Fluke 5623B User manual

5623B
Precision RTD Freezer Probe
2004, Rev. 1, 4/11
© 2004 - 2011 Fluke Corporation. All rights reserved. Specications subject to change without notice.
Users Guide
All product names are trademarks of their respective companies.
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
TestEquipmentDepot.com

i
Table of Contents
Title Page
Introduction.........................................................................................................................1
General............................................................................................................................1
Recalibration...................................................................................................................1
Before You Start..................................................................................................................1
Symbols Used .................................................................................................................1
Safety Information ..........................................................................................................2
How to Contact Fluke .....................................................................................................2
Specications ......................................................................................................................3
Installation ..........................................................................................................................4
Lead Wire Identication .................................................................................................4
PRT Care and Handling Guidelines....................................................................................4
Operation ............................................................................................................................5
Immersion Requirements................................................................................................5
Thermal EMF..................................................................................................................5
Troubleshooting ..................................................................................................................6

5623B
Users Guide
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iii
List of Tables
Table Title
Table 1. International Electrical Symbols...............................................................................................1
Table 2. Specications ............................................................................................................................3
Table 3. PRT Troubleshooting ...............................................................................................................6
Page
List of Figures
Figure Title Page
Figure 1. PRT Schematic ........................................................................................................................4

5623B
Users Guide
iv

1
Introduction
General
The Platinum Resistance Thermometer (PRT) model 5623B is designed to be a secondary
standard interpolating instrument converting temperature to resistance. The 5623B assembly
design allows for exposure to very cold temperature (–100 °C) and is an ideal reference for
verication, monitoring or calibrating control sensors in located in freezers or incubators. The
5623B may also be used as a temperature standard for calibration of industrial sensors. The
PRT is used with a readout device to detect temperature changes or actual temperature. The
5623B covers the range from –100 °C to 156 °C. Standard length is 6 inches. Custom lengths are
available on request.
Recalibration
The recalibration of the 5623B PRT should be scheduled according to the user’s company
Quality Assurance requirements. Normally, a PRT is recalibrated annually. Unless the PRT is
used only over a limited range, calibration over the full range of the PRT (–100 °C to 156 °C) is
recommended. For information on recalibrating your 5623B, contact Fluke for assistance (see
“How to Contact Fluke”).
Depending on the user’s Quality Assurance requirements, the PRT drift should be checked
periodically at the Triple Point of Water (TPW). For information on drift with respect to
mechanical shock and oxidation, refer to the “Troubleshooting” section of this manual.
Before You Start
Symbols Used
Table 1 lists the International Electrical Symbols. Some or all of these symbols may be used on
the instrument or in this manual.
Table 1. International Electrical Symbols
Symbol Description Symbol Description
XElectric Shock OOff
:Hot Surface (Burn Hazard) IOn
WRead the Users Manual (Important
Information) IFuse
BAC (Alternating Current) MBattery
DAC-DC ;C-TICK Australian EMC Mark
FDC )Canadian Standards Association
TDouble Insulated PCE Complies with European Union
Directives
.PE Ground The European Waste Electrical
and Electronic Equipment (WEEE)
Directive (2002/96/EC) Mark
CAT II
CAT II equipment is designed to protect against transients from energy-consuming
equipment supplied from the xed installation, such as TVs, PCs, portable tools, and
other household appliances.

