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28

Rev. 7

Installation

High-Resolution Four Quadrant Supply

d. Connect the coaxial cable from the 

352*5$0287

 connector on 

the back of the Model 420 to the 

352*5$0,1

 connector (7) on the 

rear of the power supply.

e. Install an instrumentation cable between the magnet support 

stand top plate connector (8) and the magnet station connector J7A 
or J7B.

f.

Install an instrumentation cable between the LHe/Temp connectors 
J8A and/or J8B on the rear of the Model 420 and the Model 13x 
Liquid Helium Level Instrument and/or temperature instrument 
(9).

g. Remote communications via IEEE-488 and/or RS-232 (or optional 

RS-422) can be accomplished by connecting suitable cabling to J11 
and/or J12, respectively.

2.5.6 Low-Current, High-Resolution Four-Quadrant Supply

AMI offers a low-current (5 A or 10 A maximum) system option to achieve 
high-resolution control of the magnet current. The system consists of a 
Model 420, a low-current four-quadrant power supply (typically the Kepco 
BOP series), and associated interconnecting cabling. Figure 2-6 illustrates 
the interconnects for a Kepco BOP 20-5M or 20-10M power supply.

Note

Due to continuous discharge voltage limitations present in the Kepco 
BOP series supplies, the charging/discharging voltage is limited to 
a maximum of 10 volts by the Model 420 for maximum safety.

Connect the cabling in the following manner:

a. Connect the positive (+) power supply terminal (1) to the positive 

vapor-cooled current lead (2) using 1/4-20 or similar hardware.

b. Connect the negative vapor-cooled current lead (3) to the positive 

(+) shunt terminal (4) on the back of the Model 420.

Caution

Do not overtighten the nuts on the current shunt terminals of the 
Model 420 (see the torque specifications on page 7). Overtightening 
can result in damage to the terminals.

c. Connect the negative (

−

) shunt terminal (5) on the back of the 

Model 420 to the negative (

−

) power supply terminal (6).

Summary of Contents for 420

Page 1: ...s Inc PO Box 2509 112 Flint Road Oak Ridge TN 37831 2509 Tel 865 482 1056 Fax 865 482 5472 Rev 7 July 2002 MODEL 420 POWER SUPPLY PROGRAMMER INSTALLATION OPERATION AND MAINTENANCE INSTRUCTIONS EXCELLENCE IN MAGNETICS AND CRYOGENICS ...

Page 2: ......

Page 3: ...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 Assu...

Page 4: ......

Page 5: ...__________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ 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 ...

Page 6: ......

Page 7: ...gle 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 E...

Page 8: ...ing 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 Disab...

Page 9: ...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 S...

Page 10: ... 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 4...

Page 11: ...ent 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 Tab...

Page 12: ...x Rev 7 List of Tables ...

Page 13: ...ifications 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 in...

Page 14: ... 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 Traini...

Page 15: ...lothing 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 ...

Page 16: ...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 r...

Page 17: ...njury 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 Ca...

Page 18: ...xvi Rev 7 Foreword Safety Summary ...

Page 19: ...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...

Page 20: ...m 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 instrum...

Page 21: ...URJUDPPHG XUUHQW 9V B 2 1 2 3 4 5 6 8 9 10 11 12 7 Table 1 1 Front Panel Description 1 40 x 2 Dot Matrix LCD Display w LED Backlight 7 Magnet Voltage Meter Zero Adjust 2 Voltage Limit LED 8 Persistent Switch Heater Control 3 Current Field Limit LED 9 Quench RESET ZERO Mode Switch 4 4 Row x 5 Column Keypad 10 Rotary Encoder Dial 5 Power Switch 11 Manual Control UP Key 6 Analog Magnet Voltage Meter ...

Page 22: ...4 Rev 7 Introduction Front Panel Layout ...

Page 23: ... 6 8 7 7 5 6 Z 6 5 3 2 5 7 Table 1 2 Rear Panel Description 1 Current Shunt Terminals 5 Program Out BNC Female Connector 2 RS 232 422 25 pin Female D sub Connector 6 Dual Magnet Station 25 pin Female D sub Connectors 3 IEEE 488 Female Connector 7 Dual Auxiliary LHe Level Temp 9 pin Male D sub Connectors 4 Quench I O 9 pin Female D sub Connector 8 Input Power IEC 320 Male Connector 1 3 Rear Panel L...

Page 24: ...6 Rev 7 Introduction Rear Panel Layout ...

Page 25: ...ntrol Temperature Coefficient 0 01 of Imax C Stability Better than 0 01 40 min warm up Programming Resolution 15 digitsa Ramp Rate Resolution 15 digits Nominal Load Inductance Range 0 5 to 100 Henries Program Out Voltage Programmable Limits 10 to 10 VDC voltage voltage mode Accuracy 0 1 Temperature Coefficient 0 005 of Vmax C Resolution 20 µV Stability Better than 35 mV P P when paused or holding ...

Page 26: ...del 360 in lbs Environmental Ambient Temperature Operating 0 C to 50 C 32 F to 122 F Nonoperating 20 C to 60 C 4 F to 140 F Relative Humidity 80 up to 31 C 88 F decreasing linearly to 50 at 50 C 122 F Altitude 2 000 m 6562 ft Indoor use Standards EMI EMC Standards EN50082 1 EN61000 4 2 EN61000 4 3 EN61000 4 4 EN55022 Class A Safety Standard EN61010 1 Installation Category Pollution Degree 2 Overvo...

