1.Very high breakdown strength
2. Excellent temperature stability
3.Easy to install due to excellent mechanical properties
Joints for polymer cables
General
Our joints for polymer cables are designed to be used independently of any type of polymer cable or cable manufacturer from 72.5 to 550 kV and up to a conductor cross section of 2500 mm2.
Joint design
Joints for polymer cables consist of a conductor clamp, an insulation body with semiconductive deflectors and middle electrode, a moisture barrier, a mechanical protection and the connections of the outer conductor.
Variety of conductor clamps
Conductor clamps connect both conductor ends of the cable. Their main task is to ensure a low contact resistance during lifetime. Our joints are designed to suit all common types of conductor clamps. Due to their many advantages, such as being easy to apply, we recommend the use of screwed conductor clamps.
Outstanding properties of the SiR insulation body
The insulation body consists of semiconductive deflectors at both sides, a semiconductive middle electrode and the insulation compound. It ensures field grading between the semiconducting layers of the cable and the conductor clamp. Made of silicone rubber (SiR), the insulation body combines outstanding electrical and mechanical properties with excellent interface behaviour. The electrical properties are designed to minimise stress, whilst mechanical properties ensure an optimum level of surface pressure on the cable. The optimum surface pressure remains constant throughout the lifetime of the joint. The field grading deflectors and middle electrode are made of solid semiconducting material. Although costly, this ensures that they function properly at all voltage loads and guarantees a long and reliable lifetime. For optimum electrical stress distribution, the insulation body is designed with the help of computer simulations.
Quality in production and testing for failure- free devices
Our insulation bodies are one-piece and fabricated in-house in an extremely clean surrounding. To ensure best quality, the fabrication is made with computerised machines. For zero failure production, every part is tested several times in the fabrication process. The insulation bodies must pass a final acceptance test. Each device is certified individually. This ensures that every joint leaving our factory is 100% reliable.
At a glance, the main advantages of the prefabricated and pretested SiR stress cones are
Very high breakdown strength of >23 kV/mm at 50/60 Hz
Excellent temperature stability of between –50 and +180°C
Very high life exponent of 40
Excellent field grading performances at higher frequency with deflectors and middle electrode of solid material
Optimised electrical stress distribution due to computer-based design
Zero failure guarantee with final high voltage pretesting
Void-free contact pressure on the cable surface at normal and elevated load conditions due to excellent elasticity of the SiR
Easy to install due to excellent mechanical properties and elasticity, no high mechanical forces needed
100% moisture protection with metal shield
Our standard joints are equipped with a real transverse moisture barrier made of a metal shield. This gives 100% moisture protection to the joint and results in a prolonged lifetime, making it highly reliable. In its basic version, the barrier is a metal sheet. In the more sophisticated version, the moisture barrier is a metal tube.
