低压电动机热继电保护的研究-电气工程专业论文.docxVIP

ABSTRACT Thermal relays have been usedωprotect low-voltage motors in MCC (Moωr Control Center) circuit for long，but some 由自mal relays and MCCB overloads cant simulate the electrical and 也.ermal characteristics ofMCC load. This protection device uses mathematical methodsωbuild the heating model of the moto瓦 and taking 也 diffi町ence of thennal effi础。f positive例时 and neg聪明-order cUlTent into 懈 account，也e 伽ermal 叫uivalent cUlTent is used in the heating model，ω 也.e problem of a # low-voltage motors thermal protection is 脆就led from the principle. The circuits principle figure is 伽stly designed， and then 伽e PCB map and 也.e circuit board are made，which 扭曲e pa此 of the hardware. Then choose 也e appropriate algorithms，including 也e reinstating of individual sampling values，the calculations of A、B and C three-phase cuηents valid values，the calculations of positive-order，negative-order，zero-order currents values，and the diploid calculations of over 103副ng. 日创ed on different overload multiples and different heating time constants deciding different protection motion time，aωm阳nt table is created. Finally a procedure ωdown1oadω 也e SCM chip is designed， and 由rough 伽e implementation of the procedure ，也e low-voltage m悦。rs protections of overheating，grounded， over-cUlTent，由.e lack of phase and blocking tuming are achieved. This device c姐 protect electrica1叫uipmentbe忧町怕也e basis of saving relays and s加州。ring 也e MCCB construction. 民锄Key words: Low叩oltage motor 白lennal relay Pro阳ction Mathematical 民锄 且 1 且 1 JM Fh AaT a斗 F3 lv rO OO AMJ hy hy hυ AU -- I A钟 o rO OO AY AU -- i 1 tA tA 1A 且 tA t且 tA ?翩 。， 匀， 句， 目录… 值 … 目录 … 盟 … … … … … … … … … … … … … … … … 效 … … 装 … 川 川 … 川 叫 川 川 … … … … … … … … 有 … … 护 … … … … … … … 川 … … … … … … … … 流 … … 最 保 … … 川 川 川 川 川 川 … 川 川 … … 川 … … 电 … …… 护 继 … 如 … … … … … … …ι …ι … …… 装 电 … 1 …… 护 继 … 如 … … … … … … …ι …ι … … 值 值 零 …常…Z盟……儿…段时……白tι…椭…… 札 … 式 流 作 和 WM 原 原 载 …