Page 27: ...e direction in the magnet thereby giving a magnetic field vector of varying magnitude but in a single direction This corresponds to operating in quadrant 1 of Figure 1 1 The electrical energy can be stored as magnetic energy as fast as the magnet and power supply voltage will allow In order to reduce the magnetic field the magnetic energy is converted to electrical energy and then to thermal energ...

Page 28: ...power supply system as show in Figure 1 4 a mechanical current reversing switch is included usually in the energy absorber This allows the current in the magnet to be reversed after the current has first been reduced to zero These systems usually incorporate some type of electronic interlock to ensure large amounts of current are not interrupted when the reversing sequence is initiated The disadva...

Page 29: ...ble magnetic field profiles are attainable without discontinuities All of the current switching is performed electronically so that system reliability is improved Disadvantages of the four quadrant system include the increased cost of the power supply if smooth continuous field polarity reversal is not a requirement and added complexity in protecting the power supply in the event of AC power loss ...

Page 30: ...12 Rev 7 Introduction Operating Characteristics ...

Page 31: ...equired return the instrument to AMI facilities as described in the Troubleshooting section of this manual If this instrument is used in a manner not specified in this manual the protection provided by the design manufacture and documentation of the instrument may be impaired 2 1 Inspecting and Unpacking Carefully remove the instrument interconnecting cabling and manual from the shipping carton an...

Page 32: ...e instrument adjacent to the power entry module Be sure your instrument is configured for your power source prior to plugging in the line cord Do not fail to connect the input ground terminal securely to an external earth ground Ensure the front panel power switch is in the OFF 2 position Verify that the instrument is configured for the proper operating voltage by referring to the label adjacent t...

Page 33: ...t closely corresponds with your system this is usually denoted by the operating characteristics of the power supply For maximum immunity to AC line noise ensure that the chassis of the Model 420 has a direct low impedance electrical connection to the chassis of the power supply to which the 352 5 0 287 is connected The connection can be made via a grounding strap or if rack mounted through the rac...

Page 34: ...tective diode may cause serious injury to personnel and damage to the power supply under certain loss of power conditions b Connect the negative vapor cooled current lead 3 to the positive shunt terminal 4 on the back of the Model 420 Caution Do not overtighten the nuts on the current shunt terminals of the Model 420 see the torque specifications on page 7 Overtightening can result in damage to th...

Page 35: ... 1 0 1 7 6 1 2 5 71 8 6 6 725 6 7 16 1 9 0 9 9 Superconducting Magnet Model 420 Rear Panel 1 2 3 4 5 6 8 9 1 92 7 0 21752 5 287387 20081 7 216 6 6 16 0 5 1 0 1 7 6 1 2 5 71 8 6 1387 32 5 RS 232 J8 S11 ON 9 9 6 1625 AMI Model 13x Rear Panel 7 AMI Model 12100PS Unipolar Supply Figure 2 1 System interconnect diagram for a unipolar supply without an energy absorber ...

Page 36: ...Model 601 Energy Absorber using 1 4 20 or similar hardware Note The use of locking hardware is recommended for all high current connections Caution Do not overtighten the nuts on the current shunt terminals of the Model 420 and the terminals of the Model 601 see the torque specifications on page 7 Overtightening can result in damage to the terminals Warning Ensure the protective diode remains inst...

Page 37: ... 6 725 6 7 16 1 9 0 9 9 Superconducting Magnet Model 420 Rear Panel 1 4 5 6 7 8 10 11 1 92 7 0 21752 5 287387 20081 7 216 6 6 16 0 5 1 0 1 7 6 1 2 5 71 8 6 1387 32 5 RS 232 J8 S11 ON 9 9 6 1625 AMI Model 13x Rear Panel 9 AMI Model 12100PS Unipolar Supply AMI Model 601 Energy Absorber Rear Panel 2 3 Figure 2 2 System interconnect diagram for a unipolar supply with an AMI Model 601 Energy Absorber ...

Page 38: ...able between the magnet support stand top plate connector 10 and the magnet station connector J7A or J7B on the rear of the Model 420 g Install an instrumentation cable between the LHe Temp connectors J8A and or J8B on the rear of the Model 420 and the Model 13x Liquid Helium Level Instrument and or temperature instrument 11 h Remote communications via IEEE 488 and or RS 232 or optional RS 422 can...

Page 39: ... The use of locking hardware is recommended for all high current connections Warning Ensure the protective diode remains installed across the output terminals of the power supply with the anode at the 1 ative terminal and the cathode at the 326itive terminal Removal of this protective diode may cause serious injury to personnel and damage to the power supply under certain loss of power conditions ...

Page 40: ...8 6 6 725 6 7 16 1 9 0 9 9 Superconducting Magnet Model 420 Rear Panel 1 2 3 6 7 13 1 92 7 0 21752 5 287387 20081 7 216 6 6 16 0 5 1 0 1 7 6 1 2 5 71 8 6 1387 32 5 RS 232 J8 S11 ON 9 9 6 1625 AMI Model 13x Rear Panel 11 AMI Model 10100 Unipolar Supply 4 5 12 8 9 10 AMI Model 600 Energy Absorber Figure 2 3 System interconnect diagram for a unipolar supply with an AMI Model 600 620 Energy Absorber ...

Page 41: ...n cable between the magnet support stand top plate connector 12 and the magnet station connector J7A or J7B on the rear of the Model 420 h Install an instrumentation cable between the LHe Temp connectors J8A and or J8B on the rear of the Model 420 and the Model 13x Liquid Helium Level Instrument and or temperature instrument 13 i Remote communications via IEEE 488 and or RS 232 or optional RS 422 ...

