Lakeshore 332 User Manual
User’s Manual
Model 332
Temperature Controller
LakeShore
Control
Setpoint
Zone
Input
Display
Setup
Setting
PID/
MHP
Setup
Curve
Entry
1 234 5+/
6 789 0
Format
Math
Alarm
Analog
Output
332 Temperature Controller
Remote/
Local
Interface
Escape
Enter
Control A
Control B
Auto
Tune
Loop
Tune
Ramp
Heater
Range
Heater
Off
Remote
Alarm
Lake Shore Cryotronics, Inc.
575 McCorkle Blvd.
Westerville, Ohio 43082-8888 USA
E-mail Addresses:
sales@lakeshore.com
service@lakeshore.com
Visit Our Website At:
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.
Revision: 1.7 P/N 119-034 14 May 2009
Lake Shore Model 332 Temperature Controller User’s Manual
1. Lake Shore warrants that this Lake Shore product (the
“Product”) will be free from defects in materials and
workmanship for the Warranty Period specified above (the
“Warranty Period”). If Lake Shore receives notice of any such
defects during the Warranty Period and the Product is shipped
freight prepaid, Lake Shore will, at its option, either repair or
replace the Product if it is so defective without charge to the
owner for parts, service labor or associated customary return
shipping cost. Any such replacement for the Product may be
either new or equivalent in performance to new. Replacement or
repaired parts 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 it has been sold by an
authorized Lake Shore employee, sales representative, dealer
or original equipment manufacturer (OEM).
3. The Product may contain remanufactured parts equivalent to
new in performance or may have been subject to incidental use.
4. The Warranty Period begins on the date of delivery of the
Product or later on the date of installation of the Product if the
Product is installed by Lake Shore, provided that if you schedule
or delay the Lake Shore installation for more than 30 days after
delivery the Warranty Period begins on the 31st day after
delivery.
5. This limited warranty does not apply to defects in the Product
resulting from (a) improper or inadequate maintenance, repair or
calibration, (b) fuses, software 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 or (f) improper
site preparation or maintenance.
6. TO THE EXTENT ALLOWED BY APPLICABLE LAW, THE
ABOVE WARRANTIES ARE EXCLUSIVE AND NO OTHER
WARRANTY OR CONDITION, WHETHER WRITTEN OR
ORAL, IS EXPRESSED OR IMPLIED. LAKE SHORE
SPECIFICALLY DISCLAIMS ANY IMPLIED WARRANTIES OR
CONDITIONS OF MERCHANTABILITY, SATISFACTORY
QUALITY AND/OR FITNESS FOR A PARTICULAR PURPOSE
WITH RESPECT TO THE PRODUCT. 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.
7. TO THE EXTENT ALLOWED BY APPLICABLE LAW, THE
REMEDIES IN THIS WARRANTY STATEMENT ARE YOUR
SOLE AND EXCLUSIVE REMEDIES.
8. EXCEPT TO THE EXTENT PROHIBITED BY APPLICABLE
LAW, IN NO EVENT WILL LAKE SHORE OR ANY OF ITS
SUBSIDIARIES, AFFILIATES OR SUPPLIERS BE 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, AND WHETHER OR NOT LAKE
SHORE HAS BEEN ADVISED OF THE POSSIBILITY OF
SUCH DAMAGES. Your use of the Product is entirely at your
own 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.
LIMITED WARRANTY STATEMENT
WARRANTY PERIOD: ONE (1) YEAR
LIMITED WARRANTY STATEMENT (Continued)
9. EXCEPT TO THE EXTENT ALLOWED BY APPLICABLE LAW,
THE TERMS OF THIS LIMITED WARRANTY STATEMENT DO
NOT EXCLUDE, RESTRICT OR MODIFY, AND ARE IN
ADDITION TO, 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).
FIRMWARE LIMITATIONS
Lake Shore has worked to ensure that the Model 332 firmware is
as free of errors as possible, and that the results you obtain from
the instrument are accurate and reliable. However, as with any
computer-based software, the possibility of errors exists.
In any important research, as when using any laboratory
equipment, results should be carefully examined and rechecked
before final conclusions are drawn. Neither Lake Shore nor anyone
else involved in the creation or production of this firmware can pay
for loss of time, inconvenience, loss of use of the product, or
property damage caused by this product or its failure to work, or
any other incidental or consequential damages. Use of our product
implies that you understand the Lake Shore license agreement and
statement of limited warranty.
FIRMWARE LICENSE AGREEMENT
The firmware in this instrument is protected by United States
copyright law and international treaty provisions. To maintain the
warranty, the code contained in the firmware must not be modified.
Any changes made to the code is at the user’s risk. Lake Shore will
assume no responsibility for damage or errors incurred as result of
any changes made to the firmware.
Under the terms of this agreement you may only use the Model
332 firmware as physically installed in the instrument. Archival
copies are strictly forbidden. You may not decompile, disassemble,
or reverse engineer the firmware. If you suspect there are
problems with the firmware, return the instrument to Lake Shore for
repair under the terms of the Limited Warranty specified above.
Any unauthorized duplication or use of the Model 332 firmware in
whole or in part, in print, or in any other storage and retrieval
system is forbidden.
TRADEMARK ACKNOWLEDGMENT
Many manufacturers and sellers claim designations used to
distinguish their products as trademarks. Where those
designations appear in this manual and Lake Shore was aware of
a trademark claim, they appear with initial capital letters and the ™
®
or
symbol.
CalCurve™, Carbon-Glass™, Cernox™, Duo-Twist™, High-
Temperature Cernox™, Quad-Lead™, Quad-Twist™, Rox™,
SoftCal™, and Thermox™ are trademarks of Lake Shore
Cryotronics, Inc.
MS-DOS
®
and Windows/95/98/NT/2000® are trademarks of
Microsoft Corp.
NI-488.2™ is a trademark of National Instruments.
PC, XT, AT, and PS-2 are trademarks of IBM.
Copyright © 2002 – 2009 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 the express written permission of Lake Shore.
A
Lake Shore Model 332 Temperature Controller User’s Manual
DECLARATION OF CONFORMITY
We: Lake Shore Cryotronics, Inc.
575 McCorkle Blvd.
Westerville OH 43082-8888 USA
hereby declare that the equipment specified conforms to the following
Directives and Standards:
Application of Council Directives: .............................. 73/23/EEC
89/336/EEC
Standards to which Conformity is declared: .............. EN61010-1:2001
Overvoltage II
Pollution Degree 2
EN61326 A2:2001
Class A
Annex B
Model Number: .......................................................... 332
Ed Maloof
Printed Name
Vice President of Engineering
Position
B
Lake Shore Model 332 Temperature Controller User’s Manual
Electromagnetic Compatibility (EMC) for the Model 332 Temperature Controller
Electromagnetic Compatibility (EMC) of electronic equipment is a growing concern worldwide.
Emissions of and immunity to electromagnetic interference is now part of the design and manufacture
of most electronics. To qualify for the CE Mark, the Model 332 meets or exceeds the requirements of
the European EMC Directive 89/336/EEC as a CLASS A product. A Class A product is allowed to
radiate more RF than a Class B product and must include the following warning:
WARNING: This is a Class A product. In a domestic environment, this product may
cause radio interference in which case the user may be required to take
The instrument was tested under normal operating conditions with sensor and interface cables
attached. If the installation and operating instructions in the User’s Manual are followed, there should
be no degradation in EMC performance.
This instrument is not intended for use in close proximity to RF Transmitters such as two-way radios
and cell phones. Exposure to RF interference greater than that found in a typical laboratory
environment may disturb the sensitive measurement circuitry of the instrument.
Pay special attention to instrument cabling. Improperly installed cabling may defeat even the best
EMC protection. For the best performance from any precision instrument, follow the grounding and
shielding instructions in the User’s Manual. In addition, the installer of the Model 332 should consider
the following:
• Shield measurement and computer interface cables.
• Leave no unused or unterminated cables attached to the instrument.
• Make cable runs as short and direct as possible. Higher radiated emissions are possible with
long cables.
• Do not tightly bundle cables that carry different types of signals.
adequate measures.
C
Lake Shore Model 332 Temperature Controller User’s Manual
TABLE OF CONTENTS
Chapter/Paragraph Title Page
1 INTRODUCTION .................................................................................................................................................... 1-1
1.0 GENERAL ......................................................................................................................................... 1-1
1.1 PRODUCT DESCRIPTION ............................................................................................................... 1-2
1.2 SENSOR SELECTION GUIDE .......................................................................................................... 1-4
1.3 SPECIFICATIONS ............................................................................................................................. 1-8
1.4 SAFETY SUMMARY ....................................................................................................................... 1-11
1.5 SAFETY SYMBOLS ........................................................................................................................ 1-12
2 COOLING SYSTEM DESIGN ................................................................................................................................. 2-1
2.0 GENERAL ......................................................................................................................................... 2-1
2.1 TEMPERATURE SENSOR SELECTION .......................................................................................... 2-1
2.1.1 Temperature Range ....................................................................................................................... 2-1
2.1.2 Sensor Sensitivity .......................................................................................................................... 2-1
2.1.3 Environmental Conditions .............................................................................................................. 2-2
2.1.4 Measurement Accuracy ................................................................................................................. 2-2
2.1.5 Sensor Package ............................................................................................................................. 2-2
2.2 CALIBRATED SENSORS ................................................................................................................. 2-2
2.2.1 Traditional Calibration .................................................................................................................... 2-2
2.2.2 SoftCal™........................................................................................................................................ 2-3
2.2.3 Standard Curves ............................................................................................................................ 2-3
2.2.4 CalCurve™ .................................................................................................................................... 2-3
2.3 SENSOR INSTALLATION ................................................................................................................. 2-5
2.3.1 Mounting Materials ......................................................................................................................... 2-5
2.3.2 Sensor Location ............................................................................................................................. 2-5
2.3.3 Thermal Conductivity ..................................................................................................................... 2-5
2.3.4 Contact Area .................................................................................................................................. 2-5
2.3.5 Contact Pressure ........................................................................................................................... 2-6
2.3.6 Lead Wire....................................................................................................................................... 2-6
2.3.7 Lead Soldering ............................................................................................................................... 2-7
2.3.8 Heat Sinking Leads ........................................................................................................................ 2-7
2.3.9 Thermal Radiation .......................................................................................................................... 2-7
2.4 HEATER SELECTION AND INSTALLATION .................................................................................... 2-7
2.4.1 Heater Resistance and Power ....................................................................................................... 2-7
2.4.2 Heater Location .............................................................................................................................. 2-8
2.4.3 Heater Types ................................................................................................................................. 2-8
2.4.4 Heater Wiring ................................................................................................................................. 2-8
2.5 CONSIDERATIONS FOR GOOD CONTROL ................................................................................... 2-8
2.5.1 Thermal Conductivity ..................................................................................................................... 2-8
2.5.2 Thermal Lag ................................................................................................................................... 2-8
2.5.3 Two-Sensor Approach ................................................................................................................... 2-9
2.5.4 Thermal Mass ................................................................................................................................ 2-9
2.5.5 System Nonlinearit y ....................................................................................................................... 2-9
2.6 PID CONTROL .................................................................................................................................. 2-9
2.6.1 Proportional (P) ............................................................................................................................ 2-10
2.6.2 Integral (I)..................................................................................................................................... 2-10
2.6.3 Derivative (D) ............................................................................................................................... 2-10
2.6.4 Manual Heater (MHP) Output ...................................................................................................... 2-10
2.7 MANUAL TUNING ........................................................................................................................... 2-12
2.7.1 Setting Heater Range .................................................................................................................. 2-12
2.7.2 Tuning Proportional ...................................................................................................................... 2-12
2.7.3 Tuning Integral ............................................................................................................................. 2-13
2.7.4 Tuning Derivative ......................................................................................................................... 2-13
2.8 AUTOTUNING ................................................................................................................................. 2-13
2.9 ZONE TUNING ................................................................................................................................ 2-14
Table of Contents i
Lake Shore Model 332 Temperature Controller User’s Manual
TABLE OF CONTENTS (Continued)
Chapter/Paragraph Title Page
3 INSTALLATION ...................................................................................................................................................... 3-1
3.0 GENERAL ......................................................................................................................................... 3-1
3.1 INSPECTION AND UNPACKING ...................................................................................................... 3-1
3.2 REPACKAGING FOR SHIPMENT .................................................................................................... 3-1
3.3 REAR PANEL DEFINITION ............................................................................................................... 3-2
3.4 LINE INPUT ASSEMBLY ................................................................................................................... 3-3
3.4.1 Line Voltage ................................................................................................................................... 3-3
3.4.2 Line Fuse and Fuse Holder ............................................................................................................ 3-3
3.4.3 Power Cord .................................................................................................................................... 3-3
3.4.4 Power Switch ................................................................................................................................. 3-4
3.5 DIODE/RESISTOR SENSOR INPUTS .............................................................................................. 3-4
3.5.1 Sensor Input Connector and Pinout ............................................................................................... 3-4
3.5.2 Sensor Lead Cable ........................................................................................................................ 3-4
