User’s Manual
Model 231 / 231P
Temperature Transmitter
Includes Coverage for:
Model 2308-01 Benchtop Enclosure
Model 2308-12 VMEbus Rackmount Case
For Use With The Following Lake Shore Sensors:
Model DT-414 Unencapsulated Silicon Diode Temperature Sensors
Series DT-420 Miniature Silicon Diode Temperature Sensors
Series DT-470 Silicon Diode Temperature Sensors
Series DT-471 Silicon Diode Temperature Sensors
Series DT-670 Silicon Diode Temperature Sensors
Series PT-100 Platinum Resistance Thermometers
Series TG-120 GaAlAs Diode Temperature Sensors
Lake Shore Cryotronics, Inc.
575 McCorkle Boulevard
Westerville, Ohio 43082-8888 USA
E-Mail Addresses:
sales@lakeshore.com
service@lakeshore.com
Visit Our Website:
www.lakeshore.com
Fax: (614) 891-1392
Telephone: (614) 891-2243
Methods and apparatus disclosed and described herein have been developed solely on company funds of Lake
Shore Cryotronics, Inc. No government or other contractual support or relationship whatsoever has existed which in
any way affects or mitigates proprietary rights of Lake Shore Cryotronics, Inc. in these developments. Methods and
apparatus disclosed herein may be subject to U.S. Patents existing or applied for. Lake Shore Cryotronics, Inc.
reserves the right to add, improve, modify, or withdraw functions, design modifications, or products at any time
without notice. Lake Shore shall not be liable for errors contained herein or for incidental or consequential damages
in connection with furnishing, performance, or use of this material.
Rev. 1.8 P/N 119-021 03 October 2013
Lake Shore Model 231 User’s Manual
LIMITED WARRANTY STATEMENT – WARRANTY PERIOD: THREE (3) YEAR
1. Lake Shore warrants that products manufactured by Lake Shore (the "Product") will be free from
defects in materials and workmanship for three years from the date of Purchaser's physical
receipt of the Product (the "Warranty Period"). If Lake Shore receives notice of any such defects
during the Warranty Period and the defective Product is shipped freight prepaid back to Lake
Shore, Lake Shore will, at its option, either repair or replace the Product (if it is so defective)
without charge for parts, service labor or associated customary return shipping cost to the
Purchaser. Replacement for the Product may be by either new or equivalent in performance to
new. Replacement or repaired parts, or a replaced Product, will be warranted for only the
unexpired portion of the original warranty or 90 days (whichever is greater).
2. Lake Shore warrants the Product only if the Product has been sold by an authorized Lake Shore
employee, sales representative, dealer or an authorized Lake Shore original equipment
manufacturer (OEM).
3. The Product may contain remanufactured parts equivalent to new in performance or may have
been subject to incidental use when it is originally sold to the Purchaser.
4. The Warranty Period begins on the date of Purchaser's physical receipt of the Product or later
on the date of operational training and verification (OT&V) of the Product if the service is
performed by Lake Shore, provided that if the Purchaser schedules or delays the Lake Shore
OT&V for more than 30 days after delivery then the Warranty Period begins on the 31st day
after Purchaser's physical receipt of the Product.
5. This limited warranty does not apply to defects in the Product resulting from (a) improper or
inadequate installation (unless OT&V services are performed by Lake Shore), maintenance,
repair or calibration, (b) fuses, software, power surges, lightning and non-rechargeable
batteries, (c) software, interfacing, parts or other supplies not furnished by Lake Shore, (d)
unauthorized modification or misuse, (e) operation outside of the published specifications, (f)
improper site preparation or site maintenance (g) natural disasters such as flood, fire, wind, or
earthquake, or (h) damage during shipment other than original shipment to you if shipped
through a Lake Shore carrier.
6. This limited warranty does not cover: (a) regularly scheduled or ordinary and expected
recalibrations of the Product; (b) accessories to the Product (such as probe tips and cables,
holders, wire, grease, varnish, feed throughs, etc.); (c) consumables used in conjunction with
the Product (such as probe tips and cables, probe holders, sample tails, rods and holders,
ceramic putty for mounting samples, Hall sample cards, Hall sample enclosures, etc.); or, (d)
non-Lake Shore branded Products that are integrated with the Product.
7. To the extent allowed by applicable law,, this limited warranty is the only warranty applicable to
the Product and replaces all other warranties or conditions, express or implied, including, but
not limited to, the implied warranties or conditions of merchantability and fitness for a particular
purpose. Specifically, except as provided herein, Lake Shore undertakes no responsibility that
the products will be fit for any particular purpose for which you may be buying the Products. Any
implied warranty is limited in duration to the warranty period. No oral or written information, or
advice given by the Company, its Agents or Employees, shall create a warranty or in any way
increase the scope of this limited warranty. Some countries, states or provinces do not allow
limitations on an implied warranty, so the above limitation or exclusion might not apply to you.
This warranty gives you specific legal rights and you might also have other rights that vary from
country to country, state to state or province to province.
8. Further, with regard to the United Nations Convention for International Sale of Goods (CISC,) if
CISG is found to apply in relation to this agreement, which is specifically disclaimed by Lake
Shore, then this limited warranty excludes warranties that: (a) the Product is fit for the purpose
for which goods of the same description would ordinarily be used, (b) the Product is fit for any
particular purpose expressly or impliedly made known to Lake Shore at the time of the
conclusion of the contract. (c) the Product is contained or packaged in a manner usual for such
goods or in a manner adequate to preserve and protect such goods where it is shipped by
someone other than a carrier hired by Lake Shore.
9. Lake Shore disclaims any warranties of technological value or of non-infringement with respect
to the Product and Lake Shore shall have no duty to defend, indemnify, or hold harmless you
from and against any or all damages or costs incurred by you arising from the infringement of
patents or trademarks or violation or copyrights by the Product.
10. THIS WARRANTY IS NOT TRANSFERRABLE. This warranty is not transferrable.
11. Except to the extent prohibited by applicable law, neither Lake Shore nor any of its
subsidiaries, affiliates or suppliers will be held liable for direct, special, incidental, consequential
or other damages (including lost profit, lost data, or downtime costs) arising out of the use,
inability to use or result of use of the product, whether based in warranty, contract, tort or other
legal theory, regardless whether or not Lake Shore has been advised of the possibility of such
damages. Purchaser's use of the Product is entirely at Purchaser's risk. Some countries, states
and provinces do not allow the exclusion of liability for incidental or consequential damages, so
the above limitation may not apply to you.
12. This limited warranty gives you specific legal rights, and you may also have other rights that
vary within or between jurisdictions where the product is purchased and/or used. Some
jurisdictions do not allow limitation in certain warranties, and so the above limitations or
exclusions of some warranties stated above may not apply to you.
Except to the extent allowed by applicable law, the terms of this limited warranty statement do not
exclude, restrict or modify the mandatory statutory rights applicable to the sale of the product to
you.
CERTIFICATION
Lake Shore certifies that this product has been inspected and tested in accordance with its
published specifications and that this product met its published specifications at the time of
shipment. The accuracy and calibration of this product at the time of shipment are traceable to the
United States National Institute of Standards and Technology (NIST); formerly known as the
National Bureau of Standards (NBS), or to a recognized natural standard.
TRADEMARK ACKNOWLEDGEMENT
Manufacturers and sellers claim many designations as trademarks to distinguish their products.
Where those designations appear in this manual and Lake Shore was aware of a trademark claim,
the designations appear in initial capital letters with a ™ or
®
symbol.
Apiezon® is a trademark of Biddle Instruments.
CalCurve™, Carbon-Glass™, Cernox™, Duo-Twist™, High-Temperature Cernox™, QuadLead™, Quad-Twist™, Rox™, SoftCal™, and Thermox™ are trademarks of Lake Shore
Cryotronics, Inc.
