Lakeshore 622 User Manual

User’s Manual

Model 620/622/623/647

Model 620/622/623/647Model 620/622/623/647

Model 620 – ±50 A, ±5 V Model 623 – ±155 A, ±30 V Model 622 – ±125 A, ±30 V Model 647 – ±72 A, ±32 V

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Magnet Power Supply

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Magnet Power Supply

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Switch Heater

Persistent

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Enter

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Power

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Lake Shore Cryotronics, Inc. 575 McCorkle Blvd. Westerville, Ohio 43082-8888 USA

E-Mail Addresses:

sales@lakeshore.com service@lakeshore.com

Visit Our Website:

www.lakeshore.com

Fax: (614) 891-1392 Telephone: (614) 891-2243

Methods and apparatus disclosed and described herein have been developed solely on company funds of Lake Shore Cryotronics, Inc. No government or other contractual support or relationship whatsoever has existed which in any way affects or mitigates proprietary rights of Lake Shore Cryotronics, Inc. in these developments. Methods and apparatus disclosed herein may be subject to U.S. Patents existing or applied for. Lake Shore Cryotronics, Inc. reserves the right to add, improve, modify, or withdraw functions, design modifications, or products at any time without notice. Lake Shore shall not be liable for errors contained herein or for incidental or consequential damages in connection with furnishing, performance, or use of this material.

Rev. 1.2 P/N 119-001 9 April 1999

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

LIMITED WARRANTY

Lake Shore Cryotronics, Inc. (henceforth Lake Shore), the manufacturer, warrants the instrument to be free from defects in material and workmanship for a period of twelve months from the date of shipment. During the warranty period, under authorized return of instruments or component parts to Lake Shore freight prepaid, the company will repair, or at its option replace, any part found to be defective in material or workmanship, without charge to the Owner for parts, service labor or associated customary shipping cost. Replacement or repaired parts will be warranted for only the unexpired portion of the original warranty.

All products are thoroughly tested and calibrated to published specifications prior to shipment. Calibration Certifications are offered for six month periods only. Where such documentation must be updated, a re-certification service is offered by Lake Shore at a reasonable cost.

LIMITATION OF WARRANTY

This warranty is limited to Lake Shore products purchased and installed in the United States, or Internationally through our approved distribution agents. This same protection will extend to any subsequent owner during the warranty period. It does not apply to damage resulting from improper or inadequate maintenance, unauthorized modification or misuse, operation outside of the environmental specifications, or from buyersupplied software interfacing. It does not apply to damage caused by accident, misuse, fire, flood or Acts of God, or from failure to properly install, operate, or maintain the product in accordance with the printed instruction provided.

This warranty is in lieu of any other warranties, expressed or implied, including merchantability or fitness for a particular purpose, which are expressly excluded. the owner agrees that Lake Shore’s liability with respect to this product shall be set forth in this warranty, and incidental or consequential damages are expressly excluded.

CERTIFICATION

Lake Shore certifies that this product has been inspected and tested in accordance with its published specifications and that this product met its published specifications at the time of shipment. The accuracy and calibration of this product at the time of shipment are traceable to the United States National Institute of Standards and Technology (NIST); formerly known as the National Bureau of Standards (NBS), or to a recognized natural standard.

TRADEMARK ACKNOWLEDGMENT

Many manufacturers and sellers claim designations as trademarks to distinguish their products. Where those designations appear in this manual and Lake Shore was aware of a trademark claim, they appear with initial capital letters and a proceeding ™ or

symbol.

CalCurve™, Carbon-Glass™, Cernox™, Duo-Twist™, Gamma Probe™, Quad-Lead™,

and Quad-Twist™ are trademarks of Lake Shore Cryotronics, Inc.

Kapton Stycast Teflon QuickBasic

is a trademark of 3M.

is a trademark of Emerson & Cuming.

is a trademark of DuPont De Nemours.

is a trademark of Microsoft Corporation.

Copyright © 1995 – 1999 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.

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

TABLE OF CONTENTS

Chapter/Paragraph Title Page

List of Illustrations ......................................................................................................................................iv

List of Tables..............................................................................................................................................iv

Foreword .................................................................................................................................................... v

Purpose and Scope ................................................................................................................................ v

Hardware Covered.................................................................................................................................. v

Warnings, Cautions, and Notes .............................................................................................................. v

General Installation Precautions ............................................................................................................. v

Electrostatic Discharge ........................................................................................................................... v

Handling Electrostatic Discharge Sensitive Components....................................................................vi

Safe Handling of Liquid Cryogens .......................................................................................................vi

Magnet Quenches ...............................................................................................................................vi

Dangerous Voltages ...............................................................................................................................vi

Before You Operate the Equipment.......................................................................................................vii

Safety Summary ....................................................................................................................................vii

Safety Symbols .....................................................................................................................................viii

1 INTRODUCTION ....................................................................................................................................1-1

1.0 General ...................................................................................................................................1-1

1.1 Features.................................................................................................................................. 1-1

1.2 Specifications..........................................................................................................................1-2

1.3 Operating Characteristics ....................................................................................................... 1-4

1.3.1 True, Four-Quadrant Bidirectional Power Flow ...................................................................1-4

1.3.2 Low Noise, High Stability Current Regulated Output...........................................................1-5

1.3.3 Highly Efficient, Air-Cooled, Compact Unit ..........................................................................1-5

2 INITIAL SETUP AND CONNECTIONS ..................................................................................................2-1

2.1 Inspecting and Unpacking ......................................................................................................2-1

2.2 MPS Mounting ........................................................................................................................ 2-1

2.3 Environmental Requirements .................................................................................................2-1

2.4 Connecting the MPS to Power................................................................................................2-1

2.4.1 Power and Ground Requirements .......................................................................................2-2

2.4.2 MPS Input Power Ratings....................................................................................................2-2

2.4.3 Input Power Connections ....................................................................................................2-2

2.5 Power Up ................................................................................................................................2-3

2.5.1 Magnet Cable Connections .................................................................................................2-3

2.5.2 Shielding, Grounding, and Noise ......................................................................................... 2-4

2.5.3 MPS Remote Inhibit and Fault Indicator Connections ......................................................... 2-4

2.5.4 AC On Indicator ...................................................................................................................2-4

2.5.5 OVP Connection..................................................................................................................2-4

2.5.6 MPS Analog Current and Voltage Monitoring Connections.................................................2-5

2.5.7 External Current Programming............................................................................................2-5

2.5.8 Remote Sense Connections................................................................................................ 2-5

2.6 Multiple Auto-Parallel Setup.................................................................................................... 2-6

2.6.1 Multiple MPS Remote Inhibit Mode .....................................................................................2-8

2.7 Post-Installation Instructions ................................................................................................... 2-9

2.8 System Shutdown and Repackaging for Storage or Shipment...............................................2-9

2.9 Returning Equipment to Lake Shore....................................................................................... 2-9

3 OPERATION...........................................................................................................................................3-1

3.0 General ...................................................................................................................................3-1

3.1 The MPS Front Panel .............................................................................................................3-1

3.2 Power UP ................................................................................................................................ 3-2

Table of Contents i

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

TABLE OF CONTENTS (Continued)

Chapter/Paragraph Title Page

3.3 Normal Display for Manual Mode ........................................................................................... 3-2

3.4 Normal Display for Manual PSH Control ................................................................................ 3-3

3.5 Normal Display for Automatic PSH Control............................................................................ 3-3

3.6 Function Menus...................................................................................................................... 3-5

3.6.1 Function Menu 1 ................................................................................................................. 3-5

3.6.1.1 Automatic Mode / Manual Mode ...................................................................................... 3-5

3.6.1.2 Interface Setup Screen .................................................................................................... 3-5

3.6.1.3 Step Limit/Zero Screen .................................................................................................... 3-6

3.6.1.4 Instrument Setup Screen .................................................................................................3-6

3.6.2 Function Menu 2 ................................................................................................................. 3-7

3.6.2.1 Outputs Only Screen........................................................................................................ 3-8

3.6.2.2 LHe Level......................................................................................................................... 3-8

3.6.2.3 Field ................................................................................................................................. 3-8

3.6.2.4 PSH Setup ....................................................................................................................... 3-8

3.6.3 Function Menu 3 ................................................................................................................. 3-8

3.6.3.1 Delays Setup Screen ....................................................................................................... 3-8

3.6.3.2 Delays Setup Screen with Dithering ................................................................................ 3-9

3.7 Manual Persistence Control Example .................................................................................... 3-9

3.8 Automatic Persistence Control Example................................................................................ 3-9

