Power calculations and grounding in EDP/UPS power networks

It is noted that, as a load, a computer system presents the designer with difficult task in terms of electrical feed dimensioning, especially in the TN-S and TN-C-S 3×230/400 V, 50 or 60 Hz network configurations. This extremely nonlinear load and its high in-rush currents and neutral wire current imposes extra requirements on the distribution network, its grounding, and UPS (uninterruptible power system) powering. The authors present guidelines for calculating crest factors, fundamental factors, and power factors for single and three-phase nonlinear loads or combinations of these two. It is concluded that the guidelines have shown their necessity as an instrument assuring the cooperation between users, EDP (electronic data processing) equipment suppliers, UPS suppliers, and electrical network designers to achieve the right solutions and results