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Lakeshore 642 User Manual

Electromagnet power supply
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Methods and apparatus disclosed and described herein have been developed solely on company funds of Lake Shore Cryotronics, Inc. No government
or other contractual support or relationship whatsoever has existed which in any way affects or mitigates proprietary rights of Lake Shore Cryotronics,
Inc. in these developments. Methods and apparatus disclosed herein may be subject to U.S. Patents existing or applied for. Lake Shore Cryotronics,
Inc. reserves the right to add, improve, modify, or withdraw functions, design modifications, or products at any time without notice. Lake Shore shall
not be liable for errors contained herein or for incidental or consequential damages in connection with furnishing, performance, or use of this material.
Revision 1.3
User's Manual
Model 642
Electromagnet

Power Supply

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
P/N 119-042
9 January 2008

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Summary of Contents for Lakeshore 642

  • Page 1: Power Supply

    User’s Manual Model 642 Electromagnet Power Supply Lake Shore Cryotronics, Inc. 575 McCorkle Blvd. Westerville, Ohio 43082-8888 USA E-mail Addresses: sales@lakeshore.com service@lakeshore.com Visit Our Website At: www.lakeshore.com Fax: (614) 891-1392 Telephone: (614) 891-2243 Methods and apparatus disclosed and described herein have been developed solely on company funds of Lake Shore Cryotronics, Inc. No government or other contractual support or relationship whatsoever has existed which in any way affects or mitigates proprietary rights of Lake Shore Cryotronics, Inc.
  • Page 2 Limited Warranty specified above. Any unauthorized duplication legal rights and you might also have other rights that vary from or use of the Model 642 firmware in whole or in part, in print, or in any country to country, state to state or province to province.
  • Page 3 Lake Shore Model 642 Electromagnet Power Supply User’s Manual...
  • Page 4 Lake Shore Model 642 Electromagnet Power Supply User’s Manual This Page Intentionally Left Blank...

  • Page 5: Table Of Contents

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual TABLE OF CONTENTS Chapter/Section Title Page INTRODUCTION ..............................1-1 GENERAL ............................. 1-1 DESCRIPTION............................1-1 SPECIFICATIONS ..........................1-3 SAFETY SUMMARY..........................1-7 SAFETY SYMBOLS..........................1-9 MAGNET SYSTEM DESIGN, INSTALLATION, AND OPERATION..............2-1 GENERAL ............................. 2-1 INTRODUCTION...........................
  • Page 6 Lake Shore Model 642 Electromagnet Power Supply User’s Manual TABLE OF CONTENTS (Continued) Chapter/Section Title Page OPERATION................................4-1 GENERAL ............................. 4-1 TURNING POWER ON ......................... 4-1 DISPLAY DEFINITION.......................... 4-2 LED ANNUNCIATORS.......................... 4-2 4.3.1 Fault LED............................4-2 4.3.2 Compliance LED..........................4-2 4.3.3...
  • Page 7 Lake Shore Model 642 Electromagnet Power Supply User’s Manual TABLE OF CONTENTS (Continued) Chapter/Section Title Page 5.1.4.2 Status Register Sets ........................5-8 5.1.4.2.1 Standard Event Status Register ....................5-8 5.1.4.2.2 Operation Event Register Set..................... 5-9 5.1.4.3 Error Status Register Sets ......................5-10 5.1.4.3.1...
  • Page 8 Lake Shore Model 642 Electromagnet Power Supply User’s Manual TABLE OF CONTENTS (Continued) Chapter/Section Title Page FIRMWARE REPLACEMENT ....................... 7-7 7.10 CONNECTOR AND CABLE DEFINITIONS ..................7-11 7.10.1 Analog I/O Connector ........................7-11 7.10.2 Magnet Connector ........................... 7-11 7.10.3 Auxiliary Connector.......................... 7-12 7.10.4...
  • Page 9 Lake Shore Model 642 Electromagnet Power Supply User’s Manual LIST OF ILLUSTRATIONS Figure No. Title Page Model 642 Front Panel ..........................1-2 A Typical Electromagnet........................... 2-1 Typical Magnet Water Hook-Up........................ 2-2 Typical Magnet Coil Wiring Showing Series and Parallel Connections............. 2-3 Typical Thermal Switch, Flow Switch and Valve Wiring................
  • Page 10 Lake Shore Model 642 Electromagnet Power Supply User’s Manual LIST OF TABLES Table No. Title Page Rear Panel Connector Identification ......................3-2 Voltage and Current Selection ........................3-3 Current Capacity and Total Lead Lengths ....................3-9 Model 642 LED Descriptions ........................4-2 Model 642 Key Descriptions ........................

