Secure power supplies for British Telecom´s major computer centres

The author describes how British Telecom provides no-break AC power to its biggest multi-office computerization project, Customer Services Systems, in almost thirty district offices. The new Customer Services Systems installations were provided with secure AC power supplies consisting of standby diesel generator, static UPS (uninterruptible power supply), and n+1 redundant frequency converters. The power systems procurement and installation standards have been managed by the part-time efforts of a small unit in the Head Office. Call-off contracts were established for all the major power supply equipment leading to economies of scale and a high degree of standardization. Several potential problems have been avoided by design and attention to the effects of one machine on another. For example, it is noted that sealed lead-acid batteries with voltages around 450 V can be installed safely in plant rooms provided precautions are observed