Teflon® is a trademark of DuPont De Nemours.
Copyright © 1993, 1998-99, 2001, 2004, 2012-13 by Lake Shore Cryotronics, Inc. All rights
reserved. No portion of this manual may be reproduced, stored in a retrieval system, or
transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or
otherwise, without express written permission of Lake Shore.
Rev. 1.8 P/N 119-021 03 October 2013
Lake Shore Model 231 User’s Manual
i
Lake Shore Model 231 User’s Manual
TABLE OF CONTENTS
Chapter/Paragraph Title Page
1 INTRODUCTION .......................................................................... 1-1
1.0 General .......................................................................... 1-1
1.1 Model 231 System Description ...................................... 1-1
1.2 Single Enclosure Case Description ................................ 1-6
1.3 Multiple Unit Enclosure Case Description ...................... 1-7
2 INSTALLATION ........................................................................... 2-1
2.0 General .......................................................................... 2-1
2.1 Inspection and Unpacking .............................................. 2-1
2.2 Repackaging For Shipment ........................................... 2-1
2.3 Sensor Installation Recommendations........................... 2-2
2.3.1 Two-Lead vs. Four-Lead Measurements .................... 2-2
2.3.1.1 Two-Lead Measurements ....................................... 2-2
2.3.1.2 Four-Lead Measurements ...................................... 2-3
2.3.2 Connecting Leads To The Sensor .............................. 2-3
2.3.3 Sensor Mounting ........................................................ 2-3
2.3.4 Measurement Errors Due To AC Noise ...................... 2-4
2.4 Sensor Curve Definition ................................................. 2-5
2.5 Power Connections ........................................................ 2-6
3 OPERATION ................................................................................ 3-1
3.0 General .......................................................................... 3-1
3.1 PCB DIP Switch Settings ............................................... 3-1
3.2 Output to Temperature Conversion ............................... 3-2
4 SERVICE ..................................................................................... 4-1
4.0 General .......................................................................... 4-1
4.1 General Troubleshooting ............................................... 4-1
4.1.1 No Output (On-Board LED Off) .................................. 4-1
4.1.2 Output Stops Before Reaching Upper Limit ............... 4-1
4.1.3 Output Is Incorrect Value (Small Error) ...................... 4-1
4.1.4 Output Is Incorrect Value (Large Error) ...................... 4-2
4.2 Model 231 Connector Definitions ................................... 4-2
4.3 Calibration ...................................................................... 4-3
4.3.1 Test Equipment Required ........................................... 4-3
4.3.2 Reference Calibration ................................................. 4-4
4.3.3 Output Calibration ...................................................... 4-5
Table of Contents
ii
Lake Shore Model 231 User’s Manual
TABLE OF CONTENTS (Continued)
Chapter/Paragraph Title Page
5 OPTIONS AND ACCESSORIES ................................................. 5-1
5.0 General .......................................................................... 5-1
5.1 Enclosures ..................................................................... 5-1
5.2 Options........................................................................... 5-1
5.3 Accessories .................................................................... 5-2
5.4 Wires .............................................................................. 5-2
5.5 Sensors .......................................................................... 5-3
5.6 Special Equipment ......................................................... 5-3
APPENDIX A – MODEL 231 CURVE TABLES ................................. A-1
APPENDIX B – GLOSSARY OF TERMINOLOGY ............................ B-1
Figure No. Title Page
1-1 Typical Model 231 Front Panel.............................................. 1-2
1-2 Single Enclosure Case Physical Dimensions ........................ 1-6
1-3 Multiple Unit Case Physical Dimensions ............................... 1-8
2-1 Typical Wall Plug-In Power Supply ....................................... 2-7
3-1 Model 231 DIP Switch (S1) ................................................... 3-1
4-1 Front Panel Connectors J2 & J3 Details ............................... 4-2
4-2 VMEbus Connector J1 Details .............................................. 4-3
4-3 Model 231 PCB Layout ......................................................... 4-4
Table No. Title Page
1-1 Model 231 Input Specifications ............................................. 1-3
1-2 Model 231P Input Specifications ........................................... 1-4
1-3 Model 231 & 231P Output Specifications .............................. 1-5
1-4 Model 2308-12 VMEbus Rackmount Case Specs ................ 1-7
2-1 Effect of Current Variation on Diode Temperature ................ 2-5
2-2 Typical DT-470 dV/dI Values for Selected Temps ................. 2-5
3-1 Conversion Parameters for Temperature in K ....................... 3-2
A-1 Lake Shore Standard Diode Curves ......................................A-1
A-2 Series PT-100 Platinum Resistance Curve ...........................A-2
LIST OF ILLUSTRATIONS
LIST OF TABLES
Table of Contents
Lake Shore Model 231 User’s Manual
CHAPTER 1
INTRODUCTION
1.0 GENERAL
Lake Shore Cryotronics designed and manufactures the Model 231 in the
United States of America. In general, reference to the Model 231 means
both the Model 231 and 231P. Specific references are made where
appropriate. This chapter provides a general description with specifications
in Paragraph 1.1, single-enclosure case description in Paragraph 1.2, and
multiple-unit enclosure case description in Paragraph 1.3.
We welcome comments on this manual. Although we try to keep it error-free,
some may occur. To report an error, describe it briefly and include the
appropriate paragraph, figure, table, and page number. Send comments to
Lake Shore Cryotronics, Attn: Technical Publications, 575 McCorkle Blvd.,
Westerville, Ohio 43082-8888. This manual is subject to change without
notice.
1.1 MODEL 231 GENERAL DESCRIPTION
The Model 231 Temperature Transmitter is available as a stand-alone unit or
for use within either of two enclosures: a Model 2308-1 single-space
enclosure, or a Model 2308-12 rackmount case that holds up to 12 units.
The Model 231 Temperature Transmitter sends temperature data from its
position near a sensor to a data acquisition channel or strip chart recorder. It
operates with Silicon diode or Gallium-Aluminum-Arsenide (GaAlAs) diode
sensors. Lake Shore Silicon diode sensors are accurate over a wide
cryogenic temperature range and are interchangeable for some applications.
The Lake Shore Series TG-120 GaAlAs diodes operate in a low to moderate
magnetic field. Excited with a 10 µA current source from the Model 231, the
sensors produce a voltage that depends on temperature. A microcontroller
reads the voltage through an A/D converter and translates it into
temperature. Either the standard temperature curve or an optional
CalCurve™ relates voltage to temperature (the Series TG-120 requires a
CalCurve).
The Model 231P uses a Series PT-100 Platinum Thermometer. The Model
231P excites the sensor with a 500 µA current to produce a measurable
signal. Either the standard platinum curve (DIN 437600) or a CalCurve is
used for temperature conversion.
Introduction 1-1
Figure 1-1. Typical
Model 231 Front Panel
Lake Shore Model 231 User’s Manual
Once the Model 231 obtains temperature data, it
transmits it as a current from 4 to 20 mA. The
current output changes linearly with sensor
temperature. Output scale depends on the selected
temperature range. Several switch selected ranges
are available. For highest accuracy and sensitivity,
set the output for a narrow temperature band. An
optional 0 to 20 mA output is also available to
convert output to a voltage reading scaled from zero.
A 500 ±0.02% precision resistor is provided for
this purpose. This resistor produces the maximum
full-scale output of 10 V.
A single +5 VDC supply powers Model 231 circuitry.
The outputs are isolated so several 231s can
operate from the same supply without interference.
The +5 VDC can also be supplied from the pins on
the VME bus connector.
Mechanical mounting is easy because the
Model 231 is built on a standard size VME card.
It fits directly into a single height (3U) VME card
holder. The transmitter does not use the electrical
bus format, only its physical shape and power
supply.
