| 摘要 |
PURPOSE:To reduce a floating capacity in a condition that an inter-polar voltage detecting device is connected and enable controlling in accordance with the condition of a part across poles by providing an insulation amplifier which sends out an input signal while maintaining an insulated condition, in the input part of an A/D converter. CONSTITUTION:Voltage from an AC power source 1 to a part across poles is divided by the output side resistor 15 and input side resistors 4, 5 of a rectifying circuit 6, and inputted into a smoothing capacitor 7, a detecting line 3, and an insulation amplifier 14, whose secondary side voltage is inputted into an NC control unit 9 via an A/D converter 8. A floating capacity 11 is hard to be charged due to high resistance value of voltage dividing resistors 4, 5, 15, and is unable to flow back due to the rectifying circuit 6 and, thereby, it is not added to the part across poles 2, while floating capacities 12, 13 are also being separated. Also, the output which has been converted into a DC voltage near the part across poles 2, is not affected by an induction n the detecting line 3, and therefore, if a floating capacity existing in the part across poles 2 is reduced, a minute discharge current can be obtained, improving a surface roughness.
|
