Patent ID: 7005883

Claim:
A battery ground fault detecting circuit applied to an uninterruptible power system having a controller and being connected to a battery box having a ground terminal, wherein said battery ground fault detecting circuit is employed for detecting whether a ground fault is occurred in a battery mounted in said battery box so that said controller executes a corresponding protection procedure thereupon, comprising: a detector electrically connected to said ground terminal of said battery box for detecting a ground current signal outputted from said ground terminal; a signal processor electrically connected to said detector for filtering and amplifying said ground current signal; a peak value comparator electrically connected to said signal processor and having a predetermined peak value for comparing said filtered and amplified ground current signal with said predetermined peak value so as to generate an AC control signal when said peak value of said ground current signal is larger than said predetermined peak value; and a signal converter electrically connected to said peak value comparator for converting said AC control signal into a DC control signal and transmitting said DC control signal to said controller for executing said corresponding protection procedure to said uninterruptible power system in response to said DC control signal.