二线制变送器端口抗扰度分析及抑制对策

Analysis on the Immunity of Two-Wire Transmitter Port and Suppression Countermeasure

为了避免二线制变送器遭受雷电浪涌的破坏,对其端口进行浪涌抗扰度试验。试验电路分为直接耦合以及阻抗耦合两种,观察变送器在组合波的不同浪涌等级冲击下的抗扰度水平。试验表明,变送器在直接耦合的状态下抗浪涌能力很低,幅值为50 V的组合波已致其损坏。而变送器在阻抗耦合的条件下,抗扰度大幅提高,10 kV的组合波对变送器也不造成损害。多种退耦电阻以及两种型号的TVS管组成的浪涌保护器在组合波冲击下,当退耦电阻阻值为2.1Ω时,TVS管的残压较小且浪涌保护器的前级泄放了大部分电流。

To avoid the two-wire transmitter suffered by lightning surge damage, the surge immunity test is carried out on its port. The test circuit is divided into direct coupling and coupling impedance,coupling, the transmitter is damaged when amplitude of the combination is 50 V.While in the condition of the impedance coupling, the immunity of transmitter is greatly improved, and the transmitter is not damaged even the amplitude of the combination wave is up to 10 kV. The results also show that the decoupling resistor will affect the residual voltage and the most appropriate value, of the decouplingresistor is 2.1Ω.