Why Your General Purpose Pressure Transmitter Failed at Startup

Ever had a general purpose pressure transmitter that passed calibration in the morning but failed by afternoon? We traced the issue to VFD interference. During startup, the pressure readings dropped 20% unexpectedly. The physics of 4-20mA loops require stable signals. Any deviation needs extra conditioning, which adds complexity. Our standard industrial pressure transmitter couldn’t handle the high-frequency switching from the VFD. As a result, we saw spiking inaccuracies at startup. First, we tested the transmitter in the lab. It showed spikes exactly when the VFD ramped up. Then, we isolated the problem to electromagnetic interference. The anti-interference capability of our existing sensor was insufficient. Therefore, we switched to the DR3401 General Purpose Pressure Transmitter. This standard 4-20mA pressure sensor features robust anti-interference design. Installation was straightforward. Within a week, we observed stable readings even during VFD ramp-up. The response time of 5ms ensures the PLC gets updated data quickly. Also, the long-term stability with less than 0.02% thermal drift prevents future drift issues. For example, the DR3401’s compact industrial design with IP67 rating fits our existing setup. How much have you spent on signal conditioners for non-standard outputs? Consider a standard 4-20mA pressure sensor like the DR3401 to simplify your system. [Learn more about VFD interference from ISA](https://www.isa.org). [Check Control Engineering for signal conditioning tips](https://www.controleng.com).

Tags: #pressuretransmitter #DR3401