3.9 Dithering in Automatic Mode ................................................................................................ 3-11

4 REMOTE OPERATION.......................................................................................................................... 4-1

4.0 General................................................................................................................................... 4-1

4.1 IEEE-488 Interface ................................................................................................................. 4-1

4.1.1 IEEE-488 Interface Settings................................................................................................ 4-1

4.1.2 IEEE-488 Command Structure ........................................................................................... 4-2

4.1.2.1 Bus Control Commands................................................................................................... 4-2

4.1.2.2 Common Commands....................................................................................................... 4-2

4.1.2.3 Interface and Device Specific Commands....................................................................... 4-2

4.1.3 Status Registers.................................................................................................................. 4-2

4.1.3.1 Status Byte and Service Request Enable Registers........................................................ 4-3

4.1.3.2 Standard Event and Standard Event Status Registers .................................................... 4-3

4.1.4 Example IEEE Setup and Program..................................................................................... 4-4

4.1.4.1 GPIB Board Installation.................................................................................................... 4-4

4.1.4.2 Run the Example QuickBasic Program ........................................................................... 4-4

4.1.5 Notes On Using the IEEE Interface .................................................................................... 4-5

4.2 Serial I/O Interface ................................................................................................................. 4-7

4.2.1 Serial Interface Hardware Configuration ............................................................................. 4-8

4.2.2 Serial Interface Settings ...................................................................................................... 4-8

4.2.3 Sample BASIC Serial Interface Program ............................................................................ 4-8

4.2.4 Notes on Using the Serial Interface .................................................................................... 4-9

4.3 Summary of IEEE-488/Serial Interface Commands............................................................. 4-10

4.3.1 Operational Commands Description ................................................................................. 4-11

4.3.2 Interface Commands Description ..................................................................................... 4-13

4.3.3 Ramping Commands Description ..................................................................................... 4-14

4.3.4 Current Zero Commands Description ............................................................................... 4-15

4.3.5 Current Step Limit Commands Description ...................................................................... 4-16

4.3.6 Computed Field Commands Description .......................................................................... 4-17

4.3.7 Common Commands Description ..................................................................................... 4-18

ii Table of Contents

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

TABLE OF CONTENTS (Continued)

Chapter/Paragraph Title Page

5 ERROR MESSAGES AND TROUBLESHOOTING ...............................................................................5-1

5.0 General ...................................................................................................................................5-1

5.1 Software Error Messages .......................................................................................................5-1

5.2 Factory Default Settings..........................................................................................................5-4

5.3 Calibration...............................................................................................................................5-5

5.4 Performance Test ...................................................................................................................5-6

5.5 Rear Panel Connector Details ................................................................................................5-8

5.6 IEEE-488 Interface Connector ................................................................................................5-9

5.7 Serial Interface Cable and Adapters ....................................................................................... 5-9

6 OPTIONS AND ACCESSORIES ............................................................................................................6-1

6.0 General ...................................................................................................................................6-1

6.1 Model 6224 IEEE-488/Serial Interface.................................................................................... 6-1

6.2 Model 6226/6476 Liquid Helium Level and Gaussmeter Input Card ...................................... 6-1

6.2.1 Hall Sensor Mounting Considerations - Models HGCT-3020 and HGCA-3020...................... 6-2

6.2.2 The Model MSA-410 and MST-410 Hall Sensors................................................................... 6-3

6.2.3 Connections ............................................................................................................................ 6-3

6.2.4 Installation...............................................................................................................................6-3

6.2.5 LHe Level................................................................................................................................ 6-4

6.2.5.1 LHe Level Operation ............................................................................................................... 6-4

6.2.5.2 Field Probe Setting and Calibration ........................................................................................ 6-5

6.2.6 Level Sensor Calibration.........................................................................................................6-5

6.2.7 Model 6226/6476 IEEE-488 Remote Operation Commands.................................................. 6-6

6.3 Model 6228 and 6228-8MUX Persistent Switch Heater Output..............................................6-9

6.3.1 Installation...............................................................................................................................6-9

6.3.2 Model 6228 Operation ............................................................................................................6-9

6.3.3 Model 6228-8MUX Operation ...............................................................................................6-10

6.3.4 PSH Card Voltage Constraints .............................................................................................6-10

6.3.5 Model 6228 Remote Operation Commands .........................................................................6-11

6.4 Model 6228-2 Persistent Switch Heater Output....................................................................6-12

6.4.1 Model 6228-2 Remote Operation Commands...................................................................... 6-13

6.5 Accessories ..........................................................................................................................6-14

APPENDIX A – UNITS FOR MAGNETIC PROPERTIES .......................................................................... A-1

APPENDIX B – MAINFRAME REMOTE OPERATION ............................................................................. B-1

B1.0 General .................................................................................................................................. B-1

B2.0 Control Bus Serial Interface Specifications............................................................................ B-1

B3.0 Control Bus Serial Interface Connector ................................................................................. B-1

B4.0 Control Bus Serial Interface Configuration ............................................................................ B-2

B5.0 Selecting the Control Bus Serial Interface Address ............................................................... B-2

B6.0 Control Bus Serial Interface Operation .................................................................................. B-3

B7.0 Control Bus Serial Interface Sample Program ....................................................................... B-4

Table of Contents iii

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

LIST OF ILLUSTRATIONS

Figure No. Title Page

1-1 Four-Quadrant Power ...................................................................................................................... 1-4

1-2 Comparison of Old and New MPS Designs ..................................................................................... 1-5

2-1 RI, FLT, ON, and OVP Connections ................................................................................................ 2-4

2-2 Analog Monitoring, Programming, & Remote Sense Connections .................................................. 2-5

2-3 Remote Sensing Connections.......................................................................................................... 2-6

2-4 Typical Multiple MPS Connections for Two MPS Units.................................................................... 2-8

3-1 MPS Front Panel.............................................................................................................................. 3-1

3-2 Typical Automatic Mode Cycle....................................................................................................... 3-10

4-1 Typical National Instruments GPIB Configuration from IBCONF.EXE............................................. 4-6

4-2 Serial Interface Adapters.................................................................................................................. 4-7

5-1 Rear Panel Connectors.................................................................................................................... 5-8

5-2 Serial Interface Connector ............................................................................................................... 5-8

5-3 IEEE-488 Connector ........................................................................................................................ 5-9

5-4 Model 2001 RJ-11 Cable Assembly Wiring ..................................................................................... 5-9

5-5 Model 2002 RJ-11 to DB-9 Adapter Wiring...................................................................................... 5-9

5-6 Model 2003 RJ-11 to DB-25 Adapter Wiring....................................................................................5-9

6-1 NbTi Filament Resistance Chart ...................................................................................................... 6-6

LIST OF TABLES

Table No. Title Page

1-1 Model 620/622/623 Input Current .................................................................................................... 1-3

1-2 Model 647 Input Current .................................................................................................................. 1-3

1-3 Model 620/622/623 DC Output Specifications ................................................................................. 1-3

1-4 Model 647 DC Output Specifications ............................................................................................... 1-3

2-1 Load Wire Lengths and Current Capacity........................................................................................ 2-3

2-2 RI, FLT, ON, and OVP Connections ................................................................................................ 2-4

2-3 Analog Monitoring, Programming, and Remote Sense Connections............................................... 2-5

2-4 Connections for a Two-MPS Autoparallel Configuration.................................................................. 2-7

4-1 Sample Basic IEEE-488 Interface Program.....................................................................................4-5

4-2 Serial Interface Specifications.......................................................................................................... 4-8

4-3 Sample Basic Serial Interface Program ........................................................................................... 4-9

5-1A Rear Panel Connector Definitions.................................................................................................... 5-8

5-1B Rear Panel CAL AND ID Switch Definitions..................................................................................... 5-8

5-2 Serial Interface Connector Definition ............................................................................................... 5-8

5-3 IEEE-488 Interface Connector Definition ......................................................................................... 5-9

6-1 Model 6226/6476 Connections ........................................................................................................ 6-3

6-2 NbTi Filament Resistance Values .................................................................................................... 6-6

A-1 Units for Magnetic Properties........................................................................................................... A-1

B-1 MPS Mainframe Control Bus Remote Command Summary............................................................ B-5

B-2 Additional MPS Mainframe Control Bus Remote Commands ......................................................... B-6

iv Table of Contents

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

FOREWORD

PURPOSE AND SCOPE

This manual contains user instructions for the Model 620/622/623/647 Magnet Power Supply (MPS). Lake Shore Cryotronics, Inc. designed, manufactures, and assembles the MPS in the United States of America.

