AMI 420 Manual

1 Cover Page
American Magnetics, Inc.
PO Box 2509, 112 Flint Road, Oak Ridge, TN 37831-2509, Tel: [phone], Fax: [phone]
Rev. 7, July 2002
MODEL 420 POWER SUPPLY
PROGRAMMER
INSTALLATION, OPERATION, AND
MAINTENANCE INSTRUCTIONS
EXCELLENCE IN MAGNETICS AND CRYOGENICS

Model 420 Power Supply Programmer
1 Declaration of Conformity
Z
Declaration of Conformity
Application of Council Directive: 72/73/EEC
Standard to which Conformity is Declared: EN 61010-1: 1993 w/A1, A2
Manufacturer’s Name: American Magnetics, Inc.
Manufacturer’s Address: 112 Flint Road, P.O. Box 2509
Oak Ridge, TN 37831-2509
U.S.A.
Type of Equipment: Power Supply Programmer
Model Number: Model 420
I, the undersigned, hereby declare that the equipment specified above
conforms to the above Directive and Standard.
Place: Oak Ridge, Tennessee, U.S.A. Signature:
Date: October 15, 1999
Full Name: Charles H. Hargis
Function: Quality Assurance Manager

Model 420 Power Supply Programmer
Model 420 Power Supply Programmer Configuration
AMI Order Number:_____________________ Shipping Date:_________________________
Model 420 Serial #:______________________ Firmware Revision:_____________________
Input Power Requirements:___________________________________________________________
Configuration Notes:
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
AMI Warranty
All products manufactured by AMI are warranted to be free of defects in materials and
workmanship and to perform as specified for a period of one year from date of shipment. In
the event of failure occurring during normal use, AMI, at its option, will repair or replace all
products or components that fail under warranty, and such repair or replacement shall
constitute a fulfillment of all AMI liabilities with respect to its products. Since, however,
AMI does not have control over the installation conditions or the use to which its products
are put, no warranty can be made of fitness for a particular purpose, and AMI cannot be
liable for special or consequential damages. All warranty repairs are F.O.B. Oak Ridge,
Tennessee, USA.
Copyright © 2002 by American Magnetics, Inc., Oak Ridge, Tennessee, USA
Rev. 7
1 Configuration

Rev. 7 v
Table of Contents
Foreword.................................................................................. xi
Purpose and Scope....................................................................xi
Contents of This Manual .........................................................xi
Applicable Hardware ..............................................................xii
General Precautions................................................................xii
Safety Summary..................................................................... xiv
1 Introduction.............................................................................. 1
1.1 Model 420 Features................................................................... 1
1.1.1 Digitally-Controlled....................................................... 1
1.1.2 Superior Resolution and Stability ................................ 1
1.1.3 Intuitive Human-Interface Design............................... 1
1.1.4 Flexible Design .............................................................. 2
1.1.5 Standard Remote Interfaces......................................... 2
1.1.6 Programmable Safety Features.................................... 2
1.2 Front Panel Layout................................................................... 3
1.3 Rear Panel Layout..................................................................... 5
1.4 Model 420 Specifications @ 25 °C .......................................... 7
1.5 Operating Characteristics......................................................... 9
1.5.1 Single-Quadrant Operation .......................................... 9
1.5.2 Dual-Quadrant Operation........................................... 10
1.5.3 Simulated Four-Quadrant Operation......................... 10
1.5.4 True Four-Quadrant Operation.................................. 11
2 Installation.............................................................................. 13
2.1 Inspecting and Unpacking...................................................... 13
2.2 Model 420 Mounting ............................................................... 13
2.3 Power Requirements............................................................... 14
2.4 Collecting Necessary Information.......................................... 15
2.5 System Interconnects.............................................................. 15
2.5.1 Unipolar Supply without Energy Absorber ............... 16
2.5.2 Unipolar Supply with AMI Model 601 Energy
Absorber....................................................................... 18
2.5.3 Unipolar Supply with AMI Model 600/620 Energy
Absorber....................................................................... 21
2.5.4 Unipolar Supply with AMI Model 610/630 Energy
Absorber and Current Reversing Switch ................... 24
2.5.5 High-Current Four-Quadrant Supply........................ 26
2.5.6 Low-Current, High-Resolution Four-Quadrant
Supply .......................................................................... 28
2.5.7 Third-Party Power Supplies ....................................... 31
1 Table of
Contents

