What is a UPS?

A UPS, acronym of Uninterruptible Power Supply, is an equipment that provides emergency power when the utility mains fails. It is equipped with batteries that start to work when the power outage occurs.

It also regulates the electric flux, reducing or increasing the different electric fluctuations and eliminating the bad harmonics of the means. It is an appropriate protection against power overvoltages, surges, spikes or brownouts.

These equipments are typically used to Project computers, networks, communication devices and any other electric device where an unexpected power surge or disruption could cause data loss or even very serious damages.

What is an AVR?

An AVR, acronym of Automatic Voltage Regulator, is an equipment designed to maintain a constant output voltage level, avoiding the typical voltage fluctuation of the utility mains. It regulates the electric flux, reducing or increasing the different electric fluctuations of the means, protecting the connected loads from power overvoltages, surges, spikes or brownouts.

Unlike UPS, AVR are not equipped with batteries, so the connected loads stop working in case of power failure.

How many types of UPS exist?

You can find three different types of UPS: Off-Line, Line-Interactive and On-Line.

Basically, the loads connected to an Off-Line UPS are powered by the utility means. The UPS batteries start to work when a power failure happens. In that moment, almost instantaneously, the UPS powers the connected loads with their own batteries.


Areas with few electric disturbances and good quality utility means.


Diagram A Line-Interactive UPS

A Line-Interactive UPS is very similar to the Off-Line UPS but it is equipped with a special microprocessor that controls the mains’ fluctuations, regulating the output voltage (Back/boost effect), without discharging the batteries. In case of power failure, the batteries automatically start to power the connected devices.


From domestic PC to small network servers, offices or small business.


Diagram A Line-Interactive UPS

An On-Line UPS, also called “double-conversion UPS”, is equipped with both an AC/DC rectifier and a DC/AC Inverter, and is continuously providing power from the batteries. That means that it is a real electric firewall for any sensitive device.


Any computer network, critical and essential (data networks, servers, telecommunications, industrial applications…)


Diagram A Line-Interactive UPS

What type of UPS should I use?

Depending on the quality of the electric mains available in your area and the kind of charge you want to protect, you can use the following types of UPS:

  • Off-Line UPS: Areas with few electric disturbances and good quality utility means
    Domestic applications or small offices.
  • Line-Interactive UPS: Areas suffering from voltage changes or unstable utility means, stormy periods
    Small domestic or office networks.
  • On-Line UPS: Areas with unstable utility means, with frequent electric surges, spikes, or power outages.
    Industrial applications, critical equipment protection.

What UPS capacity is the most suitable for me?

The Volt-ampere (VA) is the unit to measure the UPS capacity. It is also called “apparent power”. However, here you will also find the capacity measured in Watts (W), which is the real power, so you can easily decide which the most suitable UPS is following to your needs.

Here below you can find a chart with the estimated power consumptions of the most commonly used devices and systems.

Estimated consumption chart of most common devices and systems

Which is the maximum load a UPS can support?

Depending on the size and kind of UPS, different loads can be connected. The maximum load values are detailed on the datasheet, both in Watts (W) and in Volt-Amperes (VA). The load should not exceed 70%-75% of the maximum load value mentioned. Usually, manufacturers use Watts (W) to measure the power consumption of their devices.

It is important to take in account that laser printers should never be connected to a UPS as the current draw of a laser printer during start-up and printing can damage the UPS.

How long can a UPS keep running during a power outage?

The time while a UPS supplies backup power to the electrical appliances while power failure is called backup time. The unit of backup time is expressed in minutes and is applied for a load of 50% approx.

In case more backup time is needed, and as long as the charging system is up to it, more batteries can be added.

If the UPS already protects my devices, why do I need the software?

By installing the provided software on our PC and connecting the PC to the UPS through the USB or RS-232 communication ports, we get the UPS and our PC fully communicated. This way, we will be able to program the system shutdown and control all the UPS parameters, such as battery load, connected load, input and output voltage and frequency, etc. Not only can the UPS connected to the PC be controlled, but also the whole network. It even allows the remote control of the system via Internet. The software supports most of the current O.S.

In addition, some UPS have the option to connect a SNMP (Simple Network Management Protocol) Module, a system for managing devices on IP networks, used mostly in network management systems to monitor network-attached devices for conditions that warrant administrative attention.

Does a UPS need any upkeep?

Although the UPS does not need professional maintenance, it is necessary to follow some guidelines in order to increase its lifetime. Please, go to the maintenance section in this web.

What is the expected service life of a UPS?

Most UPS are good for at least five years. We advise you to change the batteries every three to four years. You must take in account that the battery lifespan is shorter when it is not being used, so, if your UPS is stored, we strongly recommend to charge and discharge its batteries regularly. With larger equipment, the lifetime of the equipment increases.

What is the warranty of a UPS?

The warranty is 1 or 2 years, depending on the USP model. Surge protectors, AVR, Off-Line and Line-Interactive UPS and On-line UPS up to 3 KVAs, which are addressed to end-users, are guaranteed for 2 years. On-Line UPS as of 3KVAs, used for industry purposes, have a warranty of 1 year. This warranty includes spare parts and repair, as long as the damage has not been due to an inappropriate use, inappropriate maintenance or natural phenomena.

The warranty includes the transport of the UPS to the LAPARA technical department for its repair and back to the customer as long as it is needed and it is justified.

lapara. Uninterruptible Power Supplies

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