KELLER’s INTERFERENCE-RESISTANT PRESSURE TRANSMITTERS
INSTROTECH, the local representative of Keller, offers a pressure transmitter for temperature compensation and protection from electromagnetic fields (EMC) in the recently approved 21Y Series. With measuring ranges between 2 bar and 1000 bar, the 21Y Series transmitters can be used at temperatures ranging from -20 °C to +100 °C in any industrial application, even in the immediate proximity of frequency converters.
Particular attention has been paid to providing low-cost calibration that guarantees a maximum Total Error Band of ±1.5 %FS over the entire standard temperature range of -10 °C to +80 °C.
Extensive data collection, such as that required by polynomial correction schemes, is replaced by a more straightforward, cost-effective method. The temperature range is divided into as many as 120 subdivisions, of 1.5 Kelvin each, by an integrated temperature sensor and an additional digital circuit. The compensation values for TK zero point and TK amplification for each of these subdivisions are calculated individually following a mathematical model and stored in the transmitter. These values are fed into the analogue signal path during operation, depending on the temperature, without reducing the 2 kHz bandwidth.
Keller 21Y Series transmitters are also characterised by being extremely resistant to electromagnetic fields. The verified values for conducted and radiated fields are significantly below the limits of the CE standard. These transmitters are also immune to external voltages between the housing and the electrical connection of up to 300 V.
The scope of the vertical range of manufacture, the modular design, and the programmable electronics mean that large-scale, customer-specific batches can be easily accommodated. Keller manufactures and stocks large quantities of pressure transducer measuring cells. They are then welded into the transmitter head with the required pressure connection, equipped with electronics, and individually calibrated over the entire temperature and pressure range in large, purpose-built test systems.
2-wire (4 to 20 mA) and 3-wire (VDC) output signal versions are available, and an extensive selection of pressure and electrical connections can be supplied as standard.