vi Rev. 7
Table of Contents
2.6 Special Configurations.............................................................31
2.6.1 Superconducting Magnets without a Persistent
Switch ...........................................................................31
2.6.2 Short-Circuit or Resistive Load...................................32
2.7 Power-Up and Test Procedure.................................................33
3 Operation.................................................................................37
3.1 Default Display Modes.............................................................37
3.1.1 Entering Numerical Values.........................................38
3.1.2 Menu Option Selection.................................................39
3.1.3 Exiting Menus ..............................................................39
3.2 Setup Menu Descriptions ........................................................39
3.2.1 Supply Setup Submenu................................................40
3.2.2 Load Setup Submenu...................................................44
3.2.3 Misc Setup Submenu ...................................................48
3.2.4 Comm Setup Submenu ................................................49
3.2.5 Example Setup .............................................................50
3.3 Ramping Functions..................................................................52
3.3.1 Ramping States and Controls......................................52
3.3.2 Ramping in Manual Mode ...........................................54
3.3.3 Ramping in Programmed Mode...................................55
3.3.4 Ramp to Zero Mode ......................................................56
3.3.5 Dial Adjustment of Current/Field in PAUSED Mode 56
3.3.6 Ramping Functions Example ......................................57
3.4 Persistent Switch Heater Control...........................................59
3.4.1 Procedure for Entering Persistent Mode ....................60
3.4.2 Procedure for Exiting Persistent Mode.......................60
3.4.3 Optional Switching of External Power Supply...........61
3.5 Quench Detection.....................................................................61
3.5.1 Disabling Automatic Quench Detection......................62
3.6 Summary of Operational Limits and Default Settings..........63
4 Remote Interface Reference ..................................................65
4.1 SCPI Command Summary ......................................................65
4.2 Programming Overview...........................................................69
4.2.1 SCPI Language Introduction.......................................69
4.2.2 SCPI Status System.....................................................70
4.2.3 Standard Event Register .............................................73
4.2.4 Command Handshaking ..............................................74
4.3 RS-232/422 Configuration .......................................................76
4.3.1 Serial Port Connector...................................................76

Rev. 7 vii
Table of Contents
4.3.2 Termination Characters.............................................. 76
4.3.3 Flow Control Modes..................................................... 77
4.4 IEEE-488 Configuration......................................................... 77
4.4.1 Termination Characters.............................................. 77
4.4.2 Device Clear................................................................. 78
4.4.3 Trigger Command........................................................ 78
4.5 Command Reference ............................................................... 79
4.5.1 System-Related Commands........................................ 79
4.5.2 Status System Commands .......................................... 80
4.5.3 SETUP Configuration Commands and Queries ........82
4.5.4 Ramp Configuration Commands and Queries........... 85
4.5.5 Ramping State Commands and Queries.................... 87
4.5.6 Switch Heater Commands and Queries..................... 88
4.5.7 Quench State Control and Queries............................. 89
4.5.8 Trigger Functions........................................................ 90
4.6 Error Messages........................................................................ 92
4.6.1 Command Errors ......................................................... 92
4.6.2 Query Errors................................................................ 93
4.6.3 Execution Errors.......................................................... 94
4.6.4 Device Errors............................................................... 94
5 Service .................................................................................... 95
5.1 Model 420 Maintenance..........................................................95
5.2 Model 420 Troubleshooting Hints .......................................... 95
5.3 Additional Technical Support............................................... 103
5.4 Return Authorization............................................................ 104
Appendix............................................................................... 105
A.1 Magnet Station Connectors ............................................. 105
A.2 Auxiliary LHe Level/Temperature Connectors ............... 106
A.3 Current Shunt Terminals..................................................... 107
A.4 Program Out BNC Connector............................................... 108
A.5 Quench I/O Connector........................................................... 109
A.6 IEEE-488 Connector ........................................................111
A.7 RS-232/422 Connector........................................................... 112
Index...................................................................................... 115