Page 42: ...r similar hardware Note The use of locking hardware is recommended for all high current connections Warning Ensure the protective diode remains installed across the output terminals of the power supply with the anode at the 1 ative terminal and the cathode at the 326itive terminal Removal of this protective diode may cause serious injury to personnel and damage to the power supply under certain lo...

Page 43: ...25 6 7 16 1 9 0 9 9 Superconducting Magnet Model 420 Rear Panel 1 2 3 6 7 14 1 92 7 0 21752 5 287387 20081 7 216 6 6 16 0 5 1 0 1 7 6 1 2 5 71 8 6 1387 32 5 RS 232 J8 S11 ON 9 9 6 1625 AMI Model 13x Rear Panel 12 AMI Model 10100 Unipolar Supply 4 5 13 8 9 10 AMI Model 610 Energy Absorber 11 Figure 2 4 System interconnect diagram for a unipolar supply with an AMI Model 610 630 energy absorber and a...

Page 44: ... J12 respectively 2 5 5 High Current Four Quadrant Supply For a true four quadrant power supply system the components include Model 420 a four quadrant power supply typically an AMI Model 4Q05100PS and associated interconnecting cabling Figure 2 5 illustrates the interconnects for an AMI Model 4Q05100PS power supply Connect the cabling in the following manner a Connect the positive power supply te...

Page 45: ... 625 5 92 7 48 1 2 56 0 5 1 0 1 7 6 1 2 5 71 8 6 6 725 6 7 16 1 9 0 9 9 Superconducting Magnet Model 420 Rear Panel 2 3 4 5 6 8 9 1 92 7 0 21752 5 287387 20081 7 216 6 6 16 0 5 1 0 1 7 6 1 2 5 71 8 6 1387 32 5 RS 232 J8 S11 ON 9 9 6 1625 AMI Model 13x Rear Panel 7 AMI Model 4Q 05100 Four Quadrant Supply Rear Panel 1 Figure 2 5 System interconnect diagram for the AMI Model 4Q 05100 power supply ...

Page 46: ... control of the magnet current The system consists of a Model 420 a low current four quadrant power supply typically the Kepco BOP series and associated interconnecting cabling Figure 2 6 illustrates the interconnects for a Kepco BOP 20 5M or 20 10M power supply Note Due to continuous discharge voltage limitations present in the Kepco BOP series supplies the charging discharging voltage is limited...

Page 47: ... SENSE V o 0 o V I o 0 o I RED BLACK S OUT OUT GRD GRD NET COM S COM 0 1 7 67 7 21 211 7256 H 9 7 03 211 7256 1387 32 5 855 17 6 817 352 5 0 287 625 5 92 7 48 1 2 56 0 5 1 0 1 7 6 1 2 5 71 8 6 6 725 6 7 16 1 9 0 9 9 Superconducting Magnet Model 420 Rear Panel 1 2 3 4 5 6 8 9 1 92 7 0 21752 5 287387 20081 7 216 6 6 16 0 5 1 0 1 7 6 1 2 5 71 8 6 1387 32 5 RS 232 J8 S11 ON 9 9 6 1625 AMI Model 13x Re...

Page 48: ...own in the diagram e Install an instrumentation cable between the magnet support stand top plate connector 8 and the magnet station connector J7A or J7B f Install an instrumentation cable between the LHe Temp connectors J8A and or J8B on the rear of the Model 420 and the Model 13x Liquid Helium Level Instrument and or temperature instrument 9 g Set the Kepco power supply 02 to voltage control to t...

Page 49: ...ersistent switch and 2 operation on a short circuit or resistive load 2 6 1 Superconducting Magnets without a Persistent Switch For superconducting magnets without a persistent switch the Model 420 requires the addition of an external stabilizing resistor in parallel with the magnet per Figure 2 7 If the stabilizing resistor is omitted the system current will oscillate when attempting to charge th...

Page 50: ...e oscillations are damped Note If you have purchased a superconducting magnet with the Model 420 AMI will normally provide a recommended stability setting for optimal operation of the magnet system If you operate the Model 420 with a different load be sure to restore the stability setting to the recommended value when the superconducting magnet is reconnected The stability setting is essentially m...

Page 51: ...current terminals This may be most easily accomplished by unfastening the heavy cables from the vapor cooled current leads and fastening them together This will allow rudimentary power supply checks without energizing the superconducting magnet 3 Energize the Model 420 by placing the power switch in the ON position 4 Enter a stability setting of 100 in the Load setup menu Refer to paragraph 3 2 2 ...

Page 52: ...iscrepancy between the current shown on the power supply display and the current displayed on the Model 420 The shunt measurement system incorporated in the Model 420 is normally more accurate than the power supply shunt The Model 420 is calibrated to 0 1 of the actual current which is typically five times more accurate than most integrated power supply shunts 12 Verify that the output current dis...

Page 53: ...20 19 Remove the short from the power supply leads and connect the leads to the vapor cooled current leads of the magnet After successful completion of this test of the Model 420 and power supply system the system is ready for operation with a superconducting magnet Refer to the ramping function example presented on page 57 for a discussion of the various available ramping methods ...

Page 54: ...36 Rev 7 Installation Power Up Procedure ...

Page 55: ...n be cycled by repeatedly pressing the 237 21 key when not within the setup menu or a setup submenu The operating values on the left side of the display are always visible during any mode of operation or menu selections 6WDWXV ROGLQJ 9V 36ZLWFK HDWHU 21 A 6WDWXV 5DPSLQJ 90 36ZLWFK HDWHU 21 N 6WDWXV ROGLQJ 9V 36ZLWFK HDWHU 21 This portion of the display is always visible Default display mode 1 Unit...

