| 摘要 |
PURPOSE:To enable measurement of super-low electric conductive fluid, for instance, 10<-7>OMEGA/cm and less, by compensating electrodes arranged extendedly along the outer periphery in the direction of pipe axis and providing these compensating electrodes with the specified electrodes in the direction respectively in which they intersect with detecting electrodes through an angle in a section perpendicular to the pipe axis. CONSTITUTION:An angle of 90 deg. is divided into 4 sectors and in each sector is provided with the compensating electrodes arranged by eight pieces in top and bottom positions respectively. On the other hand, an operational amplifier 12 as a preamplifier converting a detected potential into a non-inverted output obtained in a detecting electrode 3, and a divider 13 dividing at inside and outside diameters a, a' and angle of compensating electrode theta, an output voltage of an amplifier 12 into a products of (a/a') cos theta are installed. The voltage obtained in each output point of the divider 13 is applied to a compensating electrode 11 corresponding to each angle. Outside part of the compensating electrode 11 is covered by conventional insulating material and its outside part is covered by metallic shielding pipe and the assembly is grounded. A magnitude of signals similar with that which would have been obtained, by using a pipe of finite thickness with its outer periphery being grounded when an electroinductive pipe of infinite thickness were employed. At the same time, damping of a leader line shield of the detecting electrode by floating capacity can be compensated also. |
