Surge load experiment design and results analysis of relay
Due to the transient overvoltage or overcurrent when relay's contacts switch different loads, the relay's contacts are damaged by transient arc erosion of electrical-over-stress, which influences the reliability of relay seriously. Firstly, according to the life test requirements of one type of electromagnetic relay with permanent magnets, the load circuit and the testing program are designed, which has characteristic of adjustable surge current time. Secondly, the contacts' breaking arc and closing bounce under 2A resistive load, 5A resistive load and surge load are analyzed. The influence of surge load on relay's electrical life is studied with increasing of test cycles. Finally, based on the testing data, the optimal design of relay has been modified and the results have been analyzed, which is helpful for improving the life of the relay.
Design of simulate capacitor loads experiment and results analysis for polarized relay
Although MIL-39U16 didn't specified capacitive loads, in practical applications, there are capacitor loads, when Polarized relay contacts switch turn on and turn off there will be some surge current especially polarized relay, it will make the polarized relay or contacts switch arcing erode quickly, even contact fusion welding, which will influence the reliability of polarized relay seriously. A type of polarized electromagnetic polarized relay with permanent magnet was researched in this paper. Firstly, according to the test requirements of the polarized relay, the test program and surge load circuit are designed. And then analysis arcing time of contact under the capacitive load of surge current 5A, 8A, 13A, 16A, steady-state current 2A. Finally, how to estimate the maximum of the transient current was analyzed in this paper, then the method enhance Polarized relay's resisting surge capability and reduce surge current's influence to Polarized relay contacts improve the Polarized relay's reliability and life was researched.
Arcing of electrical contacts in telephone switching circuits
This is a presentation of a study of the mechanisms of the short arc between closely spaced contacts and its erosion effects. The study is based on optical measurements of the erosion obtained on contacts after repeated arcing on closure or opening. Most experiments reported here are essentially of the probing type designed to test specific postulates and assumptions. For short arcs initiated at 250 volts, clean palladium, iron and nickel contacts have shown a reversal, with arc duration, in the direction of net transfer. Net anode losses were obtained with short duration arcs and net cathode losses with longer duration arcs. This reversal, however, did not occur with silver, gold or copper. For longer arcs initiated as air breakdowns from 500 volts, all the above metals indicated a net loss from the cathode. For arcs initiated at 250 volts between fully activated contacts, shallow cathode losses were generally observed with little or no buildups on the anode. The first section of this paper is a summary of the experimental work done and the results obtained. In the second section, the data are analyzed and a tentative working model is proposed for the short arc and its erosion effects.