Page 56: ...stent method of entering values is used within menus requiring numerical entries Once a menu is selected the user starts an entry by pressing a digit the decimal key or the sign key The display will begin a new entry and display a cursor B as a prompt for the next digit or decimal entry Once entry is initiated the display will show an asterisk indicating that entry is in progress To accept the ent...

Page 57: ...will initiate the following initial setup menu display A cursor displayed to the left of a menu item indicates which setup submenu item will become active when the 6 783 key is again pressed The cursor can be moved to the next menu item by pressing the 237 21 key The setup menu may be exited by pressing the 6 key once Once the 6 783 key is pressed and a submenu is entered the user will be able to ...

Page 58: ... for standard AMI power supplies Use the 237 21 key to cycle through the list of selections The selection becomes effective immediately If a supply other than Custom is selected all remaining items within the Supply submenu are automatically set and cannot be edited The available selections and associated supply parameters are provided in Table 3 2 6 783 0 18 6 7 32 5 6833 0 1 287387 92 7 0 287387...

Page 59: ...ergy absorber does however change the system operating ranges per the example of Figure 3 3 Table 3 2 Available Select Power Supply options Power Supply Min Output Voltage V Max Output Voltage V Min Output Current A Max Output Current A V V Mode Input Range V AMI 12100PS 0 000 12 000 0 000 100 000 0 000 to 10 000 AMI 12200PS 0 000 12 000 0 000 200 000 0 000 to 10 000 AMI 4Q05100PS 5 000 5 000 100 ...

Page 60: ...pecified in volts and reflects the maximum compliance of a connected power supply The valid range is 0 001 to 20 000 volts This setting can be edited only if a Custom supply is selected 3 2 1 4 Min Output Current The minimum output current is specified in Amperes and reflects the minimum output current capacity of a connected power supply 20 20 200 200 20 20 200 200 V V I I AMI 12100PS OPERATING R...

Page 61: ...g voltage range required by the connected power supply The remote program voltage is the output signal commanded by the Model 420 to drive the connected power supply This setting can be edited only if a Custom supply is selected This menu item provides five preset selections and does not allow numerical entry of a range Use the 237 21 key to cycle through the list of presets The presets include 1 ...

Page 62: ...et by AMI The chart below may be used as a guide to set the stability setting for magnets with a persistent switch installed Magnets with an inductance of greater than 3 Henries that have a persistent switch installed should operate without problems with a stability setting of 0 0 3 2 2 2 Coil Constant The coil constant is a scaling factor which converts the operating current to kilogauss 10 kG 1 ...

Page 63: ...rent limit associated with a connected superconducting magnet This limit will always be observed during any ramping mode If the power supply is bipolar then the current limit applies for both the positive and negative current direction The current limit and voltage limit see page 53 define the safe operating region for the magnet within the full operating range of the power supply as illustrated i...

Page 64: ...The time may be set from 5 to 120 seconds The default is 15 seconds unless preset by AMI During the persistent switch heating period the Model 420 ramping functions are disabled The time delay is necessary to ensure that the Model 420 will not switch to a higher gain required for proper magnet operation before the magnet is actually available in the circuit If magnet operation is not stable after ...

Page 65: ...se refer to paragraph 3 5 3 2 2 8 Energy Absorber Present Indicates whether an energy absorber such as the AMI Model 610 is connected to the system Use the 237 21 key to cycle between YES and NO The default value is NO It is important for this setting to be correct since the internal gain tables of the Model 420 compensate for the additional load of the energy absorber if present The increased gai...

Page 66: ...her ramp rate is specified and displayed in time units of seconds or minutes Use the 237 21 key to cycle between selections The selected option also applies to the appropriate remote interface commands The default setting is seconds 3 2 3 3 Field Units Specifies whether the field is specified and displayed in units of kilogauss kG or Tesla T Use the 237 21 key to cycle between selections The selec...

Page 67: ...use the dial to adjust the value The default primary address is 22 The Model 420 does not support secondary addressing 3 2 4 2 Serial Baud Rate Specifies the baud rate of the serial interface Use the 237 21 key to cycle between values The default value is 9600 baud 3 2 4 3 Serial Data Bits Parity Specifies the number of data bits and parity for the serial interface Use the 237 21 key to cycle betw...

Page 68: ...e rated current to prevent accidental operation of the magnet above rated current field The magnet specification sheet also indicates whether a persistent switch is installed and provides the recommended heating current The persistent switch information is entered in the load setup submenu 6HULDO DQGVKDNLQJ 9V 1RQH 6 21 2 MAGNET SPECIFICATIONS AMI JOB 10501 MAGNET 10228 Type Solenoid MODEL A9020 3...

Page 69: ...d to as the Field to Current Ratio Obtained by dividing the rated field by the rated current if not explicitly stated 1 1806 Current Limit A 76 300 PSwitch Installed YES PSwitch Current mA 46 0 PSwitch Heated Time sec 15 Enable Quench Detect YES Energy Absorber Present NO Programmed Current A 76 2300 Voltage Limit V 4 000b b Value is the 2 V charge rate plus allowances for power lead drop at the r...

Page 70: ...ance Once the ramp rate and voltage limit are specified the Model 420 provides two modes of ramping operation manual and programmed The manual mode of operation will ramp to the current limit via manual direction control by the user The programmed mode of operation ramps to a programmed current or field setting automatically The programmed mode can be thought of as a next point operation whereby t...

Page 71: ... voltage limit constrains the commanded output voltage of a connected power supply to a value less than or equal to the limit Table 3 5 Ramping states and descriptions Mode Description Ramping Automatic ramping to the programmed current or fielda is in progress a The programmed current field setting is discussed in paragraph 3 3 3 1 Holding The programmed current has been achieved and is being mai...