  • Page 11: Introduction

    0.1 mA and flexible output programming. Lake Shore chose linear input and output power stages for the nominal 2450 W output of the Model 642. Linear operation eliminates the radiated radio frequency (RF) noise associated with switching power supplies, allowing the Model 642 to reduce the overall noise in its output and the noise radiated into surrounding electronics.

  • Page 12: Model 642 Front Panel

    Output Architecture (Continued) The Model 642 output architecture relies on low noise, linear input and output stages. The linear circuitry of the Model 642 permits operation with less electrical noise than switch-mode electromagnet power supplies. One key benefit of this architecture is CE compliance to the electromagnetic compatibility (EMC) directive, including the radiated emissions requirement.

  • Page 13: Specifications

    A keypad lock-out feature is provided to prohibit any changes made from the front panel. The Model 642 can then be operated solely with the computer via the RS-232C or IEEE-488 interface.
  • Page 14 Lake Shore Model 642 Electromagnet Power Supply User’s Manual Specifications (Continued) Output programming Internal current setting Resolution 0.1 mA (20 bit) Settling time 600 ms for 1% step to within 1 mA (of internal setting) Accuracy ±10 mA ±0.05% of setting...
  • Page 15 Lake Shore Model 642 Electromagnet Power Supply User’s Manual Specifications (Continued) Interface IEEE-488.2 interface Features SH1, AH1, T5, L4, SR1, RL1, PP0, DC1, DT0, C0, E1 Reading rate To 10 rdg/s Software support National Instruments LabVIEW driver (consult Lake Shore for availability) ™...
  • Page 16 1 year Ordering Information Part Number Ordering Information 642-204 Model 642 70 A 35 V, 2.5 kW, 204/208 VAC 642-225 Model 642 70 A 35 V, 2.5 kW, 220/230 VAC 642-380 Model 642 70 A 35 V, 2.5 kW, 380 VAC 642-408 Model 642 70 A 35 V, 2.5 kW, 400/415 VAC...

  • Page 17: Safety Summary

    Lake Shore assumes no liability for Customer failure to comply with these requirements. The Model 642 protects the operator and surrounding area from electric shock or burn, mechanical hazards, excessive temperature, and spread of fire from the instrument. Environmental conditions outside of the conditions below may pose a hazard to the operator and surrounding area.
  • Page 18 Always use all four handles when moving the unit. Because of its weight, the Model 642 should be handled by mechanical means. If for some reason it is necessary to move it by hand, a minimum of two people is required.

  • Page 19: Safety Symbols

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual Safety Summary (Continued) SAFETY SYMBOLS Number Symbol Publication Description IEC 417, No. 5031 Direct current IEC 417, NO. 5032 Alternating current IEC 417, No. 5033 Both direct and alternating current IEC 617-2, No. 02-02-06 Three-phase alternating current IEC 417, No.
  • Page 20 Lake Shore Model 642 Electromagnet Power Supply User’s Manual This Page Intentionally Left Blank 1-10 Introduction...

  • Page 21: Magnet System Design, Installation, And Operation

    Chapter 4. INTRODUCTION A magnet used with the Model 642 Power Supply is typically an iron pole, twin coil, 4-inch pole diameter, variable air gap, water cooled electromagnet. Larger magnets can be used depending on their electrical parameters and the magnetic field requirements.

