Lightning Protection Measures for Smart Instruments




I. Overview

       The industrial computers, various communication modules, security devices, and field measurement instruments in smart instrument control systems mostly use integrated circuits composed of electronic components. These micro-electronic devices generally have fatal weaknesses such as low insulation strength and low surge withstand capability. During thunderstorm seasons, they are often damaged by lightning strikes, ranging from partial damage to input/output modules of several instrument computers to complete paralysis of the entire control system, forcing shutdown for repairs and causing huge losses. Therefore, it is very necessary to add lightning protection devices to these control and production installations. The closed cup flash point automatic tester heats up according to standard methods, automatically lifts, automatically ventilates, automatically ignites, automatically displays, automatically locks the flash point value, and automatically prints results. It is widely used in electric power, petroleum, chemical, commodity inspection, scientific research, and other departments.

II. Lightning Intrusion Paths

      Lightning surge intrusion leads to computer and communication failures. When the surge exceeds the computer's tolerance, data garbling, chip damage, or even software system corruption can occur, causing interruption of data reception/transmission.

      Research on lightning protection for smart instrument control systems should start from both external and internal system lightning protection. External lightning protection measures mainly address the harm of induced lightning to measurement instruments. Surge intrusion paths mainly include signal cables introducing induced surges into measurement instrument circuits, damaging insulation, breaking down micro-electronic components, causing instrument faults, and direct induced lightning entering the instrument circuit through the instrument body, breaking down circuit modules and causing faults. The solution is to re-review the overall lightning protection measures of the installation and the grounding of signal communication cables according to lightning protection specifications, arrange wiring reasonably, and ground metal instrument boxes. For protection systems of critical interlock signals, surge protectors should be installed; internal lightning protection mainly refers to power supply lightning protection for smart instrument control systems, grounding of control display units, operating systems, engineer stations, and other data processing equipment, as well as lightning protection for signal channels entering and leaving computers and for signals and power of LAN-related switches, network cards, etc.



III. Practices for Preventing Lightning Strikes

    Improve the grounding system

    (1) The safety protection ground, control cabinet, operation console, engineer station, power cabinet, and other chassis grounds should all be connected together using flat steel.

    (2) The instrument signal ground and computer input/output signal ground are reference points for instrument measurement. All instrument working power supplies, such as the negative terminal of 24V, should be connected to this ground to form equipotential.

    (3) The intrinsic safety ground, safety barriers, isolation barriers, safety devices, etc., should also be connected to the instrument signal reference point to form an equipotential system. The grounding should be gathered at one point, and the resistance should not be greater than 1Ω.