Barnes & Thornburg
Method for detecting input AC voltage
 A rectified ac voltage which is not smoothed is compared with a reference voltage directly, and a pulse is generated when the instantaneous value of the rectified ac voltage exceeds the reference voltage. Based on the pulse generation, a judgement is performed on whether the ac voltage is reaching a predetermined value or not. These operations allow the abnormality of the ac voltage to be rapidly detected with improved accuracy. 
Fuji Electrochemical Co., Ltd.
G
G01R
inventional
Fumiaki Noboru Toshihiro
Nakao Kato Shimizu