Page 72: ...field then the ramp rate setting is displayed and set in units of kilogauss sec or Tesla sec as show below The allowable range is defined by the setting of the coil constant and the allowable range of the ramp rate in terms of current as specified on page 7 The Model 420 will ramp at the specified rate if the available compliance of the power supply is sufficient and the voltage limit is not excee...

Page 73: ...ent Field The programmed current is accessed by pressing the 352 5 00 855 17 key and may be set less than or equal to the current limit for the magnet specified in setup see paragraph 3 2 2 3 The programmed current requires a sign since it locates a single setpoint within the entire operating current range of the system If the selected default display mode contains field units the display will all...

Page 74: ...ulate the operating shunt current Note The encoder dial is velocity sensitive meaning that the faster the dial is turned the more coarse the adjustment Slow manipulation of the dial will yield very fine resolution even beyond that displayed by the instrument When the dial is manipulated the Model 420 will follow at a compliance of less than or equal to the voltage limit The ramp rate setting is no...

Page 75: ...de Point 3 The operator increases the ramp rate setting The operator also keys in a new value of 40 000 A for the programmed current setting As soon as the new programmed current is entered the Model 420 automatically begins ramping at the specified ramp rate Point 4 The operator presses the 5 03 3 86 key at an operating current of 25 15 A and the PAUSED mode is activated The Model 420 maintains t...

Page 76: ... operator increases the ramp rate and presses the 5 6 7 52 key to begin ramping to zero current The Model 420 automatically ramps the current to 0 A Point 8 The Model 420 holds the operating current of 0 A when achieved until the 5 6 7 52 key is deactivated ...

Page 77: ...accessing the load setup submenu see paragraph 3 2 2 5 In addition to the heating current the operator must also specify a heating time The heating time allows the Model 420 to delay compensating the internal control logic until the magnet is guaranteed to be in the circuit The heating time can be set from a minimum of 5 seconds to a maximum of 120 seconds within the load setup submenu see paragra...

Page 78: ...ncreased ramp rate since the magnet is no longer in the circuit Using the ZERO mode is recommended since it allows the programmed current field to remain unchanged for future sessions 7 Once at zero current de energize the power supply first then power off the Model 420 instrument 3 4 2 Procedure for Exiting Persistent Mode To exit the persistent mode of magnet operation the operator should perfor...

Page 79: ...e switched via an internal relay that opens and closes with the switch heater control functions of the Model 420 To use an external power supply for the switch heater current connect an external power supply to J4 pins 4 and 5 any polarity Then connect pins 18 and 19 of J7A or J7B to the switch heater terminals of the superconducting magnet Ensure that the external power requirements are within th...

Page 80: ... Detection The automatic quench detection feature may be disabled in the load setup submenu see paragraph 3 2 2 7 However the rear panel quench detect input connector J4 remains active If the automatic quench detection feature is disabled the Model 420 attempts to limit the error between the commanded current and the present operating current to a value that will not result in excessive voltages b...

Page 81: ...imits and defaults for the Model 420 Model 420 Setting Units Absolute Limits Default Settinga a Unless preset by factory Min Output Voltage V 0 000 to 20 000 0 000 Max Output Voltage V 0 001 to 20 000 12 000 Min Output Current A see page 7 0 000 Max Output Current A see page 7 100 000 V V Mode Input Range V 10 000 to 10 000 0 000 to 10 000 Stability Setting 0 0 to 100 0 0 0 Coil Constant kG A 0 00...

Page 82: ...64 Rev 7 Operation Summary of Operational Limits ...

Page 83: ...ommand Summary The following manual conventions are used for SCPI Standard Commands for Programmable Instruments syntax for the remote interface commands Braces enclose valid parameter choices A vertical bar separates multiple choices for each parameter Triangle brackets indicate that you must supply a value Parentheses within indicate alternative units are available For example the command PSwitc...

Page 84: ...e page 82 for more information CONFigure STABility percent CONFigure COILconst value kG A T A CONFigure CURRent LIMit current CONFigure PSwitch 0 1 CONFigure PSwitch CURRent current CONFigure PSwitch TIME time CONFigure QUench DETect 0 1 CONFigure ABsorber 0 1 CONFigure RAMP RATE UNITS 0 1 CONFigure FIELD UNITS 0 1 Status System Commands SETUP Configuration Commands ...

Page 85: ...more information SUPPly VOLTage MINimum SUPPly VOLTage MAXimum SUPPly CURRent MINimum SUPPly CURRent MAXimum SUPPly TYPE SUPPly MODE STABility COILconst CURRent LIMit PSwitch CURRent PSwitch TIME QUench DETect ABsorber RAMP RATE UNITS FIELD UNITS SETUP Configuration Queries ...

Page 86: ...re RAMP RATE FIELD rate kG s kG min T s T min CONFigure RAMP CURRent current rate A s A min CONFigure RAMP FIELD field kG T rate kG s kG min T s T min VOLTage LIMit CURRent PROGram FIELD PROGram RAMP RATE CURRent RAMP RATE FIELD RAMP CURRent RAMP FIELD VOLTage MAGnet VOLTage SUPPly CURRent MAGnet FIELD MAGnet see page 87 for more information RAMP PAUSE UP DOWN ZERO STATE Ramp Configuration Command...

Page 87: ...ents a status system for monitoring the state of the Model 420 through the Standard Event and Status Byte registers 4 2 1 SCPI Language Introduction SCPI commands conform to a tree structure where commands are grouped according to common keywords For example commands which set a Model 420 setup or operating parameter begin with the keyword CONFigure The keywords are shown in upper case and lower c...