1-2 Introduction
Thermometry:
Number of Inputs: One input
Measurement Type: Four-lead differential
Sensor Type: Silicon diode, GaAlAs diode (to 5V)
Sensor Temp. Coefficient: Negative
Sensor Units: Volt (V)
Input Range: 0 – 5 volts
Sensor Excitation: 10 µA ±0.1% DC current
Update Rate: 5 readings per second
CalCurve Storage: 1 curve, loaded in PROM at factory
Example Lake Shore Sensor: DT-470-CO
Temperature Range: 1.4 K – 325 K with DT-470
Standard Curve: Curve 10
Typical Sensor Sensitivity: –30 mV/K at 4.2 K
–1.9 mV/K at 77.35 K
–2.4 mV/K at 300 K
Measurement Resolution:
Sensor Units: 76.3 µV
Temp. Equivalence: 2.5 mK at 4.2 K
40 mK at 77.35 K
32 mK at 300 K
Measurement Accuracy:
Sensor Units: ±75 µV ±0.01% of reading
Temp. Accuracy *: ±0.07 K at 4.2 K
±0.16 K at 77.35 K
±0.12 K at 300 K
* DT-470-CO with 8001 CalCurve.
Measurement Temperature Coefficient:
Sensor Units: 0.0006% of voltage reading per °C
Temp. Equivalence: 3 mK/°C at 4.2 K
3 mK/°C at 77.35 K
1.2 mK/°C at 300 K
Typical Performance With Series TG-120 Sensor:
Similar to selected example diode sensor with improved
measurement resolution and temperature resolution at
temperatures of 4 K to 50 K. Sensor voltage must not
exceed 5 V at lowest operating temperature.
Lake Shore Model 231 User’s Manual
Table 1-1. Model 231 Input Specifications
Introduction 1-3
Thermometry:
Number of Inputs: One input
Measurement Type: Four-lead differential
Sensor Type: Platinum
Sensor Temp. Coefficient: Positive
Sensor Units: Ohm ()
Input Range: 0 – 312
Sensor Excitation: 500 µA ±0.02% DC current
Update Rate: 5 readings per second.
CalCurve Storage: 1 curve, loaded in PROM at factory.
Example Lake Shore Sensor: PT-103
Temperature Range: 14 K – 873 K with PT-103
Standard Curve: DIN 43760
Typical Sensor Sensitivity: 0.19 /K @ 30 K
0.42 /K @ 77.35 K
0.39 /K @ 300 K
0.34 /K typical up to 800 K
Measurement Resolution:
Sensor Units: 4.8 m
Temp. Equivalence: 22 mK at 30 K
11 mK at 77.35 K
13 mK at 300 K
14 mK typical up to 800 K
Measurement Accuracy:
Sensor Units: Ohms ()
Temp. Accuracy: ±0.2 K at 30 K
±0.15 K at 77.35 K
±0.3 K at 300 K
±0.7 K typical up to 800 K
Measurement Temperature Coefficient:
Sensor Units: 0.002% of voltage reading per °C
Temp. Equivalence: 0.4 mK/°C at 30 K
1 mK/°C at 77.35 K
6 mK/°C at 300 K
18 mK/°C at 800 K
Magnetic Field Use: Up to 19 teslas for T > 30 K.
Lake Shore Model 231 User’s Manual
Table 1-2. Model 231P Input Specifications
1-4 Introduction
Output:
Number of Outputs: One
Output Type: Current source, isolated from power source but not
sensor input
Output Range: 4 – 20 mA or 0 – 20 mA (for 0 – 10 V with provided
500 , 0.02%, 25 ppm resistor)
Output Compliance: 10 V (500 max load)
Output Temperature Ranges: 0 – 20 K, 0 – 100 K, 0 – 200 K,
0 – 325 K, 0 – 475 K, and 0 – 1000 K
4 – 20 mA Output:
Output Resolution:
Current: ±1.22 µA ±0.006% of full scale
Temp. Equivalence: 0–20 K = 1.5 mK 0–325 K = 24.8 mK
0–100 K = 7.6 mK 0–475 K = 36.2 mK
0–200 K = 15.3 mK 0–1000 K = 76.3 mK
Output Accuracy:
Current: ±2 µA ±0.01% of full scale
Temp. Equivalence: 0–20 K = 2.5 mK 0–325 K = 41 mK
0–100 K = 12.5 mK 0–475 K = 59 mK
0–200 K = 25 mK 0–1000 K = 125 mK
Output Temperature Coefficient:
Current (% output/°C ambient): ±0.0055%/°C
Temp. Equivalence: 0–20 K = 1 mK/°C 0–325 K = 18 mK/°C
0–100 K = 6 mK/°C 0–475 K = 26 mK/°C
0–200 K = 12 mK/°C 0–1000 K = 55 mK/°C
0 – 20 mA Output (0-10 V w/500 , 0.02% Load Resistor):
Output Resolution:
Voltage: 0.6 mV ±0.006% of full scale
Temp. Equivalence: 0–20 K = 1.2 mK 0–325 K = 19.8 mK
0–100 K = 6.1 mK 0–475 K = 29 mK
0–200 K = 12.2 mK 0–1000 K = 61 mK
Output Accuracy:
Voltage: ±3 mV ±0.03% of full scale
Temp. Equivalence: 0–20 K = 6 mK 0–325 K = 98 mK
0–100 K = 30 mK 0–475 K = 143 mK
0–200 K = 60 mK 0–1000 K = 300 mK
Output Temperature Coefficient:
Voltage (% Output/°C ambient): ±0.008%/°C
Temp. Equivalence: 0–20 K = 2 mK/°C 0–325 K = 26 mK/°C
0–100 K = 8 mK/°C 0–475 K = 38 mK/°C
0–200 K = 16 mK/°C 0–1000 K = 80 mK/°C
Lake Shore Model 231 User’s Manual
Table 1-3. Model 231 and 231P Output Specifications
Introduction 1-5
General:
Ambient Temperature Range: 15 – 35 °C
Power Requirement: +5 (±0.25) VDC, 500 mA
Size: 100 mm high × 160 mm deep × 30.5 mm wide
Mounting: VME end panel and back plane. Transmitter does
not use electrical bus format, only its physical shape and
power supply.
Note: Electronic temperature accuracy in a given temperature
range is the sum of temperature accuracies of input and output.
Sensor calibration errors are not included.
Lake Shore Model 231 User’s Manual
Table 1-3 Model 231 & 231P Output Specifications (Continued)
1.2 SINGLE ENCLOSURE CASE DESCRIPTION
Holds one Model 231. Typical dimensions appear below.
Figure 1-2. Typical Single Enclosure Case Physical Dimensions
1-6 Introduction
No. of Card Slots: 12
Size: 45 × 17.8 × 26 centimeters (17.7 × 7 × 10.25 inches)
Weight: 5.5 kilograms (12 pounds)
Output Voltage: +5 VDC, 100 mV Peak-to-Peak Ripple
Output Current: 6 Amperes (Maximum)
Input Power: Universal 85 – 265 VAC, 47 – 440 Hz., 60 Watts
Ambient Temp. Range: 15 – 35 °C (59 – 95 °F)
Lake Shore Model 231 User’s Manual
1.3 MULTIPLE UNIT ENCLOSURE CASE DESCRIPTION
The Model 2308-12 VMEbus Rackmount Case holds up to 12 Model 231
units. A +5 VDC power supply with universal input is provided with the case.
Specifications and typical dimensions of the case are shown below. Refer to
Paragraph 2.5 for further information on the built-in power supply.
CAUTION: The Model 2308-12 bus is designed only to power multiple
Model 231s. Do not use with standard VME cards.
