Testing of EHV cable connection to transformers
Testing of EHV cable connection to transformers
(OP)
Whenever EHV cables (72.5-550kV)are directly terminated to transformers, it is done through a cable pothead protruding in to an oil filled cable box.An oil to oil bushing will take the transformer winding lead to cable box and a disconnecting lead will be used to connect the bushing ternminal to pothead terminal.My questions
1) Today what type of cables are used at this voltage? PE, HDPE, XLPE, EPR ? Trust oil filled cables are no longer used.
2) After the installation work, should the cable and connection to be tested after removing the connection to bushing?As per IEC 62067-2011 Power cables with extruded insulation and their accessories for rated voltgaes 150KVto 500 KV -Test methods and requirements, two tests are recommended after installation- one DC voltage test between sheath and ground and another AC insulation test.(220 KV cable 180 kV Ac for 1 hour or 127 KV for 24 hours.) Are these tests are done always after cable installation? or only 10 kV Dc test only?
1) Today what type of cables are used at this voltage? PE, HDPE, XLPE, EPR ? Trust oil filled cables are no longer used.
2) After the installation work, should the cable and connection to be tested after removing the connection to bushing?As per IEC 62067-2011 Power cables with extruded insulation and their accessories for rated voltgaes 150KVto 500 KV -Test methods and requirements, two tests are recommended after installation- one DC voltage test between sheath and ground and another AC insulation test.(220 KV cable 180 kV Ac for 1 hour or 127 KV for 24 hours.) Are these tests are done always after cable installation? or only 10 kV Dc test only?





