Hiroaki Suzuki, Shozo Kobayashi, Tsutomu Ono, Hiroyuki Nomura, Hiroaki Kurihara, Hiroyuki Iizuka, Daisuke Muto, Satoru Tanaka
One-piece, pre-molded joints have been used all over the world for (extra) high voltage ((E)HV) XLPE cables. For those pre-molded joints, ethylene-propylene rubber (EPR) has mainly been applied for many years because of its favorable electrical and mechanical properties.
With research on mechanical and electrical properties, we have succeeded to apply a new cold-shrink technology on those pre-molded joints using silicone rubber which has lower elasticity, better mechanical properties, such as lower permanent set, and so on. With this cold-shrink technology, pre-molded sleeves can be shipped expanded onto the carrier pipes. So the customer needs no tools for assembly at the jointing site and just needs to pull out the carrier pipes.
All the type tests required on IEC standards 840 were carried out including water immersion and heat cycling tests on our newly developed 110-kV cold-shrinkable joints (CSJ) and have shown good performance in all the tests, which means we became the first manufacturer in the world to put cold-shrinkable joints using silicone rubber for (E)HV XLPE cables on the market.