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Lake Shore 625 User Manual

Manual is about: Superconducting Magnet Power Supply

Summary of 625

  • Page 1

    Revision: 1.6 p/n 119-037 9 november 2015 lake shore cryotronics, inc. 575 mccorkle blvd. Westerville, ohio 43082-8888 usa e-mail addresses: sales@lakeshore.Com service@lakeshore.Com visit our website at: www.Lakeshore.Com fax: (614) 891-1392 telephone: (614) 891-2243 methods and apparatus disclosed...

  • Page 2

    Lake shore model 625 superconducting mps user’s manual a.

  • Page 3

    Lake shore model 625 superconducting mps user’s manual b limited warranty statement warranty period: three (3) years 1. Lake shore warrants that products manufactured by lake shore (the "product") will be free from defects in materials and workmanship for three years from the date of purchaser's phy...

  • Page 4

    Lake shore model 625 superconducting mps user’s manual a 13. This limited warranty gives you specific legal rights, and you may also have other rights that vary within or between jurisdictions where the product is purchased and/or used. Some jurisdictions do not allow limitation in certain warrantie...

  • Page 5

    Lake shore model 625 superconducting mps user’s manual d.

  • Page 6

    Lake shore model 625 superconducting mps user’s manual c.

  • Page 7

    Lake shore model 625 superconducting mps user’s manual d electromagnetic compatibility (emc) for the model 625 superconducting mps electromagnetic compatibility (emc) of electronic equipment is a growing concern worldwide. Emissions of and immunity to electromagnetic interference is now part of the ...

  • Page 8

    Lake shore model 625 superconducting mps user’s manual e.

  • Page 9: Table Of Contents

    Lake shore model 625 superconducting mps user’s manual table of contents i table of contents chapter/paragraph title page 1 introduction .................................................................................................................................................... 1-1 1.0 genera...

  • Page 10

    Lake shore model 625 superconducting mps user’s manual ii table of contents table of contents (continued) chapter/paragraph title page 4.3 keypad definition .............................................................................................................................. 4-2 4.3.1 key de...

  • Page 11

    Lake shore model 625 superconducting mps user’s manual table of contents iii table of contents (continued) chapter/paragraph title page 5.1.5 ieee interface example programs .................................................................................................. 5-15 5.1.5.1 ieee-488 inter...

  • Page 12

    Lake shore model 625 superconducting mps user’s manual iv table of contents list of illustrations figure no. Title page 1-1 model 625 front panel ................................................................................................................................. 1-3 2-1 typical supercon...

  • Page 13: Chapter 1

    Lake shore model 625 superconducting mps user’s manual introduction 1-1 chapter 1 introduction 1.0 general this chapter provides an introduction to the model 625 superconducting magnet power supply. The model 625 was designed and manufactured in the united states of america by lake shore cryotronics...

  • Page 14

    Lake shore model 625 superconducting mps user’s manual 1-2 introduction at static fields, output current drift is also kept low by careful attention in the analog control circuits and layout. The high stability and low noise of the model 625 make it possible in many situations to run experiments wit...

  • Page 15

    Lake shore model 625 superconducting mps user’s manual introduction 1-3 parallel operation if an application requires more output current than a single model 625 can provide, two supplies can be connected in parallel for 120 a/5 v operation. Each unit is programmed for half of the total output curre...

  • Page 16

    Lake shore model 625 superconducting mps user’s manual 1-4 introduction 1.2 specifications output type: bipolar, four quadrant, dc current source current generation: linear regulation with digital setting and analog control current range: ±60 a compliance voltage: ±5 v maximum (nominal, both source ...

  • Page 17

    Lake shore model 625 superconducting mps user’s manual introduction 1-5 readings output current resolution: 0.1 ma accuracy: ±1 ma ±0.05% of reading update rate: 2.5 readings/s display, 10 readings/s interface compensation: compensated for lead resistance and 25 source resistance output voltage (at ...

  • Page 18

    Lake shore model 625 superconducting mps user’s manual 1-6 introduction output voltage monitor sensitivity: 1 v = 1 v accuracy: ±1% of full scale noise: 1 mv source impedance: 20 connector: shared 15-pin d-sub fault output type: relay (closed on fault) relay contact: 30 vdc @ 1 a connector: shared 2...

