Glossary

The voltage dip is characterized by a drop in voltage amplitude over several periods. They are due to the startup of major electrical loads such as engines, lifts, lighting, heating, etc., causing untimely system shutdown and failure.

Harmonic currents and voltages are created by non-linear loads connected to the distribution network. Harmonic distortion is a type of power grid pollution likely to pose problems if the sum of harmonic currents is higher than certain limit values.

In the IT field, this word describes a peripheral that is put between the power supply and the computer. By regulating the input of electricity, it prevents power line disturbances or power surges that could cause data loss or damage the computer. When the failure occurs, it replaces the power supply for a few minutes (depending on the UPS capacity), thereby giving you time to backup data.

More info: A UPS is not designed just to overcome power cuts. Its role is also to stabilize electrical power and remove interference.

The UPS is an important link in the safety of information systems. Its main task is to take over when mains power cuts occur, giving users time to save work in progress.

Power cuts are not the only incidents that these devices have to deal with. Voltage regulation and filtering are another important function.

A good UPS should ensure a continuous power supply to equipment but also provide high quality power.

A UPS has three parts:

A type 3 surge suppressor is a device that protects electrical equipment against transient overvoltage created by lighting in particular.

The principle Off Line technology is improved since the input voltage is regulated and filtered by the UPS before being delivered to the hardware.

The power supplied is therefore of better quality. A voltage regulator enables the continuous supply of quality power when major variations occur and without using the batteries whose is directly proportional to the number of charging cycles. A filter and surge protector increase the level of safety.

When a power cut occurs, the UPS switches to battery mode (switchover time <2ms) and a communication software takes charge of files backup and program shutdown.

Line Interactive technology is recommended in areas where the mains power is moderately disturbed (commercial or rural areas) and also is chosen to protect servers, CAD and minor accounting systems.

The hardware is normally supplied by the mains and the UPS will only take over in the event of a power cut or major drop in voltage.
Off Line technology enables the hardware it protects to be powered long enough for data backup to be made and/or to turn off the appliances correctly.

This switch to battery power takes a certain time (switchover in general >4ms) which will not be troublesome for computers with a switching power supply, but it could cause a problem for more critical hardware (measuring instruments).

Off Line UPSs are the most economical. They are recommended for mono-station computers (PC type) dedicated to office systems or gaming and small servers in an electrical environment with few disturbances such as an agglomeration.

The UPS supplies uninterrupted power, thereby ensuring constant and disturbance-free voltage. The device to be protected is therefore totally disconnected from the mains, which means there is no switchover time and no power disturbances.

When a mains power cut occurs a communication software automatically closes all programs after having performed the required backups.

Tests show that these On Line UPSs offer the most stable output power and the best immunity to interference.
The On Line technology is particularly recommended in industry. It is also chosen to protect the systems where even the most minor loss of data is unacceptable such as calculators, PLCs, cash registers or major IT systems for example and in a more general way any strategic applications, critical electronic systems and medical apparatus.

The sinusoidal periodicity is no longer constant. These variations, whether sudden or gradual, are essentially due to diesel generator set speed fluctuations and are very rare on the public grids of developed countries.