3.5.3 Grounding and Shielding Sensor Leads ......................................................................................... 3-5
3.5.4 Sensor Polarity ............................................................................................................................... 3-5
3.5.5 Four-Lead Sensor Measurement ................................................................................................... 3-5
3.5.6 Two-Lead Sensor Measurement .................................................................................................... 3-6
3.5.7 Lowering Measurement Noise........................................................................................................ 3-6
3.6 THERMOCOUPLE SENSOR INPUTS .............................................................................................. 3-7
3.6.1 Sensor Input Terminals .................................................................................................................. 3-7
3.6.2 Thermocouple Installation .............................................................................................................. 3-7
3.6.3 Grounding and Shielding ................................................................................................................ 3-7
3.7 HEATER OUTPUT SETUP ............................................................................................................... 3-8
3.7.1 Loop 1 Output ................................................................................................................................ 3-8
3.7.2 Loop 1 Heater Output Connector ................................................................................................... 3-8
3.7.3 Loop 1 Heater Output Wiring ......................................................................................................... 3-8
3.7.4 Loop 1 Heater Output Noise .......................................................................................................... 3-9
3.7.5 Loop 2 Output ................................................................................................................................ 3-9
3.7.6 Loop 2 Output Resistance .............................................................................................................. 3-9
3.7.7 Loop 2 Output Connector ............................................................................................................... 3-9
3.7.8 Loop 2 Heater Protection ............................................................................................................... 3-9
3.7.9 Boosting the Output Power ............................................................................................................ 3-9
3.8 ANALOG OUTPUT .......................................................................................................................... 3-10
3.9 RELAYS .......................................................................................................................................... 3-10
3.10 INITIAL SETUP AND SYSTEM CHECKOUT PROCEDURE .......................................................... 3-11
4 OPERATION ........................................................................................................................................................... 4-1
4.0 GENERAL ......................................................................................................................................... 4-1
4.1 FRONT PANEL DESCRIPTION ........................................................................................................ 4-1
4.1.1 Keypad Definitions ......................................................................................................................... 4-1
4.1.2 Annunciators .................................................................................................................................. 4-3
4.1.3 General Keypad Operation ............................................................................................................ 4-3
4.1.4 Display Definition ........................................................................................................................... 4-4
4.1.5 Heater Bar Definition ...................................................................................................................... 4-4
4.2 TURNING POWER ON ..................................................................................................................... 4-5
4.3 DISPLAY FORMAT AND SOURCE (UNITS) SELECTION ............................................................... 4-5
4.4 INPUT SETUP ................................................................................................................................... 4-7
4.4.1 Diode Sensor Input Setup .............................................................................................................. 4-7
4.4.2 Platinum Resistor Sensor Input Setup ........................................................................................... 4-8
4.4.3 NTC RTD Sensor Input Setup ........................................................................................................ 4-8
4.4.3.1 Thermal EMF Compensation ...................................................................................................... 4-9
4.4.4 Thermocouple Sensor Input Setup ............................................................................................... 4-10
4.4.4.1 Room-Temperature Compensation .......................................................................................... 4-10
4.4.4.2 Room-Temperature Calibration Procedure ............................................................................... 4-11
4.5 CURVE SELECTION ....................................................................................................................... 4-12
ii Table of Contents
Lake Shore Model 332 Temperature Controller User’s Manual
TABLE OF CONTENTS (Continued)
Chapter/Paragraph Title Page
4.5.1 Diode Sensor Curve Selection ..................................................................................................... 4-13
4.5.2 Resistor Sensor Curve Selection ................................................................................................. 4-13
4.5.3 Thermocouple Sensor Curve Selection ....................................................................................... 4-13
4.6 TEMPERATURE CONTROL ........................................................................................................... 4-14
4.6.1 Control Loops ............................................................................................................................... 4-14
4.6.2 Control Modes .............................................................................................................................. 4-15
4.6.3 Tuning Modes .............................................................................................................................. 4-15
4.7 CONTROL SETUP .......................................................................................................................... 4-15
4.8 MANUAL TUNING ........................................................................................................................... 4-17
4.8.1 Manually Setting Proportional (P) ................................................................................................ 4-17
4.8.2 Manually Setting Integral (I) ......................................................................................................... 4-17
4.8.3 Manually Setting Derivative (D) .................................................................................................... 4-18
4.8.4 Setting Manual Heater Power (MHP) Output ............................................................................... 4-18
4.9 AUTOTUNE (Closed-Loop PID Control) .......................................................................................... 4-19
4.10 ZONE SETTINGS (Closed-Loop Control) ....................................................................................... 4-20
4.11 SETPOINT....................................................................................................................................... 4-23
4.12 RAMP .............................................................................................................................................. 4-23
4.13 HEATER RANGE AND HEATER OFF ............................................................................................ 4-24
4.14 MATH .............................................................................................................................................. 4-26
4.14.1 Max/Min ....................................................................................................................................... 4-26
4.14.2 Linear ........................................................................................................................................... 4-27
4.14.3 Filter ............................................................................................................................................. 4-28
4.15 ALARMS AND RELAYS .................................................................................................................. 4-29
4.15.1 Alarms .......................................................................................................................................... 4-29
4.15.2 Relays .......................................................................................................................................... 4-31
4.16 ANALOG OUTPUT .......................................................................................................................... 4-32
4.16.1 Analog Output In Input Mode ....................................................................................................... 4-32
4.16.2 Analog Output In Manual Mode ................................................................................................... 4-34
4.16.3 Analog Output In Loop 2 Mode .................................................................................................... 4-35
4.17 LOCKING AND UNLOCKING THE KEYPAD .................................................................................. 4-35
4.18 DISPLAY BRIGHTNESS ................................................................................................................. 4-36
4.19 REMOTE/LOCAL ............................................................................................................................ 4-36
4.20 INTERFACE .................................................................................................................................... 4-36
4.21 DEFAULT VALUES ......................................................................................................................... 4-37
5 ADVANCED OPERATION ..................................................................................................................................... 5-1
5.0 GENERAL ......................................................................................................................................... 5-1
5.1 CURVE NUMBERS AND STORAGE ................................................................................................ 5-1
5.1.1 Curve Header Parameters ............................................................................................................. 5-1
5.1.2 Curve Breakpoints ......................................................................................................................... 5-2
5.2 FRONT PANEL CURVE ENTRY OPERATIONS .............................................................................. 5-2
5.2.1 Edit Curve ...................................................................................................................................... 5-4
5.2.1.1 Thermocouple Curve Considerations ......................................................................................... 5-5
5.2.2 Erase Curve ................................................................................................................................... 5-6
5.2.3 Copy Curve .................................................................................................................................... 5-6
5.3 SOFTCAL™ ...................................................................................................................................... 5-7
5.3.1 SoftCal With Silicon Diode Sensors ............................................................................................... 5-7
5.3.2 SoftCal Accuracy With Silicon Diode Sensors ............................................................................... 5-8
5.3.3 SoftCal With Platinum Sensors ...................................................................................................... 5-9
5.3.4 SoftCal Accuracy With Platinum Sensors ...................................................................................... 5-9
5.3.5 SoftCal Calibration Curve Creation .............................................................................................. 5-10
6 COMPUTER INTERFACE OPERATION ................................................................................................................ 6-1
6.0 GENERAL ......................................................................................................................................... 6-1
6.1 IEEE-488 INTERFACE ...................................................................................................................... 6-1
6.1.1 Changing IEEE-488 Interface Parameters ..................................................................................... 6-2
Table of Contents iii
Lake Shore Model 332 Temperature Controller User’s Manual
TABLE OF CONTENTS (Continued)
Chapter/Paragraph Title Page
6.1.2 IEEE-488 Command Structure ....................................................................................................... 6-2
6.1.2.1 Bus Control Commands ............................................................................................................. 6-2
6.1.2.2 Common Commands .................................................................................................................. 6-3
6.1.2.3 Device Specific Commands ........................................................................................................ 6-3
6.1.2.4 Message Strings ......................................................................................................................... 6-3
6.1.3 Status Registers ............................................................................................................................. 6-4
6.1.3.1 Status Byte Register and Service Request Register .................................................................. 6-4
6.1.3.2 Standard Event Status Register and Standard Event Status Enable Register ........................... 6-4
6.1.4 IEEE Interface Example Programs ................................................................................................. 6-5
6.1.4.1 IEEE-488 Interface Board Installation for Visual Basic Program ................................................ 6-5
6.1.4.2 Visual Basic IEEE-488 Interface Program Setup ........................................................................ 6-7
6.1.4.3 IEEE-488 Interface Board Installation for Quick Basic Program ............................................... 6-10
6.1.4.4 Quick Basic Program ................................................................................................................ 6-10
6.1.4.5 Program Operation ................................................................................................................... 6-13
6.1.5 Troubleshooting ............................................................................................................................... 6-13
6.2 SERIAL INTERFACE OVERVIEW .................................................................................................. 6-14
6.2.1 Physical Connection ..................................................................................................................... 6-14
6.2.2 Hardware Support ........................................................................................................................ 6-14
6.2.3 Character Format ......................................................................................................................... 6-15
6.2.4 Message Strings .......................................................................................................................... 6-15
6.2.5 Message Flow Control ................................................................................................................. 6-16
6.2.6 Changing Baud Rate .................................................................................................................... 6-16
6.2.7 Serial Interface Example Programs .............................................................................................. 6-17
6.2.7.1 Visual Basic Serial Interface Program Setup ............................................................................ 6-17
6.2.7.2 Quick Basic Serial Interface Program Setup ............................................................................ 6-20
6.2.7.3 Program Operation ................................................................................................................... 6-21
6.2.8 Troubleshooting ........................................................................................................................... 6-21
6.3 COMMAND SUMMARY .................................................................................................................. 6-22
6.3.1 Interface Commands (Alphabetical Listing) .................................................................................. 6-24
7 OPTIONS AND ACCESSORIES ............................................................................................................................ 7-1
7.0 GENERAL ......................................................................................................................................... 7-1
