RockwellAllen-Bradley1756-IF81756-IF16实验证明当电流过导体时，由于自由电子的碰撞，导体的温度会升高。这是因为导体吸收的点电能转换成为热能的缘故。这种现象叫做电流的热效应。电流通过导体时所产生的热量与电流强度的平方、导体本身的电阻、以及电流通过的时间成正比。这一结论称为焦耳——楞次定律，其数学表达式为：Q=I²Rt，公式中：Q：电流通过导体所产生的热量，单位：焦耳（J）；I：通过导体的电流，单位：安（A）；R：导体的电阻，单位：欧（Ω）如果热量以卡位单位，则Q=I²Rt公式可写成：Q=0.24I²Rt=0.24Pt，此公式称为焦耳-楞次定律。其中t的单位为妙，R的单位是欧，I的单位是安，热量的单位是卡。电流的热效应在生产上有许多应用。电灯是利用电流产生的热使得灯丝达到白炽状态而发光，熔断器是利用电流产生的热使其熔断而切断电源。电流的热效应也是近代工业中的一种重要加热方式，如利用电炉炼钢，电机通电烘干等。电流的热效应也有它不利的一面，由于构成电气设备的导线存在电阻，所有电气设备在工作时要发热，使温度升高。如果电流过大，温度升高多就会加速绝缘体老化，甚至损坏设备。为了保证电气设备能正常工作，各种设备都规定了限额，如额定电流、额定电压、和额定电功率等。电器设备的额定值通常用下标“e”表示，如Ie、Ue、Pe等，各种电器设备的铭牌上都有标注他们的数值。GEMultilinSMMII-PD512-120SIMotorManagerIISMMIIPD512120GeneralElectricGEMultilinSMMII-PD511-120SIMotorManagerIISMMIIPD511120GeneralElectricGEMultilinPQMPowerQualityMeterGeneralElectricPQMRelayGEMultilinD60LineDistanceRelayD60J03HMHF8LH6NM6NP6CU6CWXXGeneralElectricGEMultilinMMII-PD-1-2-240MM2MotorManagerMMIIPD12240GeneralElectricRelayGEMultilin169169Plus-100P-120MotorManagementRelayGeneralElectric169P100GEMultilinFeederProtectionRelaySR735SR735-5-5-HI-485Ver.#25D152D1.000GEMultilin369-HI-R-M-0-0369MotorManagementRelayFirmware53CMB170.000NEWGEMULTILINfeedermanagementRELAYSR745MODEL#W2P5G5HIARE,newOEMoriginalGEMultilin269269-100P-120MotorManagementRelayGeneralElectric269100P120GEMultilin369-HI-0-M-0-0-0-0369MotorManagementRelayFirmware53CMC340.000GEMultilinPQM-APowerQualityMeterGeneralElectricPQMARelayGEMultilin239MotorProtectionRelayGeneralElectricFirmware64C263C4.000GEMultilinF60FeederManagementRelayF60G00HKHF8LH6NMXXP6NUXXW7HGEGEMultilinF35FeederProtectionSystemF35G00HKHF8RH6NM8RP6NU8MW6NF35GEGEMultilinF35FeederProtectionSystemF35G00HKHF8RH6NM8RP6NUXXW6NF35GEGEMultilinHID32HighImpedanceDifferentialModuleHID125VDC8W125VDCGEMultilinC60BreakerManagementRelayC60E00HKHF8LH6EM6CPXXUXXWXXGEGEMULTILIN239MOTORPROTECTION250VAC10ARESISTIVERELAYUSEDFromCanadaGEMultilinPQM-T20-C-APowerQualityMeterGeneralElectricPQMT20CARelayGEMultilinT60TransformerManagementRelayT60G00HCHF8FH6PM8HP6PUXXWXXGEGEMultilinL90LineDifferentialRelayL90G00HCHF8FH6PLXXNXXSXXUXXW7DGEGEMultilinF35MultipleFeederManagementRelayF35G00HCHF8FH6PM8HP6PUXXWXXGEMultilinF60FeederManagementRelayF60G00HCHF8HH6PM8HP6NU8HWXXGEGEMultilinF35MultipleFeederManagementRelayF35G00HCHF8HH6PM8HP6NU8HWXXNEWGEMultilinSR760/SR750FeederProtectionRelay760-P5-G5-S5-HI-A20-R-TGEMULTILINCURRENTTRANSFORMER298-301*NIB*GEMULTILINMULTINET-FESERIALTOETHERNETCONVERTER-CHOOSEONE-MACALLDIFFGEF485-F-120MULTILINF485COMMUNICATIONCONVERTERPOWERMANAGEMENTNEWGEMULTILINVOLTAGEMANAGEMENTRELAY2PACKMIVII1000E00HI00CustomsservicesandinternationaltrackingprovidedGEMULTILINVOLTAGEMANAGEMENTRELAYMIVII1000E00HI00GEMULTILINVOLTAGEMANAGEMENTRELAYMIFIINA05E00HIOONEW*GEMULTILINHARDFIBERBRICKSWITCHYARDHARDENEDINTERFACEBRICK-4-HI-CC55GE298-101MULTILINCURRENTTRANSFORMER100:5AN600VAC3INIDR18585GE298-101MULTILINCURRENTTRANSFORMER100:5AN600VAC3INIDR18701GeneralElectricGEMultilinPQMpowerqualitymonitorPQM-T20-C-AGEMULTILIN269MotorManagementRelay269PLUS-100N-120FromCanadaGEMULTILINDIGITALI/OMODELUR6AHGEMULTILINMOTORMANAGERIIMMII-PD-1-2-120FromCanadaUSEDGEMULTILIN269PLUS-100P-120VACMOTORMANAGEMENTRELAY(TR9)Multilin/GE169-120N-120169MotorManagementRelay169120N120CustomsservicesandinternationaltrackingprovidedGEMultilin269PlusMotorManagementRelayUnit48vdcGEMultilin269PlusMotorManagementRelayUnit48vdcMultilinInc.169-120N-120169MotorManagementRelay120VGeneralElectricGEGEMultilin269PlusMotorManagementRelayUnitModel#269Plus-10C-240SNCGEMultilinModel:SM10-120Serial:F0750028120VMotorManagementRelayGeneralElectricGEPQM-T20-C-APowerQualityMeterMultilinGEMultilin269PLUS-100P-HI269MotorManagementRelayF/W52E604C0.000PlusGEMultilin169PLUS-100P-120169MotorManagementRelayP/N25-135-288-109PlusGEMultilinMM300-GEHDSCALowVoltageMotorManagerNEWFromChinaGEMULTILINSR469-P1-H1-A20MotorManagementRelayFromAustraliaGEMULTILIN269PLUS-100P-HI120VACMOTORMANAGEMENTRELAYNEWGEMULTILINSR735735METERSR735-5-5-LO-485FEEDERPROTECTIONGENERALELECTGEMultilinFeederManagementRelayMIFIIMIFIIPA55E00H100GEGeneralElectricMultilinPQM-APowerQualityMeterINSTRUMENTTRANSFORMERSINCGEMULTILIN561-151CURRENTTRANSFORMER3.25"x4.25GEMultilinSR469-CASESR469CASENEWGELimitampMultilinStarter350HP4160VCR194A118D2NewlylistedGEMultilin565-5-5-0-ARelay(InBox)/FeederManagementGEMultilinPowerManagementRelaySR469-P5-HI-A20-EFromCanadaGEPQMMultilinPOWERQUALITYMETERRefurbishedGE/MULTILIN565-5-5-O-AFEEDERMANAGEMENTRELAY**XLNT**GEMultilin735FeederManagementRelayModel#735-5-5-HI-485**TESTED**GEMultilin369-HI-R-0-0-0-0-E369MotorManagementRelayFirmware53CMC350.000GEMULTILINMODELSPM-PFSYNCHRONOUSMOTORCONTROL40A210A0.000USEDGEMultilinMotorManagementRelay469-P5-HI-A20FromCanadaGEMultilin269MotorManagementRelay269PLUS-100P-120FromCanadaGEMultilin12HFC21B1AInstantaneousOvercurrentRelayHFC21B1AGEMultilinMotorManagementRelaySR469RELAY469-P5-HI-A20FromCanadaGEMultilinMotorManagementRelaySR469RELAYSR469-P5-HI-A1FromCanadaGEMultilinMotorManagementRelay169Plus-100P-120FromCanadaGEMultilinMotorManagementRelay169PLU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