  • Page 19

    Lake shore model 625 superconducting mps user’s manual introduction 1-7 1.3 safety summary observe these safety precautions during all phases of instrument operation, service, and repair. Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety stan...

  • Page 20

    Lake shore model 625 superconducting mps user’s manual 1-8 introduction this page intentionally left blank.

  • Page 21: Chapter 2

    Lake shore model 625 superconducting mps user’s manual magnet system design 2-1 chapter 2 magnet system design 2.0 general this chapter provides information on general magnet system design. It is intended to give the user insight into superconducting materials, superconducting magnets, persistent sw...

  • Page 22

    Lake shore model 625 superconducting mps user’s manual 2-2 magnet system design the superconducting wire is wound around a non-magnetic former made from aluminum, brass, stainless steel, or other material as needed. The individual windings are electrically insulated by the insulation on the wire and...

  • Page 23

    Lake shore model 625 superconducting mps user’s manual magnet system design 2-3 the resistance of the leads must be taken into account when calculating charge rate since a voltage drop across the leads will limit the voltage that can be delivered to the terminals of the magnet. This becomes especial...

  • Page 24

    Lake shore model 625 superconducting mps user’s manual 2-4 magnet system design 2.4 magnet current leads the power supply should be placed close to the magnet to reduce the length of the lead wires. The resistance of the wires becomes very important when such large currents are being supplied to the...

  • Page 25

    Lake shore model 625 superconducting mps user’s manual magnet system design 2-5 with the magnet submerged in liquid helium, it will be at a temperature of 4.2 k at atmospheric pressure. Some magnets are rated to work at 2.2 k allowing a larger field to be generated. This temperature can be achieved ...

  • Page 26

    Lake shore model 625 superconducting mps user’s manual 2-6 magnet system design figure 2-2. Cutaway of a typical helium dewar, magnet, and insert.

  • Page 27: Chapter 3

    Lake shore model 625 superconducting mps user’s manual installation 3-1 chapter 3 installation 3.0 general this chapter provides general installation instructions for the model 625 superconducting magnet power supply. Please read this entire chapter before installing the instrument and powering it o...

  • Page 28

    Lake shore model 625 superconducting mps user’s manual 3-2 installation 3.2 rear panel definition this paragraph defines the rear panel of the model 625. See figure 3-1. Readers are referred to paragraphs that contain installation instructions and connector pin-outs for each feature. A summary of co...

  • Page 29

    Lake shore model 625 superconducting mps user’s manual installation 3-3 3.3 line input assembly this section describes how to properly connect the model 625 to line power. Please follow these instructions carefully to ensure proper operation of the instrument and the safety of operators. Line_input....

  • Page 30

    Lake shore model 625 superconducting mps user’s manual 3-4 installation 3.3.4 power switch the power switch is on the front panel of the model 625 and turns line power to the instrument on and off. When the circle is depressed, power is off. When the line is depressed, power is on. 3.4 magnet cable ...

  • Page 31

    Lake shore model 625 superconducting mps user’s manual installation 3-5 3.5.2 remote voltage sense the model 625 provides a connection for remote voltage sense leads. This connection is normally used to measure the voltage at the magnet allowing a more accurate reading of magnet voltage by eliminati...

  • Page 32

    Lake shore model 625 superconducting mps user’s manual 3-6 installation 3.6.2 remote inhibit the remote inhibit connection on the digital i/o connector is an input that instructs the power supply to immediately set the output current to 0 a. This input allows an external device to immediately shut o...

  • Page 33

    Lake shore model 625 superconducting mps user’s manual installation 3-7 3.8 instrument grounding and isolation chassis grounded circuits should have a low impedance path to earth ground for both performance and safety. This is achieved by using a 3-conductor power cord in a properly grounded outlet....

  • Page 34

    Lake shore model 625 superconducting mps user’s manual 3-8 installation dual_625_rear.Bmp figure 3-7. Connecting two power supplies in parallel.