7.1 MODELS ........................................................................................................................................... 7-1
7.2 OPTIONS .......................................................................................................................................... 7-1
7.3 ACCESSORIES ................................................................................................................................. 7-2
7.4 MODEL 3003 HEATER OUTPUT CONDITIONER ............................................................................ 7-4
8 SERVICE ................................................................................................................................................................ 8-1
8.0 GENERAL ......................................................................................................................................... 8-1
8.1 ELECTROSTATIC DISCHARGE ....................................................................................................... 8-1
8.1.1 Identification of Electrostatic Discharge Sensitive Components ..................................................... 8-1
8.1.2 Handling Electrostatic Discharge Sensitive Components ............................................................... 8-1
8.2 LINE VOLTAGE SELECTION ........................................................................................................... 8-2
8.3 FUSE REPLACEMENT ..................................................................................................................... 8-2
8.4 REAR PANEL CONNECTOR DEFINITIONS .................................................................................... 8-3
8.4.1 Serial Interface Cable Wiring ......................................................................................................... 8-5
8.4.2 IEEE-488 Interface Connector ....................................................................................................... 8-6
8.5 TOP OF ENCLOSURE REMOVE AND REPLACE PROCEDURE .................................................... 8-7
8.6 FIRMWARE AND NOVRAM REPLACEMENT .................................................................................. 8-7
8.7 LOOP 2 / ANALOG OUTPUT RANGE SELECTION ......................................................................... 8-8
8.8 JUMPERS ......................................................................................................................................... 8-8
8.9 ERROR MESSAGES ......................................................................................................................... 8-9
8.10 CALIBRATION PROCEDURE ......................................................................................................... 8-11
8.10.1 Equipment Required for Calibration ............................................................................................. 8-11
8.10.2 Diode/Resistor Sensor Input Calibration ...................................................................................... 8-12
8.10.2.1 Sensor Input Calibration Setup and Serial Communication Verfication .................................... 8-12
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Lake Shore Model 332 Temperature Controller User’s Manual
Chapter/Paragraph Title Page
8.10.2.2 10 µA Current Source Calibration and 1 µA, 100 µA, 1 mA Output Verfication ........................ 8-12
8.10.2.3 Diode Input Ranges Calibration ................................................................................................ 8-13
8.10.2.4 Resistive Input Ranges Calibration .......................................................................................... 8-14
8.10.3 Thermocouple Sensor Input Calibration ....................................................................................... 8-15
8.10.3.1 Sensor Input Calibration Setup ................................................................................................. 8-15
8.10.3.2 Thermocouple Input Ranges Calibration .................................................................................. 8-16
8.10.4 Analog Output Calibration ............................................................................................................ 8-17
8.10.4.1 Analog Output Calibration ........................................................................................................ 8-17
8.10.5 Calibration Specific Interface Commands .................................................................................... 8-18
APPENDIX A – GLOSSARY OF TERMINOLOGY ........................................................................................................ A-1
APPENDIX B – TEMPERATURE SCALES .................................................................................................................. B-1
APPENDIX C – HANDLING OF LIQUID HELIUM AND NITROGEN ............................................................................ C-1
APPENDIX D – CURVE TABLES ................................................................................................................................. D-1
LIST OF ILLUSTRATIONS
Figure No. Title Page
1-1 Model 332 Temperature Controller Front Panel ........................................................................................... 1-1
2-1 Silicon Diode Sensor Calibrations and CalCurve ......................................................................................... 2-4
2-2 Typical Sensor Installation In A Mechanical Refrigerator ............................................................................. 2-6
2-3 Examples of PID Control ............................................................................................................................ 2-11
3-1 Model 332 Rear Panel .................................................................................................................................. 3-2
3-2 Line Input Assembly ..................................................................................................................................... 3-3
3-3 Diode/Resistor Input Connector ................................................................................................................... 3-4
3-4 Thermocouple Input Definition and Common Connector Polarities .............................................................. 3-7
3-5 RELAYS and ANALOG OUTPUT Terminal Block ...................................................................................... 3-10
4-1 Model 332 Front Panel ................................................................................................................................. 4-1
4-2 Display Definition ......................................................................................................................................... 4-4
4-3 Heater Bar Definition .................................................................................................................................... 4-4
4-4 Display Format Definition ............................................................................................................................. 4-5
4-5 Record of Zone Settings ............................................................................................................................. 4-22
4-6 Deadband Example .................................................................................................................................... 4-29
4-7 Relay Settings ............................................................................................................................................ 4-31
5-1 SoftCal Temperature Ranges for Silicon Diode Sensors .............................................................................. 5-8
5-2 SoftCal Temperature Ranges for Platinum Sensors..................................................................................... 5-9
6-1 GPIB Setting Configuration .......................................................................................................................... 6-6
6-2 DEV 12 Device Template Configuration ....................................................................................................... 6-6
6-3 Typical National Instruments GPIB Configuration from IBCONF.EXE........................................................ 6-11
7-1 Model 3507-2SH Cable Assembly ............................................................................................................... 7-3
7-2 Model 3003 Heater Output Conditioner ........................................................................................................ 7-4
7-3 Model RM-1/2 Rack-Mount Kit ..................................................................................................................... 7-5
7-4 Model RM-2 Dual Rack-Mount Kit ................................................................................................................ 7-6
8-1 Power Fuse Access ...................................................................................................................................... 8-2
8-2 Sensor INPUT A and B Connector Details ................................................................................................... 8-3
8-3 HEATER OUTPUT Connector Details .......................................................................................................... 8-3
8-4 RELAYS and ANALOG OUTPUT Terminal Block ........................................................................................ 8-4
8-5 RS-232 Connector Details ............................................................................................................................ 8-4
8-6 IEEE-488 Rear Panel Connector Details ...................................................................................................... 8-6
8-7 Location of Internal Components ............................................................................................................... 8-10
B-1 Temperature Scale Comparison .................................................................................................................. B-1
C-1 Typical Cryogenic Storage Dewar ................................................................................................................ C-1
TABLE OF CONTENTS (Continued)
Table of Contents v
Lake Shore Model 332 Temperature Controller User’s Manual
LIST OF TABLES
Table No. Title Page
1-1 Temperature Range of Typical Lake Shore Sensors .................................................................................... 1-4
1-2 Model 332 Sensor Input Performance Chart ................................................................................................ 1-5
1-3 Model 332 Input Specifications ..................................................................................................................... 1-8
4-1 Sensor Input Types ...................................................................................................................................... 4-7
4-2 Sensor Curves ............................................................................................................................................ 4-12
4-3 Comparison of Control Loops 1 and 2 ........................................................................................................ 4-14
4-4 Linear Equation Configuration .................................................................................................................... 4-27
4-5 Default Values ............................................................................................................................................ 4-38
5-1 Curve Header Parameters ............................................................................................................................ 5-3
5-2 Recommended Curve Parameters ............................................................................................................... 5-3
6-1 IEEE-488 Interface Program Control Properties ........................................................................................... 6-8
6-2 Visual Basic IEEE-488 Interface Program .................................................................................................... 6-9
6-3 Quick Basic IEEE-488 Interface Program ................................................................................................... 6-12
6-4 Serial Interface Specifications .................................................................................................................... 6-15
6-5 Serial Interface Program Control Properties ............................................................................................... 6-18
6-6 Visual Basic Serial Interface Program ........................................................................................................ 6-19
6-7 Quick Basic Serial Interface Program ......................................................................................................... 6-20
6-8 Command Summary .................................................................................................................................. 6-23
8-1 Calibration Table for Diode Ranges ........................................................................................................... 8-14
8-2 Calibration Table for Resistive Ranges ...................................................................................................... 8-15
8-3 Calibration Table for Thermocouple Ranges .............................................................................................. 8-16
B-1 Temperature Conversion Table .................................................................................................................... B-2
C-1 Comparison of Liquid Helium and Liquid Nitrogen ...................................................................................... C-1
D-1 DT-470 Silicon Diode Curve ........................................................................................................................ D-1
D-2 DT-670 Silicon Diode Curve ........................................................................................................................ D-2
D-3 DT-500 Series Silicon Diode Curves ........................................................................................................... D-2
D-4 PT-100/-1000 Platinum RTD Curves ........................................................................................................... D-3
D-5 RX-102A Rox™ Curve ........................................................................................................
D-6 RX-202A Rox™ Curve ................................................................................................................................ D-5
D-7 Type K Thermocouple Curve ....................................................................................................................... D-6
D-8 Type E Thermocouple Curve ....................................................................................................................... D-7
D-9 Type T Thermocouple Curve ....................................................................................................................... D-8
D-10 Chromel-AuFe 0.03% Thermocouple Curve ................................................................................................ D-9
D-11 Chromel-AuFe 0.07% Thermocouple Curve .............................................................................................. D-10
........................ D-4
vi Table of Contents
Lake Shore Model 332 Temperature Controller User’s Manual
CHAPTER 1
INTRODUCTION
1.0 GENERAL
This chapter introduces the Model 332 Temperature Controller. The Model 332 was designed and
manufactured in the United States of America by Lake Shore Cryotronics, Inc. The Model 332
Temperature Controller is a microprocessor-based instrument with digital control of a variable current
output. The Model 332 features include the following.
z Two Sensor Inputs Supporting:
– Diodes
– Positive Temperature Coefficient (PTC) Resistance Temperature Detectors (RTDs)
– Negative Temperature Coefficient (NTC) RTDs
– Thermocouples
z Five Tuning Modes:
– Autotuning P
– Autotuning PI
– Autotuning PID
– Manual
– Zone (10 Temperature Zones)
z Two Temperature Control Loops:
– Loop 1 – 50 W Output
– Loop 2 – 10 W Output
z Bright Large-Character Display:
– 2 Row by 20 Character Vacuum Fluorescent Display
– Display of Sensor Temperature in K, °C, or sensor units in volts, ohms
z Serial Interface
z IEEE-488 Interface
z Model 330 Command Emulation Mode
z Relays
LakeShore
Control
Setup
Zone
Setting
1 234 5+/
Setpoint
PID/
MHP
6 789 0
C332-1-1.eps
Figure 1-1. Model 332 Temperature Controller Front Panel
Introduction 1-1
Input
Setup
Curve
Entry
Display
Format
Math
Alarm
Analog
Output
332 Temperature Controller
Remote/
Local
Interface
Escape
Enter
Control A
Control B
Auto
Tune
Loop
Tune
Ramp
Heater
Range
Heater
Remote
Alarm
Off
Lake Shore Model 332 Temperature Controller User’s Manual
1.1 PRODUCT DESCRIPTION
The Lake Shore Model 332 Temperature Controller creates a new standard for high-resolution
temperature measurement in an easy-to-use temperature controller. The Model 332 offers high
resolution with negative temperature coefficient (NTC) resistance temperature detectors (RTDs) to
temperatures as low as 1 K. The Model 332 includes a 50 W heater output on the first control loop
and 10 W on the second control loop. This provides greater flexibility in applications that require a
second heater.
Sensor Inputs
Automatic scalable excitation current allows the Model 332 to support Cernox™ and other NTC RTDs
to temperatures as low as 1 K. At higher temperatures, where resistance is low and concerns for sensor
self-heating are minimal, the Model 332 provides an excitation current of 1 mA for a better signal to
noise ratio and high-measurement resolution. At low temperature, where resistance is high (up to
Ω), the Model 332 provides an excitation current of 1 µA to minimize sensor self-heating and
75 k
self-heating induced error. Excitation currents of 10 µA and 100 µA are also available. Manual control of
the excitation range is available, making it possible to fix the input range. The Model 332 also uses
current reversal to eliminate thermal electromotive force (EMF) errors.
