Technology

Heat-shrink technology was developed in the early 1980s and enjoyed huge success. It uses extruded plastic tubing which, when heated, shrinks to form a tight seal over both the cable and the cable accessory coupled to it. Cable accessories with heat-shrink technology came to be used widely around the world due to their good insulating properties, impressive mechanical strength, and indefinite shelf life. On the other hand, it is impossible to guarantee uniform insulation of the cable when using heat-shrink technology, as this requires an even heating at each cable section, which in turn is highly dependent on the skill and experience of the jointer. In former decades, NKT was one of the many manufacturers to supply cable accessories that utilised heat-shrink technology.

In the late 90s, cold-applied technology began to gain ground, initially using hybrid joints. The technology takes two forms: either as a push-on sleeve, where the insulating element is pushed onto the cable, as with our straight joint JS, or a prefabricated insulating element that is expanded on a spiral, like in our JC-HS. Cold-applied technology has the obvious advantage of offering more uniform insulation compared with heat-shrink technology, along with improved electrical properties. Cold-applied technology is also safer above 10 kV, as all the elements – including field control – are integrated and there is less risk of breakdown. This is even more true for our NKT cable accessories which are naturally equipped with geometric field control elements. What’s more, cold applied products make installation even simpler and faster – and therefore providing further time and cost savings. 

But the journey has not yet ended, and the technology is being developed further. Stay tuned for more info on this topic – we have some great news to share with you soon about further product developments!