Page 88: ...ime A condition register is read only and is not cleared when you read the register A query of a condition register returns a decimal value in the appropriate output buffer which corresponds to the binary weighted sum of all bits set in the register An event register latches various events An event register is not buffered therefore once a bit is set further occurrences of that event are ignored O...

Page 89: ...t register will update the corresponding bit in the Status Byte register according to the Standard Event enable register Reading the pending messages in the output buffers will clear the appropriate Message Available bit The bit definitions for the Status Byte register are defined in Table 4 1 The Status Byte register provides the capability of generating a user defined IEEE 488 service request SR...

Page 90: ...ff and then back on and the instrument was configured for PSC 1 power on status clear The enable register setting is persistent if the Model 420 is configured for PSC 0 no status clear on power on 4 2 2 2 Serial Polling and the Service Request SRQ In order to use the SRQ feature of the Model 420 you must configure your host computer and IEEE 488 interface card to respond to the IEEE 488 service re...

Page 91: ...s do not provide return data 4 2 3 Standard Event Register The Standard Event register group reports a power on condition various error conditions and indicates when an operation has completed Any or all of the Standard Events can be reported to the Status Byte register by enabling the corresponding bit s in the Standard Event enable register see Figure 4 1 To set the Standard Event enable registe...

Page 92: ...available to help prevent command queue overflows which are discussed below 4 2 4 1 Using the OPC Command The OPC command is executed within the normal command queue Upon completed execution of the OPC command the Operation Complete bit bit 0 of the Standard Event register will be set Table 4 2 Bit definitions for the Standard Event register Bit Number Decimal Value Definition 0 Operation Complete...

Page 93: ...he OPC command for determining when execution all of the commands including OPC is completed If the Standard Event and Status Byte enable registers are correctly configured the OPC command will then result in an IEEE 488 service request when execution completes Alternately the Serial Poll function of the IEEE 488 bus may be used to determine completion of the command 4 2 4 2 Using the OPC Query Th...

Page 94: ...s wired directly i e pin 1 to pin 1 pin 2 to pin 2 etc If a DB9 connector is required at the computer interface the connector translation is provided in the Appendix The Model 420 when configured for RS 232 uses only three wires of the rear panel DB25 connector pin 2 receive pin 3 transmit and pin 7 common The RS 232 and RS 422 pinout is fully documented on page 112 in the Appendix The Model 420 i...

Page 95: ... reaches a high water mark The host device should suspend transmission on receipt of an XOFF character from the Model 420 and resume when an XON character is received Note The XON XOFF flow control should not be used as a substitute for command handshaking as documented in paragraph 4 2 4 XON XOFF characters are not generated in the case of input overflow errors error number 303 4 4 IEEE 488 Confi...

Page 96: ...and Note For the serial interface a Device Clear can be initiated by sending the Ctrl C ASCII code 03 character 4 4 3 Trigger Command The trigger command is a low level IEEE 488 bus message which you can use to initiate the trigger functions provided by the Model 420 The trigger functions supported by the Model 420 are documented in paragraph 4 5 8 on page 90 When a trigger command is received by ...

Page 97: ...ays returns 1 Ctrl C Equivalent to sending a Device Clear message over the IEEE 488 interface Ctrl C is only accepted from the serial interface This clears the output buffers of the instrument and prepares the instrument for a new command Status registers are unaffected Ctrl C corresponds to ASCII code 03 SYSTem LOCal Enables all front panel controls All front panels controls are enabled by defaul...

Page 98: ...d commands are illustrated in Figure 4 1 on page 70 STB Returns the contents of the Status Byte register The STB command is similar in function to an IEEE 488 Serial Poll however the command is executed in the order received as any other command In contrast to the IEEE 488 Serial Poll STB does not clear an SRQ condition or the Summary Bit bit 6 of the Status Byte register SRE enable_value Enables ...

Page 99: ...ries of error messages to be reported in bit 5 of the Status Byte register send ESE 60 ESE The ESE query returns a decimal sum which corresponds to the binary weighted sum of the bits enabled by the last ESE command PSC 0 1 Power On Status Clear If PSC 1 is in effect the Standard Event enable register and the Status Byte enable register are cleared at power on If PSC 0 is in effect the enable regi...

Page 100: ...igured via front panel operation of the SUPPLY setup menu and is set automatically when a preset supply type is selected SUPPly VOLTage MAXimum Returns the maximum power supply compliance in volts This value can only be configured via front panel operation of the SUPPLY setup menu and is set automatically when a preset supply type is selected SUPPly CURRent MINimum Returns the minimum output curre...

Page 101: ... STABility Returns the stability setting in percent CONFigure COILconst value kG A T A Sets the coil constant also referred to as the field to current ratio per the selected field units The coil constant must be set to a non zero positive value in order to command or query the Model 420 in units of field COILconst Returns the coil constant setting in kG A or T A per the selected field units CONFig...

Page 102: ...ted PSwitch TIME Returns the persistent switch heating time in seconds CONFigure QUench DETect 0 1 Sending 0 disables the automatic quench detection function of the Model 420 1 enables the automatic quench detection function of the Model 420 See page 61 for more information 1 is the default value QUench DETect Returns 0 indicating automatic quench detection is disabled or 1 indicating that the aut...

Page 103: ...ng the magnet current field and voltage See paragraph 3 3 on page 52 for more information regarding the ramping functions of the Model 420 CONFigure VOLTage LIMit voltage Sets the ramping voltage limit in volts The ramping voltage limit may not exceed the maximum output voltage of the power supply VOLTage LIMit Returns the ramping voltage limit in volts CONFigure CURRent PROGram current Sets the p...