  • Page 35

    Lake shore model 625 superconducting mps user’s manual installation 3-9 3.10 rack mounting the model 625 can be installed into a 19-inch rack mount cabinet using the included rack mount hardware and 19-inch rack support rails. The power supply comes from the factory with feet installed. These feet n...

  • Page 36

    Lake shore model 625 superconducting mps user’s manual 3-10 installation this page intentionally left blank.

  • Page 37: Chapter 4

    Lake shore model 625 superconducting mps user’s manual operation 4-1 chapter 4 operation 4.0 general this chapter provides operating instructions for the features of the model 625 superconducting magnet power supply. Computer interface instructions are in chapter 5. 4.1 turning power on verify that ...

  • Page 38

    Lake shore model 625 superconducting mps user’s manual 4-2 operation 4.2.2 magnet field display the instrument can be setup to display calculated field. See figure 4-2. This value is calculated using the output current reading and the field constant. See paragraph 4.13 to setup the field constant. I...

  • Page 39

    Lake shore model 625 superconducting mps user’s manual operation 4-3 psh setup setup persistent switch heater enable, current, delay time, and persistent mode ramp rate. Refer to paragraph 4.14. Quench detect setup quench detect enable and current step limit. Refer to paragraph 4.16. Display setup s...

  • Page 40

    Lake shore model 625 superconducting mps user’s manual 4-4 operation 4.4 display setup the display of the model 625 is designed so that all of the pertinent operational information is being presented in a logical manner. The most important readings, either output current and voltage or calculated ma...

  • Page 41

    Lake shore model 625 superconducting mps user’s manual operation 4-5 4.4.3 display brightness the vacuum fluorescent (vf) display on the model 625 has four brightness settings between 100% and 25% that can be changed from the front panel. The brightness setting changes the entire vf display but does...

  • Page 42

    Lake shore model 625 superconducting mps user’s manual 4-6 operation the output current setting is not allowed to change while the persistent switch heater is warming or cooling. The amount of time it takes for the psh to warm or cool is system dependant and can be setup under the psh setup key. Ref...

  • Page 43

    Lake shore model 625 superconducting mps user’s manual operation 4-7 4.7 compliance voltage limit the output compliance voltage limit of the model 625 can be set between 0.1 and 5 v. The setting is in magnitude only and will limit both positive and negative voltages. On most superconducting magnets,...

  • Page 44

    Lake shore model 625 superconducting mps user’s manual 4-8 operation to set the maximum output current limit press max settings. The first maximum setting screen appears as a prompt for the maximum output current limit. Maximum settings enter a value for max current: 60.0000 a use the data entry key...

  • Page 45

    Lake shore model 625 superconducting mps user’s manual operation 4-9 4.12 ramp segments many magnets cannot be charged or discharged at the same rate throughout its entire current capacity. Typically the magnet cannot be charged as fast when the current in the magnet is high. The model 625 has a ram...

  • Page 46

    Lake shore model 625 superconducting mps user’s manual 4-10 operation 4.13 field constant in a superconducting magnet, magnetic field is directly proportional to the current in the magnet. Because of this relationship, the model 625 is able to display a calculated field based on a user entered field...

  • Page 47

    Lake shore model 625 superconducting mps user’s manual operation 4-11 4.14.1 persistent switch heater output enable the persistent switch heater should be enabled only if there is an active persistent switch in the magnet system. If no persistent switch is being used, then the persistent switch heat...

  • Page 48

    Lake shore model 625 superconducting mps user’s manual 4-12 operation the persistent switch heater current can only be changed when the heater is off. If the current is changed while the heater is on or warming, the following error box will appear and the new setting will be ignored. Change not allo...

  • Page 49

    Lake shore model 625 superconducting mps user’s manual operation 4-13 if the persistent mode ramp rate is enabled, then the ramp rate to be used while the magnet is in persistent mode needs to be entered. Even though this ramp rate is typically much faster than the magnet ramp rate, it should not be...

  • Page 50

    Lake shore model 625 superconducting mps user’s manual 4-14 operation 4.16 quench detection a magnet quenches when a part of the superconducting wire in the magnet becomes resistive. When a section of the magnet becomes resistive, it will begin to heat and cause more of the magnet to become resistiv...

