Keller's interference-resistant pressure transmitters

June 15, 2023  170  170   

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. Depending on the temperature, these values are fed into the analogue signal path during operation 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.

Keller 21Y Specifications:

• Accuracy: + 0,5%FS
• Total error band :1,5%FS @ -10…80°C
• Pressure range: 0…2,5 to 0…1000 bar