The same equipment is not used to protect a home computer as it is for a company server, whose availability and smooth operation are essential for business.

 

For this reason, UPS systems can be divided into three main categories depending on the technology used. This division has an impact on their price, their functions, their power range and, in consequence, the equipment they protect.

 

Off-line: the entry-level for non-critical equipment

 

 

Reserve the off-line UPS for equipment with non critical use: a PC used for web surfing and email, for example.

 

It is also a good choice if the electrical network that serves your home or business is reliable.

 

In France, in urban areas, this is usually the case.

 

This type of UPS, also called Standby, behaves like a battery backup in case of a power cut: a switch automatically switches the power from the mains to the battery circuit

In other words, it is passive when mains power is available and switches on when it is cut off.

 

 

It is the most compact, quietest and most economical model, it does not rectify the voltage and simply filters out parasites and prevents lightning.

 

Moreover, the micro cut-off due to battery switching lasts several milliseconds. This is enough time to switch off the most sensitive equipment, which is not normally the case with a computer.

 

The power of these inverters is less than 1500 kVA (1500 volt-amperes), which is absolutely sufficient to power a PC, its screen and other peripherals such as a printer for the time needed.

 

 

 

On-line: imperative for a server

 

 

This is the exclusive technology in the high power range, above 5 kVA. It is reserved for professional and industrial uses, in order to ensure continuity of service and to protect strategic equipment: large servers in data centres, medical equipment, etc. It is also recommended in a highly disturbed electrical environment. It is therefore the most expensive,

 

The power is constantly delivered by the battery (it is said to be "on line"), which is continuously recharged by the mains supply. This is the most reliable UPS in the sense that the switching time is instantaneous and the protected equipment is isolated from the power grid, except in case of UPS failure or overload. In this case, a bypass circuit takes over. The input voltage is filtered and regulated, and the output voltage is optimally stable.

 

 

The term "double conversion" is often associated with this type of inverter. It means that the power is transformed twice: by a rectifier upstream of the battery, which supplies it with direct current, and then by a converter at the battery output, which produces the alternating current needed to operate the protected equipment.

 

This means that the current is transformed twice: by a rectifier upstream of the battery, which provides it with direct current, and then by a converter at the output of the battery, which produces the alternating current needed to operate the protected equipment. The result is that the efficiency is reduced (although the latest models claim efficiencies of over 90%) and the power consumption, and therefore the heat generated, increases due to the continuous operation. An on-line inverter therefore has a ventilation system, which is potentially noisy. However, this is not a problem because it is usually housed in a server room, where the presence of personnel is intermittent.

 

 

The essential measurement of real power

 

Before making your decision, it is therefore essential to calculate the total power. The following two tips will help you:

 

An office PC with a 3 GHz Pentium G processor, 4 GB of memory, a Sata hard disk, an integrated graphics circuit and a 22-inch LCD monitor: the whole system consumes between 80 to 120 watts, depending on whether the PC is used for small office tasks or more demanding applications (video encoding, etc.). A 500 VA UPS is sufficient.

 

A gaming PC with a Core i7 processor, 8 GB memory, GeForce GTX980 graphics card, Blu-Ray drive and a 24-inch LCD monitor: the power consumption rises to around 100 watts when idle and over 400 watts when fully loaded. An 800 VA inverter seems to be the minimum.

 

Then there is the power consumption of the peripherals supported by the UPS battery, if you consider it useful: modem/router (about twenty watts), amplified speakers (about ten to one hundred watts for 5.1 systems), printer (about 10 watts for inkjet)...

 

 

Formula

 

Wattage consumed x 1.6 = VA

120 WATTS X 1.6 = 192 VA or 400 VA

 

 

 

Each socket plays one or more roles

 

All these sockets protect against lightning and voltage variations. But they differ in other ways:

 

 

 

The sockets in the left-hand column are battery-backed, the others are not. The top left socket (Master) controls the power supply to the three adjacent sockets.

 

Battery backup. Battery-backed outlets often account for half of the available outlets. Connect equipment to them according to your priorities, i.e. computer, monitor, modem/router...

 

Slave to a master socket. When the equipment connected to the master socket is switched off or goes into standby (its consumption falls below a predetermined threshold), the power supply to the slave sockets is cut off automatically. The aim is to save energy. Typically, plug the computer into the master socket, and assign the slave sockets to the monitor and speakers, or even the printer.

 

Powerline compatibility. Because the inverter filters the electrical current, the high frequencies essential to the PLC signal can be neutralised. A PLC-compatible socket will tolerate a PLC module, while protecting it from power surges.

 

Remote control. These remotely controlled outlets are located on a professional UPS equipped with a network communication card (standard or optional) or on a switched racked PDU. They allow the remote switching on/off of a device, usually a server, and the sequential rebooting (several servers booting up) of the device.

 

(several servers starting up simultaneously causing a harmful voltage spike).

 

 

 

The distinction between French and C13 sockets

 

 

C13 format sockets, designed to power powerful servers, are ubiquitous above 1.5 kVA.

 

Check the format of the sockets and make sure they comply with the French standard if you are going to protect your computer. Indeed, up to 1.5 kVA, two versions of the same UPS can coexist, one with French sockets, the other with IEC 320 C13 sockets, which are intended for servers. Above 1.5 kVA, the C13 format reigns supreme.

 

Introducing a UPS into a computer or audiovisual installation often means connecting additional cables, extending them or even changing them