  • Page 22: Magnet Construction

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual MAGNET CONSTRUCTION The magnet consists of two water-cooled coils surrounding adjustable iron poles, which are fitted into an iron frame. The frame supports the poles and coils, and improves the magnet’s efficiency. The iron poles are fitted with adjusting mechanisms so that the air gap width can be set.

  • Page 23: Typical Magnet Coil Wiring Showing Series And Parallel Connections

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual POWER LEAD CROSS CONNECTION WIRING (PARALLEL WIRING) POWER LEAD BOLT BELLEVILLE WASHER CABLE CONNECTION MAGNET POWER LUG PLAIN WASHER POWER LEAD CROSS CONNECTION WIRING (SERIES WIRING) POWER LEAD Figure 2-3. Typical Magnet Coil Wiring Showing Series and Parallel Connections...

  • Page 24: Temperature Switches And Flow Switches

    The water can be turned on and off manually when the magnet is used, or automatically with a solenoid valve. The Model 642 provides automatic control and a 24 VAC at 1 A output for this purpose.

  • Page 25: Final Check-Out

    Maximum Current and Power The Model 642 was designed to operate with a magnet load resistance of 0.50 Ω, but will work with a resistance range of 0.40 Ω to 0.60 Ω. The resistance of a magnet will rise with a rise in temperature and this should be taken into account.
  • Page 26 Lake Shore Model 642 Electromagnet Power Supply User’s Manual Figure 2-5. Typical Curves of Field vs. Current for Various Air Gaps and Pole Cap Sizes (Sheet 2 of 3) Magnet System Design...

  • Page 27: Operation Under Field Control

    To obtain a linear field ramp, a magnetic sensor such as a Hall probe is placed in the air gap along with the sample being tested. The sensor is connected to a Gaussmeter. The output of the Gaussmeter is used to correct the programming input to the power supply. In this way non-linearity can be corrected. Lakeshore manufactures probes and Gaussmeters for this purpose.

  • Page 28: Avoiding Cooling Water Condensation

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 2.4.4 Avoiding Cooling Water Condensation If the temperature of the cooling water is too cool relative to the air temperature and humidity, condensation can occur. Condensation inside the power supply can cause severe damage. To avoid condensation, the power supply operator must remain cognizant of the ambient air temperature, cooling water temperature, and the relative humidity.

  • Page 29: Installation

    Moving and Handling Four handles are provided for ease of moving and handling the Model 642. The handles can be used in place of lifting lugs when cloth straps are used. Always use all four handles when moving the Model 642. Because of its weight, the Model 642 should be handled by mechanical means.

  • Page 30: Rear Panel Definition

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual REAR PANEL DEFINITION This paragraph defines the rear panel of the Model 642. Refer to Table 3-1. Readers are referred to paragraphs that contain installation instructions and connector pin-outs for each feature.

  • Page 31: Power Wiring And Set-Up

    Figure 3-1. Model 642 Rear Panel (shown with wiring cover removed) POWER WIRING AND SET-UP This section describes how to properly connect the Model 642 to the line power. Please follow these instructions carefully to ensure proper operation of the instrument and the safety of operators.

  • Page 32: Circuit Breaker Setting

    Circuit Breaker Setting The circuit breaker is an important safety feature of the Model 642. The required current setting depends on the voltage for which the unit is wired. (Refer to Table 3-2.) Verify that the circuit breaker is set correctly for the line voltage being applied to the unit.

  • Page 33: Start-Up Fuses

    Power Input Terminals The Model 642 requires a 4 conductor power cord (not included). The input to the Model 642 is wired in a delta configuration, but will operate from a delta or wye source. If operating from a wye source, the neutral line (N) is not used.

  • Page 34: Wiring Cover

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 140 mm (5.5 in) POWER CABLE STRIP 13mm (0.5 in) WIRE FERRULE (OPTIONAL) POWER TERMINALS Figure 3-6. Typical Power Input Wiring 3.3.6 Wiring Cover When the power wiring, voltage setting and current setting are complete, install the wiring cover with the six (6) 6-32 ×...