  • Page 51

    Lake shore model 625 superconducting mps user’s manual operation 4-15 use the data entry keys to enter the current step limit value between 0.0100 and 10.000 a/s. Press enter to accept the new value. Press escape to restart the setting sequence and enter a different value. Press escape again to leav...

  • Page 52

    Lake shore model 625 superconducting mps user’s manual 4-16 operation use the s or t key to select the external current program mode, internal, external, or sum. Press enter to accept the new selection and return to the normal display. Press escape to cancel the new selection and return to the norma...

  • Page 53

    Lake shore model 625 superconducting mps user’s manual operation 4-17 once the keypad lock mode has been selected, the keypad lock code must be entered to accept the change. The following screen appears as a prompt for the keypad lock code. Keypad lock enter a value for keypad lock code: use the dat...

  • Page 54

    Lake shore model 625 superconducting mps user’s manual 4-18 operation computer interface select with °® ieee term: cr lf use the s or t key to select one of the following terminators: cr/lf, lf/cr, lf, and eoi. The default is cr lf. Press enter to accept the new selection and continue to the next se...

  • Page 55: Chapter 5

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-1 chapter 5 computer interface operation 5.0 general this chapter provides operational instructions for the computer interface for the lake shore model 625 superconducting magnet power supply. Either of the two com...

  • Page 56

    Lake shore model 625 superconducting mps user’s manual 5-2 computer interface operation 5.1.1 changing ieee-488 interface parameters two interface parameters, address and terminators, must be set from the front panel before communication with the instrument can be established. Other interface parame...

  • Page 57

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-3 5.1.3.1 bus control commands a universal command addresses all devices on the bus. Universal commands include uniline and multiline commands. A uniline command (message) asserts only a single signal line. The mod...

  • Page 58

    Lake shore model 625 superconducting mps user’s manual 5-4 computer interface operation command mnemonics and parameter data necessary for each one is described in paragraph 5.3. Terminators must be sent with every message string. A query string is issued by the computer and instructs the instrument...

  • Page 59

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-5 figure 5-1. Model 625 status system (sheet 1 of 2).

  • Page 60

    Lake shore model 625 superconducting mps user’s manual 5-6 computer interface operation figure 5-1. Model 625 status system (sheet 2 of 2).

  • Page 61

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-7 5.1.4.1.6 reading registers any register in the status system may be read using the appropriate query command. Some registers clear when read, others do not. Refer to paragraph 5.1.4.1.7. The response to a query ...

  • Page 62

    Lake shore model 625 superconducting mps user’s manual 5-8 computer interface operation 5.1.4.2 status register sets as shown in figure 5-1, there are five register sets in the status system of the model 625; standard event status register, operation event register, hardware error status register, o...

  • Page 63

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-9 figure 5-3. Operation event register 5.1.4.3 error status register sets as shown in figure 5-1, there are three register sets in the error status system of the model 625; hardware error status register, operation...

  • Page 64

    Lake shore model 625 superconducting mps user’s manual 5-10 computer interface operation figure 5-4. Hardware error status register 5.1.4.3.2 operational error status register set the operational error status register reports the following instrument operational error events: magnet discharging thro...

  • Page 65

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-11 figure 5-5. Operational error status register 5.1.4.3.3 persistent switch heater error status register set the psh error status register reports the following psh error events: psh short, psh open circuit. Any o...

  • Page 66

    Lake shore model 625 superconducting mps user’s manual 5-12 computer interface operation 5.1.4.4 status byte and service request (srq) as shown in figure 5-1, the status byte register receives the summary bits from the two status register sets and the message available summary bit from the output bu...

  • Page 67

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-13 figure 5-7. Status byte register and service request enable register 5.1.4.4.3 using service request (srq) and serial poll when a status byte summary bit (or mav bit) is enabled by the service request enable reg...

  • Page 68

    Lake shore model 625 superconducting mps user’s manual 5-14 computer interface operation 5.1.4.4.4 using status byte query (*stb?) the status byte query (*stb?) command is similar to a serial poll except it is processed like any other instrument command. The *stb? Command returns the same result as ...