viii Rev. 7
List of Figures
Figure 1-1 The four regions, or quadrants, of system operation. ..............9
Figure 1-2 Single-Quadrant Magnet System..............................................9
Figure 1-3 Dual-Quadrant Magnet System..............................................10
Figure 1-4 Simulated Four-Quadrant Magnet System............................10
Figure 1-5 True Four-Quadrant System...................................................11
Figure 2-1 System interconnect diagram for a unipolar supply
without an energy absorber.....................................................17
Figure 2-2 System interconnect diagram for a unipolar supply
with an AMI Model 601 Energy Absorber..............................19
Figure 2-3 System interconnect diagram for a unipolar supply
with an AMI Model 600/620 Energy Absorber.......................22
Figure 2-4 System interconnect diagram for a unipolar supply
with an AMI Model 610/630 energy absorber and a
current reversing switch..........................................................25
Figure 2-5 System interconnect diagram for the AMI Model 4Q-05100
power supply............................................................................27
Figure 2-6 System interconnect diagram for the Kepco BOP series
power supply.............................................................................29
Figure 2-7 Illustration of stabilizing resistor in parallel with the
magnet......................................................................................31
Figure 3-1 Default display modes..............................................................37
Figure 3-2 Setup menu, submenus, and parameter diagram..................40
Figure 3-3 Example power supply operating ranges................................42
Figure 3-4 Example limits setup...............................................................45
Figure 3-5 Example magnet specification sheet.......................................50
Figure 3-6 Example of ramping to two different programmed current
settings. ....................................................................................57
Figure 4-1 The Model 420 status system..................................................70
Figure 4-2 Illustration of asterisk annunciator indicating the
Model 420 is in remote mode...................................................80
Figure A-1 Example external circuitry for quench input/output...........110
1Listof
Figures

Rev. 7 ix
List of Tables
Table 1-1 Front Panel Description............................................................ 3
Table 1-2 Rear Panel Description............................................................. 5
Table 3-1 Description of ramping mode characters............................... 38
Table 3-2 Available Select Power Supply options. ................................. 41
Table 3-3 Predefined voltage-to-voltage mode input range ranges.......43
Table 3-4 Example Setup Configuration................................................ 51
Table 3-5 Ramping states and descriptions. .......................................... 53
Table 3-6 Summary of limits and defaults for the Model 420............... 63
Table 4-1 Bit definitions for the Status Byte register. .......................... 71
Table 4-2 Bit definitions for the Standard Event register..................... 74
Table 4-3 Return values and their meanings for the
SUPPly:TYPE? query. ............................................................ 82
Table 4-4 Return values and their meanings for the
SUPPly:MODE? query. ............................................................ 83
Table 4-5 Return values and their meanings for the STATE? query. ... 88
Table 4-6 Bit definitions for the Model 420 trigger functions...............90
Table A-1 Connectors J7A and J7B pin definitions.............................. 105
Table A-2 Connectors J8A and J8B pin definitions.............................. 106
Table A-3 Connector J4 pin definitions................................................. 109
Table A-4 IEEE-488 female connector J11 description........................111
Table A-5 PC-to-Model 420 connections for RS-232 operation............112
Table A-6 PC (DB-9)-to-Model 420 connections for RS-232 operation.112
Table A-7 EIA-530 Device-to-Model 420 connections for RS-422
operation................................................................................ 113
1Listof
Tables

