Datasheet RM07D471KC1IE100 (Dersonic) - 4

編號DOC NO.: DEC-SA-WI007 版本REV.: B/1 壓敏電阻器規格承認書 日期DATE: 2021/6/17 APPROVAL SPECIFICATION FOR VARISTORS 頁碼PAGE: 3 / 15 2. 概述 INTRODUCTION 壓敏電阻是一種具有在一定的電壓條件下支援電流急速流出的電壓-電流特性的產品。 A varistor has the volt-ampere characteristics in which current suddenly starts to flow through the device at a certain voltage. 壓敏電阻的作用：保護在電子線路中的電子元器件免受過電壓的影響。如下圖所示，壓敏電阻並聯在電 路中起保護作用。當有脈衝(脈衝電流Is：由脈衝電壓Vs和阻抗Zs決定)施加在電路上时，脈衝電流 （Is）限制脈衝電壓在壓敏電阻的限制電壓Vc之內。 The varistors are used to protect components in electronic and electric circuits from overvoltage. As shown in following figure, a varistor is inserted in parallel with a circuit to be protected. When a pulse is applied to the circuit, pulse current Is, which is determined by pulse voltage Vs and pulse impedance Zs, flows to limit the pulse voltage to the varistor limit voltage Vc. 壓敏電阻器對脈衝的吸收 PULSE ABSORPTION BY VARISTOR 相互的關係可以用下面的公式來解釋： The relation can be expressed by the equations as follows: Vs=Is×Zs+Vc ∴ Vc=Vs-Is×Zs 因為Vs遠遠大於Vc，脈衝電流Is可以用以下公式求得 The pulse current Is are easily obtained by the following equation because of Vs much larger than Vc. Is≈Vs÷Zs 所以，由於可承受電壓大於最大的限定電壓，電路可以長时間的免於脈衝電壓的損壞。 Thus, the circuit can be protected from being damaged by pulse voltages as long as it has withstand voltage larger than the maximum limit voltage. 由於吸收異常電壓和電流脈衝的特性，壓敏電阻可非常高效的保護電子器件。 Owing to the characteristic, the varistors are extremely effective as protecting devices of electronic and electric equipment by absorption of abnormal voltages and lightening pulses.