The Model 332 Temperature Controller features two inputs, with a high-resolution 24-bit analog-todigital converter and separate current source for each input. Sensors are optically isolated from other
instrument functions for quiet and repeatable sensor measurements. Sensor data from each input can
be read up to ten times per second, with display updates twice each second.
Standard temperature response curves for silicon diodes, platinum RTDs, and many thermocouples are
included. Up to twenty 200-point CalCurves™ for Lake Shore calibrated sensors or user curves can be
loaded into non-volatile memory via computer interface or the instrument front panel. A built-in
SoftCal™ algorithm can also be used to generate curves for silicon diodes and platinum RTDs, for
storage as user curves.
Sensor inputs are factory configured and compatible with either Diode/RTD or Thermocouple sensors.
The choice of 2 Diode/RTD inputs, 1 Diode/RTD input and 1 Thermocouple input, or 2 Thermocouple
inputs must be specified at time of order. The configuration cannot be changed in the field. The
software selects the appropriate excitation current and signal gain levels when the sensor type is
entered via the instrument front panel.
The Diode/RTD input configuration is compatible with most diode and negative and positive
temperature coefficient RTDs. Current reversal eliminates thermal EMF errors for resistor sensors.
The Thermocouple input configuration is compatible only with thermocouple sensors. Roomtemperature compensation is included for any type of thermocouple in use. Temperature response
curves for many types of thermocouples are included. Temperature response curves may be entered
as user curves for other thermocouples.
The Lake Shore SoftCal algorithm for silicon diode and platinum RTD sensors is a good solution for
applications that need more accuracy than a standard sensor curve but not traditional calibration.
SoftCal uses the predictability of a standard curve to improve the accuracy of an individual sensor
around known temperature reference points.
Temperature Control
For the greatest flexibility in temperature control, the Model 332 has two independent, proportionalintegral-derivative (PID) control loops that drive two heater outputs of 50 W and 10 W.
A PID control algorithm calculates control output based on temperature setpoint and feedback from the
control sensor. Wide tuning parameters accommodate most cryogenic cooling systems and many small
high-temperature ovens. Control output is generated by a high-resolution digital-to-analog converter for
smooth, continuous control. A manual control mode is also included.
1-2 Introduction
Product Definition (Continued)
Lake Shore Model 332 Temperature Controller User’s Manual
Loop 1 heater output is a well-regulated variable DC current source. Heater output is optically isolated
from other circuits to reduce interference and ground loops. Heater output can provide up to 50 W of
continuous power to a resistive heater load and includes two lower ranges for systems with less cooling
power. Heater output is short-circuit protected to prevent instrument damage if the heater load is
accidentally shorted.
The Model 332 has a second control loop called Loop 2. The Loop 2 output is a single-range, variable
DC voltage source that can vary from 0 V to +10 V. The output can source up to 1 A of current
providing a maximum of 10 W of heater power. The output is short protected so the instrument is not
harmed if the heater load is accidentally shorted.
The setpoint ramp feature allows smooth continuous changes in setpoint and also makes the
approach to a setpoint temperature more predictable. The zone feature can automatically change
control parameter values for operation over a large temperature range. Values for ten different
temperature zones can be loaded into the instrument, which will select the next appropriate value on
setpoint change.
The Model 332 AutoTune feature simplifies the tuning process. With its own measurements of system
characteristics and based on characteristics of typical cryogenic systems, the AutoTune function
computes proportional, integral, and derivative setting values. The AutoTune function only tunes one
control loop at a time. Because setting an inappropriate heating range is potentially dangerous to some
loads, the Model 332 AutoTune feature does not attempt to automate that step of the tuning process.
Interface
Most functions on the instrument front panel can also be performed via computer interface. The
Model 332 is equipped with a parallel IEEE-488 interface as well as a serial RS-232C interface.
Maximum reading rates can be achieved with either interface.
High and low alarms for each input can be used in latching mode, requiring user intervention before
alarms reset. Alarms can also be used in conjunction with relays in non-latching mode, where alarms
automatically reset when the activation condition ends, to perform simple on-off control functions. Relay
assignments are configurable so that one relay may be assigned to each input or both assigned to a
single input for high/low control.
The analog voltage output can be configured to send a voltage proportional to temperature or data
acquisition system. The user may select the scale and data sent to the output, including temperature,
sensor units, or linear equation results. Under manual control, the analog voltage output can also serve
as a voltage source for any other application.
Also included is a Model 330 command emulation mode for drop-in interchangeability with Model 330
Temperature Controllers in existing systems.
Configurable Display
The Model 332 includes a bright vacuum fluorescent display that simultaneously displays up to four
readings. Frequently used functions can be accomplished from the instrument front panel with one or
two keystrokes. Display data includes input and source annunciators for each reading. Each of the four
display locations may be configured by the user. Data from either input may be assigned to any of the
four locations. The user's choice of temperature, sensor units, and maximum, minimum, or linear
equation results can be displayed. Heater range and control output as current or power can also be
continuously displayed numerically or as a bar graph for immediate feedback on control operation.
Introduction 1-3
Lake Shore Model 332 Temperature Controller User’s Manual
1.2 SENSOR SELECTION GUIDE
The Lake Shore Temperature Measurement and Control Catalog contains complete information on
selecting the appropriate Lake Shore Temperature Sensor for your application. A list of sensors that
may be used with the Model 332 is provided in Table 1-1. This paragraph provides a brief guideline
covering sensors commonly used with the Model 332. Typical performance specifications can be found
in Table 1-2. If a specific sensor model is not included in the table, use the sensitivity of the sensor at
the desired temperature to calculate temperature equivalence for your sensor.
Silicon Diodes are the best choice for general cryogenic use from 1.4 K to 500 K. Economical to use
because they follow a standard curve and are interchangeable in many applications, silicon diodes
are not suitable for use in ionizing radiation or magnetic fields.
GaAlAs Diodes offer high sensitivity from 1.4 K to above room temperature, with better sensitivity than
silicon diodes at temperatures below 25 K. They are useful in moderate magnetic fields. GaAlAs
diodes require calibration.
Platinum RTDs offer high uniform sensitivity from 30 K to over 800 K, with excellent reproducibility,
they are useful as a thermometry standard. They follow a standard curve above 70 K and are
interchangeable in many applications, but are not useful at cryogenic temperatures below 20 K.
Cernox™ and High-Temperature Cernox RTDs offer excellent sensitivity over a wide range of
temperatures, with resistance to strong magnetic fields and ionizing radiation. Cernox sensors
require calibration.
Table 1-1. Temperature Range of Typical Lake Shore Sensors
*
Diodes Model Useful Range
Silicon Diodes DT-670 1.4 – 500 K
GaAlAs Diode TG-120 1.4 – 475 K
Positive Temperature Coefficient (PTC) RTDs
100 Ω Platinum RTD PT-100, 250 Ω full scale
100 Ω Platinum RTD PT-100, 500 Ω full scale
30 – 675 K
30 – 800 K
Rhodium-Iron RTD RF-800-4 1.4 – 400 K
Negative Temperature Coefficient (NTC) † RTDs
Germanium RTD GR-200A-1500 1.4 – 100 K
Germanium RTD GR-200A-1000 1.4 – 100 K
Germanium RTD GR-200A-250 1 – 40 K
Carbon-Glass™ RTD CGR-1-500 3 – 325 K
Cernox™ RTD CX-1050 AA or SD 2– 325 K
Cernox™ RTD CX-1030 AA or SD 1 – 325 K
High-Temperature Cernox™ RTD CX-1030-SD-HT 1 – 420 K
Rox™ Ruthenium Oxide RTD RX-102A 1 – 40 K
Rox™ Ruthenium Oxide RTD RX-202A 1 – 40 K
Rox™ Ruthenium Oxide RTD RX-103A 1.4 – 325 K
Thermocouples
Chromel versus AuFe 0.07% Model 9006-002 1.4 – 610 K
Type E Model 9006-004 3.2 – 930 K
Type K Model 9006-006 3.2 – 1500 K
Type T Model 9006-008 3.2 – 670 K
* Sensors sold separately.
† Excitation current may limit the low temperature range of NTC resistors.
1-4 Introduction
Lake Shore Model 332 Temperature Controller User’s Manual
Sensor Selection Guide (Continued)
Rox™ RTD thick film sensors are useful in low temperature applications in magnetic fields, with a very
low incidence of magnetic field errors. Each model adheres to a single resistance versus
temperature curve. The Rox Models RX-102A and RX-202A are useful to temperatures as low as
50 mK, with accuracy to within ±5 mK at 50 mK; the RX-202A also offers an upper temperature
range to 300 K. The Model 332 configured with Rox RTDs should only be used down to 1 K.
Thermocouples offer uniform sensitivity over a wide temperature range and measure the highest
temperatures possible with the Model 332. While many types are inexpensive and standard curves
are available, thermocouples are less accurate than other sensors. Repeatability is highly
dependent upon installation.
Table 1-2. Model 332 Typical Sensor Performance Chart
Sensor Type Silicon Diode GaAlAs Diode
Temperature Coefficient Negative Negative Positive Negative
Input Range 0 – 2.5 V 0 – 7.5 V
Sensor Excitation*
(Constant Current)
Display Resolution (Sensor Units) 100 µV 100 µV
Example Lake Shore Sensor
Standard Sensor Curve
Typical Sensor Sensitivity †
Measurement Resolution:
Sensor Units
Temperature Equivalence
Electronic Accuracy:
Sensor Units
Temperature Equivalence
Temperature Accuracy including
electronic accuracy, CalCurve
and calibrated sensor
Control Stability:
Sensor Units
Temperature Equivalence
Magnetic Field Use
10 µA ±0.05% 10 µA ±0. 05% 1 mA 10 µA ±0.05%
DT-470-SD-13 with
1.4H calibration
Curve 10 Requires calibrated
–31.6 mV/K at 4.2 K
–1.73 mV/K at 77 K
–2.3 mV/K at 300 K
–2.12 mV/K at 475 K
10 µV
0.3 mK at 4.2 K
5.8 mK at 77 K
4.4 mK at 300 K
4.7 mK at 475 K
±80 µV ±0.005%
of reading
±5 mK at 4.2 K
±75 mK at 77 K
±47 mK at 300 K
±40 mK at 475 K
±26 mK at 4.2 K
±130 mK at 77 K
±107 mK at 300 K
±100 mK at 475 K
±20 µV
±0.6 mK at 4.2 K
±11 mK at 77 K
±8.4 mK at 300 K
±9 mK at 475 K
Recommended for
T ≥ 60 K & B ≤ 3 T
TG-120-SD with
1.4H calibration
sensor
–210 mV/K at 4.2 K
–1.25 mV/K at 77 K
–2.85 mV/K at 300 K
–3.15 mV/K at 475 K
20 µV
0.1 mK at 4.2 K
16.0 mK at 77 K
7.1 mK at 300 K
6.3 mK at 475 K
±80 µV ±0.01%
±3 mK at 4.2 K
±180 mK at 77 K
±60 mK at 300 K
±38 mK at 475 K
±20 mK at 4.2 K
±255 mK at 77 K
±180 mK at 300 K
±123 mK at 475 K
±40 µV
±0.2 mK at 4.2 K
±32 mK at 77 K
±14 mK at 300 K
±13 mK at 475 K
Recommended for
T > 4.2 K & B ≤ 5 T
of reading
100 Ω Platinum RTD
500 Ω Full scale
0 – 500 Ω 0 – 7500 Ω
10 mΩ 100 mΩ
PT-103 with
14J calibration
DIN 43760 Requires calibrated
0.19 Ω/K at 30 K
0.42 Ω/K at 77 K
0.39 Ω/K at 300 K
0.36 Ω/K at 800 K
2 mΩ
10.6 mK at 30 K
4.8 mK at 77 K
5.2 mK at 300 K
5.6 mK at 800 K
±0.004 Ω ±0.01%
of reading
±23 mK at 30 K
±14 mK at 77 K
±39 mK at 300 K
±95 mK at 800 K
±48 mK at 30 K
±39 mK at 77 K
±84 mK at 300 K
±195 mK at 800 K
±4 mΩ
±22 mK at 30 K
±9.5 mK at 77 K
±10 mK at 300 K
±11 mK at 800 K
Recommended for
T > 40 K & B ≤ 2.5 T
Rox™
RX-102A-AA with
0.3E calibration
sensor
–80 Ω/K at 4.2 K
–4 Ω/K at 20 K
–1.06 Ω/K at 40 K
40 mΩ
<1 mK at 4.2 K
10 mK at 20 K
38 mK at 40 K
±0.10 Ω ±0.04%
of reading
±8.1 mK at 4.2 K
±134 mK at 20 K
±491 mK at 40 K
±24.1 mK at 4.2 K
±238 mK at 20 K
±705 mK at 40 K
±80 mΩ
±1 mK at 4.2 K
±20 mK at 20 K
±76 mK at 40 K
Recommended for
T > 2 K & B ≤ 10 T
* Current reversal eliminates thermal EMF voltage errors for resistor sensors.