We welcome your comments concerning this manual. Although every effort has been made to keep it free of errors, some may occur. To report a specific problem, please describe it briefly and include the manual title, revision number, date, the paragraph/figure/table number, and the page number. Send comments to Lake Shore Cryotronics, Inc. Attn: Technical Publications, 575 McCorkle Blvd., Westerville, Ohio 43082-8888.

HARDWARE COVERED

The MPS is available in the following configurations:

Model 620: ±50 A, ±5 V, 250 VA Model 623: ±155 A, ±30 V, 1 kVA Model 622: ±125 A, ±30 V, 1 kVA Model 647: ±72 A, ±32 V, 2 kVA

Page A of this manual (following the title page) details the options installed in your unit. See Chapter 6 for detailed definitions of hardware configurations.

WARNINGS, CAUTIONS, AND NOTES

Warnings, cautions, and notes appear throughout this manual and precede the step to which they pertain. Multiple warnings, cautions, or notes are bulleted.

WARNING: An operation or maintenance procedure which, if not strictly observed, may result in injury, death, or long-term health hazards to personnel.

CAUTION: An operation or maintenance procedure which, if not strictly observed, may result in equipment damage, destruction, or loss of effectiveness.

NOTE: Emphasizes an operation or maintenance procedure.

GENERAL INSTALLATION PRECAUTIONS

These recommended general safety precautions are unrelated to any specific procedure and do not appear elsewhere in this manual. Personnel should understand and apply these precautions during installation.

Installation personnel shall observe all safety regulations at all times. Keep away from live circuits. Turn off system power before making or breaking electrical connections. Regard any exposed connector, terminal board, or circuit board as a possible shock hazard. Discharge charged components only when such grounding cannot damage equipment. If a test connection to energized equipment is required, make the test equipment ground connection before probing the voltage or signal.

Do not install or service equipment alone. Do not under any circumstances reach into or enter any enclosure to service or adjust equipment without the presence or assistance of another person able to render aid.

ELECTROSTATIC DISCHARGE

Electrostatic Discharge (ESD) may damage electronic parts, assemblies, and equipment. ESD is a transfer of electrostatic charge between bodies at different electrostatic potentials caused by direct contact or induced by an electrostatic field. The low-energy source that most commonly destroys Electrostatic Discharge Sensitive (ESDS) devices is the human body, which generates and retains static electricity. Simply walking across a carpet in low humidity may generate up to 35,000 volts of static electricity.

Current technology trends toward greater complexity, increased packaging density, and thinner dielectrics between active elements, which results in electronic devices with even more ESD sensitivity. Some electronic parts are more ESDS than others. ESD levels of only a few hundred volts may damage electronic components such as semiconductors, thick and thin film resistors, and piezoelectric crystals during testing, handling, repair, or assembly. Discharge voltages below 4000 volts cannot be seen, felt, or heard.

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Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

Identification of Electrostatic Discharge Sensitive Components

Below are various industry symbols used to label components as ESDS:

HANDLING ELECTROSTATIC DISCHARGE SENSITIVE COMPONENTS

Observe all precautions necessary to prevent damage to ESDS components before attempting installation. Bring the device and everything that contacts it to ground potential by providing a conductive surface and discharge paths. As a minimum, observe these precautions:

1. De-energize or disconnect all power and signal sources and loads used with unit.

2. Place unit on a grounded conductive work surface.

3. Ground technician through a conductive wrist strap (or other device) using 1 MΩ series resistor to protect

operator.

4. Ground any tools, such as soldering equipment, that will contact unit. Contact with operator's hands provides a sufficient ground for tools that are otherwise electrically isolated.

5. Place ESDS devices and assemblies removed from a unit on a conductive work surface or in a conductive container. An operator inserting or removing a device or assembly from a container must maintain contact with a conductive portion of the container. Use only plastic bags approved for storage of ESD material.

6. Do not handle ESDS devices unnecessarily or remove them from their packages until actually used or tested.

SAFE HANDLING OF LIQUID CRYOGENS

Two essential safety aspects of handling LHe are adequate ventilation and eye and skin protection. Although helium gas is non-toxic, it is dangerous because it replaces air in a normal breathing atmosphere. Liquid helium is an even greater threat because a small amount of liquid evaporates to create a large amount of gas. Store and operate cryogenic dewars in open, well-ventilated areas.

WARNING

• Liquid helium is a potential asphyxiant and can cause rapid suffocation without warning. Store and use in an adequately ventilated area. DO NOT vent the container in confined spaces. DO NOT enter confined spaces where gas may be present unless area is well-ventilated. If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention.

• Liquid helium can cause severe frostbite to exposed body parts. DO NOT touch frosted pipes or valves. For frostbite, consult a physician immediately. If a physician is unavailable, warm the affected parts with water that is near body temperature.

MAGNET QUENCHES

For protection during a magnet quench, fit the dewar with pressure relief valves of sufficient size and pressure rating to allow the helium gas to escape and to prevent excessive pressure in the dewar. Operating a magnet in a dewar without proper pressure relief is dangerous and possibly life-threatening. The magnet may transfer tremendous energy to the cryogen during a quench. Consult both the magnet and dewar manufacturers to check pressure relief valve sufficiency.

DANGEROUS VOLTAGES

High voltages are present inside the MPS. Never attempt to service the MPS. Refer all service to qualified personnel. There are no user-serviceable parts inside the MPS.

The MPS current output terminals may be dangerous. Although MPS output voltage is limited to ±40 VDC, a catastrophic failure inside the MPS could pass lethal voltages to the output terminals. Do not touch the terminals during MPS operation.

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Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

BEFORE YOU OPERATE THE EQUIPMENT

Train personnel in proper emergency measures such as electrical power shut off, fire department notification, fire extinguishing, and personnel and records evacuation. Here is a list of suggested personnel safety considerations:

• Ground Fault Interrupter (GFI) AC circuits

• Fire Extinguisher

• Magnetic Field Warnings

• Emergency Lighting

Locate in the immediate vicinity fire extinguisher(s) that extinguish all three classes of fires: A, B, and C. Class A is ordinary combustibles like wood, paper, rubber, many plastics, and other common materials that burn easily. Class B is flammable liquids like gasoline, oil, and grease. Class C is energized electrical equipment including wiring fuse boxes, circuit breakers, machinery, and appliances. Do not use chemical extinguishers even though they are less expensive and cover all classes of fires. They may damage electronic equipment. Use a Carbon Dioxide or Halon fire extinguisher.

During the planning stage, consult local experts, building authorities, and insurance underwriters on locating and installing sprinkler heads, fire and smoke sensing devices, and other fire extinguishing equipment.

Even where not required by code, install some type of automatic, battery-operated emergency lighting in case of power failure or fire.

SAFETY SUMMARY

Observe the following general safety precautions during all phases of operation, service, and repair of this instrument. Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety standards of design, manufacture, and intended use of the instrument. Lake Shore Cryotronics, Inc. assumes no liability for the customer's failure to comply with these requirements.

Ground the Instrument

To minimize shock hazard, connect the instrument chassis and cabinet to an electrical ground. The instrument is equipped with a three-conductor AC power cable. Plug this cable into either an approved three-contact electrical outlet or 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.

Do Not Operate in an Explosive Atmosphere

Do not operate the instrument in the presence of flammable gases or fumes. Operating 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.

Dangerous Procedure Warnings

A WARNING heading precedes potentially dangerous procedures throughout this manual. Instructions in the warnings must be followed.

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vii

SAFETY SYMBOLS

Direct current (power line).

Alternating current (power line).

Alternating or direct current (power line).

Three-phase alternating current (power line).

Earth (ground) terminal.

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

Equipment protected throughout by double insulation or reinforced insulation (equivalent to Class II of IEC 536 - see annex H).

Caution: High voltages; danger of electric shock. Background color: Yellow; Symbol and outline: Black.

Protective conductor terminal.

Frame or chassis terminal.

On (supply)

Off (supply)

Caution or Warning - See instrument documentation. Background color: Yellow; Symbol and outline: Black.

viii

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Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

CHAPTER 1

INTRODUCTION

1.0 GENERAL

This chapter covers Features (Paragraph 1.1), Specifications (Paragraph 1.2), and Operating Characteristics (Paragraph 1.3).

1.1 FEATURES

• True, Four-Quadrant Bidirectional Power Flow: Operate current or voltage as a source or a sink in

either positive or negative polarities. Sink power returns to the AC line instead of dissipating through an energy absorber.

