks of 400 V format. Such networks are used to power powerful industrial equipment, as well as to supply energy from substations to entire segments of the power grid (for example, the entire building). Accordingly, in the case of a UPS, it makes sense to use such an input voltage only in the most powerful models designed for a significant load — for example, an entire data centre, or an industrial workshop with high requirements for process continuity. The effective output power of such “uninterruptible power supplies” is from 4 kW, and the output voltage (see below) can be either single- or three-
...phase.
— 1 phase (230 V) / 3 phases (400 V). Uninterruptible devices that allow connection to any of the types of networks described above. Most of these devices are, in fact, models for three phases, supplemented by the ability to work also from 230 V. Note that for operation from a single-phase network, such models usually need to be connected directly to the shield, and the output power with such a connection may be lower the claimed maximum (this point needs to be specified separately).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.
Max. current
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.
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.
Rated output power
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).
Charging USB A ports
The number
of USB A connectors provided in the UPS, designed to charge external devices, such as smartphones or tablets.
This number corresponds to the number of gadgets that can be simultaneously charged. True, it is worth considering that not every UPS with this function is able to charge USB devices from its own battery, without external power supply - it is better to check this possibility before buying.
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.
DC output
The presence of
a DC connector (or several such outputs) in the device for powering external devices with direct current. A standard DC jack is round in shape and has a pin in the center. However, its dimensions may differ in depth and diameter. The voltages output to the DC output may vary.
