| 摘要 |
PURPOSE:To reduce variation in secondary voltage with a primary voltage by detecting variation in primary voltage by variation in voltage between taps of a power transformer, and switching the taps by comparing the detected voltage with a reference voltage. CONSTITUTION:A voltage between the high-voltage tap 4 and low-voltage tape 5 of a power transformer 13 is rectified and smoothed to detect variation in the AC input voltage of a power line 1 in the form of a DC voltage, and a voltage generated by dividing the detected voltage is compared with a reference voltage by an operational amplifier 30. Then, a changeover switch 2 is connected to the high-voltage tap 4 when the divided voltage is higher, or to the low-voltage tap 5 when not, thus suppressing the secondary voltage variation of a power transformer 3. So that the output of the operational amplifier 30 has hysteresis, a peripheral circuit is constituted, and oscillation occurring during the switching of the taps is prevented. |
