To obtain an uninterruptable power supply by which heavy discharge of a battery can be avoided more reliably.
The uninterruptable power supply includes a step-up/step-down chopper 8 by which when an AC input power supply 31 is normal, AC power is converted to DC power and the AC power is supplied to a load 32 through power converters 3, 5, and a battery 20 is charged, and when the AC input power supply 31 is interrupted, supply of discharge power 32 of the battery 20 to the load is stopped through the power converters 3, 5. The uninterruptable power supply includes: a discharge voltage detector 12 which detects a discharge voltage of the battery 20; a discharge time counter 52 which measures the discharge time of the battery 20; a discharge end voltage converter 51 which converts a discharge end voltage with respect to the discharge time of the battery 20, and outputs the discharge end voltage with respect to this discharge time by inputting the discharge time measured by the discharge time counter 52; and a comparator 50 which compares the discharge end voltage outputted by the discharge end voltage converter 51 with a detection discharge voltage detected by the discharge voltage detector 12 to output a discharge stopping command for stopping discharge to the step-up/step-down chopper 8 when the detection discharge voltage is equal to or lower than a predetermined value.
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Masatoshi Kurata
Kono 哲
Makoto Nakamura
Toshihiro Fukuhara
Peak Takashi
Toshiro Shirane
Sadao Muramatsu
Nobuhisa Nogawa
Yukinaga Yasujiro
Naoki Kono
Sunagawa 克
Hiroshi Katsumura
Masaji Kawai
Tatsushi Sato
Okada Kishi
Mihoko Horiuchi
Masanori Takeuchi
Ichihara Takuzo
Hajime Yamashita