• Low Noise, High Stability Current Regulation: Analog output control uses a precision shunt for current

stabilization to better than 50 PPM of full-scale current over an 8-hour period.

• ±50 A, ±5 V (Model 620), ±125 A, ±30 V (Model 622), ±155 A, ±30 V (Model 623),

or ±72 A, ±32 V (Model 647), Constant Current Output:

1. Programming resolution for Models 620/622/647 is 1.0 mA and 1 mV.

2. Programming resolution for the Model 623 is 1.2 mA and 1 mV.

• No current reversal switch required: Output current reversal is smooth and continuous with excellent

near zero current performance.

• Remote and local sensing of output voltage: Compensates for voltage drops in the output leads.

• Quiet switched-mode design: Results in a highly efficient, lightweight unit capable of air cooling.

• Front Panel Graphic Display: Allows continuous display of output while setting parameters from the

menu-driven keypad. Operating parameters that can be set and monitored are:

1. Output current and compliance setting.

2. Output current and voltage measurement.

3. Output current step limiting.

4. Output current zeroing.

5. Output ramp programming.

6. Status reporting.

7. Persistent switch heater control (with optional Model 6228 Card).

8. Liquid Helium level and Field monitoring (with optional Model 6226/6476 Card).

• Four methods of setting and monitoring all operating parameters:

1. From front panel.

2. From remote interfaces.

3. Through analog inputs and outputs.

4. Through optional Lake Shore MPS Driver Software.

• Automatic Mode: Easily controls Superconducting Magnets using the Model 6228 Persistent Switch

Heater Option Card.

• IEEE-488 Interface Option

• Model 6226/6476 Liquid Helium Level/Gaussmeter Input Option Card

• Model 6228 Persistent Switch Heater Option Card

• Protection: Overvoltage/Quench protection circuits which limit or turn off the MPS output, or turn off the

input in the event of an abnormal condition; current step limit exceeded; internal overtemperature; AC line loss detection; remote inhibit; output power exceeded. Front panel annunciators, an audio alarm, and a contact closure indicate faults.

Introduction

1-1

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

1.2 SPECIFICATIONS

Below are performance specifications for current with a 1 Henry load and voltage with a resistive load.

DC Output: True, Four-Quadrant, Bidirectional Power Flow output. Autoranging current and voltage operate as a source or a sink in either polarity in current or voltage mode. Program current and compliance voltage via the front panel, remote interfaces, or analog input. See Table 1-1 for DC Output Specifications.

Model 620 Model 622 Model 623: Model 647

Current: 0 to ±50 A Current: 0 to ±125 A Current: 0 to ±155 A Current: 0 to ±72 A Voltage: 0 to ±5 V Voltage: 0 to ±30 V Voltage: 0 to ±30 V Voltage: 0 to ±32 V Max Power: 250 VA contin. Max Power: 1 kVA contin. Max Power: 1 kVA contin. Max Power: 2 kVA contin.

Remote Sensing: Corrects for load lead drop of up to 0.5 V per lead. Operation with more drop per load lead is possible with a degradation of the load effect specification.

Output Terminals: The two rear panel output bus bars are isolated from the chassis (earth) ground.

Multiple Unit Operation: Connect up to four units in an auto-parallel configuration for increased output

current capability.

Protection: Front panel annunciators, an audio indicator, and a contact closure indicate faults.

Remote Inhibit (RI): An active RI forces output settings to 0 A and 1 V until the RI is no longer active. To

continue normal operation, enter new output settings.

Output Inhibit (OI): Press the front panel OI key to force output settings to 0 A and 1 V. To continue normal operation, enter new output settings.

Output Current Step Limit: The output current settings are forced to 0 A and 1 V if a preset current step limit is exceeded. A key entry is required to continue operation.

Utility Low Line or Loss: Maintains operation until load is discharged or utility is restored.

Utility High Line: Turns off input and maintains operation until load is discharged.

Overvoltage: Crowbars output when output terminal voltage, induced by the load exceeds ±40 VDC.

Overtemperature: Crowbars output and turns off input when internal heat sink temperature exceeds 95 °C.

AC Input: Models 620/622/623 are factory set for operation from 100, 120, 200/208, 220, or 240 VAC

(–10%, +5%) 50 to 60 Hz single phase. Model 647 is factory set for operation from 200/208, 220, or 240 VAC (–10%, +5%) 50 to 60 Hz single phase.

Input Protection: A front panel 20 A two-pole circuit breaker protects the AC input. The MPS turns off the breaker in the event of a fault.

Remote Interfaces: Serial Interface is standard; IEEE-488 is optional. All front panel functions can be controlled over the interfaces. In addition, interfaces output displayed quantities.

Input Current:

Table 1-1. Model 620/622/623 Input Current

Nominal Line

Voltage (VAC)

Line Voltage Range (VAC)

Maximum Input Current (A rms)

100 90 to 105 18

120 108 to 126 15

200/208 180 to 218 9

220 198 to 231 8

Table 1-2. Model 647 Input Current

Nominal Line

Voltage (VAC)

Line Voltage Range (VAC)

200 180 to 210 16

208 188 to 218 15

220 198 to 231 14

240 216 to 250 13

Maximum Input Current (A rms)

240 216 to 252 7

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Introduction

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

Front Panel: Contains a menu driven keyboard and graphic display for entry and display of results. Operating parameters to set and monitor from the front panel (and remote interface) include:

• Output current and compliance voltage setting.

• Output current and voltage measurement.

• Status reporting.

• Output ramp programming.

• Persistent switch heater control (with optional Model 6228 Card).

• Liquid helium level monitoring (with optional Model 6226/6476 Card).

• Field Monitoring (with optional Model 6226 Card).

• Output Current Zeroing.

• Output Current Step Limiting.

Magnet inductance and compliance (di/dt = V

/L) limit the output ramp programming charging current.

SET

Program output for a constant 0.01 to 99.99 amperes per second as long as compliance is not exceeded. Energize or de-energize the magnet at a pre-set ramp rate. Pause the ramp at any time during the ramp. During a pause, the MPS maintains output values until the ramp continues.

Operating Ambient Temperature: 15 to 35 °C (59 to 95 °F)

Dimensions: 483 mm wide x 178 mm high x 508 mm deep (19 x 7 x 20 inches)

Weight: 43.5 kilograms (96 pounds). Rack mounting is standard.

Table 1-3. Model 620/622/623 DC Output Specifications

SPECIFICATION CURRENT VOLTAGE

Digital Programming Resolution for 620/622

Digital Programming Resolution for 623

Digital Programming Accuracy

Digital Programming Repeatability

Electronic Resolution for 620/622

Electronic Resolution for 623

Electronic Accuracy

Display Resolution

Stability (Drift) at 25 ±1 °C: Percent of full scale

output change over 8-hours under constant line and load after a 30 minute warm-up.

Ripple and Noise: 10 Hz to 10 MHz at 1000 VA

Temperature Coefficient: Change in output per °C

after 30 minute warm-up.

Source Effect: Line regulation for any line change within

the rated line voltage.

Load Effect: Load regulation for a load change equal to

maximum voltage in Constant Current Mode or maximum current in Constant Voltage Mode.

Analog Resistance Programming Accuracy:

0 to 10 KΩ produces negative full scale to positive full scale current or voltage output. 5 KΩ is 0 current.

Analog Voltage Programming Accuracy:

Voltage input is ±0.01 V/A, ±0.01 V/V.

Monitoring Output Accuracy: Voltage output is

±0.01 V/A, ±0.01 V/V.

1 mA 1 mV

1.2 mA 1 mV

0.1% I

0.01% I

MAX

1 mA 1 mV

1.2 mA 1 mV

0.1% I

MAX

1 mA 1 mV

±0.005% I

MAX

20 µA rms 10 mV rms

±0.01% I

±0.005% I

±0.01% I

10% I

1% + 100 mA

MAX

±30 mV

±3 mV

±15 mV

±3 mV

3 V

2% + 100 mV

Introduction

1-3

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

Table 1-4. Model 647 DC Output Specifications

SPECIFICATION CURRENT VOLTAGE

Digital Programming Resolution:

Standard/High

Digital Programming Accuracy

Digital Programming Repeatability

Electronic Resolution:

Standard/High

Electronic Accuracy

Display Resolution: Standard/High

Stability (Drift) at 25 ±1 °C: Percent of full scale

output change over 8-hours under constant line and load after a 30 minute warm-up.

Ripple and Noise: 10 Hz to 10 MHz at 1000 VA

Temperature Coefficient: Change in output per °C

after 30 minute warm-up.

