GB1016210A - Testing electrical insulating sheaths - Google Patents

Abstract

1,016,210. Testing insulation. STANDARD TELEPHONES & CABLES Ltd. Sept. 8,1964, No. 36740/64. Heading G1U. In a method of detecting electrical leakage paths through a sheath of insulating material enclosing a conductor, the conductor is moved longitudinally past a barrier of flexible electrodes which comprises at least one row of electrodes of diverse lengths arranged such that their ends define part of a passage substantially conforming to a portion of the sectional shape of the sheath. The electrodes and conductor are connected to opposite terminals of a test voltage source, and any flow of current in the circuit, which indicates an insulation fault, is indicated on a suitable meter. In an apparatus 1 (Fig. 1) for carrying out the method, the flexible electrodes 13 consist of ball chain and are suspended from a frame 12 across the path of the sheathed conductor 8. A rigid electrode 18 having a U shaped cross section and also connected to the test voltage source is pressed against the underside of the sheathed conductor, and various sets of flexible electrodes of different lengths are suspended between the parallel limbs of this electrode so that apertures of different shapes to permit the passage of different shaped conductor sections are provided (see Fig. 3). The arrangement improves the efficiency with which large diameter sheaths are tested, since these sheaths will not force the flexible electrodes apart, as would happen if all the electrodes were of the same length.