†
Typical sensor sensitivities were taken from representative calibrations for the sensor listed.
Introduction 1-5
A
A
A
A
A
Lake Shore Model 332 Temperature Controller User’s Manual
Table 1-2. Model 332 Typical Sensor Performance Chart (Continued)
Sensor Type
Germanium
GR-200A-1500
Temperature Coefficient Negative Negative Negative Negative Negative
Input Range AutoRange AutoRange AutoRange AutoRange AutoRange
Sensor Excitation*
(Constant Current)
75 mV max
4 ranges from 75 Ω -
75 kΩ
Display Resolution (Sensor Units) 5 digits 5 digits 5 digits 5 digits 5 digits
Example Lake Shore Sensor
Standard Sensor Curve
GR-200A-1500
with1.4D calibration
Requires calibrated
sensor
–64200 Ω/K at 1.4 K
Typical Sensor Sensitivity †
Measurement Resolution:
Sensor Units
Temperature Equivalence
Electronic Accuracy:
Sensor Units
Temperature Equivalents
Temperature Accuracy including
electronic accuracy, CalCurve
and calibrated sensor
Control Stability:
Sensor Units
Temperature Equivalence
Magnetic Field Use
–668 Ω/K at 4.2 K
–0.078Ω/K at 77 K
uto Range
see Table 1-3
4
<10 µK at 1.4 K
30 µK at 4.2 K
3.8 mK at 77 K
3
1
Auto Range
see Table 1-3
4
±0.2 mK at 1.4 K
±1 mK at 4.2 K
±38 mK at 77 K
±6 mK at 1.4 K 4
±6 mK at 4.2 K
±128 mK at 77 K
3
1
3
1
±80 mΩ
±20 µK at 1.4 K
±60 µK at 4.2 K
±7.6 mK at 77 K
4
3
1
Not Recommended Not Recommended
Germanium
GR-200A-250
75 mV max
4 ranges from 75 Ω -
75 kΩ
GR-200A-250 with
0.3D calibration
Requires calibrated
sensor
–8450 Ω/K at 1 K
–68.9 Ω/K at 4.2 K
–0.054 Ω/K at 77 K
uto Range
see Table 1-3
<10 µK at 1 K
40 µK at 4.2 K
5.5 mK at 77 K
Auto Range
see Table 1-3
±0.2 mK at 1 K
±2 mK at 4.2 K
±47 mK at 77 K
±6 mK at 1 K
±7 mK at 4.2 K
±137 mK at 77 K
±80 mΩ
±20 µK at 1 K
±80 µK at 4.2 K
±11 mK at 77 K
3
2
1
3
2
1
3
2
1
3
2
1
4 ranges from 75 Ω -
CX-1070-SD with
Requires calibrated
–17600 Ω/K at 4.2 K
–-969 Ω/K at 10 K
–8.26 Ω/K at 77 K
–0.419 Ω/K at 300 K
uto Range
see Table 1-3
<10 µK at 4.2 K
<100 µK at 10 K
3.6 mK at 77 K
7.2 mK at 300 K
Auto Range
see Table 1-3
±1 mK at 4.2 K
±3 mK at 10 K
±28 mK at 77 K
±128 mK at 300 K
±7 mK at 4.2 K
±11 mK at 10 K
±78 mK at 77 K
±268 mK at 300 K
±80 mΩ
±20 mK at 4.2 K
±7.2 mK at 77 K
±14.4 mK at 300 K
Recommended for
T > 2 K & B ≤ 19 T
Cernox™
CX-1070
75 mV max
75 kΩ
1.4L calibration
sensor
4
3
2
2
4
3
2
4
3
2
4
2
Cernox™
CX-1050
75 mV max
4 ranges from 75 Ω -
75 kΩ
CX-1050-SD with
1.4L calibration
Requires calibrated
sensor
–-42800 Ω/K at 2 K
–2290 Ω/K at 4.2 K
–2.15 Ω/K at 77 K
–0.131 Ω/K at 300 K
uto Range
see Table 1-3
<10 µK at 2 K
<10 µK at 4.2 K
1.2 mK at 77 K
2.3 mK at 300 K
Auto Range
see Table 1-3
±0.3 mK at 2 K
±1 mK at 4.2 K
±30 mK at 77 K
±130 mK at 300 K
2
±6 mK at 2 K
±7 mK at 4.2 K
±80 mK at 77 K
±270 mK at 300 K
2
4
3
2
1
4
3
2
1
4
3
2
1
Cernox™
CX-1030
75 mV max
4 ranges from 75 Ω -
75 kΩ
CX-1030-SD with
1.4L calibration
Requires calibrated
sensor
–-8670 Ω/K at 1.4 K
–138 Ω/K at 4.2 K
–-.828 Ω/K at 77 K
–0.067 Ω/K at 300 K
uto Range
see Table 1-3
<10 µK at 1.4 K
20 µK at 4.2 K
3.6 mK at 77 K
4.5 mK at 300 K
Auto Range
see Table 1-3
±0.2 mK at 1 K
±2 mK at 4.2 K
±57 mK at 77 K
±224 mK at 300 K
±6 mK at 1.4 K
±8 mK at 4.2 K
±107 mK at 77 K
±364 mK at 300 K
3
2
2
1
3
2
2
3
2
2
1
1
2
±80 mΩ
±8 µK at 2 K
4
±20 µK at 4.2 K
±2.4 mK at 77 K
±4.58 mK at 300 K
Recommended for
T > 2 K & B ≤ 19 T
3
2
1
±80 mΩ
±20 µK at 1.4 K
±40 µK at 4.2 K
±7.2 mK at 77 K
±9 mK at 300 K
3
3
3
Recommended for
T > 2 K & B ≤ 19 T
3
* Current reversal eliminates thermal EMF voltage errors for resistor sensors.
†
Typical sensor sensitivities were taken from representative calibrations for the sensor listed.
NOTES:
1 NTC RTD Range 75 Ω
2 NTC RTD Range 750 Ω
3 NTC RTD Range 7500 Ω
4 NTC RTD Range 75000 Ω
1-6 Introduction
Lake Shore Model 332 Temperature Controller User’s Manual
Table 1-2. Model 332 Typical Sensor Performance Chart (Continued)
Sensor Type
Thermocouple
25 mV
Temperature Coefficient Positive Positive
Input Range ±25 mV ±50 mV
Sensor Excitation*
(Constant Current)
Not Applicable Not Applicable
Display Resolution (Sensor Units) 0.1 µV 0.1 µV
Example LSCI Sensor
Chromel versus
AuFe 0.07%
Standard Sensor Curve By Type By Type
12.6 µV/K at 4.2 K
Typical Sensor Sensitivity †
Measurement Resolution:
Sensor Units
Temperature Equivalence
Electronic Accuracy:
Sensor Units
Temperature Equivalents
Temperature Accuracy including
electronic accuracy, CalCurve
22.4 µV/K at 300 K
0.4 µV
32 mK at 4.2 K
18 mK at 300 K
±1 µV ±0.05%
‡
of reading
±288 mK at 4.2 K
±58 mK at 300 K
Calibration not available
from Lake Shore
and calibrated sensor
Control Stability:
Sensor Units
Temperature Equivalence
Magnetic Field Use
0.8 µV
64 mK at 4.2 K
36 mK at 300 K
Recommended for
T > 2 K & B < 19 T
Thermocouple
50 mV
Type K
0.92 µV/K at 4.2 K
40 µV/K at 300 K
36 µV/K at 1500 K
0.4 µV
435 mK at 4.2 K
10 mK at 300 K
11 mK at 1500 K
±1 µV ±0.05% ‡
of reading
±4.6 K at 4.2 K
±38 mK at 300 K
±722 mK at 1500 K
Calibration not
available from
Lake Shore
0.8 µV
870 mK at 4.2 K
20 mK at 300 K
22 mK at 1500 K
Not Recommended
* Current reversal eliminates thermal EMF voltage errors for resistor sensors.
†
Typical sensor sensitivities were taken from representative calibrations for the sensor listed.
‡
Accuracy specification does not include errors from room temperature compensation.
Introduction 1-7
Lake Shore Model 332 Temperature Controller User’s Manual
1.3 SPECIFICATIONS
Table 1-3. Model 332 Input Specifications
Input Type
NTC-RTD *
PTC-RTD *
Diode
Thermocouple
Input
Range
0 – 75 Ω
0 – 750 Ω
0 – 7.5 kΩ
0 – 75 kΩ
0 – 250 Ω
0 – 500 Ω
0 – 1000 Ω
0 – 2.5 V 10 µA ±0.05% 10 µV
0 – 7.5 V 10 µA ±0.05% 20 µV
±25 mV Not applicable 0.4 µV
±50 mV Not applicable 0.4 µV
Excitation Resolution
1 mA
100 µA
10 µA
1 µA
1 mA
1 mA
1 mA
0.3 mΩ +0.000%
of reading
3 mΩ +0.001%
of reading
20 mΩ +0.001%
of reading
0.15 Ω +0.003%
of reading
2 mΩ
2 mΩ
20 mΩ
Electronic
Accuracy
±0.001Ω ±0.04%
of reading
±0.01Ω ±0.04%
of reading
±0.1Ω ±0.04%
of reading
±1.0Ω ±0.04%
of reading
±0.004Ω ±0.01%
of reading
±0.004Ω ±0.01%
of reading
±0.04Ω ±0.02%
of reading
±80 µV ±0.005%
of reading
±80 µV ±0.005%
of reading
±1 µV ±0.05%
of reading
±1 µV ±0.05%
of reading
Temperature
Coefficient
0.2 mΩ/°C +15 PPM
of reading/°C
2.0 mΩ/°C +15 PPM
of reading/°C
20 mΩ/°C +15 PPM
of reading/°C
200 mΩ/°C +15 PPM
of reading/°C
0.2 mΩ/°C +5 PPM
of reading/°C
0.2 mΩ/°C +5 PPM
of reading/°C
2.0 mΩ/°C +5 PPM
of reading/°C
10 µV/°C +5 PPM
of reading/°C
20 µV/°C +5 PPM
of reading/°C
0.2 µV/°C +15 PPM
of reading/°C
0.4 µV/°C +15 PPM
of reading/°C
Display
Resolution
100 mΩ
100 mΩ
* Current reversal eliminates thermal EMF voltage errors for resistor sensors.
