| 摘要 |
PURPOSE:To detect a short circuited point by making use of the annihilation of leaking electric field and leaking magnetic field in the short circuited point if the core pipe of a heat insulating pipe clad with an electric conductor is kept grounded. CONSTITUTION:In a heat insulating pipe 1 wherein a nailing accident is caused at the point A, a core pipe 2 is grounded 6 and the AC 7 of an audible frequency is applied across a sheath material 4 and the pipe 2. On the other hand, a detector 8 which is an electric field induction detector 8 of known construction for picking up leaking electric fields and is so connected that the output thereof is inputted via an amplifier 9 to a speaker 10 is brought closely to the pipe 1, and is moved from the end part B of the pipe 1 toward the short circuiting point A, then a speaker 10 keeps sounding and as the detector 8 goes nearer the part A, the sound volume decreases and when the detector passes the short circuiting point, the sounding ceases. The silencing of the speaker indicates that leaking electric fields are generated up to the point A and the leaking electric fields annihilate at the point A. If the result thereof is used, the short circuited points by nailing, etc. are detected easily. |
