On-line monitoring method and system for dielectric loss factor of crossed interconnection cable

The invention discloses a dielectric loss factor on-line monitoring method and system for crossed interconnection cables, and the method comprises the steps: calculating the phase value # imgabs 1 # of a capacitive current according to the terminal voltage # imgabs 0 # of an A-phase cable, a B-phase cable and a C-phase cable, and in the formula, the # imgabs 2 # is the capacitance of three sections of cables a1, b2 and c3; the phase # imgabs4 # of the sum of the currents is calculated according to grounding currents # imgabs3 # on the left side and the right side of a metal sleeve grounding loop of a certain cable. The average dielectric loss angle # imgabs5 # of the cable metal sleeve grounding loop is obtained, so that the average dielectric loss factor # imgabs6 # of the cable metal sleeve grounding loop is obtained, and whether the cable metal sleeve grounding loop is degraded or not is judged according to the cable insulation dielectric loss factor # imgabs7 #. According to the invention, whether the cro