5623B
Users Guide
2
Safety Information
Use this instrument only as specied in this manual. Otherwise, the protection provided by the
instrument may be impaired.
The following denitions apply to the terms “Warning” and “Caution”.
•“Warning” identies conditions and actions that may pose hazards to the user.
•“Caution” identies conditions and actions that may damage the instrument being used.
WarningW
To avoid personal injury, follow these guidelines:
•DO NOT use this instrument to measure the temperature of any hazardous
live component (>30 V ac rms, 42 V ac peak, or 60 V dc).
•Use of this instrument at high temperatures for extended periods of time can
cause the handle to become hot.
•Follow all safety guidelines listed in the Users Guide.
•Calibration Equipment should only be used by trained personnel.
•UsetheProductonlyasspecied,ortheprotectionsuppliedbytheProduct
can be compromised.
•DO NOT use the Product around explosive gas, vapor, or in damp or wet
environments.
CautionW
To avoid possible damage to the instrument, follow these guidelines:
•DO NOT drop or hit the probe in any way. This will cause damage to
the probe internally and affect its calibration.
•Read “PRT Care and Handling Guidelines” before removing the PRT
from the shipping box. Incorrect handling can damage the PRT and
void the warranty.
•Keep the shipping container in case it is necessary to ship the PRT.
Incorrect packaging of the PRT for shipment can cause irreparable
damage.

Precision RTD Freezer Probe
Specications
3
Specications
See Table 2 for a list of the specications.
Table 2. Specications
Parameter Range
Temperature Range –100 °C to 156 °C
Nominal Resistance at 0.01 °C 100 Ω ±0.1 Ω
Temperature Coefcient 0.003925 Ω/Ω/ °C
Drift [1] ±0.1 °C at 0.010 °C
Hysteresis ±0.01 °C maximum
Sheath Dimensions (Length x Diameter) 152 mm x 6.35 mm (6 in x 0.25 in)
Sheath Material Inconel™ 600
Transition Junction Temperature Range [2] –100 °C to 156 °C
Minimum Immersion Length [3] (<5 mK error) 114 mm (4.5 in)
Lead-wire Cable Type Teon™ -insulated, 22 AWG, Silver-plated Stranded
Copper
Lead-wire Length 609.6 cm (240 in)
Calibration Includes Manufacturer’s NVLAP-Accredited
Calibration
[1] After 100 hours at maximum temperature.
[2] Temperatures outside this range will cause irreparable damage.
[3] Per ASTM E 644

5623B
Users Guide
4
Installation
Lead Wire Identication
The 5623B PRT is equipped with a four-wire cable (see Figure 1). Four lead wires are used to
cancel lead wire resistance. For best results, the readout device should be equipped to handle
four-terminal resistors. The lead wires are two different colors. Lead wire pairs attached to each
end of the sensor are identied by red and white insulation.
White Red
White Red
5623B Lead Wires.eps
Figure 1. PRT Schematic
PRT Care and Handling Guidelines
CautionW
Read this section before removing the PRT from the shipping
box or case.
Care must be taken in handling the PRT to maintain calibration accuracy. Care should still be used
when handling the PRT even though the Inconel sheath is durable and provides good protection
for the sensor. Correct handling of the PRT will prolong the life expectancy. When not in use, the
PRT should be stored in an optional protective case that can be purchased by contacting Fluke
(see “How to Contact Fluke”). The handle is designed to be immersed.
PRT Handling Guidelines
•Keep the thermometer as clean as possible.
•Immerse the thermometer in the appropriate liquid for the temperature range. If a dry block
is used, the well diameter should allow the PRT to comfortably slip in and out without excess
movement. For best results, immerse the thermometer as deep as possible to avoid “stem
effect” (the temperature error caused by the conduction of heat away from the sensor).
•Allow sufcient time for the thermometer to stabilize before making measurements. This
allows for the best accuracy.
•Use the correct drive current with the thermometer to prevent error in temperature or
resistance. Fluke recommends 1 mA.
•Use the protective shipping box provided or other protection when the thermometer is not in
use.
•DO NOT subject the thermometer to any physical shock or vibration.
•DO NOT use pliers or other devices to squeeze the sheath. This action can permanently
damage the PRT.
•DO NOT subject the thermometer to temperatures above the highest specied operating
temperature.
•DO NOT expose the thermometer’s handle or cables to extreme temperatures. The temperature
limits of the handle and cables are: –100 °C to 156 °C.
•DO NOT screw a clamp down so tight that it dents the sheath. This can permanently damage
the PRT.