Table 1-4. Model 2308-12 VMEbus Rackmount Case Specifications
Introduction 1-7
Lake Shore Model 231 User’s Manual
Figure 1-3. Typical Multiple Unit Case Physical Dimensions
1-8 Introduction
Lake Shore Model 231 User’s Manual
CHAPTER 2
INSTALLATION
2.0 GENERAL
This chapter covers inspection and unpacking in Paragraph 2.1, repackaging
for shipment in Paragraph 2.2, sensor installation recommendations in
Paragraph 2.3, sensor curve definitions in Paragraph 2.4, and power
connections in Paragraph 2.5.
2.1 INSPECTION AND UNPACKING
Inspect shipping containers for external damage. Make all claims for
damage (apparent or concealed) or partial loss of shipment in writing to
Lake Shore within 5 days from receipt of goods. If damage or loss is
apparent, please notify the shipping agent immediately.
Open the shipping containers. Use the packing list included with the system
to verify receipt of the instrument, sensor, accessories, and manual. Inspect
for damage. Inventory all components supplied before discarding any
shipping materials. If there is freight damage to the instrument, file proper
claims promptly with the carrier and insurance company and notify Lake
Shore. Notify Lake Shore immediately of any missing parts. Lake Shore
cannot be responsible for any missing parts unless notified within 60 days
of shipment. Refer to the standard Lake Shore Warranty on the A Page
(immediately behind the title page).
2.2 REPACKAGING FOR SHIPMENT
To return the Model 231 or accessories for repair or replacement, obtain a
Return Goods Authorization (RGA) number from Technical Service in the
United States, or from the authorized sales/service representative from
which the product was purchased. Instruments may not be accepted without
a RGA number. When returning an instrument for service, Lake Shore must
have the following information before attempting any repair.
1. Instrument model and serial number.
2. User name, company, address, and phone number.
3. Malfunction symptoms.
4. Description of system.
5. Returned Goods Authorization (RGA) number.
Repack the system in its original container (if available). Affix shipping labels
and FRAGILE warnings. Write RGA number on the outside of the container
or on the packing slip. If not available, consult Lake Shore for shipping and
packing instructions.
Installation 2-1
I+
V+
I–
V–
Two-Lead
Measurements
Lake Shore Model 231 User’s Manual
2.3 SENSOR INSTALLATION RECOMMENDATIONS
Refer to the Lake Shore Product Catalog for installation details and sensor
specifications. Call Lake Shore for copies of application notes or sensor
installation questions. Below are general recommendations on sensor
installation:
1. Do not ground the sensor.
2. Shield leads and connect shield wire to SHIELD on screw terminal
connector only. Do not connect shield at other end of cable.
3. Keep leads as short as possible.
4. Use twisted-pair wire. Use Lake Shore Duo-Twist™ wire (or equivalent)
for two-wire, or Quad-Twist™ wire (or equivalent) for four-wire
applications.
5. Thermally anchor lead wires.
2.3.1 Two-Lead versus Four-Lead Measurements
In two-lead measurement, the leads that measure sensor voltage also carry
the current. The voltage measured at the instrument is the sum of the
temperature sensor voltage and the IR voltage drop within the two current
leads. Since heat flow down the leads can be critical in a cryogenic
environment, wire of small diameter and significant resistance per foot is
preferred to minimize this heat flow. Consequently, a voltage drop within the
leads may exist.
Four-lead measurement confines current to one pair of leads and measures
sensor voltage with the other lead pair carrying no current.
2.3.1.1 Two-Lead Measurement
Sometimes system constraints dictate
two-lead measurement. Connect the
positive terminals (V+ and I+) together
and the negative terminals (V– and I–)
together at the instrument, then run
two leads to the sensor.
Expect some loss in accuracy; the voltage measured at the voltmeter equals
the sum of the sensor voltage and the voltage drop across the connecting
leads. The exact measurement error depends on sensor sensitivity and
variations resulting from changing temperature. For example, a 10 lead
resistance results in a 0.1 mV voltage error. The resultant temperature error
at liquid helium temperature is only 3 mK, but, because of the lower
sensitivity (dV/dT) of the diode at higher temperatures, it becomes 10 mK at
liquid nitrogen temperature.
2-2 Installation
I+
V+
I–
V–
Four-Lead
Diode
DT-470-SD
Diode Sensor Leads
AnodeCathode
Lake Shore Model 231 User’s Manual
2.3.1.2 Four-Lead Measurement
All sensors, both two-lead and four-lead
devices, can be measured in a four-lead
configuration to eliminate the effects of lead
resistance. The exact point at which the
connecting leads solder to the two-lead
sensor normally results in a negligible
temperature uncertainty.
Always use four-lead measurement configuration
when a Series PT-100 Platinum Sensor is attached to the Model 231P.
2.3.2 Connecting Leads To The Sensor
Excessive heat flow through connecting leads to any temperature sensor
may differ the temperature between the active sensing element and the
sample to which the sensor mounts. This reflects as a real temperature
offset between what is measured and the true sample temperature.
Eliminate such temperature errors with proper selection and installation of
connecting leads.
To minimize heat flow through the leads, select leads of small diameter and
low thermal conductivity. Phosphor-bronze or Manganin wire is commonly
used in sizes 32 or 36 AWG. These wires have a fairly low thermal
conductivity, yet electrical resistance is not large enough to create
measurement problems.
Thermally anchor lead wires at several temperatures between room
temperature and cryogenic temperatures to guarantee no heat conduction
through the leads to the sensor.
2.3.3 Sensor Mounting
Before installing a diode sensor, identify
which lead is the anode and which is
the cathode. When viewed with the
base down and the leads towards the
observer, the anode is on the right and
the cathode is on the left. The Lake
Shore DT-470-SD silicon diode sensor
lead configuration is shown to the right.
For other sensors, read accompanying
literature or consult the manufacturer to positively identify sensor leads.
Lead identification should remain clear even after sensor installation. Record
the sensor serial number and location.
On the DT-470-SD, the base is the largest flat surface. It is sapphire with
gold metalization over a nickel buffer layer. The base is electrically isolated
from the sensing element and leads; make all thermal contact to the
Installation 2-3
Lake Shore Model 231 User’s Manual
sensor through the base. A thin braze joint around the sides of the SD
package electrically connect to the sensing element. Avoid contact to the
sides with any electrically conductive material.
When installing the sensor, make sure there are no electrical shorts or
current leakage paths between the leads or between the leads and ground.
If IMI-7031 varnish or epoxy is used, it may soften varnish-type lead
insulations so that high resistance shunts appear between wires if sufficient
time for curing is not allowed.
Slide Teflon® spaghetti tubing over bare leads when the possibility of
shorting exists. Avoid putting stress on the device leads and allow for
thermal contractions that occur during cooling which could fracture a solder
joint or lead if installed under tension at room temperature.
For temporary mounting in cold temperature applications, apply a thin layer
of Apiezon® N Grease between the sensor and sample to enhance thermal
contact under slight pressure. The preferred method for mounting the
DT-470-SD sensor is the Lake Shore CO Adapter.
CAUTION: Lake Shore will not warranty replace any device damaged by
user-designed clamps or solder mounting.
For semi-permanent mountings, use Stycast epoxy instead of Apiezon® N
Grease. NOTE: Do not apply Stycast epoxy over the DT-470-SD package —
sensor stress may shift the readings. In all cases, periodically inspect the
sensor mounting to verify good thermal contact to the mounting surface is
maintained.
For the Model 231P, Series PT-100 Platinum Sensors follow the same basic
procedures for diode type sensors. However, Platinum sensors have no lead
polarity, and some of the materials used at cold temperatures will not
tolerate the high-temperature range of the Platinum sensor.
