Keller Swiss-Built Series 21/21 Pro Piezoresistive pressure transmitters standard and programmable (pro) versions
The KELLER Series 21 / 21 PRO are extremely reliable and cost effective pressure transmitters. These pressure transmitters use a programmable KELLER-ASIC microchip called!±ProgRes!± (programmable resistors). The !±ProgRes!± chip enables the transmitters to be up and calibrated using automated test equipment, for improved product quality and lower costs. The PRO versions also have the unique feature that they can be programmed or reranged by the end user, via the hand held PP-96 programmer. Since its first introduction in1989, the Series 21 / 21 PRO was an immediate success, thousands of transmitters and hundreds of programmers are in daily service worldwide.This transmitter uses the KELLERSeries 6 SC capsule as the core. The sensor is a piezo-resistive silicon pressure sensor, mounted in an oil filled capsule. The media pressure is isolated by a stainless steel diaphragm and transferred to the silicon sensor hydraulically via the oil.
The !±ProgRes!± circuit has programmable resistor networks, to set the Zero / Gain and therm coefficients. All Series 21 / 21 PRO transmitters are subjected to comprehensive test procedures which cycle both pressure and temperature, the various parameters are then automatically calibrated and set by the computer controlled test rig at the end of the run. A final test
then checks that the settings are correct and within specification, only then are the transmitters are released for use. Note: The standard Series 21 transmitters are NOT user pro-grammable.
The programmable version transmitters, Series 21PRO has the data lines brought out to an Amphenol 8-pin connector, allowing simple and precise adjustment of Zero and Span. The KELLER Programmer PP-96 is used to facilitate programming of individual transmitters. The PP-96-10 can handle up to 10 identical transmitter at one time. The signal output of a PRO version transmitter may be adjusted to give full-scale between 40% and 120% of the nominal range, and !à20% zero adjustment
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