xRev. 7
List of Tables

Rev. 7 xi
Foreword
Purpose and Scope
This manual contains the operation and maintenance instructions for the
American Magnetics, Inc. Model 420 Digital Power Supply Programmer.
The manual outlines the instructions for instrument use in various system
configurations. Since it is not possible to cover all equipment combinations
for all magnet systems, the most common configurations arediscussed and
the user is encouraged to contact an authorized AMI Technical Support
Representative for information regarding specific configurations not
explicitly covered in this manual.
Contents of This Manual
Introduction introduces the reader to the functions and characteristics of
the instrument. It provides the primary illustrations of the front and rear
panel layouts as well as documenting the performance specifications.
Operational theory is also provided in the form of circuit diagrams.
Installation describes how the instrument is unpacked and installed in
conjunction with ancillary equipment in typical superconducting magnet
systems. Block-level diagrams document the interconnects for various
system configurations.
Operation describes how the instrument is used to control a
superconducting magnet. All instrument displays and controls are
documented. The ramping functions, persistent switch heater controls,
and the quench detect features are also presented.
Remote Interface Reference documents all remote commands and
queries available through the RS-232 and IEEE-488 interfaces. A quick-
reference summary of commands is provided as well as a detailed
description of each.
Service provides guidelines to assist the user in troubleshooting possible
system and instrument malfunctions. Information for contacting AMI
Technical Support personnel is also provided.
The Appendix documents the rear panel connectors.

xii Rev. 7
Foreword
Applicable Hardware
Applicable Hardware
The Model 420 has been designed to operate with a wide variety of switch
mode and linear power supplies from a variety of manufacturers. However,
not all compatible power supplies have been tested. The Model 420
Programmer has been tested and qualified with the following power
supplies:
AMI Model 12100PS switching power supply (12V @ 100A)
AMI Model 12200PS switching power supply (12V @ 200A)
AMI Model 7.5-140PS switching power supply (7.5V @ 140A)
AMI Model 10100PS switching power supply (10V @ 100A)
AMI Model 10200PS switching power supply (10V @ 200A)
AMI Model 4Q-05100 4-Quadrant switching power supply (±5V @ ±100A)
Xantrex Model XFR 12-100 switching power supply (12V @ 100 A)
Xantrex Model XFR 12-220 switching power supply (12V @ 220 A)
Xantrex Model XHR 7.5-130 switching power supply (7.5V @ 130 A)
Hewlett-Packard 6260B linear power supply (10V @ 100 A)
Kepco BOP 20-5M 4-Quadrant linear power supply (±20V @ ±5A)
Kepco BOP 20-10M 4-Quadrant linear power supply (±20V @ ±10A)
Consult with an AMI Technical SupportRepresentative for other approved
power supplies.
General Precautions
Cryogen Safety
The two most common cryogenic liquids used in superconducting magnet
systems are nitrogen and helium. Both of these cryogens are extremely
cold at atmospheric pressure (−321°F and −452°F, respectively). The
following paragraphs outline safe handling precautions for these liquids.
Personnel handling cryogenic liquids should be thoroughly instructed and
trained as to the nature of the liquids. Training is essential to minimize
accidental spilling. Due to the low temperature of these materials, a
cryogen spilled on many objects or surfaces may damage the surface or
cause the object to shatter, often in an explosive manner.
Inert gases released into a confined or inadequately ventilated space can
displace sufficient oxygen to make the local atmosphere incapable of
sustaining life. Liquefied gases are potentially extreme suffocation
hazards since a small amount of liquid will vaporize and yield a very large
volume of oxygen-displacing gas. Always ensure the location where the
cryogen is used is well ventilated. Breathing air with insufficient oxygen
content may cause unconsciousness without warning. If a space is suspect,
purge the space completely with air and test before entry. If this is not
possible, wear a forced-air respirator and enter only with a co-worker
standing by wearing a forced-air respirator.

