PC3000 Complete Installation guide iss 12 - Elektro-Trading
PC3000 Complete Installation guide iss 12 - Elektro-Trading
PC3000 Complete Installation guide iss 12 - Elektro-Trading
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Calibration of the cold junction sensor<br />
<strong>PC3000</strong> <strong>Installation</strong><br />
4 Channel Analogue Input Module<br />
The Cold Junction Sensor is calibrated on one range only, normally the 10mV range.<br />
The millivolt input must have been calibrated prior to this process.<br />
Zero<br />
+<br />
-<br />
<strong>12</strong>v 9.999v 0v + mV -<br />
EUROTHERM 239<br />
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Extension Cable<br />
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A reference thermocouple or a temperature compensated millivolt source may be<br />
used to provide a known ‘hot junction’ temperature. This data is then used to<br />
compute the cold junction sensor calibration data. The parameter Lin_Type must be<br />
set to match the required thermocouple type and the parameter Input_Type should be<br />
set to the appropriate millivolt range prior to calibration. It is calibrated in the factory<br />
using type ‘K’ thermocouple. It is recommended that calibration is performed using<br />
this sensor type, although other sensor types may be selected as required.<br />
If a temperature compensated source such as the Eurotherm Controls 239 is<br />
employed, this must be connected to the wiring terminals using thermocouple<br />
extension cable appropriate to the sensor type selected on the 239. Ensure that both<br />
the extension cable and the sensor type selected on the 239 match the Lin_Type<br />
selected for the module.<br />
The procedure is as follows:<br />
(1) Ensure that the following parameters are reset to their default values:<br />
Parameter Value<br />
Filter_Time 0s<br />
Pre_Scaler 1<br />
Pre_Offset 0<br />
Post_Scaler 1<br />
Post_Offset 0<br />
(2) Set the 239 to the correct number of millivolts for the equivalent hot junction<br />
temperature e.g 60°C. Alternatively an ice cell may be used.<br />
(3) Enter the temperature of the ice cell or 239 equivalent millivolt signal into the<br />
parameter, Cal_CJC_P.<br />
(4) Allow 15 seconds for the input voltage to be averaged. Note that if the prescribed<br />
time is not allowed, and the next step is performed before the input has been<br />
averaged, the resultant calibration may be in error.<br />
nc<br />
Terminal Number<br />
Function CH1 CH2 CH3 CH4<br />
I+ 2 5 9 <strong>12</strong><br />
NC 3 6 10 13<br />
I- 4 7 11 14<br />
9-15
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