Insulation diagnosis and positioning method for insulated bus pipe

An insulation diagnosis and defect positioning method for an insulated bus pipe, comprising:

• disconnecting a first end of the insulated bus pipe from other equipment and a second end of the insulated bus pipe from other equipment, keeping connection between a ground electrode and a line ground wiring of the insulated bus pipe and applying a test voltage between the ground electrode and a conductor portion of the insulated bus pipe;
• recording the test voltage and a test frequency when measuring a ground current of each of a plurality of grounded segments of the insulated bus pipe;
• identifying the plurality of grounded segments according to a ground shielded short wiring, and recording a quantity, a number and a length of intermediate couplings comprised in each grounded segment;
• measuring a length of each grounded segment and a ground current of each grounded segment at the test voltage, and calculating a ground current per unit length of each grounded segment;
• in a case where a consistent test voltage is applied to different grounded segments with a consistent test frequency and the different grounded segments have a same structure, comparing the ground currents per unit length of different grounded segments;
• checking manufacturer experience data, where the manufacturer experience data comprises a capacitance cb per unit length of an insulated bus pipe body, a capacitance cj per unit length of the intermediate coupling or ex-factory test data of the capacitance of each intermediate coupling:
• capacitances of the intermediate couplings numbered k, k+1, . . . , k+n comprised in each grounded segment are respectively Cjk, Cjk+1, . . . Cjk+n, calculating a capacitance current value of each grounded segment by the following formula:
• IC=Ut·(2πf·ΣC), where ΣC=cb·lb+cj·lj or ΣC=cb·lb+Cjk+Cjk+1+ . . . +Cjk+n, wherein Ut is the test voltage, f is the test frequency, lb is a total length of the insulated bus pipe body comprised in each grounded segment, lj a total length of the intermediate couplings comprised in the plurality of grounded segments, k is a positive integer and n is a non-negative integer;
• and comparing the ground current of each grounded segment with the capacitance current value of each grounded segment;
• and
• diagnosing an insulation status and implementing defect positioning of the insulated bus pipe according to the comparing result of the ground currents per unit length of different grounded segments and the comparing result between the ground current of each grounded segment and the capacitance current value of each grounded segment.