Written by: Roselius, Herb
Ambient temperature sensor 4 to 20 mA displays -40 to +150 °F.
In order to provide the best resolution over the temperature range of interest, most temperature measurement circuits output a signal that requires a significant offset as well as a span adjustment. There are very few applications which output 0 V or mA for 0° or 1 V or 1 mA for 1000°
Ranges as listed below are much more likely:
- 4 to 20 mA to display -40 to +150 °F for ambient temperatures.
- 0 to 10 V to display -60 to +500 °F (-51 to +260 °C) for temperature chambers.
- 1 to 5V to display -150 to +100 °F (-101 to +38 °C) for cold testing.
- 4 to 20 mA to display +300 to +900 °F (+149 to +482 °C) for plastics molding.
- 0 to 5V to display +1000 to +2500 °F (+538 to +1371 °C) for kilns.
In the past some of these have been very difficult to do especially those which required a large offset with a small span or an offset in the wrong direction. All these can be readily handled today with a single DPL-3 or DPV-3 (note the +1000 to +2500 °F range would require using the DPV-4 to get the higher resolution).
Using a DPL-3,
4 mA input can be adjusted to display -40.0
20 mA input can be adjusted to display 150.0