Source Effect: Line regulation for any line change within

the rated line voltage.

Load Effect: Load regulation for a load change equal to

maximum voltage in Constant Current Mode or maximum current in Constant Voltage Mode.

Analog Resistance Programming Accuracy:

0 to 10 KΩ produces negative full scale to positive full scale current or voltage output. 5 KΩ is 0 current.

Analog Voltage Programming Accuracy:

Voltage input is ±0.01 V/A, ±0.01 V/V.

Monitoring Output Accuracy: Voltage output is

±0.01 V/A, ±0.01 V/V.

10 mA / 1 mA 10 mV / 1 mV

0.1% I

0.01% I

MAX

1% V

0.1% V

MAX

4 mA / 1 mA 1 mV / 1 mV

0.1% I

10 mA / 1 mA 10 mV / 1 mV

±0.005% I

MAX

0.1% V

±0.01% V

MAX

40 µA rms 20 mV rms

0.1% I

0.005% I

0.1% I

10% I

MAX

1% + 100 mA

0.1% V

0.05% V

0.1% V

10% V

MAX

2% + 100 mV

1.3 OPERATING CHARACTERISTICS

Many Lake Shore MPS operating characteristics ideally suit it for charge and discharge cycling of superconducting magnet loads. These characteristics significantly differentiate a Lake Shore MPS from a conventional MPS. Consider them when choosing the best MPS for a particular application.

1.3.1 True, Four-Quadrant Bi-directional Power Flow

Lake Shore MPS: Sets either positive or negative

current and voltage values. This true, four-

+V-VOutput

Voltage

quadrant operation significantly simplifies test procedures and system design by eliminating external switching or operator intervention to reverse current polarity. The smooth, continuous transition through zero current allows users to analyze samples at very small current increments

-I

Energy flows

from magnet to AC line

Energy flows from AC line to magnet

(as small as 1 mA) about zero. Power flow is bidirectional. Sink power (energy stored in the magnet) returns to the AC line instead of

Output

Current

Energy flows from AC

line to magnet

Energy flows from magnet to AC line

dissipating in an energy absorber. The MPS either transfers power from the AC line to the magnet, or from the magnet back to the AC line. The MPS also tolerates AC line faults; in the event of utility power failure, it draws power from the charged load to maintain operation until utility restoration.

Output Voltage

Figure 1-1. Four-Quadrant Power

1-4

Introduction

Ouput Current

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

Conventional MPS: Consists of a unipolar power supply with an energy absorber to dissipate magnet energy during discharge. The energy absorber prevents reverse voltage generated during the discharge from damaging the unipolar supply output. Other conventional supplies dissipate magnet energy in the power supply output transistor pass-bank. This two-quadrant performance requires the output stage to absorb considerable power during the discharge. In addition, uniform charge and discharge rates are not always ensured.

Current reversal requires external current reversal switches or manual lead reversal. These units provide pseudo-four-quadrant operation which introduces discontinuities at the current reversal point produced by switching the leads. Current reversal switches may incorporate direction detection diodes which reduce available magnet charging voltage and dissipate additional power. Current reversal switches must also interlock to prevent lead reversal when current is present. Current reversal switches complicate high power cabling requirements, increase chances of introducing output current instabilities, and require time to reverse leads. Manual lead reversal introduces discontinuity at the current reversal point. A discontinuous transition through zero current may require a small external supply for near zero current analysis. Utility power failure in a conventional supply generally results in a magnet quench.

1.3.2 Low Noise, High Stability Current Regulated Output

Lake Shore MPS: Maintains a high-stability,

low-noise, current-regulated output. Digital

Computer

setting and monitoring electronics, and computer interfacing integrate into power management and precision analog control circuitry. This integration maintains high output stability and repeatability. Extensive output filtering and noise cancellation circuitry keep MPS output noise very low. The MPS front panel graphic display allows continuous display of output current and voltage while setting parameters from the menu-driven keypad. In addition to the front panel and remote interface programming, the MPS includes analog inputs and outputs for setting and monitoring operating parameters. The MPS requires only 7 inches of rack space.

Analog

Current

Programmer

Analog Programmed

Power Supply

Current Reversal

Energy Absorber

Analog Voltage

Programmer

DVM Current Monitor

DVM Voltage Monitor

Now

Replaced

by:

Computer

Lake Shore MPS

True, Four-Quadrant

Bi-Directional

Power Flow

Conventional MPS: Some use a compliance limited output with current monitoring to charge the magnet. Others require output current to

Magnet Load

drive against the output current limit to prevent output current drift. Most use multi-turn

Figure 1-2. Comparison of Old and New MPS Designs

potentiometers and digital (or analog) panel meters for front panel current and compliance voltage setting. The elegance and repeatability of keypad entry is not available. There is no digital setting or monitoring integration in the output control circuitry. Most achieve computer interfacing by adding computer controlled voltage sources to analog program the output current and voltage. Additional inputs must be added to digitize the output current and voltage. Setting and monitoring resolution is one to two orders of magnitude poorer than the standard MPS provides. External setting and monitoring complicates cabling. Degradation of the output current stability due to the addition of external cabling is undefined. Output noise specifications are rarely given and sometimes vary with the type of magnet load driven. These multiple unit configurations require up to 36 inches of rack space.

Introduction

1-5

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

1.3.3 Highly Efficient, Air Cooled, Compact Unit

Lake Shore MPS: Quiet switched-mode design. The output uses a proprietary pulse width modulated

technique that incorporates power hybrid circuitry. Extremely low conduction loss components minimize internal power dissipation. The MPS is not a direct off-line switching supply. The output is fully floating and isolated from ground. Active power factor correction draws a sinusoidal AC current waveform from the utility, minimizes AC line harmonics, and lowers AC current required. Power factor is the ratio of real power (measured in watts) to the apparent power (measured in volt-amperes). The combination of quiet switchedmode design and active power factor correction results in a compact, highly efficient, air-cooled unit.

Conventional MPS: Most use linear regulated outputs. The output transistor pass-bank internally dissipates power not delivered to the magnet. Some units use an off-line switching supply to provide the bulk power and add output regulation. There is no input power factor correction. Low overall efficiency means higher input power and current. Without power factor correction, a non-sinusoidal current with high peaks places tremendous stress on fuses, circuit breakers, outlets, and wiring. Dedicated lines may be required because of potential interaction with other equipment. These factors result in low overall efficiency, large size, and considerable weight.

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Introduction

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

CHAPTER 2

INITIAL SETUP AND CONNECTIONS

2.1 INSPECTING AND UNPACKING

The MPS ships in a special cardboard box with integrated forklift skid openings. Do not stack anything on top of the MPS box. Upon receipt, set the box on a level surface with the pallet side down. Inspect the shipping container for external damage. Make all claims for damage (apparent or concealed) or partial loss of shipment in writing to Lake Shore within five (5) days from receipt of goods. If damage or loss is apparent, notify the shipping agent immediately.

Cut off the plastic strapping and lift off the lid. Locate the MPS packing list and use it to check for receipt of all components, cables, accessories, and manuals. Inspect each item for damage. Use two people to lift the MPS. Retain internal packing material and box for reshipment. Fill out and send the warranty card.

If there is freight damage to any instruments, promptly file proper claims with the carrier and insurance company and notify Lake Shore Cryotronics. Notify Lake Shore of any missing parts immediately. Lake Shore cannot be responsible for any missing parts unless notified within 60 days of shipment. See the standard Lake Shore Cryotronics, Inc. Warranty on the A Page (immediately behind the title page).

2.2 MPS MOUNTING

After unpacking the MPS and verifying receipt of all packing list items, mount the instrument in a suitable location. The MPS ships with feet installed and is ready for use as a bench top instrument. The MPS also ships with 19-inch rack mounting hardware installed for mounting in a standard 19-inch rack enclosure.

CAUTION: To install the MPS in a 19-inch rack mount enclosure at any position other than the bottom, install a slide rail or runner to support the MPS.

2.3 ENVIRONMENTAL REQUIREMENTS

Operate the MPS in an area with an ambient temperature range of 20 to 30 °C (68 to 86 °F). The unit may be operated within the range of 15 to 35 °C (59 to 95 °F) with reduced accuracy.

The MPS is intended for laboratory use: no specific humidity or altitude specifications have been determined. However, relative humidity of 20 to 80 percent (no condensation) and altitudes from sea level to 2.4 km (8,000 feet) are generally acceptable.

WARNING: To prevent electrical fire or shock hazards, do not expose this instrument to moisture.

