Supplying of the computer centre by safety powers

In the computer centre, a safe electrical supply is crucial. Very common is the UPS, which is however suitable for short blackouts only. During a long black out it is necessary to use a larger UPS or rotary generators. In this article the authors describe their experience obtained by measurement in various situations: A large UPS, or a small UPS used simultaneously with unsuitable generator. The attention is paid to the voltage curve and transient phenomena during switching-on of these sources.