Research On Design Technology Of Clapper Power Relay For Long Life Under Ac Load

Clapper power relay has such advantages as small size, light weight, low coilpower consumption, high sensitivity and large load cut-off range, and as a result, itis widely applied in heating type household appliances. It is mainly used to cut offAC load and its annual output can reach hundreds of millions. The electrical life ofpower relay is directly related to the service life and security of home appliances.So it is of great significance to focus on the research on design technology ofclapper power relay for long life.Firstly, the failure mode and failure mechanism of power relay were analyzedin detail. This power relay is classified into normally open type and switch type.The electrical life tests of two type relays were done by using the test analysissystem. During the experiment the failure degradation parameter and electrical lifewere monitored. The main failure mode and failure mechanism of power relay underAC load were explicitly analyzed by adopting the method of AC arc theory andmathematical statistics. On this basis, the action process and temperature rise ofrelay were collected by the use of high speed camera and infrared camera which canverify the corresponding analysis results.Secondly, the dynamic characteristics of power relay was jointly simulated andoptimized. The dynamic characteristics of relay was simulated by using jointsimulation technology based on virtual prototype, and the simulation results wereverified by measuring the coil current and action parameters. Aiming at theexistence problem of relay release rebound and taking the solution of this problemas optimization goal, the optimization scheme of movable spring was put forwardby modifying dimension parameters and replacing reed material. Compared with therelay before optimization, the rebound time and rebound range were greatly reduced.Thirdly, combined with the theoretical derivation and experiment, the keyfactors affecting relay`s arc time were analyzed in detail and the best contact gapwas proposed. Contact gap was confirmed to be the key factors influencing arc timethrough the theoretical analysis. The implementation model on increasing contactgap was determined on the basis of product size and processing technology. Thedistribution change law of arc time was found out by comparing relays with fivedifferent contact gaps. Combined with the results of simulation and test, the bestcontact gap of the clapper power relay was confirmed.Lastly, the optimization schemes of normally open relay and switch relay weredeveloped respectively on the basis of cost and processing technology. Besides they were verified by the electrical life test.The presented ideas and methods of this study can also be applied to the designand optimization of other kinds of clapper power relay.