  • Page 35: Mains Wiring

    The flow or temperature switch must have a normally closed contact rated at 5 V at 10 mA. A contact closure is required to enable the Model 642 output. If a switch is not used, a jumper is required.

  • Page 36: Power Supply Connector

    The flow switch must have a normally closed contact rated at 5 V at 10 mA contact closure is required to enable the Model 642 output. If a switch is not used, a jumper is required. 24 VAC at 1 A is provided to operate a water control solenoid valve for the power supply cooling water.

  • Page 37: Magnet Cable Connections

    Lake Shore sells magnet cables in 10 and 20 foot lengths. Refer to Paragraph 6.2 for ordering accessories. Figure 3-13 shows how the output cables are connected to the Model 642. A plain washer and a spring or Belleville washer are provided. The Belleville washer is required to maintain contact pressure through varying material thickness due to heating.

  • Page 38: Output Cable Connection

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual BOLT BELLEVILLE WASHER PLAIN WASHER OUTPUT LUG MAGNET CABLE Figure 3-13. Output Cable Connection LUG COVER 38 mm (1.5 in) MOUNTING SCREWS Figure 3-14. Output Lug Cover Installation 3-10 Installation...

  • Page 39: Analog Input/Output Connections

    3.5 V = 35V. Both outputs have a source impedance of 20 Ω. 3.10 COMPUTER INTERFACE The Model 642 can be programmed externally with a computer. Both RS-232C and IEEE-488 ports are provided. 3.10.1 RS-232C Interface Connection An RS-232C port has been provided to allow remote computer control of the power supply. (Refer to Chapter 5, Computer Interface Operation) 3.10.2...

  • Page 40: Detachable Handles

    In addition, if the equipment rack which houses the Model 642 is to be shipped, the Model 642 must be anchored to the shelf. Threaded inserts are provided in the bottom of the Model 642 for this purpose. Four (4) ¼-20 × ½ in bolts (not included) are required.

  • Page 41: Operation

    Instructions for checking line voltage selection are given in Paragraph 3.3.1. CAUTION: Be sure the unit is connected to an appropriate load before applying power. The Model 642 will not turn on if an Emergency Stop Switch is not connected or a jumper is not put in its Note: place on the “Auxiliary”...

  • Page 42: Display Definition

    4.3.3 Power Limit LED The Model 642 has a hardware power limit to protect the internal power MOSFETs. If the power supply is driving a load which has a resistance lower than the supply’s rated minimum, the power required may be higher than the devices can safely handle.

  • Page 43: Keypad Definition

    KEYPAD DEFINITION The Model 642 has 22 keys separated into 3 groups on the instrument front panel. The sixteen keys in the center of the grouping combines instrument setup and data entry. The keys below control the output current and ramping. The keys to the right control the computer interface mode of the instrument.

  • Page 44: General Keypad Operation

    SETTING OUTPUT CURRENT The main purpose of the Model 642 Electromagnet Power Supply is to supply a very precise and stable current to a magnet load. Before setting output current, make sure that the instrument is properly setup for the magnet system that is being used.
  • Page 45 CURRENT RAMP RATE The output current of the Model 642 will always ramp from one current setting to another. There is no way to turn off the current ramping function, but if a very fast ramp rate is desired, a ramp rate as high as 99.999 A/s can be entered.

  • Page 46: Current Ramp Rate

    This key is equivalent to using the Output Setting key and entering 0 A except that it works even when the Model 642 is being programmed externally.

  • Page 47: Maximum Setting Limits

    MAXIMUM SETTING LIMITS The Model 642 offers a maximum setting limit for output current and ramp rate. Typical properties of the magnet will dictate these parameters. These maximum parameters should be entered before the magnet system is used to prevent damage.

  • Page 48: Magnet Water

    The Off menu selection can be used to turn it off. In the Disabled mode, the Model 642 assumes that no valve is installed and the line for Magnet Water status will not be displayed.

  • Page 49: External Current Programming

    EXTERNAL CURRENT PROGRAMMING The output current of the Model 642 can be set internally, externally, or by the sum of the external and internal settings. Normally, the current is controlled internally by entering a setting from the front panel using the Output Setting key.

