| 摘要 |
PURPOSE:To operate a protecting means when an output exceeds a constant standard and to adjust the time up to the operation by resetting an output generating means which operates the protecting means in response to each pulse of a pulse train signal generated when phase order is normal. CONSTITUTION:When the phase order of the respective phases R, S, and T of an input power source are normal, the contact 5a of an integrator 5 is made and broken at the constant period of the pulse train outputted by an OR element 4 to perform discharging, pulse by pulse, and the reset; and the output of the integrator 5 based upon a comparator 6 does not reaches the set value of a detection level setter 8 and the protecting means for a control circuit does not operate. When the phase order is abnormal, on the other hand, the element 4 does not generate the pulse train and the integrator 5 is not reset, so the output level exceeds the set value of the setter 8 and the protecting means operates to detect the abnormality of the phase order. Further, the time up to the detection of the abnormality of the phase order is set optionally by adjusting the reference value setter of the integrator or the setter 8.
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