Innovative Dry Type Outdoor Terminations for Sustainable High and Extra High Voltage Cable Systems

Inhalt:
Dry outdoor terminations are becoming increasingly important. The advantages are unrestricted suitability in water pro-tection areas and a smaller hazard area in the event of an accident. Such terminations can generally be installed much more easily and quickly and convince with its sustainability and practical aspects. Dry type AC solutions up to the highest operating voltage of Um = 550 kV and conductor cross sections up to 3200 mm2 are available. A distinction is made between gas-filled and gas-free variants with and without a support function. A new approach is made with an internal self-supported design which is complete dry-type and gas-free insulated. The complete outdoor termination consists of a pre-tested element made of stretchy silicone rubber with integrated field control element and shield modules according to the required creepage distance. Furthermore, the design has a sealing and a connection bolt. The supporting elements made of fibreglass-reinforced plastic are integrated inside the push-on element made of silicone rubber and provide the termination with the necessary strength with regards to its cantilever load. Several type tests acc. to IEC 60840 for voltages up to Um = 170 kV were already carried out. Acc. to IEC 60840 edition 5.1 published in 2023 the requirements of canti-lever load tests for composite insulators (MML) are not applicable for such designs. Instead, a limited flexibility allows for controlled deflection and self-returning to initial position again after relief of force. Tests with reduced values of force and with deflection during operation were carried out. Additional tests to IEC 60840 with salt fog (artificial pollution test), switching impulse voltages and the increased requirements of VDE 0276-632 convinced the initially critical cus-tomers. This design has already gained initial use and operating experience in high voltage systems and convinces oper-ators and installation companies with its sustainability and practical aspects. Designs for higher voltage ratings than Um = 300 kV will be limited due to mountability and consideration of the electrical interfaces.