UNINTERRUPTIBLE POWER SUPPLY

摘要

PROBLEM TO BE SOLVED: To increase the life of a lead storage battery in an uninterruptible power supply of firm utility power supply system by reducing the frequency of charging and discharging of a lead storage battery. SOLUTION: A transformer 7 having three windings is used. When the voltage of a utility power supply 1 is below the permissible level, it is boosted with the transformer 7 to supply power to a load 9. When the voltage of the utility power supply 1 is over the permissible level, it is stepped down by use of the transformer 7 to supply power to the load 9. For example, power supply by discharging a lead storage battery 5 may be permitted only when the voltage of the utility power supply 1 is 80 V max. or 125 V min. The voltage of the utility power supply 1 rarely shows 80 V max. or 125 V min., thus enabling to reduced the frequency of charging and discharging of the lead storage battery 5.