Comparison APC Back-UPS 500VA BX500MI 500 VA vs APC Back-UPS ES 700VA BE700G-RS 700 VA

— Standby. The simplest type of UPS, familiar to most ordinary users. Its main purpose is the ability to “softly” shut down work in case of power problems. When the voltage level is normal, the UPS supplies power to the load from the mains, and when the voltage drops or fails, it switches to its own battery. The resource of this battery is usually small — on the order of several minutes, which is usually enough only to save data. Also, such UPSs can smooth out short-term power surges, however, if such surges occur constantly, this wears out the battery and adversely affects the source itself. Redundant UPSs are widely used in home and office environments, they are usually of low power.

— Smart. A kind of development of the idea of backup UPS; such sources not only provide power in case of a decrease or loss of voltage in the network — they also play the role of voltage stabilizers. The design of such UPSs includes a special regulator (usually in the form of a transformer) that compensates for changes in input voltage and supplies a stable voltage to the output. This allows you to supply constant voltage to the load without the use of batteries, making such blocks well suited for operation in networks with unstable voltage — they not only protect the load, but also do not wear out themselves. Interactive UPSs also mostly have low power and battery capacity and are used to protect individual dev...ices.

— Inverter (online). Another name is "double conversion". The most advanced type of UPS providing the highest degree of protection. The name comes from the inverter — an output voltage generator that directly supplies power to the load. The inverter itself simultaneously receives power from two sources — from the network and from a charged battery. In the event of a critical decrease or loss of voltage in the network, the inverter continues to supply energy, only from the battery. Such a scheme avoids voltage surges when switching from the mains to the battery (which is a serious drawback of the two types of UPS described above and can even damage the especially sensitive electronics connected to them). Inverter UPSs have the highest power (up to the ability to power an entire building) and can be designed for a three-phase connection (see "Input voltage"), and some models allow you to select batteries of different capacities, depending on specific needs. On the other hand, inverter UPSs are not very efficient, noisy and expensive, so they are mainly used when high power or advanced protection is critical.

— Low voltage. Miniature UPS for low-voltage electronics backup. Mini devices provide a low voltage DC output (typically 9V, 12V, 15V, or 18V). Traditional sockets are not provided for in their design, and you can usually connect one consumer to them. For example, when there is a power outage from a backup mini-UPS, a short-term autonomous power supply is established for the router (for up to one hour), security systems.

— Normal (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.

— Rack (in a 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 rack standard is 19", however there are other options, so it would be a good idea 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.

— 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 u...sed for heating 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.

UPS continuous operation time from a fully charged battery when connected to a load with a power equal to the UPS output power (maximum or effective, depending on the type of load, see the relevant paragraphs for details). For a UPS designed to work with a home or office PC, a time of about 10-15 minutes is considered sufficient, this is enough to save data and complete work. To power servers, it is worth using devices with an operating time of 20 minutes or more.

UPS continuous operation time from a fully charged battery when connected to a load with a power equal to half the output power of the UPS (maximum or effective, depending on the type of load, see below for details). The operating time with such a load is much longer than for a full load, and even in the simplest models it can reach 20-30 minutes.

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.

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" mode...ls, this figure can be 8 – 10 kVA and higher.