Friday, July 30, 2010
draw and explain the calibration procedure of smart temperature xmitter,sensor is thermocouple
a.prepare calibration data sheets, and technical manual of the xmitter for calibration
b.prepare test equipments and accs needed
c.connect compensating cable to the input side of the temperature transmitter
red color wire must be connected to the negative - terminal and yellow wire connect to the + terminal.The other ends connect to a standard simulator(calibrating instruments) yokogawa 2553 DC current voltage standard transmation 1045.
d. connect power supply 24 vdc, its + terminal connect to the other end of the 250 ohms resistor precision whle the other end to the + terminal of the transmitter, The -terminal of the power supply will be connected to the - probe of the fluke 87 and its + probe will be connected the probe of HHT to the terminals of the x mitter (HHT probe has no polarity)
e.power "on" both the power supply and the HHT
f.check the configuration of the xmitter, If not yet configured provide datas fro down loading and configure ncluding its range
g.if in case the x mitter has been configured, get the range and do the 5 points datas for the calibration, get the ambient temp where you are doing the calibration and know the equivalent MV thru its standard temp convection table.
h.get the equivalent MV signal of the 5 points datas and minus the ambient MV signal to the 5 points MV signals. The remaining Mv will your input signal to the x mitter.
i.send MV signal fhru the calibrator from 0.25,50,75 and 100 of the range and its corresponding 4 to 20 MA output.Then decreasing signal from 100,75,50,25 and 0 % of its range. Record the datas of the calibration data sheet under the as found. If in case the output signal did not match to the desired value or accuracy is not satisfied, then adjustments are to be made.
j.thru the hht adjust zero and span until all readings are Ok or within the accuracy limit.again do the 5 points for both increasing and decreasing signals. if all the results are within tolerance base on its accuracy list themn the calibration is complete.So these datas will be our as corrected or as left. compete the calibration data sheet and provide calibration sticker to the xmitter, shut off thepower and disconnect all the wirings.
k. housekeeping.
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