2.3.4 Measurement Errors Due To AC Noise
Poorly shielded leads or improperly grounded measurement systems can
introduce AC noise into the sensor leads. In diode sensors, the AC noise
shifts the DC voltage measurement due to the diode non-linear
current/voltage characteristics. When this occurs, measured DC voltage is
too low and the corresponding temperature reading is high. The
measurement error can approach several tenths of a kelvin. To determine if
this problem exists, perform either procedure below.
1. Place a capacitor across the diode to shunt induced AC currents.
Capacitor size depends on the noise frequency. If noise is related to
power line frequency, use a 10 µF capacitor. If AC-coupled digital noise
is suspected (digital circuits or interfaces), use a 0.1 to 1 µF capacitor. In
either case, if measured DC voltage increases, there is induced noise in
the measurement system.
2-4 Installation
Lake Shore Model 231 User’s Manual
2. Measure AC voltage across the diode with an AC voltmeter or
oscilloscope. Most voltmeters do not have the frequency response to
measure noise associated with digital circuits or interfaces (which
operate in the MHz range). For a thorough discussion of this potential
problem, and the magnitude of error which may result, request the paper
“Measurement System-Induced Errors In Diode Thermometry,” J.K.
Krause and B.C. Dodrill, Rev. Sci. Instr. 57 (4), 661, April, 1986
from Lake Shore.
To greatly reduce potential AC noise, connect twisted leads (pairs) between
the measurement instruments and the diode sensors. Use 32 or 36 AWG
Lake Shore Duo-Twist Cryogenic Wire, which features phosphor bronze wire
twisted at 3.15 twists per centimeter (8 twists per inch). Refer to the Lake
Shore Product Catalog or contact Lake Shore for further information.
2.4 SENSOR CURVE DEFINITION
Model 231 sensor curves include Curve 10, DT-670, Platinum Curve
(DIN 43760), and a factory installed CalCurve for a calibrated sensor.
After selecting the proper curve, refer to Paragraph 3.1 to set the
Model 231 DIP switch.
Curve 10: Lake Shore DT-470 Series silicon diodes follow the same
standard temperature response Curve 10, which makes them
interchangeable. Lake Shore programs Curve 10 into its Temperature
Controllers, Digital Thermometers, and Temperature Transmitters.
DT-470 Series silicon diode sensors come in five bands of tracking
accuracy, allowing selection based on both performance and expense.
Installation 2-5
MODEL
INPUT POWER
2007-12
2007-22
120 V 60 Hz. power source
230 V 50 Hz. power source
Lake Shore Model 231 User’s Manual
DT-670: DT-670 Series Silicon Diode Sensors come in five bands of tracking
accuracy, allowing selection based on both performance and price.
Platinum Curve: Users of the Model 231P have the option of the standard
platinum curve, or the CalCurve. The standard platinum curve detailed in
Appendix B conforms to DIN 43760:1980; IEC 751:1983; and 1904:1984.
CalCurve: CalCurve is the easiest way to combine the additional
performance of a Lake Shore calibrated sensor with the Model 231. The
CalCurve is a read-only memory chip (PROM) with specific sensor
calibration stored on it. The CalCurve improves combined sensor/instrument
accuracy to within ±0.25K or better over the calibrated temperature range of
the sensor.
The 8001-231 CalCurve is factory-installed upon order of an instrument with
a calibrated sensor. To order an instrument to be used with a currently
owned Lake Shore calibrated sensor, Lake Shore requires the sensor model
number and serial number at the time of order. The Model 8002-231 is for
field installations of the CalCurve in an existing Model 231.
The CalCurve is required with a Lake Shore TG-120 Series GalliumAluminum-Arsenide Diode Temperature Sensor.
2.5 POWER CONNECTIONS
The Model 231 is powered by the +5 VDC supply in the VME rack or an
external power supply. The voltage must be regulated to within ±0.25 VDC.
Each Model 231 draws up to 500 mA from the supply. The external power
supply connector must be S-760 or S-765 Switchcraft (or equivalent) plug
(0.218 inch O.D., accepts 0.08 inch diameter pin) with the +5 VDC on the
sleeve and return on the center pin.
A wall plug-in power supply Model 2007-XX +5 VDC Regulated Power
Supply can be used with the Model 231. Power Supply input is based on
local power requirements as follows:
CAUTION: Never ground both the sensor and the 4 – 20 mA output.
Ground the sensor, or the output, but not both.
2-6 Installation
Lake Shore Model 231 User’s Manual
The Model 2308-10 VMEbus rackmount case has a built-in power supply for
up to twelve Model 231s. The built-in power supply has a universal input:
85 to 265 VAC, 47 to 440 Hz, 60 watts.
C-231-2-1.eps
Figure 2-1. Typical Wall Plug-In Power Supply
Installation 2-7
Lake Shore Model 231 User’s Manual
This Page Intentionally Left Blank
2-8 Installation
Lake Shore Model 231 User’s Manual
CHAPTER 3
OPERATION
3.0 GENERAL
This chapter covers Printed Circuit Board (PCB) DIP Switch Settings in
Paragraph 3.1 and Output Current and Voltage-to-Temperature Conversion
in Paragraph 3.2.
3.1 PCB DIP SWITCH SETTINGS
Before placing the unit into service, the Model 231 DIP switch (S1) must be
properly configured. Once an operating range is selected, the corresponding
range number should be enabled on the Model 231 PCB DIP Switch (S1).
See Figure 3-1. Select only one range at a time. The range is enabled when
the switch is closed (ON). Units ship from the factory with the DIP switch set
to RANGE4 closed (0 to 325 K).
For the Model 231, set the CURVE switch to open for the DT470 Curve 10
or the CalCurve option (if present) or closed for the DT-670 Curve. For the
Model 231P, set the CURVE switch to open for the platinum curve or
closed for the CalCurve option. Unless CalCurve is specified, units ship
from the factory with the DIP switch set to CURVE open.
C-231-3-1.eps
Figure 3-1. Model 231 DIP Switch (S1) Settings
Operation 3-1
4 – 20 mA
0 – 10 V
RANGE
TEMP. (K)
A (K) B (K/mA)
C (K/V)
RANGE1
0 – 20
–5.00 1.2500
2.0
RANGE2
0 – 100
–25.00 6.2500
10.0
RANGE3
0 – 200
–50.00 12.5000
20.0
RANGE4
0 – 325
–81.25 20.3125
32.5
RANGE5
0 – 475
–118.75 29.6875
47.5
RANGE6
0 – 1000
–250.00 62.5000
100.0
Lake Shore Model 231 User’s Manual
Current/Voltage (I/V) OUT is for selection of proper output type. Open is for
4 – 20 mA and closed is for 0 – 20 mA. The 4 – 20 mA is an industry standard,
while the 0 – 20 mA is provided to translate output into voltage scaled up to
10 V. For a 0 – 10 V output, use the supplied 500 ±0.02% precision
resistor as a load across the OUT+ and OUT– terminals. Load resistors less
than 500 can be used to convert output to voltage using the following
formula:
Unless otherwise specified, units ship from the factory with the I/V OUT DIP
switch set to open.
3.2 OUTPUT TO TEMPERATURE CONVERSION
The output current or voltage is directly proportional to the temperature
reading. For the 4 – 20 mA output, the following formula converts output
current to temperature:
T = A + B x I
, where T = temperature in kelvin, I
OUT
= output current in
OUT
mA, and A and B are constants (from Table 3-1) depending on temperature.
For the 0 – 20 mA output (using the included 500 resistor for 0 – 10 V), the
following formula converts output voltage to temperature:
T = C x V
, where T = temperature in kelvin, V
OUT
= output voltage, and
OUT
C is a constant (from Table 3-1) depending on temperature.
Table 3-1. Conversion Parameters for Temperature in K
3-2 Operation
Lake Shore Model 231 User’s Manual
CHAPTER 4
SERVICE
4.0 GENERAL
This chapter cover general troubleshooting in Paragraph 4.1, Model 231
connectors in Paragraph 4.2, and calibration in Paragraph 4.3.