Page 104: ...rammed current in amperes and the ramp rate in amperes second or amperes minute per the selected ramp units with one command string Note that both parameters are required RAMP CURRent Returns the programmed current in units of amperes and the ramp rate in units of amperes second or amperes minute per the selected ramp units The two return values are separated by a comma For example RAMP CURRENT 50...

Page 105: ... constant 4 5 5 Ramping State Commands and Queries The ramping state commands control and query the ramping state of the Model 420 For more information regarding each state see paragraph 3 3 on page 52 If the ramping state is commanded remotely the front panel display and switch LEDs will update and accurately reflect the commanded ramping state RAMP Places the Model 420 in the programmed ramping ...

Page 106: ... Turns the persistent switch heater OFF and ON Sending 0 turns the switch heater OFF Sending a 1 turns the switch heater ON The default value is 0 PSwitch Returns a 0 indicating the switch heater is OFF or a 1 indicating the persistent switch heater is ON VOLTage PSwitch Returns the persistent switch heater voltage measurement in volts A value of 0 V indicates a shorted connection A value exceedin...

Page 107: ...d state Sending a 0 clears any quench condition equivalent to pressing the 5 6 7 52 front panel switch Send a 1 sets a quench condition Setting the quench state to 1 is equivalent to a quench detection by the instrument i e the power supply output is forced to 0 V the quench output of the rear panel connector J4 is asserted and all ramping functions are disabled QUench Queries the quench state If ...

Page 108: ... the appropriate output buffer s Data placed in the serial interface buffer is transmitted immediately Data placed in the IEEE 488 output buffer must be collected by the host device Note that trigger output data may be placed in both the serial and the IEEE 488 output buffers if desired Table 4 6 Bit definitions for the Model 420 trigger functions Bit Number Decimal Value Definition 0 Magnet Volta...

Page 109: ...s and Queries ETE enable_value Enables trigger functions according to the definitions in Table 4 6 To enable the trigger functions you must write a decimal enable_value which corresponds to the binary weighted sum of the functions you wish to enable For example to enable formatted output of the time magnet field and the magnet voltage to the serial interface send the command ETE 109 The return dat...

Page 110: ...ay contain up to 80 characters Errors are classified in the following categories command errors query errors execution errors and device errors Each category corresponds to the identically named bit in the standard event register see page 70 If an error occurs in any one of the categories the corresponding bit in the standard event register is set and remains set until cleared by the user 4 6 1 Co...

Page 111: ...o switch installed The user attempted to activate the persistent switch heater when no switch is installed Before activating the persistent switch heater the user must indicate a switch is installed and set the switch current and heating time see page 46 4 6 2 Query Errors 201 Unrecognized query The query string sent identified as a query by a was not identified as valid Check the query string for...

Page 112: ...erflow errors 304 Error buffer overflow More than 10 errors have occurred For further errors to be recorded in the internal buffer at least one error must be cleared 4 6 4 Device Errors 401 Checksum failed The non volatile memory which stores the calibration data for the Model 420 is corrupted Contact an Authorized AMI Technical Representative for further instructions Do not continue to use the Mo...

Page 113: ... Additional Technical Support on page 103 This instrument contains CMOS components which are susceptible to damage by Electrostatic Discharge ESD Take the following precautions whenever the cover of the instrument is removed 1 Disassemble the instrument only in a static free work area 2 Use a conductive workstation or work area to dissipate static charge 3 Use a high resistance grounding wrist str...

Page 114: ... board Warning This procedure is to be performed only when the instrument is completely de energized by removing the power cord from the power receptacle Failure to do so could result in personnel coming in contact with high voltages capable of producing life threatening electrical shock a Ensure the instrument is de energized by disconnecting the power cord from the power source Disconnect the po...

Page 115: ... Ensure the instrument is de energized by disconnecting the power cord from the power source Disconnect the power cord from the connector located on the rear panel of the instrument 2 Remove the instrument top cover and replace the computer memory backup battery BT1 Note When replacing the battery replace with a 3 6 volt AA size lithium cell International size reference ER14505 Comply with the pol...

Page 116: ... indicated by the 92 7 0 7 LED there may be a problem with the power supply Verify the power supply is on and the program out connection from the Model 420 to the program voltage input to the power supply is intact 2 Verify the power supply is configured for remote programming voltage to voltage mode Consult the manufacturer s operations manual for the necessary power supply configuration 3 Ensure...

Page 117: ...ng of the magnet requires either an energy absorbing component or a four quadrant power supply If a unipolar supply is used without an energy absorbing component only the resistance of the power leads is available as a mechanism for discharging the magnet 1 Ensure that the persistent switch heater is on and the switch heating time has expired Ramping is disabled during the switch heating period 2 ...

Page 118: ...tage and current controls when the supply is remotely programmed 3 Ensure that the Model 420 supply setup submenu is configured to match the connected power supply e g check that the Model 420 is configured for the proper voltage to voltage programming range according to paragraph 3 2 1 6 on page 43 5 2 8 The four quadrant power supply will only supply current in one direction 1 Ensure the Model 4...

Page 119: ...ear very similar to a quench 2 Ensure there is adequate LHe level in the cryostat For systems operating at less then 4 2K ensure the magnet is cooled to the temperature specified by the magnet manufacturer 3 Disable the Model 420 quench detection feature see paragraph 3 5 1 on page 62 if you suspect the Model 420 is falsely indicating a quench condition 5 2 12 The Model 420 will not lower the fiel...

Page 120: ...em whenever magnet current flows and cause excessive heating This can be identified by observing a change in the apparent field to current ratio since some of the current is bypassing the coil If the boil off rate returns to normal with the magnet de energized this may indicate a defective diode 3 Ensure that there are no inadvertent thermal paths between the cryogenic environment and the 300K env...