  • Page 69

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-15 5.1.5 ieee interface example programs two basic programs are included to illustrate the ieee-488 communication functions of the instrument. The first program was written in visual basic. Refer to paragraph 5.1.5...

  • Page 70

    Lake shore model 625 superconducting mps user’s manual 5-16 computer interface operation figure 5-8. Gpib0 setting configuration figure 5-9. Dev 12 device template configuration.

  • Page 71

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-17 5.1.5.2 visual basic ieee-488 interface program setup this ieee-488 interface program works with visual basic 6.0 (vb6) on an ibm pc (or compatible) with a pentium- class processor. A pentium 90 or higher is rec...

  • Page 72

    Lake shore model 625 superconducting mps user’s manual 5-18 computer interface operation table 5-4. Ieee-488 interface program control properties current name property new value label1 name caption lblexitprogram type “exit” to end program. Label2 name caption lblcommand command label3 name caption ...

  • Page 73

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-19 table 5-5. Visual basic ieee-488 interface program public gsend as boolean 'global used for send button state private sub cmdsend_click() 'routine to handle send button press gsend = true 'set flag to true end s...

  • Page 74

    Lake shore model 625 superconducting mps user’s manual 5-20 computer interface operation 5.1.5.3 ieee-488 interface board installation for quick basic program this procedure works on an ibm pc (or compatible) running dos or in a dos window. This example uses the national instruments gpib-pcii/iia ca...

  • Page 75

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-21 ibconf.Exe.Eps figure 5-10. Typical national instruments gpib configuration from ibconf.Exe.

  • Page 76

    Lake shore model 625 superconducting mps user’s manual 5-22 computer interface operation table 5-6. Quick basic ieee-488 interface program ' ieeeexam.Bas example program for ieee-488 interface ' ' this program works with quickbasic 4.0/4.5 on an ibm pc or compatible. ' ' the example requires a prope...

  • Page 77

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-23 5.1.5.5 program operation once either example program is running, try the following commands and observe the response of the instrument. Input from the user is shown in bold and terminators are added by the prog...

  • Page 78

    Lake shore model 625 superconducting mps user’s manual 5-24 computer interface operation 5.2 serial interface overview the serial interface used in the model 625 is commonly referred to as an rs-232c interface. Rs-232c is a standard of the electronics industries association (eia) that describes one ...

  • Page 79

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-25 5.2.3 hardware support the model 625 interface hardware supports the following features. Asynchronous timing is used for the individual bit data within a character. This timing requires start and stop bits as pa...

  • Page 80

    Lake shore model 625 superconducting mps user’s manual 5-26 computer interface operation message strings (continued) a query string is issued by the computer and instructs the instrument to send a response. The query format is: >. Query mnemonics are often the same as commands with the addition of a...

  • Page 81

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-27 5.2.7.1 visual basic serial interface program setup the serial interface program works with visual basic 6.0 (vb6) on an ibm pc (or compatible) with a pentium-class processor. A pentium 90 or higher is recommend...

  • Page 82

    Lake shore model 625 superconducting mps user’s manual 5-28 computer interface operation table 5-8. Serial interface program control properties current name property new value label1 name caption lblexitprogram type “exit” to end program. Label2 name caption lblcommand command label3 name caption lb...

  • Page 83

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-29 table 5-9. Visual basic serial interface program public gsend as boolean 'global used for send button state private sub cmdsend_click() 'routine to handle send button press gsend = true 'set flag to true end sub...

  • Page 84

    Lake shore model 625 superconducting mps user’s manual 5-30 computer interface operation 5.2.7.2 quick basic serial interface program setup the serial interface program listed in table 5-10 works with quickbasic 4.0/4.5 or qbasic on an ibm pc (or compatible) running dos or in a dos window with a ser...

  • Page 85

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-31 5.2.7.3 program operation once either example program is running, try the following commands and observe the response of the instrument. Input from the user is shown in bold and terminators are added by the prog...

  • Page 86

    Lake shore model 625 superconducting mps user’s manual 5-32 computer interface operation 5.3 command summary this paragraph provides a listing of the ieee-488 and serial interface commands. A summary of all the commands is provided in table 5-11. All the commands are detailed in paragraph 5.3.1, whi...

