In the fields of modern industrial process control and precision measurement, pressure transmitters play a key role in converting physical pressure signals into standard electrical signals. Their measurement accuracy and long-term stability are directly related to production safety, energy measurement, and quality control. However, the complex and harsh electromagnetic environments of industrial sites—such as high-frequency transients generated by the start-stop of variable-frequency motors, radio-frequency interference radiated by high-power wireless equipment, and grid harmonics as well as ground potential fluctuations—can all invade the transmitter internally through power lines, signal lines, or spatial coupling. These interferences can, at best, cause spikes and drift in the output signal, and at worst, overwhelm the weak sensor signal or even damage the precision detection circuitry, seriously threatening the reliability of the measurement system. Against this backdrop, feedthrough capacitors have become core components for safeguarding the signal purity of pressure transmitters and enhancing their electromagnetic compatibility, thanks to their unique “through-type” structure and exceptional high-frequency noise suppression capabilities.

The design of threaded mount feedthrough capacitors is ingenious and rigorous. Their main body consists of a metal housing with external threads, filled internally with high-performance ceramic dielectric, through which a central conductor passes. During installation, a continuous, low-impedance 360-degree electrical connection is formed between the metal threads and the metal cover. This provides an ideal path for high-frequency interference to be directly channeled into the casing (ground). Any high-frequency noise attempting to enter through the leads is bypassed to the grounded housing via the low-impedance path of the feedthrough capacitor before it can enter the cavity, thus preventing interference with the fragile internal detection circuitry. Particularly important is the secondary sealing process applied to the upper lead hole port after the feedthrough capacitor is installed: an epoxy resin layer is used. This step is critical, as the cured epoxy resin forms a robust and stable moisture barrier, effectively isolating internal components from moisture, corrosive gases, and dust in the air. Internally, the lower lead of the threaded feedthrough capacitor is reliably connected to the detection circuit board inside the cavity via short wires; externally, its upper lead extends through the epoxy resin sealing layer to connect with field wiring terminals or cables. This structure achieves the integration of “filtering” and “sealing,” eliminating the risk of dielectric constant changes in the capacitive sensor or failure of the detection circuit due to moisture ingress, while also preventing the accumulation of condensation on the circuit board due to poor sealing.

Therefore, in such high-demand pressure transmitters, the role of feedthrough capacitors extends far beyond conventional power filtering. They construct a comprehensive defense line that integrates electromagnetic shielding, high-frequency filtering, mechanical sealing, and electrical connectivity, making them indispensable “guardians of precision” in industrial automation systems.