Thermometry
Number of Inputs: 2
Input Configuration: Each input is factory configured as either Diode/RTD or Thermocouple
Measurement Type Four-lead differential with current reversal Two lead, room temperature compensated
Excitation Constant current Not Applicable
Supported Sensors
Diodes: Silicon, GaAlAs, RTDs: 100
Platinum, 1000
Carbon Glass, Cernox, ROX, Thermox
Standard Curves
DT-470, DT-500D, DT-670, PT-100, PT1000, RX-102A, RX-202A
Input Connector 6 pin DIN Ceramic isothermal block
Isolation: Sensor inputs optically isolated from other circuits but not each other
A/D Resolution: 24 bit
Input Accuracy: Sensor dependent – Refer to Table 1-3
Measurement Resolution: Sensor dependent – Refer to Table 1-3
Maximum Update Rate: 10 readings per second on each input with the following exceptions:
5 readings per second when configured as NTC RTD 75 kΩ with reversal on.
5 readings per second on input A when configured as thermocouple.
Auto Range: Auto Range available to automatically select appropriate NTC RTD range.
User Curves: Room for twenty 200-point CalCurves or user curves
SoftCal: Improves accuracy of DT-470 Diode to ±0.25 K from 30 to 375 K. Improves accuracy of
Platinum RTDs to ±0.25 K from 70 to 325 K. Stored as user curves
Math: Maximum, Minimum, and Linear Equation (Mx
Filter: Averages 2 to 64 input readings
Diode/RTD Thermocouple
Ω
Most thermocouple types
Ω Platinum, Germanium,
Type E, Type K, Type T, AuFe0.07% vs. Ch,
AuFe0.03% vs. Ch
+ B) or M (x + B)
1 mΩ
10 mΩ
1 Ω
10 mΩ
10 mΩ
100 µV
100 µV
1 µV
1 µV
1-8 Introduction
Lake Shore Model 332 Temperature Controller User’s Manual
Specifications (Continued)
Control
Control Loops: 2
Control Type: Closed Loop Digital PID with Manual Heater Power Output, or Open Loop
Tuning: AutoTune (one loop at a time), Manual PID, Zones
Control Stability: Sensor dependent, refer to performance chart
PID Control Settings:
Proportional (Gain): 0
Integral (Reset): 1
Derivative (Rate): 1
Manual Heater Power: 0
– 1000 with 0.1 setting resolution
– 1000 (1000/s) with 0.1 setting resolution
– 200% with 1% resolution
– 100% with 0.001% setting resolution
Zone Control: 10 temperature zones with P, I, D, Manual Heater Power Output, and Heater Range
Setpoint Ramping: 0.1 to 100 K/min
Protection: Curve Temperature limits, Power up heater off, Short-circuit protection
Loop 1 Loop 2
Heater Output Type Variable DC current source Variable DC voltage source
Heater Output D/A Resolution 18 bit 16 bit
Max Heater Power 50 W 10 W
Max Heater Output Current 1 A 1 A
Heater Output Compliance 50 V 10 V
Heater Source Impedance N/A
0.1 Ω maximum
Heater Output Ranges 3 decade steps in power 1
Heater Load Type Resistive Resistive
Heater Load Range
Heater Load for Max Power
Heater Noise (<1 kHz.) RMS
Isolation
10 Ω to 100 Ω recommended 10 Ω minimum
50 Ω 10 Ω
50 µV +0.017% of output voltage
Optical isolation between output and
<0.3 mV
None
other circuits
Heater Connector Dual banana Detachable terminal block
Loop 1 Full Scale Heater Power at Typical Resistance
Heater Resistance Heater Range Heater Power
10 Ω
25 Ω
50 Ω
Low
Med
High
Low
Med
High
Low
Med
High
100 mW
1 W
10 W
250 mW
2.5 W
25 W
500 mW
5 W
50 W
Front Panel
Display: 2 line by 20 character, 9 mm character height, vacuum fluorescent display
Number of reading displays: 1 to 4
Display Units: K, °C, V, mV, Ω
Display Source: Temperature, sensor units, max, min, and linear equation
Display Update Rate: All readings twice per second
Temperature Display Resolution: 0.001° between 0°
Sensor Units Display Resolution: Sensor dependent, to 5 digits
Other Displays: Setpoint, Heater Range, and Heater Output (user selected)
Setpoint Setting Resolution: Same as display resolution (actual resolution is sensor dependent)
Heater Output Display: Numeric or graphical display in percent of full scale for power or current
Heater Output Resolution: 1% numeric or 2% graphical
Display Annunciators: Control Input, Remote, Alarm, Tuning, Ramp, Max, Min, Linear
Keypad: 20 full-travel keys, numeric and specific functions
Front Panel Features: Front panel curve entry, display brightness control, keypad lock-out
– 99.999°, 0.01° between 100° – 999.99°, 0.1° above 1000°
Introduction 1-9
Lake Shore Model 332 Temperature Controller User’s Manual
Specifications (Continued)
Interface
IEEE-488.2 Interface
Features: SH1,AH1,T5,L4,SR1,RL1,PP0,DC1,DT0,C0,E1
Reading Rate: To 10 readings per second on each input
Software Support: LabView Driver
Serial Interface
Electrical Format: RS-232C
Max. Baud Rate: 9600 Baud
Connector: DE-9
Reading Rate: To 10 readings per second on each input (at 9600 Baud)
Special Interface Features: Model 330 command emulation mode
Alarms
Number: 4, High and Low for each input
Data Source: Temperature, Sensor Units, Linear Equation
Settings: Source, High & Low Setpoint, Deadband, Latching or Non-Latching, Audible On/Off
Actuators: Display annunciator, beeper, relays
Relays
Number: 2
Contacts: Normally Open (NO), Normally Closed (NC), and Common (COM)
Contact Rating: 30 VDC at 5 A
Operation: Activate relays on high, low, or both alarms for either input or manual
Connector: Detachable terminal block
Analog Voltage Output (when not used as control loop 2 output)
Scale: User selected
Update Rate: 10 readings per second
Data Source: Temperature, Sensor Units, Linear Equation
Settings: Input, Source, Top of scale, Bottom of scale, or manual
Range: ±10 V
Resolution: 0.3 mV
Accuracy: ±2.5 mV
Maximum Output Power: 1 W (jumper selected)
Minimum Load Resistance: 100 Ω (short-circuit protected)
Source Impedance: 0.01 Ω
General
Ambient Temperature: 15 – 35 °C at rated accuracy. 10 – 40 °C at reduced accuracy
Power Requirement: 100, 120, 220, 240 VAC, +6% –10%, 50 or 60 Hz., 150 VA
Size: 217 mm wide × 90 mm high × 368 mm deep (8.5 × 3.5 × 14.5 inches), half rack
Weight: 4.8 kilograms (10.5 pounds)
Ordering Information
Standard Temperature Controllers
Part Number Description (Input configuration cannot be changed in the field)
332S Two Diode/Resistor Inputs
332S-T1 One Diode/Resistor, One Thermocouple Input
332S-T2 Two Thermocouple Inputs
Power Options (Select one, the instrument will be configured for selected power and fuses)
VAC-100 Instrument configured for 100 VAC with U.S. power cord
VAC-120 Instrument configured for 120 VAC with U.S. power cord
VAC-220 Instrument configured for 220 VAC with European power cord
VAC-240 instrument configured for 240 VAC with European power cord
VAC-120-All Instrument configured for 120 VAC with U.S. power cord and universal European
power cord and fuses for 220/240 setting (extra charge for this option)
1-10 Introduction
Specifications (Continued)
Accessories Included
Part Number Description
106-009 Heater output connector (dual banana jack)
G-106-233 Sensor input mating connector (6-pin DIN plugs); 2 included
106-234 Terminal block, 8-pin
MAN-332 User manual
CalCurve™ Options
8001-332 CalCurve, factory-installed, consists of a calibrated sensor breakpoint table factory-
8002-05-332 CalCurve, field-installed, consists of a calibrated sensor breakpoint table loaded into
Accessories Available
4005 1 meter (3.3 feet) long IEEE-488 (GPIB) computer interface cable assembly. Includes
RM-1/2 Rack mount kit for one ½ rack temperature controller in a 483 mm (19 inch) rack,
RM-2 Rack mount kit for two ½ rack temperature controllers in a 483 mm (19 inch) rack,
Refer to Chapter 7 of this manual for a complete description of Model 332 options and accessories.
Specifications are subject to change without notice.
Lake Shore Model 332 Temperature Controller User’s Manual
installed into non-volatile memory
non-volatile memory
extender required for simultaneous use of IEEE cable and relay terminal block
90 mm (3.5 inches) high
135 mm (5.3 inches) high
1.4 SAFETY SUMMARY
Observe these general safety precautions during all phases of instrument operation, service, and
repair. Failure to comply with these precautions or with specific warnings elsewhere in this manual
violates safety standards of design, manufacture, and intended instrument use. Lake Shore
Cryotronics, Inc. assumes no liability for Customer failure to comply with these requirements.
The Model 332 protects the operator and surrounding area from electric shock or burn, mechanical
hazards, excessive temperature, and spread of fire from the instrument. Environmental conditions
outside of the conditions below may pose a hazard to the operator and surrounding area.
• Indoor use.
• Altitude to 2000 meters.
• Temperature for safe operation: 5 °C to 40 °C.
• Maximum relative humidity: 80% for temperature up to 31 °C decreasing linearly to 50% at 40 °C.
• Power supply voltage fluctuations not to exceed ±10% of the nominal voltage.
• Overvoltage category II.
• Pollution degree 2.
Ground The Instrument
To minimize shock hazard, the instrument is equipped with a three-conductor AC power cable.
Plug the power cable into an approved three-contact electrical outlet or use a three-contact adapter
with the grounding wire (green) firmly connected to an electrical ground (safety ground) at the power
outlet. The power jack and mating plug of the power cable meet Underwriters Laboratories (UL) and
International Electrotechnical Commission (IEC) safety standards.
Introduction 1-11
Safety Summary (Continued)
Lake Shore Model 332 Temperature Controller User’s Manual
Ventilation
The instrument has ventilation holes in its side covers. Do not block these holes when the instrument is
operating.
Do Not Operate In An Explosive Atmosphere
Do not operate the instrument in the presence of flammable gases or fumes. Operation of any electrical
instrument in such an environment constitutes a definite safety hazard.
Keep Away From Live Circuits
Operating personnel must not remove instrument covers. Refer component replacement and internal
adjustments to qualified maintenance personnel. Do not replace components with power cable
connected. To avoid injuries, always disconnect power and discharge circuits before touching them.
Do Not Substitute Parts Or Modify Instrument
Do not install substitute parts or perform any unauthorized modification to the instrument. Return the
instrument to an authorized Lake Shore Cryotronics, Inc. representative for service and repair to ensure
that safety features are maintained.
Cleaning
Do not submerge instrument. Clean only with a damp cloth and mild detergent. Exterior only.
1.5 SAFETY SYMBOLS
1-12 Introduction
Lake Shore Model 332 Temperature Controller User’s Manual
CHAPTER 2
COOLING SYSTEM DESIGN
2.0 GENERAL
Selecting the proper cryostat or cooling source is probably the most important decision in designing a
temperature control system. The cooling source defines minimum temperature, cool-down time, and
cooling power. (Information on choosing a cooling source is beyond the scope of this manual.) This
chapter provides information on how to get the best temperature measurement and control from cooling
sources with proper setup including sensor and heater installation.
