How to protect transducers from electromagnetic and radio-frequency interference

June 29, 2018

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Design engineers have a lot to consider when selecting components for use in end-user products and equipment. Original Equipment Manufacturers (OEMs) that follow a strict Design for Manufacturing and Assembly (DFMA) methodology will have few, if any, problems with pressure transducers. However, OEMs that do not adhere to DFMA practices in their factory increase the likelihood of reoccurring issues, including transducer failure.

(This article is part of a series focused on OEM design considerations. CLICK HERE to view the previous article in the series)

A pressure transducer converts pressure into an electrical signal and is by nature susceptible to the negative effects of electromagnetic emissions or electrical disturbances. Transducer manufacturers do their best to protect the transducer from outside disturbances, but certain design considerations could reduce or prevent effects from electromagnetic interference (EMI) and radio-frequency interference (RFI).

Finding other sources of interference

It is recommended to locate motor generator sets at a safe distance from machinery installed with transducers and its associated wiring to prevent faulty signals and other troubles caused by induced voltage. Other EMI/RFI sources to avoid include contractors, power lines, computers, walkie talkies, cell phones and large machinery that produce varying magnetic fields. The most common ways of reducing EMI/RFI noise are shielding, filtering and suppression. Contact the pressure transducer manufacturer for help on how these preventative measures can be implemented.

BLOG: How do extreme temperatures in the factory affect transducer performance?

OEMs that follow National Electrical Code (NEC) guidelines, run low voltage lines in conduits separate from high voltage raceways, such as for a pump skid application. Other OEMs, however, run power and signal cables in the same conduit. As a result, they may experience signal lines with extra induced voltage, which may run the length of the low voltage wires, presenting a possible electrical problem for an application like pump skids.

Also, it is advisable for OEMs to have different power sources for the transducer and control system. The risk comes from de-energized relays in the control circuit creating back an electromagnetic field (EMF) that will travel to the power source, causing a voltage spike. If it’s more than the supplier’s maximum rated voltage, the transducer will be permanently damaged and burn marks can be visible on the circuitry.

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Topics: General Industrial OEM, Test and Measurement, General Industrial