价格:未填
供应:99999
发货:3天内
电机启动型热敏电阻器 马达启动用正温度系数热敏电阻器，只要用于电冰箱、空调马达启动、空调变频机启动、马达过热保护等。 工作原理：马达启动器是利用PTC陶瓷的电流－时间特性，当电压施加于PTCR时，开始有大电流I流过，经过一定时间ts后，随着PTCR温度的升高，电阻值迅速增大，导致电流也急剧下降，这段时间ts可以从0.1s到几秒，其值取决于PTCR的热容量、电阻值、热耗散条件、负载电阻及工作电压，当外电压撤销时，PTCR将冷却至常温电阻值。利用这个原理，在家用电冰箱和空调机等电器马达启动上得到了广泛的使用。应该说明，当使用PTCR的延迟性能时，如果要重复同一延迟时间，应间隔一定时间tr（即所谓的恢复时间），使PTCR恢复到原始状态温度，所以应避免立即重复动作，否则PTCR不能提供持续的大电流，使压缩机无法正常启动工作，会导致压缩机烧毁。 电机在启动时，要克服本身的惯性，同时还要克服负载的反作用力（如冰箱压缩机启动时必须克服制冷剂的反作用力），因此电机启动时需要较大的电流和转矩。当转动正常后，为了节约能源，需要的转矩又要大幅度下降。给电机加一组辅助线圈，只在启动时工作，正常后它就断开。将PTC热敏电阻串联在启动辅助线圈，启动后PTC热敏电阻进入高阻态切断辅助线圈，正好可以达到这种效果. 产品优势：采用带有PTCR的启动电路具有经济、可靠、电路简单等特点，优于过去的重锤式启动电路，它具有无触点、低噪声、高可靠、长寿命等特点。 PTCThermistorsforMotor-Starting Applications Motor-startingPTCThermistorsaremainlyusedinfridgeandair-conditionermotor-starting,air-conditionertransducer-starting,motorover-heatingprotection. WorkingTheories Motor-starterisamachinethatmakesuseofthePTCpotterycurrent-timefeature.WhenPTCRisputonbypressure,theheavycurrentbeginstopassthrough,andaftercertaintime,withtheincreasingofthePTCtemperature,resistancevaluegoesupsharplyandcausecurrenttofalldownsuddenly.Duringthistime,tscanchangefrom0.1stoseveralseconds.ThespecifictimedependsonPTCR sheatingcapacity,resistancevalue,heatingdissipationcondition,overloadedresistanceandoperatingvoltage.Whentheouterelectricitypressureretreats,PTCwillbecomecoolandaltertonormalresistance.Makinguseofthistheory,PTCisappliedextensivelyinhouseholdrefrigeratorandair-conditionermotor-starterandsoon.Onepointshouldbenoticedthatwhenusingthedelay-timefeatureofPTC,weshouldmakethePTCrecovertoitsoriginaltemperatureeverycertaintimetr(Thatiswhatwecalledrecoveringtime).Sosuddenrepeatedmovementsshouldbeavoided,otherwisePTCcannotprovideconstantheavycurrent,andthecompressorcannotstartorworknormally,whichwillcausethecompressorburnt. Whentheelectricitymotorisbeingstarted,ithastoovercomeitsinertiaandthecounterforceofloading(eg:Itscounterforcemustbeovercomewhenrefrigeratorcompressorstarts),sostartingtheelectricitymotorneedsrelativelyheavycurrentandtorque.Whenitrunsnormally,andthetorqueneededhastobebroughtdowntosaveenergy.Givemotorelectricityacircleassistantloop,anditworksonlywhenthemotorstartsanditwillbreakupafterthecurrentgoesregularly.ThiseffectcanbereachedbyconnectingthePTCThermistorinseriesinstartingassistantloopandcuttingofftheassistantloopwhenPTCRentersthestateofhighresistance. Advantages ThestartingcircuitwithPTCownsthefeatureofbeingeconomic,reliable,simplewhichisbetterthantheheavyhammerstartingcircuitAdditionally,Ithasthecharacteristicsofbeingcontactless,lowernoise,highreliability,longserviceandsoon.