Chapter 2 contains the following major topics. Temperature sensor selection is covered in
Paragraph 2.1. Calibrated sensors are covered in Paragraph 2.2. Sensor installation is covered in
Paragraph 2.3. Heater selection and installation is covered in Paragraph 2.4. Considerations for good
control are covered in Paragraph 2.5. PID Control is covered in Paragraph 2.6. Manual Tuning is
covered in Paragraph 2.7. AutoTuning is covered in Paragraph 2.8. Finally, Zone Tuning is covered in
Paragraph 2.9.
2.1 TEMPERATURE SENSOR SELECTION
This section attempts to answer some of the basic questions concerning temperature sensor selection.
Additional useful information on temperature sensor selection is available in the Lake Shore
Temperature Measurement and Control Catalog. The catalog has a large reference section that
includes sensor characteristics and sensor selection criteria.
2.1.1 Temperature Range
Several important sensor parameters must be considered when choosing a sensor. The first is
temperature range. The experimental temperature range must be known when choosing a sensor.
Some sensors can be damaged by temperatures that are either too high or too low. Manufacturer
recommendations should always be followed.
Sensor sensitivity is also dependent on temperature and can limit the useful range of a sensor. It is
important not to specify a range larger than necessary. If an experiment is being done at liquid helium
temperature, a very high sensitivity is needed for good measurement resolution at that temperature.
That same resolution may not be required to monitor warm up to room temperature. Two different
sensors may be required to tightly cover the range from helium to room temperature, but lowering the
resolution requirement on warm up may allow a less expensive, one sensor solution.
Another thing to consider when choosing a temperature sensor is that instruments like the Model 332
are not able to read some sensors over their entire temperature range. Lake Shore sells calibrated
sensors that operate down to 50 millikelvin (mK), but the Model 332 is limited to above 1 K in its
standard configuration.
2.1.2 Sensor Sensitivity
Temperature sensor sensitivity is a measure of how much a sensor signal changes when the
temperature changes. It is an important sensor characteristic because so many measurement
parameters are related to it. Resolution, accuracy, noise floor, and even control stability depend on
sensitivity. Many sensors have different sensitivities at different temperatures. For example, a
platinum sensor has good sensitivity at higher temperatures but has limited use below 30 kelvin (K)
because its sensitivity drops sharply. It is difficult to determine if a sensor has adequate sensitivity
over the experimental temperature range. This manual has specifications (Table 1-2) that include
sensor sensitivity translated into temperature resolution and accuracy at different points. This is
typical sensor response and can be used as a guide when choosing a sensor to be used with the
Model 332.
Cooling System Design 2-1
Lake Shore Model 332 Temperature Controller User’s Manual
2.1.3 Environmental Conditions
The experimental environment is also important when choosing a sensor. Environmental factors such
as high vacuum, magnetic field, corrosive chemicals, or even radiation can limit the use of some
types of sensors. Lake Shore has devoted much time to developing sensor packages that withstand
the temperatures, vacuum levels, and bonding materials found in typical cryogenic cooling systems.
Experiments done in magnetic fields are becoming very common. Field dependence of temperature
sensors is an important selection criteria for sensors used in these experiments. This manual briefly
qualifies the field dependence of most common sensors in the specifications (Table 1-2). Detailed
field dependence tables are included in the Lake Shore Temperature Measurement and Control
Catalog. When available, specific data on other environmental factors is also included in the catalog.
2.1.4 Measurement Accuracy
Temperature measurements have several sources of error that reduce accuracy. Be sure to account
for errors induced by both the sensor and the instrumentation when computing accuracy. The
instrument has measurement error in reading the sensor signal and error in calculating a temperature
using a temperature response curve. Error results from the sensor being compared to a calibration
standard and the temperature response of a sensor will shift with time and with repeated thermal
cycling (from very cold temperatures to room temperature). Instrument and sensor makers specify
these errors but there are things a user can do to maintain good accuracy. For example, choose a
sensor that has good sensitivity in the most critical temperature range, as sensitivity can minimize the
effect of most error sources. Install the sensor properly following guidelines in Paragraph 2.3. Have
the sensor and instrument periodically recalibrated, or in some other way null the time dependent
errors. Use a sensor calibration that is appropriate for the accuracy requirement.
2.1.5 Sensor Package
Many types of sensors can be purchased in different packages. Some types of sensors can even be
purchased as bare chips (without any package). A sensor package generally determines its size,
thermal and electrical contact to the outside, and sometimes limits temperature range. When different
packages are available for a sensor, the user should consider the mounting surface for the sensor
and how leads will be heat sinked when choosing.
2.2 CALIBRATED SENSORS
There can sometimes be confusion in the difficult task of choosing the right sensor, getting it calibrated,
translating the calibration data into a temperature response curve that the Model 332 can understand,
then getting the curve loaded into the instrument. Lake Shore provides a variety of calibration and curve
loading services to fit different accuracy requirements and budgets.
2.2.1 Traditional Calibration
Calibration is done by comparing a sensor with an unknown temperature response to an accepted
standard. Lake Shore temperature standards are traceable to the U.S. National Institute of Standards
and Testing (NIST) or the National Physical Laboratory in Great Britain. These standards allow Lake
Shore to calibrate sensors from 50 mK to above room temperature. Calibrated sensors are more
expensive than uncalibrated sensors of the same type because of the labor and capitol equipment
used in the process.
This type of calibration provides the most accurate temperature sensors available from Lake Shore.
Errors from sensor calibration are usually smaller than the error contributed by the Model 332. The
Lake Shore Temperature Measurement and Control Catalog has complete accuracy specifications for
calibrated sensors.
2-2 Cooling System Design
Lake Shore Model 332 Temperature Controller User’s Manual
Traditional Calibration (Continued)
Calibrated sensors include the measured test data printed and plotted, the coefficients of a
Chebychev polynomial that has been fitted to the data, and two tables of data points to be used as
interpolation tables. Both interpolation tables are optimized to allow accurate temperature conversion.
The smaller table, called a breakpoint interpolation table, is sized to fit into instruments like the Model
332 where it is called a temperature response curve. Getting a curve into a Model 332 may require a
CalCurve™ described below or hand entering through the instrument front panel.
It is important to look at instrument specifications before ordering calibrated sensors. A calibrated
sensor is required when a sensor does not follow a standard curve if the user wishes to display in
temperature. Otherwise, the Model 332 will operate in sensor units like ohms or volts. The Model 332
may not work over the full temperature range of some sensors. The standard inputs in are limited to
operation above 1 K even with sensors that can be calibrated to 50 mK.
2.2.2 SoftCal™
SoftCal is a good solution for applications that do not require the accuracy of a traditional calibration.
The SoftCal algorithm uses the well-behaved nature of sensors that follow a standard curve to
improve the accuracy of individual sensors. A few known temperature points are required to perform
SoftCal.
Lake Shore sells SoftCal calibrated sensors that include both the large interpolation table and the
smaller breakpoint interpolation table. A CalCurve may be required to get the breakpoint table into a
Model 332 where it is called a temperature response curve. Refer to Paragraph 2.2.4.
The Model 332 can also perform a SoftCal calibration. The user must provide one, two, or three
known temperature reference points. The range and accuracy of the calibration is based on these
points. Refer to Paragraph 5.3.
2.2.3 Standard Curves
Some types of sensors behave in a very predictable manner and a standard temperature response
curve can be created for them. Standard curves are a convenient and inexpensive way to get
reasonable temperature accuracy. Sensors that have a standard curve are often used when
interchangeability is important. Some individual sensors are selected for their ability to match a
published standard curve and sold at a premium, but in general, these sensors do not provide the
accuracy of a calibrated sensor. For convenience, the Model 332 has several standard curves
included in firmware.
2.2.4 CalCurve™
The CalCurve service provides the user with a convenient way get the temperature response curve
from Lake Shore calibrated sensors into instruments like the Model 332. It can be performed at the
factory when calibrated sensors and instruments are ordered together. The factory installed CalCurve
option is Model 8001-332 and should be ordered with the calibrated sensor. A CalCurve can be done
in the field when additional or replacement sensors are installed. Curve data is loaded into some type
of non-volatile memory that is installed into the instrument by the user. In the case of the Model 332,
the curve is loaded into a non-volatile memory that can be installed into the instrument. The fieldinstalled version is a Model 8002-05-332 and should be ordered with the calibrated sensor.
Customers that have a PC-compatible computer with an RS-232C or IEEE-488 interface have
another option. The Model 8000 is included with the calibrated sensor and can be loaded by the user.
Cooling System Design 2-3
Lake Shore Model 332 Temperature Controller User’s Manual
Lake Shore Silicon Diode
Temperature Sensor
Regarding accuracy, there are
3 things that can be done with
a temperature sensor:
Standard
Standard sensors are interchange-
able within published tolerance
bands. Below is a list of Standard
Curve 10 DT-470 Tolerance
(Accuracy) Bands.
Band
2 K* -
100 K
11 ±0.25 K ±0.5 K ±1.0 K
11A ±0.25 K ±1% of Temp.
12 ±0.5 K ±1.0 K ±2.0 K
12A ±0.5 K ±1% of Temp.
13 ±1 K ±1% of Temp.
* Temperatures down to 1.4 K only with
a Precision Calibrated Sensor.
To increase accuracy, perform a
SoftCal with the controller and
sensor. After sensor calibration, the
custom sensor curve replaces the
standard Curve 10.
100 K -
305 K
305 K -
375 K
SoftCal
Calibration
A Lake Shore SoftCal applies only to
Silicon Diodes. A 2-point SoftCal
takes data points at 77.35 K and
305 K. A 3-point SoftCal takes data
points at 4.2 K, 77.35 K, and 305 K.
Typical 2-Point Accuracy
±1.0 K 2 K to <30 K
±0.25 K 30 K to <60 K
±0.15 K 60 K to <345 K
±0.25 K 345 K to <375 K
±1.0 K 375 K to 475 K
Typical 3-Point Accuracy
±0.5 K 2 K to <30 K
±0.25 K 30 K to <60 K
±0.15 K 60 K to <345 K
±0.25 K 345 K to <375 K
±1.0 K 375 K to 475 K
Enter voltages at the 2 or 3 data
points into SoftCal capable
controllers. A calibration report
comes with the sensor.
Precision
Calibration
Lake Shore precision calibrates
most sensor types by taking up to
99 data points concentrated in
areas of interest. Typical silicon
diode calibration accuracy is listed
below.
Temp. Typical Maximum
<10 K 12 mK 20 mK
10 K 12 mK 20 mK
20 K 15 mK 25 mK
30 K 25 mK 45 mK
50 K 30 mK 55 mK
100 K 25 mK 50 mK
300 K 25 mK 50 mK
340 K 100 mK
480 K 100 mK
A curve is fitted to these points.
A detailed report including Raw
Temperature Data, Polynomial
Fits, and Interpolation Tables
comes with the sensor.
A CalCurve can be generated
for either SoftCal or the
CalCurve
- or -
Precision Calibration:
8001-332
Factory installs a NOVRAM
with CalCurve breakpoint
pairs loaded in it.
C-332-2-1.eps
Users download CalCurve
breakpoint pairs in ACSII format
from a floppy disk.
8000 8002-05-332
User calculates break-
points and manually enters
data into the controller
Users install a NOVRAM
with CalCurve breakpoint
pairs loaded in it.