Provide adequate ventilation. The fan-cooled MPS draws air in from the sides and exhausts it from the rear; install it with sufficient space at the rear and sides for air flow. Filter dust and other particulate matter at the site to a reasonable level. For salt air, corrosive gases, or other air pollutants, consult an air-conditioning expert for special filtering arrangements.

2.4 CONNECTING THE MPS TO POWER

Read and thoroughly understand sections 2.4.1 through 2.4.3 and the safety recommendations in the Foreword before connecting the MPS to power. Failure to do so may expose operating personnel to lethal voltages or damage the magnet and/or MPS.

Setup & Connections

2-1

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

2.4.1 Power and Ground Requirements

The AC power source for the MPS should be frequency and voltage regulated and isolated from sources that may generate Electromagnetic Interference (EMI). The MPS is designed for single-phase 3-wire alternating current (AC) power; do not use two-wire (without ground) AC power. Lake Shore recommends Ground Fault Interrupter (GFI) and Transient Surge Protection circuitry at the AC source.

In areas where AC voltage varies, consider using a constant voltage transformer. For power outages, consider using an Uninterruptible Power Supply (UPS).

CAUTION: Do not attempt to apply electrical power until the MPS is checked for proper line voltage settings.

Factory-preset MPS line voltage requirements allow proper operation at the shipping destination. The line voltage setting is indicated on the rear panel. Before applying power to the main input power cable, check for correct input power settings for the power source voltage.

Ground the instrument panels and cabinets. The safety ground provides a true ground path for electrical circuitry and, in the event of internal electrical faults such as shorts, carries the entire fault current to ground to protect users from electrical shock. The MPS has a three-conductor power input connector which grounds the MPS chassis when plugged into a 3-wire receptacle.

EMI is both a natural and man-made electromagnetic phenomena which, either directly or indirectly, may degrade electronic system performance. Natural EMI includes thunderstorms, solar disturbances, cosmic rays, etc. Man-made EMI includes fixed and mobile transmitters, high voltage power lines, power tools and appliances, florescent lights, and other equipment containing motors, heaters, etc. Protect the AC source from EMI. Consider transient surge protectors for lightning protection.

2.4.2 MPS Input Power Ratings

Operate the Model 620/622/623 from a nominal 100, 120, 200/208, 220, or 240 VAC (–10%, +5%) single-phase AC power source, 50 to 60 Hz. Table 1-1 lists input voltage range and maximum current required for each nominal input.

Operate the Model 647 from a nominal 200/208, 220, or 240 VAC (–10%, +5%) single-phase AC power source, 50 to 60 Hz. Table 1-2 lists input voltage range and maximum current required for each nominal input.

A rear panel label indicates MPS factory-preset nominal line voltage. Normally, the line voltage setting is not changed in the field. Consult the factory to reconfigure the input power.

2.4.3 Input Power Connections

The MPS uses a three-prong detachable input power connector (supplied) to mate with the UL/CSA/IEC approved rear panel AC input connector. The user supplies a three conductor power cord rated for at least 85 °C operation. For 100 or 120 VAC operation, each conductor must be AWG #14 or larger. For 200/208, 220 or 240 VAC operation, each conductor must be AWG #16 or larger. Larger wires may be required to prevent excessive voltage drop in the AC power lines if the unit is located an extended distance from the main AC distribution terminals.

WARNING: For proper circuit breaker protection, mate the wire connected to the “L” terminal of the connector to the “L” (hot) side of the line and mate the wire connected to the “N” terminal to the “N” (neutral) side of the line. Mate the wire connected to the “GND” terminal to earth ground. Do not operate this instrument without an adequate ground connection.

CAUTION: Before applying power to the MPS, verify that the AC source matches the line voltage listed on the rear panel.

NOTE: Make connections to the AC power line in accordance with applicable electrical codes. The

international color code for identifying utility supply conductors is green/yellow for earth (“GND”), blue for neutral (N), and brown for line (L). The US and Canadian codes are green for earth (“GND”), white for neutral (N), and black for line (L).

2-2

Setup & Connections

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

Use this procedure to connect input power to the MPS:

1. Loosen the two connector cover screws and open the cover.

2. Slip the strain relief over the power cable with the flanged end at the end to be terminated.

3. Attach the wires to the connector in accordance with prevailing color codes: green or green/yellow to the “GND” terminal, white or blue to the “N” terminal, and black or brown to the “L” terminal.

4. Position the strain relief, close the cover, and then tighten the cover screws.

5. Connect the other end of the power cord to an appropriate AC power source.

6. Plug the power cord into the detachable power connector plug on the MPS rear panel.

2.5 POWER UP

Read and follow instructions in Paragraphs 2.1 thru 2.4.3 and safety recommendations in the Foreword before applying power to the MPS. Do not connect the MPS to the magnet at this point. Short the output terminals together with a #4 gauge or larger cable. This protects the magnet against incorrect configurations.

Turn on the MPS. It requires approximately 2 seconds for initialization. Initially, all front panel annunciators come on and the alarm sounds for a short time. Within 1 second, the Fault and Persistent Switch Heater On annunciators and the alarm turn off. If the MPS detects a high or low AC line fault, it blinks the front panel Fault annunciator and turns off the input circuit breaker. If this occurs, verify that the AC source matches the line voltage listed on the MPS rear panel. The MPS front panel AC On LED lights any time the MPS is connected to the AC line and the MPS power switch is ON.

Initially, the entire display clears and the alarm sounds for a short time. The MPS initializes itself and displays the model identification. The Normal Display screen appears with a blinking asterisk indicating each update when the unit is in normal operation.

2.5.1 Magnet Cable Connections

WARNING: Turn off the AC power before changing any rear panel connections and verify that all connections are securely tightened before reapplying power.

CAUTION: Initially, setup the MPS without connecting it to the magnet. This lessens the chance for inadvertent damage to the load while the user learns MPS operation.

Make MPS load connections at the +OUT and –OUT terminals on the rear panel. These plated copper bus bars accommodate 1/4 inch mounting hardware. Use load wires heavy enough to limit the voltage drop to less than 0.5 volts per lead. This ensures proper regulation and prevents overheating while carrying the output current. Use remote sensing to compensate for any voltage drop in the load leads and

Table 2-1. Load Wire Lengths and Current Capacity

Area Capacity Resistivity Total Lead Length (feet)

AWG (mm2) Amperes

0 2 4 6 8

53.5

33.6

21.2

13.3

8.4

245 180 135 100

ΩΩΩΩ/1000 feet

0.09827

0.1563

0.2485

0.3951

0.6282

75 A 100 A 125 A

135

85 53 33 21

101

64 40 25 —

81 51 32 — —

obtain a more accurate voltage reading. Stranded AWG #4 wire is capable of carrying in excess of 125 amperes. Keep conductor temperature under 85 °C for a 35 °C ambient. Table 2-1 lists the ampere capacity and total +OUT and –OUT lead lengths for load connections.

If connecting multiple loads to the unit, use separate pairs of wires to connect each load to the output terminals. Cut each pair of connecting wires as short as possible.

Setup & Connections

2-3

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

2.5.2 Shielding, Grounding, and Noise

For noise reduction, tightly twist and shield the leads from the MPS to the magnet. Connect the shield to the MPS chassis as shown in Figure 2-3.

WARNING: DO NOT place magnet leads in contact with other MPS/system connections or metal parts.

In some instances, the user's measurement leads may pick up noise from the magnet leads. Although this common mode noise may affect the user's measurement it rarely affects the current in the magnet. If the user's measurement is earth grounded, some improvement is almost always possible by tying the –OUT terminal of the MPS to earth ground – either at the MPS chassis or, if the user's system has one, the common system earth ground point.

WARNING: If the –OUT terminal is tied to earth ground, make certain the +OUT cable from the MPS contacts no other earth ground point - it forces the MPS output current into this other ground point. If the other ground point is a small wire, it may melt or catch fire.

2.5.3 MPS Remote Inhibit and Fault Indicator Connections

The MPS has a Fault Indicator (FLT) output and a discrete Remote Inhibit (RI) input which are both interface independent and provide fault indication and remote output shutdown in the event of catastrophic failure. The Fault Indicator relay contact is open when the MPS detects no faults. When the MPS detects an internal fault, a remote inhibit, or an output inhibit, it lights the front panel Fault LED and closes the relay contact. The contact closure alerts other system components of the fault. In an auto-parallel system (up to four MPS units

TERMINAL LABEL DEFINITION

Table 2-1. RI, FLT, ON, and OVP Connections

1 2

3 4

5 6

RI+ RI–

FLT+ FLT–

ON+

ON–

7 NONE

OVP

Remote Inhibit – Active low, TTL-compatible input to remotely force the output settings to 0 A and 1 V. Also activate RI by shorting +RI to -RI with a relay contact closure or a switch.