4.1 GENERAL TROUBLESHOOTING
4.1.1 No Output (On-Board LED Off)
Check that external power supply output is +5 VDC. If not, replace supply.
If using the front panel input jack (J2), make certain center post of connector
coming from power supply is NEGATIVE. If not, correct wiring. If using front
panel input jack (J2), verify external power supply is regulated at +5 VDC
and can supply a minimum of 500 mA. Also verify that OUT+ and SHIELD
are not connected to each other.
Due to extensive protection circuitry installed in Model 231, all the above
problems eventually cause the 0.5 A slow blow fuse to burn out. After
correction, replace the blown fuse with identical size and type.
4.1.2 Output Stops Before Reaching Upper Limit
Normally caused by too high resistance of output monitoring device.
Absolute maximum acceptable resistance is 500 . Also verify that proper
range DIP switch is selected.
4.1.3 Output Is Incorrect Value (Small Error)
Can be caused by incorrect curve selection for the sensor type. See
Figure 3-1. Another cause for a small error is the output resistor for output
current to voltage conversion is not high precision. When using voltage out,
the output resistor must be ±0.02% accurate (or better) and have low drift.
Service 4-1
J3
J2
OUT +
OUT –
SHIELD
SENS I+
SENS V+
SHIELD
SENS V–
SENS I–
Lake Shore Model 231 User’s Manual
4.1.4 Output Is Incorrect Value (Large Error)
Can be caused by incorrect sensor wiring. To test wiring, place voltmeter
between SENS V+ and SENS V– connection. With sensor connected, power
up the Model 231. With the sensor at room temperature, the voltmeter
should read about 0.5 VDC for a diode sensor, or about 55 mV for a
platinum sensor. If voltage is higher than 5 VDC, then sensor connections
may be open. If sensor voltage polarity is negative, SENS V+ and SENS V–
leads are reversed. With the sensor at operating temperature, the voltage
readings should correspond to Curve 10 for diode sensors, or DIN 43760 for
platinum sensors, as detailed in Appendix A.
4.2 MODEL 231 CONNECTORS
There are three connectors on the Model 231. The two front panel
connectors are the 8 pin terminal block (J3) and the power connector (J2).
See Figure 4-1. The rear connector (J1) is for connecting to the VMEbus.
See Figure 4-2.
Figure 4-1. Front Panel Connectors J2 and J3 Details
4-2 Service
PIN NO.
ROW A
ROW B
ROW C
1-8
9
10
11
12-14
15
16
17
18
19
20-31
32
Not Used
GND
Not Used
GND
Not Used
GND
Not Used
GND
Not Used
GND
Not Used
+5 VDC
Entire Row
Not Present
Not Used
GND
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
+5 VDC
A
B
C
32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
(Entire Row B
is not present)
= Pin Used
= Pin Not Used
J1 – VM Ebus Connector – End View
Lake Shore Model 231 User’s Manual
Figure 4-2. VMEbus Connector J1 Details
4.3 CALIBRATION
This section covers various aspects of Model 231 calibration: Required Test
Equipment (Paragraph 4.3.1), Reference Calibration (Paragraph 4.3.2), and
Calibration (Paragraph 4.3.3). See Figure 4-3 for the Model 231 PCB layout.
Allow 5 minutes warm-up before calibration.
4.3.1 Required Test Equipment
1. A digital voltmeter (DVM) that measures DC voltage between 0 and
10 V accurately to 0.0001 V.
2. A regulated +5 V DC power supply with tolerance within ±0.25 V,
capable to source 500 mA on an S-760 or S-765 Switchcraft (or
equivalent) power plug (0.218 inch outside diameter, accepts 0.08 inch
diameter pin). +5 V is on sleeve with center pin return.
3. Mating screw terminal to Model 231 front panel signal connector.
4. A 500 , 0.02% (or better) precision resistor.
5. Three jumper wires.
Service 4-3
Lake Shore Model 231 User’s Manual
4.3.2 Reference Calibration
Perform this reference calibration before output calibration.
1. Connect DVM negative lead to Model 231 reference ground (REF GND)
on TP2, and positive lead to VREF on TP3.
2. Adjust trimpot R33, VREF TRIM, until DVM reads 2.5000 V ±0.0001 V.
P-231-4-3.bmp
Figure 4-3. Model 231 PCB Layout
4-4 Service
Lake Shore Model 231 User’s Manual
4.3.3 Output Calibration
1. Connect 500 , 0.02% resistor to Model 231 pins OUT+ and OUT–.
2. Use jumper wires 1 and 2 to short V+ to I+ and V– to I–.
3. Record configuration of DIP Switch (S1) positions 1 thru 6.
4. Place DIP Switch (S1) positions 1 through 6 to open.
5. Place DVM across 500 resistor. Reading should be about 10 V.
6. Use jumper wire 3 to short V+ to V–. (Leave Jumpers 1 and 2 in place.)
7. DVM reading should drop to about 0 V. Allow 10 seconds for reading to
stabilize.
8. Adjust trimpot R25, OUTPUT OFFSET, until DVM reading is between 0
and 0.0001 V.
9. Remove jumper wire 3 between V+ and V–. (Leave Jumpers 1 and 2 in
place.)
10. DVM reading should be about 10 V.
11. Adjust trimpot R27, OUTPUT GAIN, until DVM reading is 10.0000
±0.0001 V.
12. Re-check offset calibration (Step 8) and adjust as needed. Re-check
gain calibration (Step 11) and adjust as needed.
13. Remove all jumpers.
14. Return configuration of DIP Switch (S1) positions 1 thru 6 to that
recorded in Step 3.
15. Calibration is complete.
Service 4-5
Lake Shore Model 231 User’s Manual
This Page Intentionally Left Blank
4-6 Service
Model
Description Of Enclosure
2308-1
Benchtop Enclosure for one Model 231 PCB.
2308-12
VMEbus rack mount case with built-in power supply for
up to 12 Model 231s.
Model
Description Of Option
8001-231
Factory Installed CalCurve. Allows instrument to more
accurately use the calibration data to calculate and
output current proportional to temperature. Requires a
calibrated sensor.
8002-231
Field Installed CalCurve. Requires field installation of a
new microprocessor/memory IC. Allows instrument to
more accurately use the calibration data to calculate
and output current proportional to temperature.
Requires a calibrated sensor.
Lake Shore Model 231 User’s Manual
CHAPTER 5
OPTIONS AND ACCESSORIES
5.0 GENERAL
This chapter lists Model 231 enclosures, options, accessories, sensors,
wires, and special equipment.
5.1 ENCLOSURES
5.2 OPTIONS
Options & Accessories 5-1
Model
Description Of Accessory
MAN-231
Model 231 User’s Manual
106-739
Input Terminal Mating Connector
2007-12
Wall Plug-in Power Supply, 120 V 60 Hz power source
2007-22
Wall Plug-in Power Supply, 230 V 50 Hz power source
103-626
Resistor, Precision, 500 , ±0.02%
P/N
Description Of Cable
9001-005
Quad-Twist™ Cryogenic Wire. Two twisted pairs,
phosphor-bronze wire, 36 AWG, 0.127 mm (0.005 inch)
diameter.
9001-006
Duo-Twist™ Cryogenic Wire. Single twisted pair,
phosphor-bronze wire, 36 AWG, 0.127 mm (0.005 inch)
diameter.
9001-007
Quad-Lead™ Cryogenic Wire. Phosphor-bronze wire,
flat, 32 AWG, 0.203 mm (0.008 inch) diameter.
9001-008
Quad-Lead™ Cryogenic Wire. Phosphor-bronze wire,
flat, 36 AWG, 0.127 mm (0.005 inch) diameter.
