Pyromation T82 - Manual (Page 36)

Technical data T82
36
Designation/measuring range Performance characteristics
Resistance
transmitters (W) 10 to 400 W
10 to 2
000 W
±0.04 W
±0.8 W 0.03 %
0.03 %
Voltage transmitter
(mV) –20 to 100 mV ±10 µV 0.03 %
1) % refers to the set span. Accuracy = digital + D/A accuracy
Physical input measuring range of sensors
10 to 400 W Cu50, Cu100, polynomial RTD, Pt50, Pt100, Ni100, Ni120
10 to 2 000 W Pt200, Pt500, Pt1000
–20 to 100 mV Thermocouples type: B, C, D, E, J, K, L, N, R, S, T, U
Sensor adjustment Sensor transmitter matching
RTD sensors are one of the most linear temperature measuring elements. Nevertheless, the output
must be linearized. To significantly improve temperature measurement accuracy, the device
allows the use of two methods:
• Callendar-Van-Dusen coefficients (Pt100 resistance thermometer)
The Callendar-Van-Dusen equation is described as:
The coefficients A, B and C are used to match the sensor (platinum) and transmitter in order to
improve the accuracy of the measuring system. The coefficients for a standard sensor are
specified in IEC 751. If no standard sensor is available or if greater accuracy is required, the
coefficients for each sensor can be determined specifically with the aid of sensor calibration.
• Linearization for copper/nickel resistance thermometers (RTD)
The polynomial equation for copper/nickel is as follows:
The coefficients A and B are used for the linearization of nickel or copper resistance
thermometers (RTD). The exact values of the coefficients derive from the calibration data and
are specific to each sensor.
Sensor transmitter matching using one of the methods explained above significantly improves the
temperature measurement accuracy of the entire system. This is because the transmitter uses the
specific data pertaining to the connected sensor to calculate the measured temperature, instead of
using the standardized sensor curve data.
1-point adjustment (offset)
Shifts the sensor value
2-point adjustment (sensor trimming)
Correction (slope and offset) of the measured sensor value at transmitter input
Current trimming (current output fine adjustment)
Correction of the 4 or 20 mA current output value
Non-repeatability
Input
10 to 400 W 15 mW
10 to 2 000 W 100 ppm * measured value
–20 to 100 mV 4 µV