Page 121: ...e sure you are sending valid commands If you experience continued trouble with the IEEE 488 interface you may have an incompatible IEEE 488 card in your host computer In the past AMI has found subtle differences between manufacturers of IEEE 488 cards that have introduced communication errors AMI attempts to establish compatibility with as many products as possible however it is difficult to test ...

Page 122: ...to be returned to AMI for repair warranty or otherwise require a return authorization number to ensure your order will receive proper attention Please call an AMI representative at 865 482 1056 for a return authorization number before shipping any item back to the factory ...

Page 123: ...tions Pin Function Pin Function 1 LHe Sensor I Red 14 Spare 2 LHe Sensor I Black 15 Spare 3 LHe Sensor V Yellow 16 Spare 4 LHe Sensor V Blue 17 Spare 5 Temperature Sensor I Red 18 External Switch Heater Currenta a See discussion on page 61 for further details on the use of an optional external power supply for heating the persistent switch 6 Temperature Sensor I Black 19 External Switch Heater Cur...

Page 124: ...Auxiliary LHe Level Temperature Connectors The two 9 pin D sub male Auxiliary LHe Level and Temperature connectors are identically wired and connected pin for pin internally The connectors route the incoming signals from the Magnet Station Connectors to external level and or temperature instruments If an AMI Liquid Helium Level Instrument is purchased with the Model 420 and magnet system an LHe le...

Page 125: ... maximum noise immunity use shielded cabling and connect one end of the shield to the J8A or J8B connector shell A 3 Current Shunt Terminals The Current Shunt Terminals should be connected so that positive direction current flows from the terminal to the terminal Refer to the diagrams in the Installation section page 13 for detailed descriptions of the system interconnections Warning Exercise caut...

Page 126: ...escriptions of the system interconnections or refer to the manual for your power supply The coaxial shield is the output return The center conductor is the program out voltage Note For maximum noise immunity the Model 420 chassis and the chassis of any connected power supply should be tightly electrically coupled This can be accomplished through the rack mounting or by using a grounding strap betw...

Page 127: ...ctor are connected to the Model 420 chassis ground J4 is a 9 pin D sub female connector Table A 3 Connector J4 pin definitions Pin Function 1 Quench Output 2 Quench Output 3 Ground 4 Optional External Power Supplya a See discussion on page 61 for further details on the use of an optional external power supply for heating the persistent switch 5 Optional External Power Supply 6 Quench Input 7 Quenc...

Page 128: ...ench external input to earth ground 500VDC Quench External Output 4N35 optocoupler output Maximum on state optocoupler output saturation voltage 0 5 mA out Vce sat across rated temp 0 35V Maximum off state optocoupler output leakage current Iceo across rated temperature 2 5µA Maximum allowable off state optocoupler output voltage Vceo across rated temperature 30V Maximum allowable optocoupler outp...

Page 129: ... 8 NDAC Not Data Accepted 9 IFC Interface Clear 10 SRQ Service Request 11 ATN Attention 12 SHIELD Cable Shield connected to 420 chassis gnd 13 DIO5 Data In Out Bit 5 14 DIO6 Data In Out Bit 6 15 DIO7 Data In Out Bit 7 16 DIO8 Data In Out Bit 8 17 REN Remote Enable 18 GND Ground Twisted pair with DAV 19 GND Ground Twisted Pair with NRFD 20 GND Ground Twisted Pair with NDAC 21 GND Ground Twisted Pai...

Page 130: ... A 5 PC to Model 420 connections for RS 232 operation PC DTE DB 25 Pin Model 420 DCE DB 25 Pin DTE Function 2 2 TD 3 3 RD 4 4 RTS 5 5 CTS 6 6 DSR 7 7 GND 8 8 DCD 20 20 DTR 22 22 RI Table A 6 PC DB 9 to Model 420 connections for RS 232 operation PC DTE DB 9 Pin Model 420 DCE DB 25 Pin DTE Function 3 2 TD 2 3 RD 7 4 RTS 8 5 CTS 6 6 DSR 5 7 GND 1 8 DCD 4 20 DTR 9 22 RI 56 56 6 5 3257 ...

Page 131: ... 530 Device to Model 420 connections for RS 422 operation EIA 530 Device DTE DB 25 Pin Model 420 DCE DB 25 Pin DTE Function 2 21 TX 3 16 RX 4 12 RTS 5 13 CTS 6 11 DSR 7 7 GND 8 14 DCD 10 8 DCD 13 5 CTS 14 2 TX 16 3 RX 19 4 RTS 20 15 DTR 22 6 DSR 23 20 DTR ...

Page 132: ...114 Rev 7 Appendix RS 232 422 Connector ...

Page 133: ...gging 90 default display modes 37 default settings 63 E entering values 38 ESD precautions 95 F features 1 2 field display 38 front panel layout 3 I IEEE 488 configuration 77 device clear 78 SRQ 72 termination characters 77 trigger command 78 installation power 14 rack mounting 13 unpacking 13 K keys enter 38 esc 38 39 manual control 53 54 option 39 programmed current field 55 ramp rate 54 ramp pa...

Page 134: ...ndard event register 73 status byte 71 status system 70 status system diagram 70 return authorization 104 RS 232 422 configuration 76 connector 76 flow control modes 77 termination characters 76 S safety cryogens xii equipment xv legend xv quenches xiv setup comm submenu 49 example 50 load submenu 44 menu tree diagram 40 misc submenu 48 submenus 39 supply submenu 40 short circuit operation 32 spec...

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