Fault Indicator – A relay contact that closes to indicate a fault. Contact rating: 0.25 A resistive at 100 VDC, 3 W, 25 VA.

ON Indicator – A relay contact that closes to indicate when the front panel circuit breaker is in the ON position. Contact rating: 0.25 A resistive at 100 VDC, 3 W, 25 VA.

Factory Use Only. Do not connect to this terminal.

In auto-parallel MPS configurations, OVP ensures that the activation of one MPS Over Voltage Protection circuit activates all the other parallel MPS units' protection circuits.

connected in parallel) these signals connect in parallel between each of the MPS units (See Paragraph 2.6 for details

MODE

INT

CAL AND ID V l

RI FLT ON

+- + - + - OVPImVm 12345678910

on connections between two auto-parallel units). Make connections to a rear panel detachable terminal block defined in Table 2-2 and Figure 2-1.

See Table 5-1B for

DIP Switch Definitions

EXT

Figure 2-1. RI, FLT, ON and OVP Connections

2.5.4 AC On Indicator

The MPS provides a discrete ON indicator. Terminals 5 and 6 on the terminal block connector, shown in Figure 2-1 above, connect to relay contacts that close when the front panel circuit breaker is in the ON position. There is also a front panel LED that lights when the MPS is ON and connected to AC power.

2.5.5 OVP Connection

In auto-parallel MPS configurations, this connection synchronizes the firing of the Over Voltage Protection (OVP) circuits of each MPS (see Paragraph 4.7.4). See Paragraph 2.6 and Figure 2-4 for auto-parallel connections.

2-4

Setup & Connections

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

2.5.6 MPS Analog Current And Voltage Monitoring Connections

The MPS provides amplified and buffered current and voltage monitor output signals

Table 2-2. Analog Monitoring, Programming,

and Remote Sense Connections

at the terminal block on the back panel. Connect these signals to external meters

TERMINAL LABEL DEFINITION

to indicate output current and voltage. Obtain the Current Monitor signal through

9 Im connections to terminals 9 (Im) and 11 (m) with positive output currents producing a positive monitor voltage of 10 mV/A from Im to m.

Obtain the Voltage Monitor signal through connections to terminals 10 (Vm) and 11 (m) with positive terminal voltages

10 Vm

11 m

12 Vp

13 +Vs producing a positive monitor voltage of 10 mV/V from Vm to m.

14 –Is

2.5.7 External Current Programming

Remotely program MPS output current by an external voltage or potentiometer.

15 Ip

Enable external analog programming via the rear panel I MODE switch. When the I MODE switch is in the INT I position, external current mode is disabled. When the I MODE switch is in the EXT I position,

16 +Is

the external programming voltage is summed with the internal programming voltage. Set the internal programming to

–S

zero for external programming only. Apply an external voltage from lp to m of 0 to

1.25 volts or use a 10 KΩ potentiometer to control the output current over the entire range. Make connections to rear panel

OVP Im Vm m Vp +Vs -ls lp +ls -S +S 7 8 9 101112131415161718

detachable terminal block defined in Tables 2-3 and 2-4 and Figures 2-1 and 2-

2. The MPS produces 100 A of output current for 1 V at the current programming input.

Output Current Monitor – Voltage output from Im to GND(M) is ±10 mV/A.

Output voltage monitor – Voltage output from Vm to GND(M) is ±10 mV/V.

Monitor and program ground. GND(m).

Not Used.

Negative voltage supply for programming external current with a potentiometer

Current programming input voltage. Voltage input from Ip to GND(m) produces ±100 A/V. Voltage may come from a voltage source or from the center tap of a potentiometer connected from Is to +Is.

Positive voltage supply for programming external current with a potentiometer.

Remote voltage sense correction. Correction for load lead drops of up to

0.5 V per lead.

NOTE: MPS protection circuits reduce the effect of open external programming leads.

10K 10K

An open external programming lead forces external programming voltage to approximately 0 volts.

Figure 2-2. Analog Monitoring , Programming,

and Remote Sense Connections

2.5.8 Remote Sense Connections

The factory configures the MPS to sense, but not control remote voltage. Call Lake Shore to reconfigure the MPS to control voltage at the load. When using remote sense, the MPS measures voltage at the magnet instead of at the MPS output terminals allowing a more accurate reading of magnet voltage by eliminating voltage drops in the leads connecting the MPS to the magnet. If using remote sense, the MPS bases the voltage at the voltage monitor output on the remote sense voltage instead of the MPS terminal voltage.

Use AWG #24, shielded, twisted pair wiring for sense leads to minimize pickup of external noise. Any noise on the sense leads may appear at the unit output. Ground sense shield to the MPS back panel.

Make Remote Sense Connections to the rear panel detachable terminal block defined in Table 2-3 and Figure 2-2.

Setup & Connections

2-5

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

NOTE: The MPS includes a protection circuit which reduces the effect of open sense leads during remote voltage sensing operation. If the +S lead opens, the

MPS Rear View

output voltage changes because it is sensed between +OUT and the negative side of the load. If the –S lead opens, the output voltage changes because it is sensed between the positive side of the load and –OUT. If both leads open, the output voltage is sensed internally.

The procedure below configures the MPS for remote voltage sensing as shown in Figure 2-3.

1. Turn off the unit.

2. If present, disconnect any wires between the +OUT and –OUT terminals and the +S and –S connections on the MPS rear panel.

Maintain polarity! Connect -S to -OUT and +S to +OUT.

3. Connect the sense leads from the MPS +S and –S connections to the load. Maintain polarity when making these connections.

CAUTION: Maintain polarity between +S and +OUT and –S and –OUT. The +S and –S inputs control the output voltage. Improper polarity may apply

Figure 2-3. Remote

Sensing Connections

damaging voltages to the load.

4. Connect the ground shield to the mounting screw. Make sure that the shield does not come into electrical contact with either magnet lead.

2.6 MULTIPLE AUTO-PARALLEL SETUP

Connect up to four MPS units in an auto-parallel configuration for increased output current capability. The maximum total current allowed is the sum of the maximum currents of the individual units. For example four 623 MPS units provide 4 × 155 = 620 amps total current. The maximum total power is the sum of the maximum power ratings of the individual units.

Assign each unit a unique address: 1 for MPS 1, 2 for MPS 2, etc. The MPS at address 1 polls the control bus to determine if an auto-parallel configuration is present and how many MPS units are involved. When multiple MPS units are present, MPS 1 sends the output current and voltage limits, ramp status, output current step limit, and other operating parameters to the other MPS units so all units operate identically.

For two MPS configuration, each MPS is programmed for half of the total output current. This is true for the ramp destination current and ramp rate. Each MPS contributes half the output current required. MPS 1 software polls MPS 2 to determine the total output current. The output voltage, current settings during a ramp, and instrument status from MPS 1 are reported (since the values are the same for both units.)

NOTE: When multiple MPS units are present, install the Model 6228 persistent switch heater output option in MPS 1 for proper operation.

An analog signal is also provided for remote activation of the output over voltage protection (OVP) circuit. The signals connect in parallel so that the output OVP circuits of each MPS activate in unison.

CAUTION: Consult Lake Shore prior to operating multiple MPS units in auto-parallel mode.

Use the procedure below and see Figure 2-4 to connect multiple MPS units in auto-parallel configuration:

1. Turn off all units and completely disconnect power at the source before changing MPS configuration.

2. Determine which MPS to assign as MPS 1 and configure it as follows:

a. Locate the CAL AND ID DIP switches on the rear panel. Turn ON (up position) switches 1 and 4. Turn

OFF (down position) switches 2, 3, and 5 through 8. (Switch 4 ON designates multiple MPS operation. Switches 3, 2, and 1 respectively OFF, OFF, and ON assign the MPS address as 1). Note that the CAL AND ID switch numbers are upside down (as viewed from the rear panel). Switch 1 is on the right and switch 8 is on the left. Take care to use the correct switch numbers.

b. Move the I MODE switch to the INTernal (up) position.

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Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

c. Locate Communications Microprocessor (CMP) in the MPS rear panel. The CMP is the module with

two RJ-11 telephone jacks. Loosen two screws securing CMP to MPS rear panel and slide CMP out. Just inside the CMP front panel, there is a set of DIP switches. Verify that switches 5, 6, and 7 are ON (closed) and switches 1 through 4 and 8 are OFF (OPEN). (Switches 1–4 define the control bus as Serial (RS-232C). Switches 5–8 define the control bus as RS-485 multidrop. Switch 8 terminates the bus for long communications loop runs. Close switch 8 to terminate the control bus only if the MPS units are a significant distance from each other.) Replace the CMP.