Figure 2-1. Silicon Diode Sensor Calibrations and CalCurve
2-4 Cooling System Design
Lake Shore Model 332 Temperature Controller User’s Manual
2.3 SENSOR INSTALLATION
This section highlights some of the important elements of proper sensor installation. Lake Shore
sensors are shipped with installation instructions that cover that specific sensor type and package. The
Lake Shore Temperature Measurement and Control Catalog includes an installation section as well.
Lake Shore offers a line of Cryogenic Accessories to further help users properly install sensors. Many
of the materials discussed are available through Lake Shore and can be ordered with sensors or
instruments.
2.3.1 Mounting Materials
Choosing appropriate mounting materials is very important in a cryogenic environment. The high
vacuum used to insulate cryostats is one source of problems. Materials used in these applications
should have a low vapor pressure so they do not evaporate or out-gas and spoil the vacuum
insulation. Metals and ceramics do not have this problem but greases and varnishes must be
checked. Another source of problems is the wide extremes in temperature most sensors are exposed
to. The linear expansion coefficient of a material becomes important when temperature changes are
so large. Never try to permanently bond materials with linear expansion coefficients that differ by
more than three. A flexible mounting scheme should be used or the parts will break apart, potentially
damaging them. The thermal expansion or contraction of rigid clamps or holders could crush fragile
samples or sensors that do not have the same coefficient. Thermal conductivity is a property of
materials that can change with temperature. Do not assume that a heat-sink grease that works well at
room temperature and above will do the same job at low temperatures.
2.3.2 Sensor Location
Finding a good place to mount a sensor in an already crowded cryostat is never easy. There are less
problems if the entire load and sample holder are at the same temperature. Unfortunately, this not the
case in many systems. Temperature gradients (differences in temperature) exist because there is
seldom perfect balance between the cooling source and heat sources. Even in a well-controlled
system, unwanted heat sources like thermal radiation and heat conducting through mounting
structures can cause gradients. For best accuracy, sensors should be positioned near the sample, so
that little or no heat flows between the sample and sensor. This may not, however, be the best
location for temperature control as discussed below.
2.3.3 Thermal Conductivity
The ability of heat to flow through a material is called thermal conductivity. Good thermal conductivity
is important in any part of a cryogenic system that is intended to be the same temperature. Copper
and aluminum are examples of metals that have good thermal conductivity, while stainless steel does
not. Non-metallic, electrically-insulating materials like alumina oxide and similar ceramics have good
thermal conductivity, while G-10 epoxy-impregnated fiberglass does not. Sensor packages, cooling
loads, and sample holders should have good thermal conductivity to reduce temperature gradients.
Surprisingly, the connections between thermally conductive mounting surfaces often have very poor
thermal conductivity.
2.3.4 Contact Area
Thermal contact area greatly affects thermal conduction because a larger area has more opportunity
to transfer heat. Even when the size of a sensor package is fixed, thermal contact area can be
improved with the use of a gasket material. A soft gasket material forms into the rough mating surface
to increase the area of the two surfaces that are in contact. Good gasket materials are soft, thin, and
have good thermal conductivity. They must also withstand the environmental extremes. Indium foil
and cryogenic grease are good examples.
Cooling System Design 2-5
Lake Shore Model 332 Temperature Controller User’s Manual
2.3.5 Contact Pressure
When sensors are permanently mounted, the solder or epoxy used to hold the sensor act as both
gasket and adhesive. Permanent mounting is not a good solution for everyone because it limits
flexibility and can potentially damage sensors. Much care should be taken not to over heat or
mechanically stress sensor packages. Less permanent mountings require some pressure to hold the
sensor to its mounting surface. Pressure greatly improves the action of gasket material to increase
thermal conductivity and reduce thermal gradients. A spring clamp is recommended so that different
rates of thermal expansion do not increase or decrease pressure with temperature change.
2.3.6 Lead Wire
Different types of sensors come with different types and lengths of electrical leads. In general a
significant length of lead wire must be added to the sensor for proper heat sinking and connecting to
a bulk head connector at the vacuum boundary. The lead wire must be a good electrical conductor,
but should not be a good thermal conductor, or heat will transfer down the leads and change the
temperature reading of the sensor. Small 30 to 40 AWG wire made of an alloy like phosphor bronze is
much better than copper wire. Thin wire insulation is preferred and twisted wire should be used to
reduce the effect of RF noise if it is present. The wire used on the room temperature side of the
vacuum boundary is not critical so copper cable is normally used.
Vacuum Shroud
To Room
Temperature
Refrigerator
Expander
Vacuum Space
Radiation Shield
Dental Floss
Tie-Down
Therm al Anchor
(Bobbin)
-or-
Cryogenic Tape
Refrigerator
Second
Stage
Thermal Anchor
Cryogenic Wire
diameter,
(small
(Bobbin)
large AWG)
Cold Stage and
Sensor
Sample Holder
Drawing
Not To Scale
Optical Window
Heater
(wiring not shown
for clarity)
(If Required)
P-331-2-2.bmp
Figure 2-2. Typical Sensor Installation In A Mechanical Refrigerator
2-6 Cooling System Design
Lake Shore Model 332 Temperature Controller User’s Manual
2.3.7 Lead Soldering
When additional wire is soldered to short sensor leads, care must be taken not to overheat the
sensor. A heat sink such as a metal wire clamp or alligator clip will heat sink the leads and protect the
sensor. Leads should be tinned before bonding to reduce the time that heat is applied to the sensor
lead. Solder flux should be cleaned after soldering to prevent corrosion.
2.3.8 Heat Sinking Leads
Sensor leads can be a significant source of error if they are not properly heat sinked. Heat will
transfer down even small leads and alter the sensor reading. The goal of heat sinking is to cool the
leads to a temperature as close to the sensor as possible. This can be accomplished by putting a
significant length of lead wire in thermal contact with every cooled surface between room temperature
and the sensor. Lead wires can be adhered to cold surfaces with varnish over a thin insulator like
cigarette paper. They can also be wound on a bobbin that is firmly attached to the cold surface. Some
sensor packages include a heat sink bobbin and wrapped lead wires to simplify heat sinking.
2.3.9 Thermal Radiation
Thermal (black body) radiation is one of the ways heat is transferred. Warm surfaces radiate heat to
cold surfaces even through a vacuum. The difference in temperature between the surfaces is one
thing that determines how much heat is transferred. Thermal radiation causes thermal gradients and
reduces measurement accuracy. Many cooling systems include a radiation shield. The purpose of the
shield is to surround the load, sample, and sensor with a surface that is at or near their temperature
to minimize radiation. The shield is exposed to the room temperature surface of the vacuum shroud
on its outer surface, so some cooling power must be directed to the shield to keep it near the load
temperature. If the cooling system does not include an integrated radiation shield (or one cannot be
easily made), one alternative is to wrap several layers of super-insulation (aluminized Mylar) loosely
between the vacuum shroud and load. This reduces radiation transfer to the sample space.
2.4 HEATER SELECTION AND INSTALLATION
There is a variety of resistive heaters that can be used as the controlled heating source for temperature
control. The mostly metal alloys like nichrome are usually wire or foil. Shapes and sizes vary to permit
installation into different systems.
2.4.1 Heater Resistance and Power
Cryogenic cooling systems have a wide range of cooling power. The resistive heater must be able to
provide sufficient heating power to warm the system. The Model 332 can supply up to 50 W of power
to a heater (if the heater resistance is appropriate). The Model 332 heater output current source has a
maximum output of 1 A, limiting maximum power to:
Max Power (watts) = (1 ampere)2 × Resistance (ohms).
Even though the Model 332 output is a current source, it has a voltage limit (called the compliance
voltage) of 50 V, which also limits maximum power:
Max Power (watts)
(50 volts)
=
Resistance (ohms)
2
.
Both limits are in place at the same time, so the smallest of the two computations gives the maximum
power available to the heater. A heater of 50 Ω allows the instrument to provide its maximum power
of 50 watts. A typical smaller resistance of 25 Ω allows 25 watts of power, while a typical larger
resistance of 100 Ω is limited by compliance voltage to 25 watts. The resistor chosen as a heater
must be able to withstand the power being dissipated in it. Pre-packaged resistors have a power
specification that is usually given for the resistor in free air. This power may need to be derated if
used in a vacuum where convection cooling can not take place and it is not adequately heat sinked to
a cooled surface.
Cooling System Design 2-7
2.4.2 Heater Location
For best temperature measurement accuracy the heater should be located so that heat flow between
the cooling power and heater is minimized. For best control the heater should be in close thermal
contact with the cooling power. Geometry of the load can make one or both of these difficult to
achieve. That is why there are several heater shapes and sizes.
2.4.3 Heater Types
Resistive wire like nichrome is the most flexible type of heater available. The wire can be purchased
with electrical insulation and has a predictable resistance per given length. This type of heater wire
can be wrapped around a cooling load to give balanced, even heating of the area. Similar to sensor
lead wire, the entire length of the heater wire should be in good thermal contact with the load to allow
for thermal transfer. Heat sinking also protects the wire from over heating and burning out.
Resistive heater wire is also wound into cartridge heaters. Cartridge heaters are more convenient but
are bulky and more difficult to place on small loads. A typical cartridge is ¼ inch in diameter and
1 inch long. The cartridge should be snugly held in a hole in the load or clamped to a flat surface.
Heat sinking for good thermal contact is again important.
Foil heaters are thin layers of resistive material adhered to, or screened on to, electrically insulating
sheets. There are a variety of shapes and sizes. The proper size heater can evenly heat a flat surface
or around a round load. The entire active area should be in good thermal contact with the load, not
only for maximum heating effect, but to keep spots in the heater from over heating and burning out.
Lake Shore Model 332 Temperature Controller User’s Manual
2.4.4 Heater Wiring
When wiring inside a vacuum shroud, we recommend using 30 AWG copper wire for heater leads.
Too much heat can leak in when larger wire is used. Heat sinking, similar to that used for the sensor
leads, should be included so that any heat leaking in does not warm the load when the heater is not
running. The lead wires should be twisted to minimize noise coupling between the heater and other
leads in the system. When wiring outside the vacuum shroud, larger gage copper cable can be used,
and twisting is still recommended.
2.5 CONSIDERATION FOR GOOD CONTROL
Most of the techniques discussed above to improve cryogenic temperature accuracy apply to control as
well. There is an obvious exception in sensor location. A compromise is suggested in Paragraph 2.5.3.
2.5.1 Thermal Conductivity
Good thermal conductivity is important in any part of a cryogenic system that is intended to be at the
same temperature. Most systems begin with materials that have good conductivity themselves, but as
sensors, heaters, sample holders, etc., are added to an ever more crowded space, the junctions
between parts are often overlooked. In order for control to work well, junctions between the elements
of the control loop must be in close thermal contact and have good thermal conductivity. Gasket
materials should always be used along with reasonable pressure.
2.5.2 Thermal Lag
Poor thermal conductivity causes thermal gradients that reduce accuracy and also cause thermal lag
that make it difficult for controllers to do their job. Thermal lag is the time it takes for a change in
heating or cooling power to propagate through the load and get to the feedback sensor. Because the
feedback sensor is the only thing that lets the controller know what is happening in the system, slow
information to the sensor slows the response time. For example, if the temperature at the load drops
slightly below the setpoint, the controller gradually increases heating power. If the feedback
information is slow, the controller puts too much heat into the system before it is told to reduce heat.
The excess heat causes a temperature overshoot, which degrades control stability. The best way to
improve thermal lag is to pay close attention to thermal conductivity both in the parts used and their
junctions.
2-8 Cooling System Design
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