  • Page 87

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-33 table 5-11. Command summary command function page *cls clear interface cmd ................................................... 34 *ese event status enable cmd ........................................... 34 *ese?...

  • Page 88

    Lake shore model 625 superconducting mps user’s manual 5-34 computer interface operation 5.3.1 interface commands (alphabetical listing) *cls clear interface command input: *cls[term] remarks: clears the bits in the status byte register and standard event status register and terminates all pending o...

  • Page 89

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-35 *opc operation complete command input: *opc[term] remarks: used in conjunction with bit 0 (opc of the standard event status register. If sent as the last command in a command sequence, bit 0 will be set when the...

  • Page 90

    Lake shore model 625 superconducting mps user’s manual 5-36 computer interface operation *tst? Self-test query input: *tst?[term] returned: [term] format: n 0 = no errors found, 1 = errors found remarks: the model 625 reports status based on test done at power up. *wai wait-to-continue command input...

  • Page 91

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-37 erst? Error status query input: erst? [term] returned: , , [term] format: nnn,nnn,nnn remarks: the integers returned represent the sum of the bit weighting of the error bits. Refer to paragraph 5.1.4.3 for a lis...

  • Page 92

    Lake shore model 625 superconducting mps user’s manual 5-38 computer interface operation ieee ieee-488 interface parameter command input: ieee , , [term] format: n,n,nn specifies the terminator. Valid entries: 0 = ,1 = , 2 = , 3 = no terminator (must have eoi enabled). Sets eoi mode: 0 = enabled, 1 ...

  • Page 93

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-39 lock? Keyboard lock query input: lock?[term] returned: , [term] format: n,nnn (refer to command for description) mode ieee interface mode command input: mode [term] format: n 0 = local, 1 = remote, 2 = remote wi...

  • Page 94

    Lake shore model 625 superconducting mps user’s manual 5-40 computer interface operation psh persistent switch heater command input: psh [term] format: n [term] specifies if the persistent switch heater is to be turned on or off: 0 = heater off, 1 = heater on, 99 = heater on overriding output curren...

  • Page 95

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-41 qnch? Quench parameter query input: qnch? [term] returned: , [term] format: n, +n.Nnnn (refer to command for description) rate output current ramp rate setting command input: rate [term] format: +n.Nnnn specifie...

  • Page 96

    Lake shore model 625 superconducting mps user’s manual 5-42 computer interface operation rdgi? Current output reading query input: rdgi? [term] returned: [term] format: ±nn.Nnnn actual measured output current. Rdgrv? Remote voltage sense reading query input: rdgrv? [term] returned: [term] format: ±n...

  • Page 97

    Lake shore model 625 superconducting mps user’s manual computer interface operation 5-43 setf output field setting command input: setf [term] format: ±nnn.Nnne±nn specifies the output field setting: 0.0000 – ±601.000e+03 g or 0.0000 – ±60.1000e+00 t. Remarks: sets the field value that the output wil...

  • Page 98

    Lake shore model 625 superconducting mps user’s manual 5-44 computer interface operation trig trigger output current setting command input: trig [term] format: ±nn.Nnnn sets the value in which the output current will ramp to when the instrument is triggered: 0.0000 – ±60.1000a. Remarks: this command...

  • Page 99: Chapter 6

    Lake shore model 625 superconducting mps user’s manual options and accessories 6-1 chapter 6 options and accessories 6.0 general this chapter provides information on power line configurations and accessories available for the model 625 mps. 6.1 models the list of model 625 part numbers is provided a...

  • Page 100

    Lake shore model 625 superconducting mps user’s manual 6-2 options and accessories.

  • Page 101

    Lake shore model 625 superconducting mps user’s manual options and accessories 6-3 this page intentionally left blank.

  • Page 103: Chapter 7

    Lake shore model 625 superconducting mps user’s manual service 7-1 chapter 7 service this chapter provides basic service information for the model 625 superconducting magnet power supply. Customer service of the product is limited to the information presented in this chapter. Factory trained service...