3. Configure the second MPS as MPS 2:

a. Locate the CAL AND ID switches on the rear panel. Turn ON (up position) switches 2 and 4. Turn

OFF (down position) switches 1, 3, and 5 through 8. (Switch 4 ON designates Multiple MPS operation. Switches 3, 2 and 1 as OFF, ON, OFF, respectively, assign the MPS address as 2.)

b. Move the I MODE switch to the INTernal (up) position.

c. On the CMP, verify that switches 5, 6 and 7 are ON (closed) and switches 1 through 4 and 8 are OFF

(OPEN). Replace the CMP.

4. Connect the control bus. Use Lake Shore Model 2001 Modular Cables (provided) to interconnect the two

MPS CMP units.

5. Connect the MPS 1 over voltage protection (OVP) pin 8 to MPS 2 pin 8.

6. Connect the RI and FLT signals. Connect the +RI (terminal 1) to the +FLT (terminal 3) on MPS 2. Connect

the –RI (terminal 2) to the –FLT (terminal 4) on MPS 2. Do the same on MPS 1. Connect the +RI/+FLT connection of MPS 2 to the +RI/+FLT connection of MPS 1. Connect the –RI/–FLT connection of MPS 2 to the –RI/–FLT connection of MPS 1. If an external contact closure will remotely inhibit operation, connect it across the +RI and –RI terminals of MPS 1. The +FLT and –FLT contact closure of MPS 1 indicates a fault.

7. Connect the +OUT terminal of MPS 1 to the +OUT terminal of MPS 2. Connect the –OUT terminal of MPS

1 to the –OUT terminal of MPS 2. Make these leads as short as possible to minimize output potential differences between the two MPS units and large enough to handle the maximum MPS current. Connect the output terminals to the load using leads large enough to handle the total output current of both MPS units.

NOTE: For proper operation, turn on MPS 1 and then MPS 2 within 15 seconds of MPS 1.

8. Verify all connections as summarized in Table 2-4.

9. To add a third MPS or a fourth MPS in parallel, make the RI/FLT,

OVP, CMP and output connections in parallel with the connections of MPS 1 and MPS 2. For MPS 3, set the CAL AND ID switches on the rear panel as follows : switches 5 through 8 are OFF, switches 4, 3, 2 and 1 are ON, OFF, ON, ON respectively. For MPS 4, set the rear panel CAL AND ID switches as follows : switches 5 through 8 are OFF, switches 4, 3, 2 and 1 are ON, ON, OFF, OFF respectively. Configure the CMP switches for MPS 3 and MPS 4 as those in MPS 1 and

Table 2-3. Two-MPS Autoparallel

Configuration Connections

MPS 1 MPS 2

Control Bus

8 (OVP) 1 (+RI), 3 (+FLT) 2 (–RI), 4 (–FLT) +OUT

–OUT

MPS 2.

NOTE: For proper operation, turn on MPS 1 and then the remaining MPS units within 15 seconds.

Control Bus 8 (OVP) 1 (+RI), 3 (+FLT) 2 (–RI), 4 (–FLT) +OUT –OUT

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Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

RI FLT ON

MODE

INT

+ - + - + - OVPIm Vm mVp +Vs -ls lp +ls -S +S

LINE

-10% +5% 50-60 Hz

FIXED INTERNALLY

208

100

220

120

NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO TRAINED SERVICE PERSONNEL.

240

CAL AND ID V l

WARNING:

1 2 3 4 5 6 7 8 9 101112131415161718

EXT

10K 10K

-OUT +OUT

MPS #1 Rear View

RI FLT ON

MODE

INT

+ - + - + - OVPIm Vm mVp +Vs -ls lp +ls -S +S

LINE

-10% +5% 50-60 Hz FIXED INTERNALLY

208

100

220

120

NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO TRAINED SERVICE PERSONNEL.

240

CAL AND ID V l

WARNING:

1 2 3 4 5 6 7 8 9 101112131415161718

EXT

10K 10K

-OUT +OUT

MPS #2 Rear View

LOAD

Figure 2-4. Typical Multiple MPS Connections for Two MPS Units

2.6.1 Multiple MPS Remote Inhibit Mode

In multiple MPS configuration, if the MPS RI indicators activate from an external contact closure, the MPS units enter Multiple MPS Remote Inhibit Mode. They activate output overvoltage protection circuits and turn off output circuits. If a charged load is present, OVP circuits discharge it. The front panel Fault annunciators turn ON, and the internal audio indicators beep about once per second. If a MPS detects a fault, it initiates Multiple MPS Remote Inhibit Mode by closing the FLT contacts. No delay is allowed (CAL AND ID switch 7 OFF, down position) and multiple MPS operation (CAL AND ID switch 4 ON, up position) must be selected. After the load discharges, turn OFF all units to reset.

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Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

2.7 POST-INSTALLATION INSTRUCTIONS

The MPS is electrically and mechanically inspected and operationally tested prior to shipment. It should be damage-free and in perfect working order upon receipt. To confirm this, visually inspect the instrument for damage and test it electrically to detect any concealed damage upon receipt. Study the entire MPS User’s Manual before attempting to run the unit. See Chapter 3 for any questions on front panel control operation.

2.8 SYSTEM SHUTDOWN AND REPACKAGING FOR STORAGE OR SHIPMENT

Follow these general guidelines for system shutdown for storage or reshipment. If returning something, call Lake Shore first to obtain a Return Goods Authorization (RGA) Number.

1. Turn off the power to all instruments. Unplug the power cord.

2. Remove or disconnect any interface cables and the magnet current output cables.

3. Repack the MPS upside down in the original box. If returning the MPS to Lake Shore and original box is

unavailable, please call Lake Shore for a replacement box.

4. Label the box for storage or shipment.

2.9 RETURNING EQUIPMENT TO LAKE SHORE

To return the MPS for repair or replacement, obtain a Return Goods Authorization (RGA) number from a factory representative before returning the instrument to our service department. When returning an instrument for service, Lake Shore requires the following information before attempting any repair:

1. Instrument model and serial number.

2. User's name, company, address, and phone number.

3. Malfunction symptoms.

4. Description of system.

5. Returned Goods Authorization number.

Consult the factory for shipping instructions. Ship the MPS upside down in the original shipping box.

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Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

CHAPTER 3

OPERATION

3.0 GENERAL

This chapter covers seven areas: MPS Front Panel (Paragraph 3.1), Power Up (Paragraph 3.2), Setting Current on an MPS with Manual PSH Control (Paragraph 3.3), Setting Current with Automatic PSH Control (Paragraph 3.4), Instrument Setup Screens (Paragraph 3.5), Function Menus (Paragraph 3.6), and an Automatic Persistence Control Example (Paragraph 3.7).

Setup the MPS software with the MPS output terminals shorted together as in section 3.2. This ensures that while the user learns MPS operation, an inadvertent keystroke causes no damage to the magnet.

3.1 THE MPS FRONT PANEL

Figure 3.1 below shows the MPS Front Panel. The up or down Display Cursor Control keys move the line indicator to the line containing a value to be changed. Use either the Data Entry Keypad to enter the desired value or the up or down Numeric Entry keys to increment or decrement the value. The Enter key accepts the update, while the Esc key discards the change and returns to the prior value. Move the cursor to a particular digit with the right and left Display Cursor Control keys and change it with the Numeric Entry keys.

Magnet Power Supply

Functions

Function

A. Display Screen

G. Data Entry Up and Down Keys. Increment and

B. Display Function Keys

C. Display Menu Selection Keys

D. Data Entry Keypad

E. Escape Key. Restores an old value and

returns from a Function Screen to Normal Screen. Also Aborts a ramp or automatic process.

F. Interface Keys

H. Output Inhibit Key

I. Display Cursor Control Keys

J. Enter Key. Accepts a change.

K. Power Indicator

L. Fault Indicator

M. Persistent Switch Heater Indicator

N. Power Switch

Figure 3-1 MPS Front Panel

Cursor

Normal

Display

Data Entry

7 8 9

4 5 6

1 2 3

Switch Heater

Power

Persistent

Mode

Local

Esc

Remote

Output

Inhibit

Enter

+/-

Fault

OFF

decrement numeric values, Pause/Restart ramps, or execute some functions.

Operation

3-1

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