Fluke 5608, 5609 Operating Manual

5608/5609

Hart Scientific

Platinum Resistance Thermometer

User’s Guide

Rev. 712601

Limited Warranty & Limitation of Liability

Each product from Fluke Corporation, Hart Scientific Division ("Hart") is warranted to be free from de
fects in material and workmanship under normal use and service. The warranty period is one year(s)
for the Platinum Resistance Thermometer. The warranty period begins on the date of the shipment.
Parts, product repairs, and services are warranted for 90 days. The warranty extends only to the
original buyer or end-user customer of a Hart authorized reseller, and does not apply to fuses, dispos
able batteries or to any other product, which in Hart's opinion, has been misused, altered, neglected,
or damaged by accident or abnormal conditions of operation or handling. Hart warrants that software
will operate substantially in accordance with its functional specifications for 90 days and that it has
been properly recorded on non-defective media. Hart does not warrant that software will be error
free or operate without interruption. Hart does not warrant calibrations on the Platinum Resistance
Thermometer.

Hart authorized resellers shall extend this warranty on new and unused products to end-user cus
tomers only but have no authority to extend a greater or different warranty on behalf of Hart. War
ranty support is available if product is purchased through a Hart authorized sales outlet or Buyer has
paid the applicable international price. Hart reserves the right to invoice Buyer for importation costs
of repairs/replacement parts when product purchased in one country is submitted for repair in an
other country.

Hart's warranty obligation is limited, at Hart's option, to refund of the purchase price, free of charge
repair, or replacement of a defective product which is returned to a Hart authorized service center
within the warranty period.

To obtain warranty service, contact your nearest Hart authorized service center or send the product,
with a description of the difficulty, postage, and insurance prepaid (FOB Destination), to the nearest
Hart authorized service center. Hart assumes no risk for damage in transit. Following warranty repair,
the product will be returned to Buyer, transportation prepaid (FOB Destination). If Hart determines
that the failure was caused by misuse, alteration, accident or abnormal condition or operation or
handling, Hart will provide an estimate or repair costs and obtain authorization before commencing
the work. Following repair, the product will be returned to the Buyer transportation prepaid and the
Buyer will be billed for the repair and return transportation charges (FOB Shipping Point).

THISWARRANTYISBUYER'SSOLEANDEXCLUSIVEREMEDYANDISINLIEUOFALLOTHERWAR
RANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. HART SHALL NOT BE LIABLE FOR
ANY SPECIAL, INDIRECT, INCIDENTAL. OR CONSEQUENTIAL DAMAGES OR LOSSES, INCLUDING LOSS
OF DATA, WHETHER ARISING FROM BREACH OF WARRANTY OR BASED ON CONTRACT, TORT, RELI
ANCE OR ANY OTHER THEORY.

Since some countries or states do not allow limitation of the term of an implied warranty, or exclu
sion or limitation of incidental or consequential damages, the limitations and exclusions of this war
ranty may not apply to every buyer. If any provision of this Warranty is held invalid or unenforceable
by a court of competent jurisdiction, such holding will not affect the validity or enforceability of any
other provision.

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Rev. 712601

Fluke Hart Scientific • 799 E. Utah Valley Drive • American Fork, UT 84003-9775 • USA
Phone: [phone] • Telefax: +1.801.763.1010 • E-mail: [e-mail]

www.hartscientific.com

Subject to change without notice. • Copyright © 2005 • Printed in USA

Table of Contents

1 Before You Start . . . . . . . . . . . . . . . . . . . . . . 1

1.1 Symbols Used . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Safety Information . . . . . . . . . . . . . . . . . . . . . . . 2

1.2.1 Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.2.2 Cautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.3 Authorized Service Centers . . . . . . . . . . . . . . . . . . 3

2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5

2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.2 Application. . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.3 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.4 Recalibration. . . . . . . . . . . . . . . . . . . . . . . . . . 5

