Everything about UPS.

In the article, you will find information about UPS units that can be used in your home or business, both for local backup of a single device and for ensuring uninterrupted power throughout the building.
The UPS market is constantly changing, not only in terms of new manufacturers, but also in terms of new UPS models and new technologies. If you find something interesting, it is worth describing it in this topic.

The three basic types of power supplies are well known, but which one should you choose?

Why do we use UPS?

UPS (Uninterruptible Power Supply) allows you to maintain the power supply of the device when there is a power cut. The backup time is limited by the capacity of the UPS battery. You can use UPS to power devices that will disrupt your operation in the event of a power failure. For example, a laptop with a battery in the event of a power outage will continue to operate, but may lose its LAN or Wlan connection if the network devices lose power. UPS will reduce the impact of short power outages, if the outage is prolonged, save your work and shut down the systems safely. The UPS can also reduce the transmission of some disturbances from the utility grid. The tandem power generator + UPS will help reduce the impact of longer power outages, but this is a topic for a separate article.

Offline UPS.

When electricity runs out, the offline UPS starts the inverter (usually with an output transformer) and starts generating power for the connected equipment. The pause between the power failure and the start of operation is not zero, which may affect the receiver. Depending on the version, the UPS can generate an output voltage closer to a rectangle or a sine wave. Offline UPS can also protect loads against overvoltage by built-in elements (most often varistors) and to some extent filter network disturbances (filters based on inductance and capacitance). Offline UPS is mainly suitable for low-power devices, whose power supplies allow you to maintain continuous operation despite a momentary power outage.
The advantage of the power supply is its low price and low energy losses (the UPS does not convert energy when the mains power is present). Offline UPS will work well when powering a small LAN or WAN node (router + switch), possibly a WLAN device, as well as a PC or a low-power server.

UPS offline line-interactive.

In addition to the features of a typical offline power supply, this UPS can stabilize the output voltage without switching to battery operation, and maintain synchronization with the input voltage phase. The UPS will allow to maintain the nominal mains voltage with fluctuations in the input voltage, when the input voltage window is exceeded, the UPS will enter the voltage generation mode. The scope of application similar to that in the case of offline, line-interactive UPS should be used where there are frequent periodic drops or excesses of the nominal mains voltage.

UPS online.

This type of UPS rectifies the input voltage and then re-generates the AC voltage (double conversion). UPS online starts working immediately. The output voltage is independent of the shape and frequency of the input voltage. The online UPS processes the input voltage all the time, which unfortunately causes losses. UPS recommended for all sensitive and critical IT equipment and power greater than a few kilowatts. An online UPS can supply hundreds of kilowatts, and it can also run in parallel with other units on a single rail to provide power in MW. The disadvantage of an online UPS is the higher cost of purchase, operation, as well as greater power loss when the input voltage is present.

Buffer power supplies.

With DC power, it is possible to use buffer power supplies. A buffer PSU is supplied with DC or AC voltage and produces a constant output voltage. The buffer power supply is characterized by low losses and immediate starting of operation during a power failure. It is mainly suitable for powering devices such as CCTV equipment, alarm control panels, etc.

DC power systems.

In some solutions, you may find devices powered with DC