Fluke 9140 9.2 Dry-well Characteristics

2. Place the probe to be calibrated, the unit under test (UUT), in another

well.

3. With the reference inserted into one well and the probe under test in-

serted into a second well, make measurements of each.

4. Swap the locations of the reference probe and probe under test. Allow

plenty of time for thermal settling.

5. Make another set of measurements of the reference probe and the probe

under test.

6. Average the two measurements of the reference probe. Average the two

measurements of the probe under test. Averaging the two measurements

in this way eliminates error due to temperature gradients between the

two wells.

7. You may now compare the averaged measurement of the probe under

test with the averaged measurement of the reference probe.

For best results repeat the test several times at the same temperature and at dif-

ferent temperatures.

This method can be used with different typeso fp robesbut the user must deter-

mine the uncertainty of the measurement.

9.1.3 Calibration of Multiple Probes

Fully loading the calibrator with probes increases the time required for the tem-

perature to stabilize after inserting the probes. Be sure that the temperature has

stabilized before starting the calibration.

Multiple probes may be calibrated simultaneously using either the direct or

comparison calibration method. Stem effect willcause less error in the compar-

ison calibration method than with the direct calibration method.

9.2 Dry-well Characteristics

9.2.1 Vertical Gradient

There is a temperature gradient vertically in the test well. The heater has been

applied to the block in such a way as to compensatefor nominal heat losses out

of the top of the dry-well and minimize vertical temperature gradients.How-

ever,actual heat losses will vary depending on the number and types of probes

inserted into the calibrator and the block temperature. For best results, insert

probes the full depth of well.

9.2.2 Heating and Cooling Rates

Figures 7 and 8show typical heating cooling rates ofthe 9140 dry-well

calibrator.

9140 Dry-well Calibrator

User’s Guide

40

Contents

Main Page Table of Contents 8 Digital Communication Interface . . . . . . . . . . . . . . . . 33 9 Test Probe Calibration . . . . . . . . . . . . . . . . . . . . . . 39 Page Figures Page 1 Before You Start 1.1 Symbols Used Table1 lists the symbols used on the instrument or in this manual and the meaning of each symbol. 1.2 Safety Information 1.2.1 WARNINGS Page 1.2.2 CAUTIONS 1.3 Authorized Service Centers Page 2 Introduction 3 Specifications and Environmental Conditions 3.1 Specifications 3.2 Environmental Conditions 9 3 Specifications and Environmental Conditions Specifications 3.3 Warranty 4 Quick Start 4.1 Unpacking 4.2 Set-Up 4.3 Power 4.4 Setting the Temperature 5 Parts and Controls 5.1 Rear Panel 5.2 Front Panel 5.3 Constant Temperature Block Assembly 5.3.1 Constant Temperature Block 5.3.2 Probe Sleeves and Tongs Page 6 General Operation 6.1 Calibrator Set-Up 6.2 Changing Display Units Un= C 6.3 Switching to 230 V Operation 6.4 Setting the Temperature 6.5 Calibrating Probes Page 7 Controller Operation 7.1 Well Temperature 100.0 C 7.2 Temperature Set-point 7.2.1 Programmable Set-points Page S 7.3 Scan S 7.4 Temperature Display Hold 7.4.1 Hold Temperature Display 143.5 C U c 144.8 7.4.2 Mode Setting 7.4.3 Switch Wiring 7.4.4 Switch Test Example 7.5 Secondary Menu 7.5.1 Heater Power 100.0 C S+EAccess heater power in secondary menu SEC 12.0P 7.5.2 Proportional Band S+EAccess heater power in secondary menu SEC S 12.0P S 7.6 Controller Configuration 7.6.1 Calibration Parameters CAL 7.7 Operating Parameters PAr 7.8 Serial Interface Parameters SErIAL bAUd Page Page 8 Digital Communication Interface 8.1 Serial Communications 8.1.1 Wiring 8.1.2 Setup 8.1.3 Serial Operation 8.2 Interface Commands Users Guide Tabl e 2 9140 controller communications commands 36 37 8 Digital Communication Interface Interface Commands Tabl e 3 9140 controller communications commands continued 9 Test Probe Calibration 9.1 Comparison Methods 9.1.1 Calibrating a Single Probe 9.1.2 Comparison Calibration 9.1.3 Calibration of Multiple Probes 9.2 Dry-well Characteristics 9.2.1 Vertical Gradient 9.2.2 Heating and Cooling Rates WARNING:DO NOT remove inserts when heating or when the unit is hot. 9.2.3 Stabilization and Accuracy Figure 8 Typical Cooling Rate 41 9 Test Probe Calibration Dry-well Characteristics BlockTemperature C Page 10 Calibration Procedure 10.1 Calibration Points 10.2 Calibration Procedure 10.2.1 Compute DELTA: 10.2.2 Compute R0& ALPHA: 10.2.3 Accuracy & Repeatability 11 Maintenance 12 Troubleshooting 12.1 Troubleshooting Problems, Possible Causes, and Solutions 12.2 CE Comments 12.2.1 EMC Directive 50 12.2.2 Low Voltage Directive (Safety) Users Guide