METHOD FOR MEASURING MECHANICAL STRESS REMAINING INSIDE XLPE POWER CABLE INSULATION

摘要

PURPOSE: A method for measuring mechanical stress remaining inside XLPE power cable insulation is provided to quantitatively measure distribution state of stress over the cable insulation without applying thermal stress. CONSTITUTION: A method for measuring mechanical stress remaining inside XLPE power cable insulation includes the steps of positioning an incandescent light source(1) emitting lights having the minimum brightness more than 0.0465W/cm2, polarized light plates(3,5) having vertical parallel transmissivity of 500 times more, a cable test piece(4) positioned between the polarized light plates, a compensator(6) measuring retardation changing according to distribution and concentration of stress; measuring retardation by sensing the emitted lights passing through the first polarized light plate to be firstly polarized, generating double refraction at the cable test piece, thereafter passing the second polarized light plate to be polarized; and calculating quantitative value of mechanical stress remaining inside the test piece by substituting the measured retardation for a general formula.