1k-thepowerswitchisusedtoconnect(orcut)theconnectiontotheelectricpower(220v/50Hz).Thert--startingresistanceischargedtothefilterelectrolyticcapacitanceatthestartofthewelder.Inorderto***oidexcessivesurgecurrentdamageswitchandtriggerturn-ontripping,thestart-upresistanceisconnectedtolimitthesurgecurrent.Afternormaloperation,thestartingresistanceisshort-circuitedbytherelay.Inorderto***oidthedamageofstartingresistancecausedbysurgecurrentimpact,thestartingresistor(ptcandntc),)areusedinthecircuit.Theyh***egoodimpactresistance.)