On-line type Uninterruptible Power Supply (U.P.S.)

The U.P.S. or Uninterruptible Power Supply comprises a rectifier which is powered by the voltage of the network. This "primary winding" of the U.P.S. charges the batteries. The DC voltage supplied passes through a converter which transforms it to AC voltage. The voltage of this "secondary winding" (referred to as "high quality" voltage) powers the machinery, in our case, the computer.

Advantages:

In the case of a power cut, the batteries immediately power the converters without affecting the machinery.
Autonomy, depending on the capacity of the batteries and the charge.
In the case of a fault internal to the U.P.S., short-circuit or excessive inrush current, the charge automatically switches over to the backup network (network 2, by-pass), via the static contacter.
Protection against upstream contamination of the electrical network (galvanic isolation to be confirmed on the Neutral of the output of the converter).
Stable output voltage.
Allows for the use of a different neutral point connection downstream.

Disadvantages:

Cost of equipment (investment, depreciation).
Onerous installation (creation of a suitable air conditioned premises).
In general an isolating transformer must be installed on network 2 (by-pass).

Note: It is necessary to install an isolating transformer on the back-up network (network 2, by-pass) so as to ensure galvanic isolation when this source is being used. Furthermore, this device is mandatory if different neutral point connections are used upstream and downstream of the U.P.S.

The power supply interfaces should be of the electronic type (IGBT transistor technology). Ferro-resonant type interfaces are not suitable for computer hardware.

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