It's been a several years since I visited the ISA Expo. As a provider of instrumentation training and on-site instrumentation services, I'm always looking for something unique and/or better in handheld field test equipment. I found one such device this year at the PIE booth.
Practical Instrument Electronics (PIE) was demonstrating their new, patented mA loop calibrator with a diagnostic feature. The PIECAL Model 334Plus was connected to a Rosemount smart temperature transmitter simulating a field calibration of the device. As part of the simulation, PIE introduced either moisture across the transmitter's output terminals or a stray current to demonstrate a current leakage condition that might typically be found in a transmitter housing or poor grounding. The demonstration showed that what is normally interpreted as a zero shift in the transmitter's calibration was, in fact, a current leakage condition. What was truly exciting was that the leakage value was displayed on the same display screen as the transmitter's mA output signal. By subtracting the leakage value from the output signal you could easily see that the transmitter was within calibration and that the error was due to the current leakage caused by the moisture across the output terminals or by the ground fault condition. This information would save hours in performing an unnecessary calibration that, if done, would have actually compromised the integrity of the loop.
In addition to the loop diagnostic technology, I found several other excellent features like the rubber boot, the ease of changing the batteries, the back-lit five digit display and the 250Ω HART resistor. I also discovered that the HART resistor is active not only in the POWER/MEASURE mode (for bench set-up and calibration) but it is also active in the READ mode when there is insufficient loop load resistance and the calibrator is connected in series with the transmitter. Most loop calibrators only have the HART resistor present in POWER/MEASURE mode for bench set-up and calibration. And at $795, it is the best value from any manufacturer for what it does.
Needless to say, I was very impressed.
Process Control Specialists, LLC