Endress+Hauser RMA 421 - Page 74

6.4 Temperature measurement in a furnace
The temperature in a furnace is being measured using a thermocouple Type S
(PtRh-Pt) and displayed. The range of 1100°C to 1300°C is to be retransmitted
to a DCS in the form of a 4-20 mA current signal. A warning lamp illuminates
should the value go below 1150°C, below 1100°C the material feeder is
switched off.
In fault condition the current signal ramps to minimum safety. The terminal
temperature compensation point is used for cold junction compensation.
Example:
Input/Output:
- Input thermocouple Type S
- Internal temperature compensation
- 1100°C equals 4 mA
- 1300°C equals 20 mA
- Fault condition equals 3.6 mA at the analogue output
Set point 1:
- Minimum safety
- Switch point 1150 (°C)
- Hysteresis 10 (°C)
Set point 2:
- Minimum safety
- Switch point 1100 (°C)
- Hysteresis 50 (°C)
Setting up:
Menu group Address Value
Analogue input
INPUT Input range RANG
Curve CURVE
Comparison temperature COMPT
TYP5
°C
INT
Analogue output OUTPT Output range RANG
Scale analogue output 0% OUTLO
Scale analogue output 100% OUTHI
Fault operation FAIL
4-20
11000
13000
MIN
Set point/fault monitor LIM1 Mode MODE1
Set point
SETP1
Hysteresis HYST1
MIN
1150,0
10,0
Set point/fault monitor LIM2 Mode MODE2
Set point SETP2
Hysteresis HYST2
MIN
1100,0
50,0
Process transmitter
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