  • Page 104

    Lake shore model 625 superconducting mps user’s manual 7-2 service 7.3 fuse drawer the model 625 may be configured for two basic ac power configurations: 100 or 120 vac and 220 or 240 vac. Each configuration requires the appropriate fuses and fuse holder. Units produced for use with 100 or 120 vac h...

  • Page 105

    Lake shore model 625 superconducting mps user’s manual service 7-3 line_input.Bmp figure 7-2. Power fuse access 7.5 fuse replacement use the following procedure to remove and replace the line fuses. Warning: to avoid potentially lethal shocks, turn off the power supply and disconnect it from ac powe...

  • Page 106

    Lake shore model 625 superconducting mps user’s manual 7-4 service the error messages are divided into two groups. Instrument hardware errors are related to the instruments internal circuits. When one of these errors occurs, the output crowbar scr will be thrown, the fault led will be lit and there ...

  • Page 107

    Lake shore model 625 superconducting mps user’s manual service 7-5 7.7 output source impedance the current output of the model 625 has a 25 Ω source impedance, resulting from a 25 Ω resistor across the output terminals. This is necessary to keep the output of the power supply stable into the purely ...

  • Page 108

    Lake shore model 625 superconducting mps user’s manual 7-6 service 7.8.2 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 b...

  • Page 109

    Lake shore model 625 superconducting mps user’s manual service 7-7 7.10 firmware replacement there are two integrated circuits (ic) that may potentially require replacement. See figure 7-3 for the ic location. • main firmware erasable programmable read only memory (eprom) (u22) – contains the user i...

  • Page 110

    Lake shore model 625 superconducting mps user’s manual 7-8 service 625 pcb.Bmp figure 7-3. Location of important internal components.

  • Page 111

    Lake shore model 625 superconducting mps user’s manual service 7-9 7.12 connector and cable definitions the analog i/o, psh output, digital i/o, and rs-232 (dte), and ieee-488 interface connectors are defined in figures 7-4 thru 7-8. Analog_output.Bmp pin name pin name 1 2 3 4 5 6 7 8 voltage sense ...

  • Page 112

    Lake shore model 625 superconducting mps user’s manual 7-10 service digital_io.Bmp pin name pin name 1 2 3 4 5 6 7 8 9 10 11 12 13 fault out common nc remote inhibit common nc trigger out common (not used) nc trigger in common nc nc nc nc nc nc 14 15 16 17 18 19 20 21 22 23 24 25 fault out nc remote...

  • Page 113

    Lake shore model 625 superconducting mps user’s manual service 7-11 7.12.1 serial interface cable wiring the following are suggested cable wiring diagrams for connecting the model 625 serial interface to various customer personal computers (pcs). Model 625 to pc serial interface – pc with de-9p mode...

  • Page 114

    Lake shore model 625 superconducting mps user’s manual 7-12 service 7.12.2 ieee-488 interface connector connect to the ieee-488 interface connector on the model 625 rear with cables specified in the ieee-488-1978 standard document. The cable has 24 conductors with an outer shield. The connectors are...

  • Page 115

    Lake shore model 625 superconducting mps user’s manual service 7-13 7.13 calibration lake shore maintains a fully automated calibration fixture for the model 625 that measures existing performance of the unit and then recalibrates the using nist traceable resistance and voltage standards. In additio...

  • Page 116

    Lake shore model 625 superconducting mps user’s manual 7-14 service 7.13.2 calibration equipment 1. Shunt resistor. The output current of the model 625 must be measured externally as the primary reference for calibration. When current is measured, it is the result of the current through the known re...

  • Page 117

    Lake shore model 625 superconducting mps user’s manual service 7-15 7.13.3.3 calibrate output voltage reading zero this step assumes that the previous two steps are successful and the current through the shunt resistor is quite low resulting in virtually no voltage across the model 625 output termin...

  • Page 118

    Lake shore model 625 superconducting mps user’s manual 7-16 service calibrate output current gain (continued) 1. Send “calg 10, 0”. To set the output current gain trim constant to 0. 2. Set the model 625 output current to +55 a (ramp rate 20 a/s nominal). 3. Wait 30 seconds for settling. 4. Measure ...