3 Specifications . . . . . . . . . . . . . . . . . . . . . . . 7

3.1 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.2 Electrical Circuit . . . . . . . . . . . . . . . . . . . . . . . . 8

4 Installation . . . . . . . . . . . . . . . . . . . . . . . . 9

4.1 Environmental Issues . . . . . . . . . . . . . . . . . . . . . 9

4.2 Mounting. . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4.3 Lead Wire Identification . . . . . . . . . . . . . . . . . . . . 9

5 PRT Care and Handling Guidelines. . . . . . . . . . . . 11

5.1 PRT Care . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5.2 PRT Handling Guidelines . . . . . . . . . . . . . . . . . . . 11

6 Operation. . . . . . . . . . . . . . . . . . . . . . . . . 13

6.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

6.2 Comparison Calibration of Other Instruments. . . . . . . . . 13

6.3 Immersion Requirements . . . . . . . . . . . . . . . . . . . 13

6.4 Thermal EMF . . . . . . . . . . . . . . . . . . . . . . . . . 14

6.5 Transition Junction . . . . . . . . . . . . . . . . . . . . . . 14

7 Accessories. . . . . . . . . . . . . . . . . . . . . . . . 15

7.1 Case Options . . . . . . . . . . . . . . . . . . . . . . . . . 15

i

7.2 PRT Termination . . . . . . . . . . . . . . . . . . . . . . . 15

8 Troubleshooting . . . . . . . . . . . . . . . . . . . . . 17

8.1 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . 17

ii

Figures

Figure 1 PRT Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Figure 2 Probe Termination Examples . . . . . . . . . . . . . . . . . . . . . . . 15

iii

Tables

Table 1 International Electrical Symbols . . . . . . . . . . . . . . . . . . . . . . 1

Table 2 Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

iv

1 Before You Start

1.1 Symbols Used

Before You Start

1

Table 1 lists the International Electrical Symbols. Some or all of these sym
bols may be used on the instrument or in this manual.

Table 1 International Electrical Symbols

Symbol Description

AC (Alternating Current)

AC-DC

Battery

CE Complies with European Union Directives

DC

Double Insulated

Electric Shock

-

Fuse

PE Ground

Hot Surface (Burn Hazard)

Read the User’s Manual (Important Information)

Off

On

1

5608/5609

User’s Guide

Symbol Description

Canadian Standards Association

OVERVOLTAGE (Installation) CATEGORY II, Pollution Degree 2 per
I E C1010-1 refer s to the level of Impul se W ithsta nd Volta ge p rotect ion
provided. Equipment of OVERVOLTAGE CATEGORY II is energy-con
suming equipment to be supplied from the fixed installation. Exam
ples include household, office, and laboratory appliances.

C-TICAustralianEMCMark

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The European Waste Electrical and Electronic Equipment (WEEE) Di
rective (2002/96/EC) mark.

1.2 Safety Information

Use this instrument only as specified in this manual. Otherwise, the protec­tion provided by the instrument may be impaired.

The following definitions apply to the terms “Warning” and “Caution”.

“Warning” identifies conditions and actions that may pose hazards to the
user.

“Caution” identifies conditions and actions that may damage the instrument
being used.

1.2.1

To avoid personal injury, follow these guidelines.

Warnings

•

DO NOT use this instrument to measure the temperature of any haz
ardous live component.

•

DO NOT use this unit for any application other than calibration work.

•

DO NOT use this unit in environments other than those listed in the
user’s manual.

•

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 user’s manual.

•

Calibration Equipment should only be used by Trained Personnel.

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1.2.2
Cautions

To avoid possible damage to the instrument, follow these guidelines.

•

DO NOT remove the label from the handle. This cautions the user con

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cerning the delicate nature of the instrument.

2

DO NOT drop or bang the probe in any way. This will cause damage to

•

the probe internally and affect its calibration.
Read Section 5 entitled “PRT Care and Handling Guidelines” before re

•

moving the PRT from the shipping box or case. Incorrect handling can
damage the PRT and void the warranty.

