Precision Filters, Inc. today introduced its latest advance in piezoelectric charge and IEPE signal conditioning for shock, pressure and vibration measurements—the 28316C, part of the 28000 Series product line. Now with PFI’s 4-pole best-in-class FLAT/PULSE low-pass filters, the card provides 16 channels of precision signal conditioning for IEPE accelerometers or remote charge converters (RCCs).
The high-density, 16-channel 28316C card supports up to 256 individually programmable IEPE/RCC signal conditioning channels per chassis. IEPE supply current may be set to 0, 2, 4, or 8 mA. Gain may be selected from x1/16 to x512 with 0.1% resolution. Auto-gain ranging may be used to assign the best A/D converter dynamic range. 4-pole FLAT/PULSE low-pass filters may be configured for frequency or time domain measurements to respectively have either maximally flat passband or linear phase with optimized pulse response. Filter corner frequencies may be set to one of five values between 100 Hz and 30 kHz or bypass. To avoid ground loops, input isolation mode may be selected when conditioning grounded IEPE accelerometers. Finally, each channel may alternatively be utilized as an AC filter/amplifier with balanced differential input.
In addition to monitoring sensor cable open and short status, a further indication of sensor health is provided by a sensor bias point detector, which determines whether the sensor bias voltage is within limits, as set by user-specified thresholds. As an indication of signal integrity, an overload detector identifies large out-of-band signals the filter might remove. For both detectors, status is indicated in both the host computer GUI and on front panel LEDs. Further, each channel has dual independently buffered outputs for additional diagnostic monitoring or connection to auxiliary recording devices without corrupting the primary data path.
As a Go/No-Go test, a small AC calibration current may be superimposed on the DC IEPE supply, which reacts with the sensor output impedance to stimulate a sensor-based AC test signal. This may be used as a measure of IEPE sensor health, as output impedance is highly stable in normally functioning IEPE sensors. In addition, as all test and measurement systems require periodic calibration, Precision Filters incorporates rigorous Factory Acceptance Test (FAT) capability. The built-in 28000 System test hardware and software enables NIST traceable calibration tests to be carried out on site, without removing the system from the equipment rack, greatly reducing system downtime and calibration cost.
The 28316C supports a mixed-mode transducer interface in conformance with the IEEE 1451.4 Smart Transducer Interface standard. The related TEDS (Transducer Electronic Data Sheet) information—including manufacturer name, serial number, and calibration data—is readable by the system for use in system scaling, identification, bookkeeping, troubleshooting, and other functions. While conventional TEDS readers for signal conditioning are limited to a maximum cable length of 400 feet, Precision Filters’ proprietary Long Distance TEDS (LDTEDS™) can operate with cable lengths of up to 1,500 feet, critical for the use of TEDS data in applications such as weapons test, vibration test on large structures, safety, and environmental testing.
For more information on the 28316C piezoelectric charge and IEPE signal conditioning card, please visit our Charge and IEPE Conditioning page.