Examples of input /output wiring and connections
MEASURE CH1 | SIMULATION CH1 |
Thermocouples, mV mA Active loop
+PS
+- 
+IN
- | |
| RTD |
mA Passive Loop
+
+PS
-- 
+IN
RTD
Rtd (2 wire)
+PS
- 
+IN
RTD
Rtd ( 3 wire)
+PS
- 
+IN
RTD
Rtd (4 wire)
NOT CONNECTED 
+PS
- 
+IN
RTD
Thermocouples, mV mA Active loop
+PS
+- 
+IN
- | |
| RTD |
mA Passive Loop
+
+PS
-- 
+IN
RTD
Rtd (2 wire)
+PS
- 
+IN
RTD
Rtd ( 3 wire)
+PS
- 
+IN
RTD
Rtd (4 wire)
| +PS |
- | +IN |
| |
| RTD |
7.2Thermocouple wires
When making measurements where additional wires have to be connected to the thermocouple leads, care must be exercised in selecting these wire types, not only where they are claimed to be of the same composition as the thermocouple involved, but, also, of their "quality".
Performance results where high precision is required and in circumstances where some types of thermocouple wire leads are added to the original installation should be reviewed carefully for the impact of the choice of the additional wire leads.
The quality of thermocouple wire is established by the limit of error to be expected with its use. There are three recognizable levels of quality:
-Special or Premium grade
-Standard grade
-Extension wire grade
The error limits determining the grade quality differ from thermocouple type to thermocouple type, reflecting the degree of difficulty in maintaining the precise levels of purity of the metal used.
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