Rev. 7 xiii
Foreword
General Precautions
Cryogenic liquids, due to their extremely low temperatures, will also burn
the skin in a similar manner as would hot liquids. Never permit cryogenic
liquids to come into contact with the skin or allow liquid nitrogen to soak
clothing. Serious burns may result from careless handling. Never touch
uninsulated pipes or vessels containing cryogenic liquids. Flesh will stick
to extremely cold materials. Even nonmetallic materials are dangerous to
touch at low temperatures. The vapors expelled during the venting process
are sufficiently cold to burn flesh or freeze optic tissues. Insulated gloves
should be used to prevent frost-bite when operating valves on cryogenic
tanks. Be cautious with valves on cryogenic systems; the extremes of
temperature they undergo causes seals to fail frequently.
In the event a person is burned by a cryogen or material cooled to
cryogenic temperatures, the following first aid treatment should be given
pending the arrival and treatment of a physician or other medical care
worker:
1. If any cryogenic liquid contacts the skin or eyes, immediately flush
the affected area gently with tepid water (102°F −105°F, 38.9°C −
40.5°C) and then apply cold compresses.
2. Do not apply heat. Loosen any clothing that may restrict
circulation. Apply a sterile protective dressing to the affected area.
3. If the skin is blistered or there is any chance that the eyes have
been affected, get the patient immediately to a physician for
treatment.
Containers of cryogenic liquids are self pressurizing (as the liquid boils off,
vapor pressure increases). Hoses or lines used to transfer these liquids
should never be sealed at both ends (i.e. by closing valves at both ends).
When pouring cryogenic liquids from one container to another, the
receiving container should be cooled gradually to prevent damage by
thermal shock. The liquid should be poured slowly to avoid spattering due
to rapid boil off. The receiving vessel should be vented during the transfer.
Introduction of a substance at or near room temperature into a cryogenic
liquid should be done with great caution. There may be a violent gas boil-
off and a considerable amount of splashing as a result of this rapid boiling.
There is also a chance that the material may crack or catastrophically fail
due to forces caused by large differences in thermal contraction of different
regions of the material. Personnel engaged in this type of activity should
be instructed concerning this hazard and should always wear a full face
shield and protective clothing. If severe spraying or splashing could occur,
safety glasses or chemical goggles along with body length protective
aprons will provide additional protection.

xiv Rev. 7
Foreword
Safety Summary
The properties of many materials at extremely low temperatures may be
quite different from the properties that these same materials exhibit at
room temperatures. Exercise extreme care when handling materials cooled
to cryogenic temperatures until the properties of these materials under
these conditions are known.
Metals to be used for use in cryogenic equipment application must posses
sufficient physical properties at these low temperatures. Since ordinary
carbon steels, and to somewhat a lesser extent, alloy steels, lose much of
their ductility at low temperatures, they are considered unsatisfactory and
sometimes unsafe for these applications. The austenitic Ni-Cr alloys
exhibit good ductility at these low temperatures and the most widely used
is 18-8 stainless steel. Copper, Monel®, brass and aluminum are also
considered satisfactory materials for cryogenic service.
Magnet Quenches
When an energized superconducting magnet transitions from
superconducting state to normal state, the magnet converts magnetic
energy to thermal energy thereby rapidly converting the liquid helium to a
vapor. When this phase transformation occurs, pressures can build rapidly
in the cryostat due to the fact that one part of liquid helium will generate
782 parts of gaseous helium at STP. The cryostat must be designed to
allow the generated vapor to rapidly and safely vent to an area of lower
pressure. Cryostats are designed with pressure relief valves of sufficient
capacity so as to limit the pressure transients within the container in
order to prevent damage to the vessel. Operating a superconducting
magnet in a cryostat without properly sized relief mechanisms or disabled
relief mechanism is unsafe for the operator as well as for the equipment. If
there is any doubt as to the sufficiency of the pressure relief system,
contact the manufacturer of the magnet and cryostat for assistance.
Safety Summary
Superconducting magnet systems are complex systems with the potential
to seriously injure personnel or equipment if not operated according to
procedures. The use of cryogenic liquids in these systems is only one factor
to consider in safe and proper magnet system operation. Proper use of
safety mechanisms (pressure relief valves, rupture disks, etc.) included in
the cryostat and top plate assembly are necessary. Furthermore, an
understanding of the physics of the magnet system is needed to allow the
operator to properly control the large amounts of energy stored in the
magnetic field of the superconducting coil. The Model 420 Programmer has
been designed with safety interlocks to assist the operator in safe
operation, but these designed-in features cannot replace an operator’s
understanding of the system to ensure the system is operated in a safe and
deliberate manner.

