Cable partial discharge test process remember discharge

- May 02, 2018-

Engaged in the middle voltage xlpe power Cable Factory partial discharge test personnel, have been tested cable residual electric shock experience. Therefore, during the partial discharge test of cable, the cable must be fully discharged before disassembly after the cable end insulation Core Oil cup is disassembled.

Because some of the test personnel cable residual charge discharge mode is incorrect, the test cable insulation core retained in the residual charge electric shock and the phenomenon of electric injury test personnel also occur. During the partial discharge and high pressure test of the three-core XLPE cable, the two insulated cores which are not tested in the cable are generally in a suspended state, some testers discharge only the core of the test and do not discharge the remaining two cores, which is likely to be electrocuted and electrically injured by the inductive residual charge in the other two cores. , and the inductive residual charge in the other two cores is quite strong when the insulation core being tested by the cable is penetrated.

Therefore, in the three-core XLPE power cable for partial discharge high-voltage test, after the test, must be in all the insulation core after discharge, can remove the oil cup, or there will be electric shock and electric injury risk. In the use of suspension of the oil Cup for the cable bureau high pressure test, sometimes there will be oil cup electrode and cable copper conductor core contact bad phenomenon. During the pressurization test, it is possible to pull the arc phenomenon by the higher test voltage, forced to contact the two together, the test can be carried out smoothly, but the test completed, the voltage reduction process, when the test voltage to a certain value, the short arc may disappear between the two, at this time the cable tested conductor and test equipment instantly cut off the contact. Because of the capacitance characteristics of the insulation core of the cable, it is possible to store the strong residual charge instantly on the insulation core. These residual charges are temporarily free of discharge channels and are stored on the conductor of the cable's insulated core. After the test, even if the operator of the Oil Cup has just completed the full discharge of metal electrodes, but because the oil cup metal electrode and the cable insulation core is not actually connected, the middle of the transformer insulation oil gap between insulation isolation, the distribution of capacitors in the middle, In fact, the electrical charge on the cable core is still not released, so that the tester will be removed near the end of the oil cup, electric shock and electrical injury. Therefore, the use of hanging oil Cup to do the Bureau test personnel, must ensure that the cable near the end of the Oil cup installation and cable conductor to maintain good contact, or even according to the procedures, may also occur cable residual electric shock phenomenon. So hanging type oil cup metal electrode at the bottom of the copper thimble, spring must be good and reliable, such as spring drop, thimble scattered incomplete, there is a timely replacement and treatment. In order to ensure good contact, if necessary, the conductor will be cut out or nails into the cable conductor, strengthen contact.