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Systems in applications ranging from aerospace, automotive, to power distribution are all crucially comprised of electrical connectors. Every system with removable electrical components will have electrical connectors, and likewise these systems will be susceptible to the contact losses and failure modes of these connections. Corrosion is one of the largest causes of failure for electrical connectors...
This paper experimentally explores thin film micro-contact pairs of Au-Au, Au-Ru and Au-RuO2 through the utilization of thin-film contact resistance and spreading resistance theory. Contacts of various combinations of material pairs, including evaporated Au lower planar contact and sputtered Au, Ru or Au-RuO2 upper hemispherical contact were fabricated and their performance monitored through many...
In earlier work it was recommended that accelerated tests, using elevated currents, be used to evaluate the performance of contact designs using materials that may be susceptible to electro-migration. This is necessary since it was found in earlier work that the type of self-diffusion in some cases had a major impact on time to failure. Since the type of diffusion is generally not known in advance,...
The reliability of Micro Electro Mechanical Switches (MEMS switches) still remains the main focus of attention, but only a few studies have dealt with their bouncing behavior. In this paper we investigate and compare contact bounces in three different types of electrostatic RF MEMS switches tested under similar hot switching conditions (5V/500μA). An instrumented test bench has been developed for...
Studies have been conducted of AgCu contacts to investigate the influence of current frequency on the rate of the arc erosion at contact opening. The work is performed on a special designed test rig at the current of 100 A, frequencies ranging from 50 Hz to 1000 Hz, operating voltage of 110 V, contact gap of 3 mm for 1000 operations. It was found that that the rate of erosion depends nonmonotonically...
In electric power transmission, copper and aluminum are mainly used as conductor materials. To improve the contact behavior, the contact surfaces of e.g. high-voltage switching devices are often coated with silver or nickel. Due to economic reasons, connecting conductors are usually uncoated. In that case, an electrical joint with only one coated contact partner is formed. With respect to the permissible...
Knowledge of the contact resistance-contact force characteristics is essential for the design and diagnostics of electrical contacts, especially for low pressure contacts in connectors. Since the electrical contacts often have to be mated after a long period of storage, not only the characteristics of virgin contact surfaces but also those of aged contact surfaces are of substantial importance. The...
Vibration-induced fretting corrosion is a major cause of failure in electrical connector systems. To date, most work in this area has been mainly concerned with vibration orthogonal to the line of the connector and wire harness set (transverse vibration). The present study considers the effects of vibration parallel to the connector/wire harness line (axial vibration) A series of studies using single...
Silver tungsten carbide (AgWC) contacts are often applied to circuit breaker applications due to their good arcing erosion properties. The low material loss is beneficial for repeatable high interruption capacity. This paper characterizes the influences of contact material microstructure and sintering agents on the switching properties of AgWC40 material. A detailed description of the microstructure...
Applied Relay Testing Ltd is a specialist Company that has created a range of advanced test products dedicated to relays and switch devices covering the areas of low-level parametric measurement, life-testing and high-voltage qualification. Traditional relay life test systems are often constrained to only basic functionality such as the measurement of closed contact resistance and confirmation that...
Supply voltage of the dc power system in an electrical vehicle or an airplane keeps increasing with the increment of their electric energy consumptions, which raises a claim on high voltage contactors or relays. Special design on contact system or arc chamber in the contactor for arc quenching is necessary to meet the requirement of dc high voltage break. In this paper, arc behaviors when a bridge-type...
Experiments with arcs confined in tubes and Miniature Circuit Breakers — MCBs with gassing walls of different engineering plastic compounds were carried out. In the first part of the investigation the arc chamber consisted of small tubes of the different materials. The arc-current source was a damped capacity bank with high charging voltages. For the second part of the investigation customary 32 A...
The electromagnetic relays have lots of structures and are applied widely in the automation control system in aerospace. Firstly, the structures of aerospace electromagnetic relays (AEMR) were classified. According to the structure arrangement, there are three layers, two layers and one layer structures; from electromagnetic system, there are clapper type, balance armature type, polarized magnetic...
The physical phenomena related to the melting of electric contacts are classified and the relations to electric characteristics are examined. The solid phase and/or the liquid phase exist at melting temperature. Joule heats from the electric circuit accumulate the latent heat till the melting of the contacts. We studied how the phase changes are ruled by electric circuit. The melting phenomena at...
Through past testing it has been observed that the endurance life of contacts tested using DC automotive type loads is better if the polarity of the test is set to use the terminal contact as the anode as opposed to using the thin contact spring as the anode. A DOE approach was used to look at the effect on contact erosion and transfer for changing the thermal characteristics of the terminal with...
Nano-indentation manipulator operated in SEM was constructed in order to investigate the electrical contacts on a nanometer scale. Then it is simultaneously possible to observe and control indentation movement and to measure the load force and electrical resistance. Particularly in order to investigate the influence of thick oxide layer on the electrical resistance during indentation, a tin substrate...
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