High Electromagnetic Radiation Environments: Impacts and Countermeasures

Water quality online monitoring instruments serve as the technological backbone of aquatic environmental management. Their measurement accuracy and operational stability directly influence water quality assessment and environmental decision-making. In practice, however, these instruments are often deployed in industrial zones, near substations, along high-voltage transmission lines, and in other locations characterized by complex electromagnetic environments. 

Prolonged exposure to high electromagnetic radiation poses a significant and often underestimated threat to monitoring reliability. Understanding the mechanisms of electromagnetic interference (EMI) and implementing effective protective measures are essential for ensuring the integrity of monitoring systems.

Mechanisms of Electromagnetic Interference

EMI affects water quality monitoring equipment through two primary pathways: radiated coupling and conducted coupling.

Radiated coupling occurs when electromagnetic radiation sources—such as high-voltage equipment, variable frequency drives (VFDs), and large motors—emit energy in the form of spatial electromagnetic waves. These waves enter the electronic systems of monitoring instruments and superimpose upon normal measurement signals, degrading the signal-to-noise ratio.

Conducted coupling, by contrast, involves interference signals invading equipment through conductive paths such as power supply lines and signal transmission cables. The 50 Hz power-frequency electromagnetic fields and line surges inherent in power systems can create persistent interference through these routes. EMI can be coupled into sensor wiring and electronics, causing significant signal distortion.

Impacts on Instrument Performance and Data Quality

The consequences of high electromagnetic radiation on water quality online monitors manifest across multiple dimensions.

Measurement Data Anomalies – EMI disrupts the signal stability of detection circuits, causing raw signals collected by sensors to become erratic. Electrochemical sensors such as pH and dissolved oxygen electrodes, which output extremely weak potential signals, are particularly vulnerable—electromagnetic radiation coupled into signal transmission lines can directly cause data fluctuations, spikes, or outright distortion. Instruments based on optical or chemical colorimetric principles, including permanganate and COD analyzers, also suffer as their signal processing modules become susceptible to interference, potentially yielding results that are erroneously high, low, or wildly unstable.

Reduced Repeatability and Transmission Interruption – Under strong electromagnetic fields, repeated measurements of the same homogeneous water sample may yield significantly different results, undermining data consistency. Simultaneously, electromagnetic radiation interferes with the modulation and demodulation of wireless signals, leading to data packet loss, latency, or even complete transmission failure. For buoy stations and outdoor monitoring stations that rely on 4G, LoRa, or other wireless transmission methods, strong EMI can suppress communication signals to the point where the device cannot connect to the base station.