WIRE & CABLE | PEX COMPOUNDS
electrical properties. The Buss machine is very mild so is much better for electrical properties,” he explains. According to Labbé, the polarity induced by carbonyl groups is thought to contribute to in- creased cable service temperatures, leading to higher electrical losses. This is problematic for MV and HV AC cables because of the frequency at which they operate but also for the EHV DC cables increas- ingly used to carry electricity over long distances. Beyond the initial compounding step, it is also
important that the temperature of the molten compound passing from the melt filtration system to the PEPA unit is tightly controlled. “We have a temperature window where we can inject the peroxide in the melt – it has to be below 135°C, or the peroxide will start to decompose, but above the LDPE melting point, let’s say above 115°C,” Labbé says.
Schematic shows the layout of a traditional ‘soaking’ system for production of PEX-a XLPE cable insulation compounds for HV and EHV AC and DC power cables (upper image) and the new LSHC (Linear Short Hyper Clean) process. Elimination of the soaking tower in the LSHC approach is said to reduce contamination risk, as well as reducing capital and energy costs by around 40%
Masterbatch Markets Asia 2023
Masterbatch Markets Asia 2023
Understand the implications of recent developments, the impact they have had on the masterbatch market in Asia and the direction the sector will take in the future
Understand the implications of recent developments, the impact they have had on the masterbatch market in Asia and the direction the sector will take in the future
www.ami.ltd/masterbatch-asia-report
www.ami.ltd/masterbatch-asia-report
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Source: Buss Corp
Because the peroxide is added to the molten compound, rather than relying on diffusion into a solid pellet, Labbé claims the LSHC process achieves a much more consistent dosing level. “With soaking, if you measure the peroxide content pellet by pellet you will see you have some pellets almost without peroxide and some with 3 or 4%. The homogeneity is not there and if we have too much inhomogeneity in the XLPE we may have something like pumping in the cable extruder. This will translate to cable diameter variation,” he says. “The second thing is the peroxide we are using [dicumyl peroxide — DCP] has a tendency to exude at 4°C. With the traditional process a conditioned warehouse is needed to maintain temperatures between 15 and 30°C, otherwise the peroxide blooms out. With our new process the peroxide is
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