Melanie Mani introduces a new standard for high-performance contact elements
Medium- and high-voltage systems are designed for long maintenance intervals. The first overhaul often does not occur until after 25 or more years of operation. By then, up to 10,000 mating cycles may have occurred. Innovative connection solutions are equally suited for both cost-sensitive static applications without mating cycles and for dynamic applications with numerous mating and sliding cycles.
A switchgear is made up of electrical equipment used to control, measure, protect and regulate network load during the generation, transfer and distribution of electrical energy. Metal encapsulated switchgears are particularly widely used within distribution networks due to their reliability and easy installation. Among a switchgear’s main components are circuit breakers, disconnectors, load switches, drive mechanisms, busbars and protective equipment, all of which are generally distributed across four independent compartments (busbar compartment, circuit breaker compartment, cable compartment and a control compartment). To guarantee the necessary electrical connections of the in-dividual power-conducting and power-switching components, a reliable connector is required.
If the switchgear has been in operation over a longer period, static and dynamic contacts can wear, thus steadily increasing their contact resistance. This, in turn, means higher temperatures as well as a further increase in contact resistance until the contact ultimately fails altogether. Since the switchgear is a contained unit, it can be particularly dangerous as this kind of problem is often not detected in time. This means that contacts burn out, leading to short circuits, network power outages as well as risks for the system’s operator.
New electrical connection technology from Stäubli
Stäubli’s Multilam technology tackles these very issues, creating parallel contact points between two contact surfaces. Each contact ridge has been specially designed for high levels of electricity and forms an independent, elastic and “power-conducting bridge” thanks to which contact resistance is heavily reduced in its entirety. The contact resistance can be calculated exactly according to the contact power, geometric structure and elastic characteristics of each ridge as well as the strength and characteristics of the surface material used. Simultaneously, a constant rate of contact power between the contact surfaces is kept stable, thereby ensuring constantly low levels of contact resistance throughout their entire lifespan.
With a rated current of 240A/cm and a short circuit current of 4.4kA/cm, compact connections with a high power density can be produced. Its large working area and tolerance compensation of 2.8mm mean that requirements in regard to contact design as well as necessary production tolerances are well accounted for on the one hand, and that high levels of flexibility in use can be guaranteed on the other. The special design and internal tension of the ML-CUX allows for its simple manual insertion into a straight, cost-effective, low-depth slot, even with larger contact diameters. Thanks to the two-component design of ML-CUX, electrical and mechanical performance are also able to be separated from each other. They are both optimised independently of each other to increase performance. With characteristics such as a high current carrying capacity, high tolerance as well as flexibility and easy assembly, the ML-CUX offers notable advantages within the high- and medium-voltage range of power engineering. Very high short circuit currents are crucial here such as 550kV Ik=63kA/3s, Ip=170kA, or 12kV Ik=31.5kA/4s, Ip=100kA at a maximum operating temperature of 1050C, which have already been successfully implemented in the case of disconnectors, circuit breakers and busbars.
Oliver Semling at Stäubli comments: “We believe that the new Multilam flexo line is setting a new standard. Material savings, more compact designs, maximum efficiency, durability and flexibility are brought together in a way that was previously impossible for spring contact elements. When viewed holistically, the newest Multilam generation combines all crucial electrical and mechanical characteristics, but, above all, essential economic characteristics, in a way that reduces the overall operating costs of systems as well as investment costs for operators.”
Melanie Mani is with Stäubli