Contact degradation of automotive relays is studied in order to understand the relationships among switching operations (make, break, and make-and-break) and load (resistor, lamp, and motor). This information is essential in proper relay design, specification, and application in automotive electrical systems. Contact resistance was measured and the eroded surfaces were analysed to explain the degradation process. Significant dependence of degraded contact resistance on types of load and switching operation is found. Prominent pips and craters that can cause premature relay failures are formed during the make operation by anode-to-cathode transfer. Break arcs transferred material from cathode to anode and formed a porous layer to increase contact resistance. The amount of material transferred decreased with shorter arcing time, and also decreased with load inductance. The degradation process is explained as an interaction among switching mechanics, load current characteristics, and arc phenomena.
Contact erosion in automotive DC relays
Kontakterosion in Gleichstrom-Relais bei Kraftfahrzeugen
1990
9 Seiten, 10 Quellen
Conference paper
English
Contact erosion in automotive DC relays
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