二次回路中电快速瞬变脉冲群骚扰的研究

为有效抑制电快速瞬变脉冲群（EFT/B）骚扰对微机保护装置的干扰，研究了EFT/B骚扰的形成和耦合机理。分析了开关分断操作形成EFT/B骚扰的过程;通过对二次回路中控制继电器操作时形成EFT/B骚扰的研究，分析得出出口继电器线圈上耦合的骚扰电压严重干扰微机保护装置的直流电源电压;采取续流二极管、电磁屏蔽和RC保护等主动防护措施抑制EFT/B骚扰的形成和耦合。结果表明，可从干扰源和耦合途径上有效抑制EFT/B骚扰对微机保护装置的干扰。

Study on EFT/B in Secondary Circuit and Initiative Countermeasures

The formation and coupling principle of electrical fast transient/burst(EFT/B)is studied to effectively protect microprocessor protection devices from the EFT/B disturbance.The forming process of EFT/B caused by switch operation is dealt with.By analyzing the EFT/B disturbance formed by operating control relay in the secondary circuit,it is observed that the coupled disturbance voltage of the output relay coil can badly interfere with the DC power source voltage of the microprocessor protection devices.Such initiative countermeasures as fly-wheel diode,electromagnetic shielding and RC protection are used to restrain the formation and coupling of EFT/B disturbance.The results indicate that the EFT/B disturbance from the interference source and coupling path can be effectively restrained.