Keep the shipping container in case it is necessary to ship the PRT. In

•

correct packaging of the PRT for shipment can cause irreparable dam
age.

1.3 Authorized Service Centers

Please contact one of the following authorized Service Centers to coordinate
service on your Hart product:

Fluke Corporation,
Hart Scientific Division

799 E. Utah Valley Drive
American Fork, UT 84003-9775
USA

Before You Start

1

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Phone: [phone]
Telefax: +1.801.763.1010
E-mail: [e-mail]

Fluke Nederland B.V.

Customer Support Services
Science Park Eindhoven 5108
5692 EC Son
NETHERLANDS

Phone: [phone]
Telefax: [phone]
E-mail: [e-mail]

Fluke Int'l Corporation

Service Center - Instrimpex
Room 2301 Sciteck Tower
22 Jianguomenwai Dajie
Chao Yang District
Beijing 100004, PRC
CHINA

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5608/5609

User’s Guide

Phone: [phone]
Telefax: [phone]
E-mail: [e-mail]

Fluke South East Asia Pte Ltd.

Fluke ASEAN Regional Office
Service Center
60 Alexandra Terrace #03-16
The Comtech (Lobby D)
118502
SINGAPORE

Phone: [phone]
Telefax: [phone]
E-mail: [e-mail]

When contacting these Service Centers for support, please have the follow­ing information available:

• Model Number

•

Serial Number

•

Complete description of the problem

4

2 Introduction

2.1 General

The Hart Platinum Resistance Thermometers (PRT) models 5608 and 5609,
are designed to be a secondary standard interpolating instrument convert
ing temperature to resistance. The PRTs are used with a readout device to
detect temperature changes or actual temperature.

2.2 Application

Hart 5608 and 5609 thermometers are classified as secondary standards. A
secondary standard is used to transfer the ITS-90 from a standards labora
tory to a customer’s laboratory. Secondary standards are calibrated using a
primary standard that has been calibrated in a primary calibration labora
tory through a process called realizing the ITS-90.

2.3 Calibration

In order for any instrument to be used as a standard it must be calibrated.
These instruments are sold uncalibrated unless calibration is requested at
time of purchase. They are satisfactory as secondary standards and may be
calibrated by comparison to primary standards.

Introduction

2

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2.4 Recalibration

The recalibration of the 5608/5609 Secondary PRT should be scheduled ac
cordingtotheuser'scompanyQualityAssurancerequirements.Normally,a
PRT is recalibrated annually. Unless the PRT is used only over a limited
range, calibration over the full range of the PRT is recommended. For infor
mation on calibration services for the 5608/5609, contact an Authorized
Service Center for an RMA number and current pricing (see Section 1,
Before You Start)

Depending on the user’s Quality Assurance requirements, the PRT drift
should be checked periodically at the Triple Point of Water (TPW). Section 8,
Troubleshooting, provides information on drift with respect to mechanical
shock and oxidation. If the R
calibration tolerances, a full recalibration should be scheduled.

cannot be restored after annealing to within

tp

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5

3 Specifications

3.1 Specifications

Table 2 Specifications

Parameter Value

Temperature range 5608: –200 °C to 500 °C

Nominal resistance at 0.01 °C

Temperature coefficient

Accuracy

Sensor length 30 mm ± 5 mm (1.2 in ± 0.2 in)

Sensor location 3mm±1mmfromtip(0.1in±0.1in)

Sheath dimensions, length x
diameter

Sheath diameter tolerance 5608: ± 0.1 mm (± 0.004 in)

Sheath material Inconel™ 600

Minimum insulation resistance

Transition junction
temperature range

[1]

Short-term repeatability

[3]

Drift

[2]

Hysteresis ±0.01°Cmaximum

[4]

Specifications

3

5609: –200 °C to 670 °C

100 Ω ±0.5Ω

0.0039250 Ω/Ω/°C

See footnote

±0.01°Cat0.010°C
±0.02°Catmaxtemp

±0.01°Cat0.010°C
±0.02°Catmaxtemp

5608-9: 229 x 3.18 mm (9 in x 0.125 in)
5608-12: 305 mm x 3.18 mm (12 in x 0.125 in)

