| 摘要 |
PURPOSE:To lead out a continuous wire breaking detection signal by holding a terminal of a signal line at an intermediate potential if the signal line is broken, and detecting that by an intermediate potential detecting circuit. CONSTITUTION:The resistance values of resistances 23-26 are so selected that if the signal line for a signal (a) or (a') is broken, a terminal 21 or 22 is held at a specified potential cV. Then the intermediate potential detecting circuit 28 detects that and outputs a wire breaking detection signal Da. Further, even if the signal line for the signal a' is broken, an intermediate potential detecting circuit 29 outputs a wire breaking detection signal Da'. Thus, whether or not a signal line are broken by signals of the different polarities in one phase can be detected. In this case, the terminals 21 and 22 are held at the intermediate potential cV while the wire breaking is caused, so the wire breaking detection signals Da and Da' never intermit.
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