Frequent cuestions about UPS: ¿Which are the differences between the many UPS technologies, types (standby, off-line, interactive, interactive line, on-line and on-line double conversion operation)?

Stand by & Online
They are essencially the same thing. In both systems, the inverter is always off, allowing IT loads to go through the UPS. In case of energy failure, the equipment is turned on and provides energy to the devices. Basically, in a normal situation both systems provide non-conditioned supply directly to the IT loads, as the electricity company is the one that is actually providing power. Although, there are some equipments with voltage stabilization in which the output voltage differs from the input voltage.
Interactive & Interactive line
There are two types: with quasi-sine output and with sine output (better quality equipments). In this systems the inverter is generally in standy, but it is actually working at the same time as the electricity network , sinc the switching time is almost non-existing in the sine output equipments. This systems are ment to protect the devices attached to them from surges as they have a stabilazer. Some of them can prevent almost 80% of damage when power failure occurs
On-Line & On-Line double conversion
In this equipments, the inverter is always on..This means there is no transfer time when electric failure occurs in the electric network. They provide a safe and conditioned supply, protecting the devices from electrical noise, frequency and voltage stability. Both equipments have galvanic isolation between input and output trhough double conversion. This type of system guarantees the safest protection for the devices