—
Any quality dual shield twisted pair wire for dewar to
Model 231 connector.
Lake Shore Model 231 User’s Manual
5.3 ACCESSORIES
5.4 WIRES
5-2 Options & Accessories
Sensor No.
Description Of Sensor
Series DT-414
Unencapsulated Silicon Diode mounted on a
flat substrate. This chip-level sensor offers
minimal thermal mass and minimal physical
size. Die attachment is with silver epoxy. The
exposed gold wires are fragile. Uses the same
silicon chip used in the DT-470 Series.
Series DT-420
Miniature Silicon Diode Temperature Sensor.
Same silicon chip used in the DT-470.
Configured for installation on flat surfaces.
Series DT-470
Silicon Diode Temperature Sensor.
Interchangeable, repeatable, accurate, wide
range customized for cryogenics.
Series DT-471
An economical version of the DT-470 for
applications where temperature measurements
below 10 K are not required.
Series DT-670
Lake Shore’s newest silicon diode temperature
sensor. Interchangeable, repeatable, accurate,
wide range customized for cryogenics.
Series TG-120
A wide range Gallium-Aluminum-Arsenide
(GaAlAs) Diode Sensor well suited for
temperature measurement in low to moderate
magnetic fields.
Series PT-100
Platinum Resistance Thermometer is an
excellent choice for cryogenic temperature
sensing and control in the range from 30 K to
873 K (–243 °C to 600 °C).
5.5 SENSORS
Lake Shore Model 231 User’s Manual
Options & Accessories 5-3
Lake Shore Model 231 User’s Manual
This Page Intentionally Left Blank
5-4 Options & Accessories
Break-
DT-670 Curve
Curve 10
point No.
Temp.(K)
Voltage
Temp.(K)
Voltage
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
499.9
475.0
445.0
400.0
330.0
285.0
250.0
215.0
185.0
160.0
140.0
120.0
100.0
85.0
70.0
52.0
36.0
30.0
27.0
26.0
25.0
24.0
23.0
21.0
15.0
12.0
9.0
3.8
1.9
1.4
0.0
0.00000
0.14703
0.21870
0.32600
0.49026
0.59422
0.67357
0.75123
0.81604
0.86861
0.90948
0.94910
0.98709
1.01423
1.04026
1.06998
1.09543
1.10612
1.11272
1.11566
1.11945
1.12592
1.14082
1.18219
1.27532
1.33400
1.41020
1.59237
1.63785
1.64411
6.55360
499.9
475.0
460.0
435.0
390.0
340.0
280.0
230.0
195.0
165.0
140.0
115.0
95.0
77.4
60.0
44.0
36.0
31.0
28.0
27.0
26.0
25.0
24.0
20.0
15.5
12.0
9.0
3.8
2.0
1.4
0.0
0.00000
0.09032
0.12536
0.18696
0.29958
0.42238
0.56707
0.68580
0.76717
0.83541
0.89082
0.94455
0.98574
1.02044
1.05277
1.08105
1.09477
1.10465
1.11202
1.11517
1.11896
1.12463
1.13598
1.21555
1.29340
1.36687
1.44850
1.64112
1.68912
1.69808
6.55360
Lake Shore Model 231 User’s Manual
APPENDIX A
MODEL 231 CURVE TABLES
Table A-1. Lake Shore Standard Diode Curves
Curve Tables A-1
Class B
T (K)
R () *
dR/dT (/K)
±K
±
14.0
20.0
30.0
40.0
50.0
70.0
100.0
150.0
200.0
300.0
400.0
500.0
600.0
700.0
800.0
900.0
1000.0
1.797
2.147
3.508
5.938
9.228
17.128
29.987
50.815
71.073
110.452
148.616
185.035
221.535
256.243
289.789
322.176
353.402
+0.035
+0.084
+0.190
+0.291
+0.361
+0.414
+0.411
+0.405
+0.399
+0.388
+0.376
+0.364
+0.353
+0.341
+0.330
+0.318
+0.306
1.32
1.17
0.92
0.67
0.43
0.93
1.43
1.93
2.43
2.93
3.43
3.93
0.55
0.48
0.37
0.27
0.17
0.35
0.52
0.68
0.83
0.97
1.09
1.20
Lake Shore Model 231 User’s Manual
Table A-2. Series PT-100 Platinum Resistance Curve
Temperature in kelvin (K), resistance in ohms (), and slope in ohms per
kelvin (/K). Temperature coefficient (237.15 – 373.15): 0.00385 //K.
Conforms to DIN 43760:1980; IEC 751:1983: and BS 1904:1984.
A-2 Curve Tables
* R (0 °C) = 100 Standard 751 IEC 1983 from 70 K to 1000 K.
Anode Cathode
+ –
Anode Cathode
+ –
Lake Shore Model 231 User’s Manual
APPENDIX B
GLOSSARY OF TERMINOLOGY
absolute zero. The temperature of –273.15 °C, or –459.67 °F, or 0 K, thought to be
the temperature at which molecular motion vanishes and a body would have no
heat energy.1
accuracy. The degree of correctness with which a measured value agrees with the
true value.2
electronic accuracy. The accuracy of an instrument independent of the sensor.
sensor accuracy. The accuracy of a temperature sensor and its associated
calibration or its ability to match a standard curve.
ambient temperature. The temperature of the surrounding medium, such as gas or
liquid, which comes into contact with the apparatus.1
anode. The terminal that is positive with respect to the other terminal when the diode
is biased in the forward direction.2
asphyxiant gas. A gas which has little or no positive toxic effect but which can bring
about unconsciousness and death by displacing air and thus depriving an organism
of oxygen.
calibration. To determine, by measurement or comparison with a standard, the
correct (accurate) value of each scale reading on a meter or other device, or the
correct value for each setting of a control knob.1
cathode. The terminal from which forward current flows to the external circuit.2
Celsius (°C) Scale. A temperature scale that registers the freezing point of water as
0 °C and the boiling point as 100 °C under normal atmospheric pressure. Celsius
degrees are purely derived units, calculated from the Kelvin Thermodynamic Scale.
Formerly known as “centigrade.” See Temperature for conversions.
cgs system of units. A system in which the basic units are the centimeter, gram, and
second.2
cryogen. See cryogenic fluid.1
cryogenic. Refers to the field of low temperatures, usually –130 °F or below, as
defined by 173.300(f) of Title 49 of the Code of Federal Regulations.
cryogenic fluid. A liquid that boils at temperatures of less than about 110 K at
atmospheric pressure, such as hydrogen, helium, nitrogen, oxygen, air, or methane.
Also known as cryogen.1
cryostat. An apparatus used to provide low-temperature environments in which
operations may be carried out under controlled conditions.1
curve. A set of data that defines the temperature response of a temperature sensor. It
is used to convert the sensor signal to temperature.
Curve 10. The voltage versus temperature characteristic followed by all DT-400
Series Silicon Diode Temperature Sensors.
degree. An incremental value in the temperature scale, i.e., there are 100 degrees
between the ice point and the boiling point of water in the Celsius scale and 180
degrees between the same two points in the Fahrenheit scale.
Glossary B-1
Lake Shore Model 231 User’s Manual
drift, instrument. An undesired but relatively slow change in output over a period of
time, with a fixed reference input. Note: Drift is usually expressed in percent of the
maximum rated value of the variable being measured.2
electrostatic discharge (ESD). A transfer of electrostatic charge between bodies at
different electrostatic potentials caused by direct contact or induced by an
electrostatic field.
error. Any discrepancy between a computed, observed, or measured quantity and the
true, specified, or theoretically correct value or condition.2
excitation. Either an AC or DC input to a sensor used to produce an output signal.
Common excitations include: constant current, constant voltage, or constant power.