5609-12: 12 in x 0.25 in
5609-15: 15 in x 0.25 in
5609-20: 20 in x 0.25 in
5609-300: 300 mm x 6 mm
5609-400: 400 mm x 6 mm
5609-500: 500 mm x 6 mm

5609-12: ± 0.006 in
5609-15: ± 0.006 in
5609-20: ± 0.006 in

5609-300: ± 0.1 mm
5609-400: ± 0.1 mm
5609-500: ± 0.1 mm

5608: 500 MΩ at 23 °C
5608: 20 MΩ at 500 °C

5609: 500 MΩ at 23 °C
5609: 10 MΩ at 670 °C

–50ºCto200°C

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5608/5609

User’s Guide

Parameter Value

Transition junction dimensions 71mmx12.5mm(2.8inx0.49in)

Minimum immersion length
(< 5 mK error)

[5]

5608: 80 mm (3.1 in)
5609: 100 mm (3.9 in)

Maximum immersion length 305 mm (12 in)

Response time

[5]

5608: 9 seconds typical
5609: 12 seconds typical

Self heating (in 0 °C bath) 5608: 75 mW/°C

5609: 50 mW/°C

Lead-wire cable type Teflon,™ 24 AWG

Lead-wire length 1.8 m (6 ft)

Lead-wire temperature range –50 °C to 250 °C

Calibration Calibration not included; NVLAP-accredited calibra

tion optional, lab code 200348-0. Please see calibra
tion uncertainty table and its explanation of
changeable uncertainties.

[1]

“Accuracy” is a difficult term when used to describe a resistance thermometer. The
simplestwaytoderivebasic“accuracy”istocombinetheprobedriftspecificationand
calibration uncertainty with readout accuracy at a given temperature.

[2]

Three thermal cycles from min to max temp, includes hysteresis, 99.9 % confidence

[3]

After 100 hrs at max temp, 99.9 % confidence

[4]

Temperatures outside this range will cause irreparable damage. For best performance,
transition junction should not be too hot to touch.

[5]

Per ASTM E 644

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3.2 Electrical Circuit

The PRTs are provided with a terminal box handle. The two meter cable has
four 24 AGW lead wires in a Teflon® jacket with a stainless steel spring
strain relief.

8

4 Installation

BLACK

RED

GREEN

WHITE

4.1 Environmental Issues

Ideally, temperature calibration equipment should be used in a calibration
laboratory or other facility specifically designed for this purpose. Environ
mental requirements include:

Stable temperature and relative humidity <80%

•

Clean, draft-free area

•

Low noise level: low radio frequency, magnetic or electrical interfer

•

ence
Low vibration levels

•

4.2 Mounting

Most often temperature standards, primary and secondary, are used to cali­brate other temperature-sensitive equipment. The PRT must be mounted
carefully to avoid any damage to the sheath or sensor. If the fluid bath used
does not have a lid designed for PRT insertion, clamps should be used to
ensurethehandleandcablearenotimmersed.Do not screw the clamps
too tight. Over tightening will damage the sheath. If metal comparison
blocks are used in the bath, maintain a close fit between the thermometer
sheath and the well in the comparison block. However, allow for the ther­mal expansion of the thermometer sheath when determining block well
tolerances.

Installation

4

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4.3 Lead Wire Identification

The 5608 and 5609 PRTs are equipped with a four-wire cable. The same
circuit schematic applies to both PRTs (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.

Figure 1 PRT Schematic

The lead wires are four different colors. Lead wire pairs attached to each
end of the sensor are identified as shown in Figure 1.