Rev. 7 xv
Foreword
Safety Summary
Recommended Safety Equipment
First Aid kit
Fire extinguisher rated for class C fires
Leather gloves
Face shield
Signs to indicate that there are potentially damaging magnetic fields
in the area and that there are cryogens are in use in the area.
Safety Legend
Instruction manual symbol: the product is marked with this
symbol when it is necessary for you to refer to the instruction
manual in order to protect against damage to the product or
personal injury.
Hazardous voltage symbol.
Alternating Current (Refer to IEC 417, No. 5032).
Off (Supply) (Refer to IEC 417, No. 5008).
On (Supply) (Refer to IEC 417, No. 5007).
Warning
The Warning sign denotes a hazard. It calls attention to a procedure or
practice, which if not correctly adhered to, could result in personal injury.
Do not proceed beyond a Warning sign until the indicated conditions are
fully understood and met.
Caution
The Caution sign denotes a hazard. It calls attention to an operating
procedure or practice, which if not adhered to, could cause damage or
destruction of a part or all of the product. Do not proceed beyond a Caution
sign until the indicated conditions are fully understood and met.
2
,

xvi Rev. 7
Foreword
Safety Summary

Rev. 7 1
1 Introduction
1.1 Model 420 Features
The AMI Model 420 Digital Programmer is a sophisticated power supply
controller which allows an operator to manage a superconducting magnet
system with unprecedented accuracy and ease of use. The Model 420 is the
heart of a modern superconducting magnet system; when it is used in
conjunction with a four-quadrant power supply, it provides for a degree of
flexibility and accuracy previously unavailable in an economical
commercial product.
1.1.1 Digitally-Controlled
The Model 420 is controlled by a microcomputer-based controller which
controls all analog data conversion, display/keypad functions, communica-
tions I/O, generation of analog programming signals for the external power
supply, and control law computations. The Model 420 incorporates digital
signal processing (DSP) functions that provide for accurate control, low
drift, and flexibility of use.
1.1.2 Superior Resolution and Stability
The Model 420 Programmer utilizes high resolution converters to trans-
late signals between the analog and digital domains. Precision instrumen-
tation techniques and potentiometer-free designs are employed
throughout the instrument to ensure accurate signal translation for a wide
range of conditions. The magnet current is sampled at 20-bit resolution in
hardware and is software-programmable to 15-digits resolution. All pause
and hold functions are performed in the digital domain which provides for
excellent stability and drift (<0.01%) of the programmed magnetic field.
1.1.3 Intuitive Human-Interface Design
The Model 420 Programmer was designed so as to simplify the interface
where possible. All functions were analyzed and subsequently
programmed so that the most commonly used functions are addressed
with the least number of keystrokes. The menus are also presented in a
logical fashion so that the operation of the Model 420 is intuitive to the
user.
The provision of a velocity-sensitive rotary encoder on the front panel also
allows the operator to fine-adjust many of the operating parameters of the
magnet system.

2Rev. 7
Introduction
Features
1.1.4 Flexible Design
The Model 420 Programmer was engineered to be compatible with many
magnet power supplies. From simple single-quadrant supplies, to more
elaborate four-quadrant units, the Model 420 is user-configurable such
that the operational paradigm complies with the specific magnet power
supply system.
1.1.5 Standard Remote Interfaces
The Model 420 Programmer provides an RS-232 (or optionalRS-422) serial
port as well as an IEEE-488 parallel port as standard features. In contrast
to other magnet power supply system designs, an expensive additional
analog-to-digital conversion system is not required to collect data via a
host computer. All settings can be controlled via the remote interfaces and
the front panel can be remotely locked to prevent accidental operation. The
Model 420 also provides trigger functions for data collection and/or logging
during operation.
1.1.6 Programmable Safety Features
The Model 420 Programmer is designed to allow the operator to program
the instrument from the front panel or remotely with operational
parameters which must not be exceeded for the given conditions of the
system. Once set, should an operator inadvertently attempt to take the
magnet system to an excessive magnetic field strength or charge at an
excessive voltage, the programmer will not accept the parameter and alert
the operator that a value was rejected because it was outside the user-
defined limits.