  • Page 119

    Lake shore model 625 superconducting mps user’s manual service 7-17 calibrate output current gain (continued) note: the model 625 has an internal, 25 resistor in parallel with the output terminals. The “v measured /25” factor accounts for the current that is diverted from the external shunt that flo...

  • Page 120

    Lake shore model 625 superconducting mps user’s manual 7-18 service 7.13.3.8 calibrate voltage reading gain 1. Add the larger load resistor in series with the shunt resistor. 2. Set the model 625 output compliance limit to 5 v. 3. Send “calg 5, 1”. To set the output voltage reading gain constant to ...

  • Page 121

    Lake shore model 625 superconducting mps user’s manual service 7-19 7.13.3.10 calibrate external current programming voltage reading gain 1. Connect the psh output in parallel with the dvm, a 100 resistor, (as a load) and the external current programming input lines. 2. Send “calg 7, 1”. To set the ...

  • Page 122

    Lake shore model 625 superconducting mps user’s manual 7-20 service calibration-specific interface commands (continued) calg? Gain calibration constant query input: calg? [term] format: nn 1 – 10. Returned: [term] format: ±nnnnnnn (refer to command for description) calsave calibration save command i...

  • Page 123: Appendix A

    Lake shore model 625 superconducting mps user’s manual glossary of terminology a-1 appendix a glossary of terminology accuracy. The degree of correctness with which a measured value agrees with the true value. 2 electronic accuracy. The accuracy of an instrument independent of the sensor. Sensor acc...

  • Page 124

    Lake shore model 625 superconducting mps user’s manual a-2 glossary of terminology boiling point. The temperature at which a substance in the liquid phase transforms to the gaseous phase; commonly refers to the boiling point at sea level and standard atmospheric pressure. Calibrate. To determine, by...

  • Page 125

    Lake shore model 625 superconducting mps user’s manual glossary of terminology a-3 four-lead. Measurement technique where one pair of excitation leads and an independent pair of measurement leads are used to measure a sensor. This method reduces the effect of lead resistance on the measurement. Gamm...

  • Page 126

    Lake shore model 625 superconducting mps user’s manual a-4 glossary of terminology kelvin scale. The kelvin thermodynamic temperature scale is the basis for all international scales, including the its-90. It is fixed at two points: the absolute zero of temperature (0 k), and the triple point of wate...

  • Page 127

    Lake shore model 625 superconducting mps user’s manual glossary of terminology a-5 permeability. Material parameter which is the ratio of the magnetic induction (b) to the magnetic field strength (h): µ = b/h. Also see initial permeability and differential permeability. Platinum (pt). A common tempe...

  • Page 128

    Lake shore model 625 superconducting mps user’s manual a-6 glossary of terminology seebeck effect. The development of a voltage due to differences in temperature between two junctions of dissimilar metals in the same circuit. 1 self-heating. Heating of a device due to dissipation of power resulting ...

  • Page 129: Appendix B

    Lake shore model 625 superconducting mps user’s manual temperature scales b-1 appendix b units for magnetic properties table b-1. Conversion from cgs to si units quantity symbol gaussian & cgs emu a conversion factor, c b si & rationalized mks c magnetic flux density, magnetic induction b gauss (g) ...

  • Page 130

    Lake shore model 625 superconducting mps user’s manual b-2 temperature scales table b-2. Recommended si values for physical constants quantity symbol value (si units) permeability of vacuum µ 0 4 × 10 -7 h m -1 speed of light in vacuum c 2.9979 × 10 8 m s -1 permitivity of vacuum 0 = (µ 0 c 2 ) -1 8...

  • Page 131: Appendix C

    Lake shore model 625 superconducting mps user’s manual handling lhe and ln 2 c-1 appendix c handling liquid helium and nitrogen c1.0 general use of liquid helium (lhe) and liquid nitrogen (ln 2 ) is often associated with the model 625 superconducting mps. Although not explosive, there are a number o...

  • Page 132

    Lake shore model 625 superconducting mps user’s manual c-2 handling lhe and ln 2 c4.0 liquid helium and nitrogen safety precautions transferring lhe and ln 2 and operation of the storage dewar controls should be in accordance with the manufacturer/supplier’s instructions. During this transfer, it is...