| 摘要 |
PURPOSE:To enable measurement of insulation resistance at a high efficiency in an electric circuit large in the floating earth capacity by connecting a current transformer and an oscillation transformer pierced by a ground wire of a transformer with a loop wire containing a capacitor. CONSTITUTION:An oscillation transformer OT for oscillating a low frequency voltage as measuring signal or the core of a transformer to which a low frequency is applied is pierced by the earth line of a transformer T through which a low frequency voltage is applied to electric circuits 1 and 2. A leakage current of a low frequency component fed back to the earth line is detected with a zero phase current transformer ZCT whereby the insulation resistance of the electric circuits 1 and 2 is measured by use of an effective component in the leakage current iG. In this case, the current transformer ZCT and the oscillation transformer OT are connected with a loop line CL having a capacitor connected thereto while the line CL pierces the transformer OT in the same direction as the line EL and the current transformer ZCT in the opposite phase. This can suppress a reactive component due to a floating earth capacity in the current iG. |
