Switching to battery
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.
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.
Peak output power
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.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.
Cold start
The ability to turn on the uninterruptible power supply in the "cold start" mode.
A
cold start is a turn-on mode in which there is no external power, and the load connected to the UPS is powered immediately from the uninterruptible battery (which, of course, must be charged). This mode is especially useful in emergency cases — for example, if you urgently need to print a document, but there is no light.
Control interfaces
Many modern UPSs can be connected to a computer or other special devices. This provides advanced options for monitoring the parameters of the UPS and managing its functions: without leaving the computer, you can monitor the battery status, network parameters, load, enable special modes, apply automatic adjustment, etc. Such a connection can be made according to the following standards:
—
RS-232. It's a COM port. Initially designed to connect various peripherals to a computer. Today it is also quite widespread, however, due to its relatively large size, it is installed mainly on stationary PCs.
—
USB. A universal port for connecting various peripherals to a computer, the most popular interface of this kind today — at least one USB port has an absolute majority of computers and laptops.
-LAN. A port used to connect to wired computer networks. Models with this interface can often be connected as a network device, which allows, if necessary, to control them from any computer on this network.
—
SmartSlot. A slot in the UPS case for installing expansion cards (SmartSlot cards). The development of APC, is used mainly in the devices of its production. Such cards can provide a very diverse set of features: additional connection ports beyond the standard ones (for example, a LAN control port), a web managemen
...t interface, support for SNMP, Secure HTTP and other protocols, connection of temperature / humidity sensors, and much more. To date, a wide range of cards is being produced, making it easy to choose a set of additional functions depending on the specific situation. Most UPS models have one SmartSlot, but if necessary, you can use a special expander and install two cards, and the largest models can have two slots as standard.
— "Dry contact". In uninterruptible power supplies, the term "dry contact" refers to a professional interface used to transfer data on the operation of the UPS to specialized external equipment. Such an interface usually has a whole set of contacts (on the order of 10), often in the form of terminals. And the scheme of its operation can be simply described as follows: when certain parameters are reached, the control relay closes or opens a given set of “dry contacts”, on the basis of which the control device receives information about one or another parameter of the UPS operation.Screen
The presence of the UPS own
display makes management more convenient. Various operating characteristics can be displayed on the external screen: mains voltage and frequency, operating mode, load level, battery charge, bypass status, etc.
