| 摘要 |
PURPOSE:To obtain a detection apparatus in which a phase jump in parallel off can be detected so as to be distinguished from a state that a sudden-change load is turned on by installing a phase-jump detection circuit in which a zero-crossing timing detected after the elapse of a prescribed cycle is compared with a regular phase when a phase shift is detected. CONSTITUTION:In a first phase-jump detection circuit 16, a detection signal (b) is received from a zero-crossing detector 15, its detection timing is compared with a regular zero-crossing phase of a system voltage Vin, and a phase-shift detection signal (c) is output when an advance or a delay within a definite range or higher exists. A second phase-jump detection circuit 19 which has received the detection signal (c) compares the detection timing of the zero-crossing detection signal (b) with a regular phase after a prescribed cycle. At this time, in the case of a system parallel off, a phase shift is left so as to be counted. On the other hand, when a sudden-change load is turned on, the system voltage Vin is returned to a normal state, and the phase shaft is not detected. Consequently, a single-operation detection signal (f) is generated in the system parallel off, and it is not generated when the sudden-change load is turned on. |
