Electromagnetic protection circuit of analog signal input line

Abstract

The invention discloses an electromagnetic protection circuit of an analog signal input line. The electromagnetic protection circuit comprises two analog input lines connected with a protected circuit, wherein a grounding wire is connected between the two analog input lines, air discharge pipes and varistors are sequentially connected between the two analog input lines and the grounding wire respectively in parallel, and a transient voltage suppression device is connected between positions, behind connecting points of the varistors, of the two analog input lines. The protection circuit can provide multistage precise protection with wide broadband and high impact energy for lightning stroke surging, electromagnetic interference, radio-frequency interference and the like, effectively weaken interference signals and guarantee safety of normal signal level waveforms and backward stage circuits. The electromagnetic protection circuit resolves the technical problem of various kinds of electromagnetic interference protection in an analog input channel of an instrument control system of a nuclear power plant.

Description

technical field [0001] The invention relates to the field of electricity, in particular to a protection circuit for protecting an analog input of an instrument and control system of a nuclear power plant from electromagnetic interference (EMI). Background technique [0002] The instrument and control system of nuclear power plants is the "nerve center" of nuclear power plants, and is an important equipment to ensure the safe and reliable operation of nuclear power plants. It inputs and outputs a large number of signals at all times. According to research reports: electromagnetic interference, radio frequency interference and Lightning surges have been confirmed as environmental factors that affect the performance of safety-level electrical equipment. Therefore, ensuring the electromagnetic compatibility of safety-level digital instrumentation and control systems is an important step to meet the safe and reliable operation of nuclear power plants. Most of my country's nuclear...

AI Technical Summary

Problems solved by technology

[0005] In order to solve the problem of poor protection against electromagnetic interference on the analog input signal circuit in the prior art, the present invention provides an analog electromagnetic protection circuit capable of realizing multi-level electromagnetic protection. The specific scheme is as follows: an analog signal input circuit The electromagnetic protection circuit includes two analog input lines respectively connected to the protected circuit, characterized in that a ground wire is connected between the two analog input lines, and a ground wire is connected between the two analog input lines and the ground wire. Air discharge tubes and varistors are respectively connected in parallel in sequence, and a transient voltage suppression device is connected between the two analog input lines after the connection point of the varistors

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