9

PRT Care and Handling Guidelines

5 PRT Care and Handling

Guidelines

5.1 PRT Care

CAUTION: READ THI S SECTION BEFORE REMOVING THE PRT

FROM THE SHIPPING BOX OR CASE

The 5608 and 5609 Platinum Resistance Thermometers (PRTs) are delicate
instruments. Care must be taken in handling the PRTs to maintain calibra
tion accuracy. The stress free design of the PRT sensor reduces the effects of
mechanical shock. In addition, contamination problems of the sensor at high
temperature have been eliminated. However, 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 the protective
case.

Note: The PRT sheath changes color after use at high temperatures.

The PRT may arrive with a brown tint to the sheath due to calibration
at high temperatures.

5

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The handle is not designed to be immersed. The temperature limits of the
handle are: –50°C to 200°C. Temperatures outside these limits can damage
the sealed portion of the handle and the connectors.

5.2 PRT Handling Guidelines

•

DO anneal the thermometer after shipment. Shipping the thermometer
can cause mechanical shocks that effect the accuracy of the thermome
ter. Therefore, if possible, we advise that the thermometer be annealed
before use. The 5608 thermometer should be annealed at 500°C for
four hours. The 5609 at 660°C for four hours.

•

DO keep the thermometer as clean as possible. Always remove any
fluid from the sheath immediately after taking the thermometer from a
bath.

•

DO immerse the thermometer in the appropriate liquid for the temper
ature 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). Do not submerge the handles.

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11

5608/5609

User’s Guide

DO allow sufficient time for the thermometer to stabilize before making

•

measurements. This allows for the best accuracy.
DO use the correct drive current with the thermometer to prevent error

•

in temperature or resistance. Hart Scientific recommends 1mA.
DO anneal the 5608 thermometer at 500°C and the 5609 thermome

•

ter at 600 to 661°C for 12 hours if they become oxidized.
DO use the protective shipping box or case provided or other protec

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tion 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

•

specified operating temperature.
DO NOT expose the thermometer’s handle or cables to extreme tem

•

peratures. The temperature limits of the handle are: –50°C to 200°C
DO NOT submerge the handle or cable in liquids.

•

DO NOT screw a clamp down so tight that it dents the sheath. This can

•

permanently damage the PRT.

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12

6 Operation

6.1 General

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.

6.2 Comparison Calibration of Other
Instruments

The uniformity and stability of the heat source and the degree of accuracy
required determine the number of temperature measurements necessary.
However, to follow “good” practice procedures, always measure the triple
point of water (R
equation provides the most accurate measurement of the ratio:

R

W

All PRTs experience errors caused by self-heating of the element.
Self-heating is a combination of two factors, heat dissipation and heat sink.
Self-heating error can be reduced to have a negligible effect if the PRT is
used with the same excitation current and medium in which it was
calibrated.

t

=

t

R

tp

) after each temperature measurement. The following

tp

Operation

6

6.3 Immersion Requirements

Stem effect can cause measurement errors for any thermometer. Errors pro
duced by not following the immersion depth guidelines are due to heat lost
or gained by the sensing element through the thermometer stem. In addi
tion, heat losses occur due to radiation losses from the sensing element to
the housing.

The immersion depth for standards is dependent on several factors includ
ing accuracy requirements and type of liquid. Therefore, we recommend
minimum immersion depths as stated in the preceding paragraph and in the
specifications. However, remember the handle limitations. The handle is not
designed to be immersed. The temperature limits of the handle are –50°C to
200°C. Temperatures outside these limits can damage the handle. Convec
tion 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 (.5 inches)
until there is a significant difference in readings. Allow the thermometer to
stabilize at each new depth. Plot the results to see the stem effect.

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13

5608/5609

User’s Guide

6.4 Thermal EMF

6.5 Transition Junction

Two factors contribute to thermal EMF, chemical consistency and physical
consistency. Variations in chemical structure due to impurities can contrib
ute 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
beasourceofthermalEMF.ThethermalEMFiscausedbyadifferencein
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 significant. 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 re
versible current.