Precision RTD Freezer Probe
Operation
5
Operation
For best results, be familiar with the operation of the heat source and the readout instrument. Be
sure to follow the manufacturer’s instructions for the readout instrument and the heat source.
Immersion Requirements
Stem effect can cause measurement errors for any thermometer not immersed in the uid at
least 114 mm (4.5 in). This error is due to heat lost or gained by the sensing element through
the thermometer stem. In addition, heat losses occur due to radiation losses from the sensing
element to the housing. The immersion depth for standards is dependent on several factors
including accuracy requirements and type of liquid. Therefore, we recommend a 114 mm (4.5 in)
minimum immersion depth. The handle is designed to be immersed. The temperature limits of the
handle are –100 °C to 156 °C. Temperatures outside these limits can damage the handle and the
probe. Convection of heat from the heat source must be kept within the handle limits. The exact
immersion depth required can be determined by performing a gradient test taking measurements
approximately every 1.27 cm (0.5 in) until there is a signicant difference in readings. Allow the
thermometer to stabilize at each new depth. Plot the results to see the stem effect.
Thermal EMF
Two factors contribute to thermal EMF, chemical consistency and physical consistency. Variations
in chemical structure due to impurities can contribute to thermal EMF. Also discrepancies in
crystal structure can contribute to thermal EMF. These factors are minimized by annealing the full
length of wire before construction of the PRT.
Likewise, connection to extension lead wires and readout instruments can be a source of thermal
EMF. The thermal EMF is caused by a difference in temperature between two connections. If the
two connections are the same temperature, there will be little or no thermal EMF effects.
However, if there is a substantial temperature difference between connections, the thermal EMF
effects will be signicant. Therefore, cover or insulate any exposed bridge or galvanometer
terminals to lessen the source of error. The effects of thermal EMF can be canceled by using an ac
bridge or a dc bridge with reversible current.

5623B
Users Guide
6
Troubleshooting
In the event that the probe appears to function abnormally, this section may be of use in solving
the problem. Several possible problem conditions are described along with likely causes and
solutions. If a problem arises, please read this section carefully and attempt to understand and
solve the problem. If the probe seems faulty or the problem cannot otherwise be solved, contact
Fluke for assistance (see “How to Contact Fluke”). Be sure to have the model number and serial
number of your probe available.
Table 3. PRT Troubleshooting
Problem Solution
Data changes greater than 0.1 °C
are observed.
Mechanical shock can cause temperature errors as great as 0.5 °C. If
this is observed, rst measure and record the Rtpw.
Data changes less than 0.1 °C. Slight mechanical shock can cause temperature errors less than 0.1 °C.
Data unstable. • If the data is unstable at the Triple Point of Water (TPW), check
connections for evidence of a bad connection. If the connector
appears to be in good condition and the connections are good, the
PRT may be damaged. Contact Fluke for assistance (see “How to
Contact Fluke”).
• If the data is unstable at high temperatures, it may be due to electrical
noise in the system. Reduce the temperature and observe the data.
If it is stable, electrical noise is interfering with the measurements at
high temperatures. Check the grounding of the readout device and
the heat source. A faulty ground on either device could interfere with
high temperature measurements. A ground wire attached to the metal
sheath of the PRT may help to reduce electrical noise interference.
Temperature readout is different
than expected. For example, the
heat source is set at 150 °C, the
PRT measures 125 °C.
• Measure the PRT resistance at TPW.
• The PRT sensor may be shorted if the measured resistance at 0 °C is
signicantly less than the probe’s nominal resistance. For example, a
probe whose nominal resistance is 100 Ωbut measures 70 Ωat 0 °C.
• If the resistance of the PRT is only a few ohms, there may be a short
in the four lead-wires.
• If the PRT is open, the resistance will be “Out of Limits” or in the
kilohm or megohm range.
For more information or assistance, Contact Fluke (see “How to
Contact Fluke”).