Fahrenheit (°F) Scale. A temperature scale that registers the freezing point of water
as 32 °F and the boiling point as 212 °F under normal atmospheric pressure. See
Temperature for conversions.
four-lead. measurement technique where one pair of excitation leads and an
independent pair of measurement leads are used to measure a sensor. This
method reduces the effect of lead resistance on the measurement.
GaAlAs. Gallium-aluminum-arsenide semiconducting material used to make the
special Lake Shore TG family of diode temperature sensors.
gaussian system (units). A system in which centimeter-gram-second units are used
for electric and magnetic qualities.
ground. A conducting connection, whether intentional or accidental, by which an
electric circuit or equipment is connected to the earth, or to some conducting body
of relatively large extent that serves in place of the earth. Note: It is used for
establishing and maintaining the potential of the earth (or of the conducting body) or
approximately that potential, on conductors connected to it, and for conducting
ground current to and from the earth (or of the conducting body).2
hazard communication standard (HCS). The OSHA standard cited in 29 CFR
1910.1200 requiring communication of risks from hazardous substances to workers
in regulated facilities.
hertz (Hz). A unit of frequency equal to one cycle per second.
international system of units (SI). A universal coherent system of units in which the
following seven units are considered basic: meter, kilogram, second, ampere,
kelvin, mole, and candela. The International System of Units, or Système
International d'Unités (SI), was promulgated in 1960 by the Eleventh General
Conference on Weights and Measures. For definition, spelling, and protocols, see
Reference 3 for a short, convenient guide.
interpolation table. A table listing the output and sensitivity of a sensor at regular or
defined points which may be different from the points at which calibration data was
taken.
IPTS-68. International Practical Temperature Scale of 1968. Also abbreviated as T68.
isolated (neutral system). A system that has no intentional connection to ground
except through indicating, measuring, or protective devices of very-high
impedance.2
ITS-90. International Temperature Scale of 1990. Also abbreviated as T90. This scale
was designed to bring into as close a coincidence with thermodynamic
temperatures as the best estimates in 1989 allowed.
Kelvin (K). The unit of temperature on the Kelvin Scale. It is one of the base units
of SI. The word “degree” and its symbol (°) are omitted from this unit. See
Temperature Scale for conversions.
B-2 Glossary
Factor Prefix Symbol
1024 yotta Y
1021 zetta Z
1018 exa E
1015 peta P
1012 tera T
109 giga G
106 mega M
103 kilo k
102 hecto h
101 deka da
Factor Prefix Symbol
10-1 deci d
10-2 centi c
10-3 milli m
10-6 micro µ
10-9 nano n
10
-12
pico p
10
-15
femto f
10
-18
atto a
10
-21
zepto z
10
-24
yocto y
Lake Shore Model 231 User’s Manual
Kelvin Scale. The Kelvin Thermodynamic Temperature Scale is the basis for all
international scales, including the ITS-90. It is fixed at two points: the absolute zero
of temperature (0 K), and the triple point of water (273.16 K), the equilibrium
temperature that pure water reaches in the presence of ice and its own vapor.
liquid helium (LHe). Used for low temperature and superconductivity research:
minimum purity 99.998%. Boiling point at 1 atm = 4.2 K. Latent heat of
vaporization = 2.6 kilojoules per liter. Liquid density = 0.125 kilograms per liter.
EPA Hazard Categories: Immediate (Acute) Health and Sudden Release of
Pressure Hazards
DOT Label: Nonflammable Gas
DOT Class: Nonflammable Gas
DOT Name: Helium, Refrigerated Liquid
DOT ID No: UN 1963
liquid nitrogen (LN2). Also used for low temperature and superconductivity research
and for its refrigeration properties such as in freezing tissue cultures: minimum
purity 99.998%, O2 8 ppm max. Boiling point at 1 atm = 77.4 K. Latent heat of
vaporization = 160 kilojoules per liter. Liquid density = 0.81 kilograms per liter.
EPA Hazard Categories: Immediate (Acute) Health and Sudden Release of
Pressure Hazards
DOT Label: Nonflammable Gas
DOT Class: Nonflammable Gas
DOT Name: Nitrogen, Refrigerated Liquid
DOT ID No: UN 1977
material safety data sheet (MSDS). OSHA Form 20 contains descriptive information
on hazardous chemicals under the OSHA Hazard Communication Standard (HCS).
These data sheets also provide precautionary information on the safe handling of
the gas as well as emergency and first aid procedures.
MKSA System of Units. A system in which the basic units are the meter, kilogram,
and second, and the ampere is a derived unit defined by assigning the magnitude
4 x 10–7 to the rationalized magnetic constant (sometimes called the permeability
of space).
NBS. National Bureau of Standards. Now referred to as NIST.
National Institute of Standards and Technology (NIST). Government agency
located in Gaithersburg, Maryland and Boulder, Colorado, that defines
measurement standards in the United States.
platinum (Pt). A common temperature sensing material fabricated from pure platinum
to make the Lake Shore PT family of resistance temperature sensor elements.
prefixes. SI prefixes used throughout this manual are as follows:
Glossary B-3
Boiling point of water
Freezing point of water
Absolute zero
kelvin Celsius Fahrenheit
0 K
273.15 K
373.15 K
–273.15 °C
0 °C
100 °C
–459.67 °F
32 °F
212 °F
Triple point of w ater 273.16 K
Lake Shore Model 231 User’s Manual
probe. A long, thin body containing a sensing element which can be inserted into a
system in order to make measurements. Typically, the measurement is localized to
the region near the tip of the probe.
repeatability. The closeness of agreement among repeated measurements of the same
variable under the same conditions.
2
self-heating. Heating of a device due to dissipation of power resulting from the
excitation applied to the device. The output signal from a sensor increases with
excitation level, but so does the self-heating and the associated temperature
measurement error.
sensitivity. The ratio of the response or change induced in the output to a stimulus or
change in the input. Temperature sensitivity of a resistance temperature detector is
expressed as S = dR/dT.
setpoint. The value selected to be maintained by an automatic controller.1
SI. Système International d'Unités. See International System of Units.
silicon diode. Temperature sensor based on the forward voltage drop at constant
current through a pn semiconductor junction formed in crystalline silicon.
stability. The ability of an instrument or sensor to maintain a constant output given a
constant input.
temperature scales. See Kelvin Scale, Celsius Scale, and ITS-90. Proper metric
usage requires that only kelvin and degrees Celsius be used. However, since
degrees Fahrenheit is in such common use, all three scales are delineated as
follows:
To convert kelvin to Celsius, subtract 273.15.
To convert Celsius to Fahrenheit: multiply °C by 1.8 then add 32, or: °F = (1.8 x
°C) + 32.
To convert Fahrenheit to Celsius: subtract 32 from °F then divide by 1.8, or: °C =
(°F. 32 )/ 1.8.
tolerance. The range between allowable maximum and minimum values.
two-lead. Measurement technique where one pair of leads is used for both excitation
and measurement of a sensor. This method will not reduce the effect of lead
resistance on the measurement.
References:
1 Sybil P. Parker, Editor. Dictionary of Scientific and Technical Terms: Third
Edition. New York: McGraw Hill, 1969 (IBSN 0-395-20360-0)
2 Christopher J. Booth, Editor. The New IEEE Standard Dictionary of Electrical and
Electronic Terms: IEEE Std 100-1992, Fifth Edition. New York: Institute of
Electrical and Electronics Engineers, 1993 (IBSN 1-55937-240-0). Definitions
printed with permission of the IEEE.
3 Nelson, Robert A. Guide For Metric Practice, Page BG7-8, Physics Today,
Eleventh Annual Buyer’s Guide, August 1994 (ISSN 0031-9228 coden PHTOAD
B-4 Glossary
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