Exceeding the temperature range of the transition junction will cause a
breach in the seal of the instrument. Maintaining the seal is critical to pre­venting moisture from entering the device. If moisture penetrates the seal,
the PRT's short term repeatability, hysteresis, and insulation resistance may
be adversely affected. Insulation resistance also decreases rapidly as the
transition junction temperature increases, even if the seal is not broken.
When the insulation resistance becomes sufficiently low, performance suf­fers. A good rule of thumb is that the transition junction is too hot when it is
hot enough to burn your thumb.

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14

7 Accessories

Bare Wire

(customer option)

Spade Lug

(standard)

5-Pin DIN

(customer option)

1

2

4

5

3

7.1 Case Options

The 5608/5609 PRT comes in a rigid case appropriate for the length of the
probe.

Model 2601 protective case for thermometer probes 12 inches in

•

length or shorter.
Model 2609 protective case for thermometer probes 15 inches in

•

length or longer.

7.2 PRT Termination

The 5608/5609 PRT can be terminated in three ways (Figure 2) depending
on the user’s requirements:

Gold Plated Spade Lug

•

Bare Wire

•

5-Pin Din Connector

•

Accessories

7

Figure 2 Probe Termination Examples

15

8 Troubleshooting

8.1 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, con
tact an Authorized Service Center (see Section 1.3) for assistance. Be sure to
have the model number and serial number of your probe available.

Problem Causes and Solutions

Data changes greater than

0.1°C are observed

Data changes less than

0.1°C

Data unstable

Mechanical shock can cause temperature errors as great

•

as 0.5°C. If this is observed, first measure and record the
R

Next anneal the 5608 PRT at 500°C and the 5609

tp.

PRT at 660°C overnight. Measure the R
nealing should decrease the R
recalibrate the PRT.

Slight mechanical shock can cause temperature errors

•

less than 0.1°C. If this is observed, first measure and re­cord the R
5609 PRT at 660°C overnight. Measure the R
The annealing should decrease the R
nealing, R
R

is stable, recalibrate the PRT. If the Rtpdoes not stabi-

tp

lize, contact an Authorized Service Center (see Section

1.3).

•

Oxidation of the platinum sensor may occur after pro
longed use between 200 and 450°C. This oxidation will
demonstrate itself by an increase in R

0.1°C. To reduce the effects of oxidation, anneal the
5608 PRT at 500°C and the 5609 PRT at 600 to 661°C
overnight (12 hr.). Measure the R
nealing, R
nealing process should return R
tolerances. If the R
PRT is usable. If the R
ance, but it is stable, recalibrate the PRT.

•

If the data is unstable at the Triple Point of Water (TPW),
check the connector. If the connector is correct, contact
an Authorized Service Center (see Section 1.3). The PRT
may be damaged and need repair.

•

If the data is unstable at high temperatures, it may be
due to electrical noise in the system. Reduce the temper
ature and observe the data. If it is stable, electrical noise
is interfering with the measurements at high tempera
tures. 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.

Troubleshooting

again. The an

tp

. If the Rtpis stable,

tp

Next anneal the 5608 PRT at 500°C and the

tp.

measurement cycle several times. When the

tp

measurement cycle several times This an

tp

is within calibration tolerance, the

tp

is not within calibration toler

tp

tp

tp

again. Repeat the an

tp

to within calibration

tp

again.

tp

. Repeat the an-

of less than

8

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17

5608/5609

User’s Guide

Problem Causes and Solutions

Temperature readout differ
ent than expected, e.g. the
heat source is set at 300°C,
the PRT measures 275°C.

-

Measure the PRT resistance at TPW.

•

If the resistance of the PRT is less than the rated resis

•

tance, e.g. 70Ω for the 5608/5609, there may be a short
in the sensor. Contact an Authorized Service Center (see
Section 1.3).

If the resistance of the PRT is only a few ohms, there

•

may be a short in the four lead-wires. Contact an Autho
rized Service Center (see Section 1.3).

If the PRT is open, the resistance will be “Out of Limits”

•

or in the kilohm or megohm range. Contact an Autho
rized Service Center (see Section 1.3).

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