Uninterruptible power supply for a computerised online system

The implementation of a static UPS (uninterruptible power supply) for a computerized online system in a hotel environment is discussed. The system has three modes of operation: normal, emergency, and recovery. In the normal mode, the system acts as a buffer between the main power supply and the computer loads. The rectifier and charger provide current to the inverter while maintaining the Ni-Cd batteries at their full rated charge. The emergency mode begins when the main power is interrupted and the standby generator of the hotel is started. In the time lapse between these two events, the UPS acts as a voltage stabilizer and maintains a continuous power supply. The recovery mode begins when the normal supply resumes. The rectifier and charger outputs are then restored and begin to drive the inverter, taking over from the battery while at the same time starting to recharge them. When the batteries are fully recharged, the system returns to the normal mode. Details of the installation and sizing criteria as well as of testing of the UPS are presented.<>