  • Page 50: Computer Interface

    COMPUTER INTERFACE There are two computer interfaces on the Model 642, a serial RS-232C interface and an IEEE-488 interface. These interfaces are used to connect the instrument to a computer for automated control or data taking. Refer to Chapter 5.

  • Page 51: Changing Ieee-488 Interface Parameters

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 4.17.2 Changing IEEE-488 Interface Parameters Two interface parameters, address and terminators, must be set from the front panel before IEEE-488 communication with the instrument can be established. Other interface parameters can be set via the interface using the device specific commands provided in Paragraph 5.3.

  • Page 52: Default Parameter Values

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual Table 4-3. Default Parameter Values Output Settings Keypad Locking Output Current* ........0 A State..........Unlocked Current Ramp Rate..... 99.999 A/s Lock Code ..........123 Maximum Settings Computer Interface Max Output Current......70.1 A Baud............

  • Page 53: Computer Interface Operation

    Paragraph 7.12.2. Cables can be purchased from Lake Shore or other electronic suppliers. Cable lengths are limited to 2 meters for each device and 20 meters for the entire bus. The Model 642 can drive a bus with up to 10 loads. If more instruments or cable length is required, a bus expander must be used.

  • Page 54: Changing Ieee-488 Interface Parameters

    Remote/Local Operation Normal operations from the keypad are referred to as ‘Local’ operations. The Model 642 can also be configured for ‘Remote’ operations via the IEEE-488 interface or the Remote key. The Local key will take the instrument out of ‘Remote’...

  • Page 55: 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 Model 642 recognizes two of these messages from the BUS CONTROLLER: Remote (REN) and Interface Clear (IFC). The Model 642 sends one Uniline Command: Service Request (SRQ).

  • Page 56: Status System

    5.1.4.1 Overview The Model 642 implements a status system compliant to the IEEE 488.2 – 1992 standard. The status system provides a method of recording and reporting instrument information and is typically used to control the Service Request (SRQ) interrupt line. A diagram of the status system is shown in Figure 5-1. The status system is made up of register sets, the Status Byte register and the Service Request Enable register.

  • Page 57: Status Byte Register

    Used Used Used OPSTR? Operation Event Enable Register Name OPSTE, Used Used Used Used Used OPSTE? PRLM = Power Limit RAMP = Ramp Done COMP = Compliance Figure 5-1. Model 642 Status System (Sheet 1 of 2) Computer Interface Operation...
  • Page 58 1 of 2 LLV = Low Line Voltage TH = Temperature High EPE = External Current Program Error CAL = Calibration Error Error Status Enable Register Name ERSTE, ERSTE? Figure 5-1. Model 642 Status System (Sheet 2 of 2) Computer Interface Operation...

  • Page 59: Service Request Enable Register

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 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 will be a decimal value that corresponds to the binary-weighted sum of all bits in the register, Refer to Table 5-1.

  • Page 60: Standard Event Status Register

    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 642; Standard Event Status Register, Operation Event Register, Hardware Error Status Register, Operational Error Status Register, and the Persistent Switch Error Register.

  • Page 61: Operation Event Register Set

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 5.1.4.2.2 Operation Event Register Set The Operation Event Register reports the following instrument events: ramp done, compliance. Any or all of these events may be reported in the operation event summary bit through the enable register, see Figure 5-3. The Operation Event Enable command (OPSTE) programs the enable register and the query command (OPSTE?) reads it.

  • Page 62: Error Status Register Sets

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 5.1.4.3 Error Status Register Sets As shown in Figure 5-1, there are two register sets in the error status system of the Model 642; Hardware Error Status Register, and Operational Error Status Register. 5.1.4.3.1...

  • Page 63: Operational Error Status Register Set

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 5.1.4.3.2 Operational Error Status Register Set The Operational Error Status Register reports the following instrument operational error events: remote enable fault detected, power supply flow switch fault detected, magnet flow switch fault detected, high line voltage, low line voltage, temperature high, external current program error, calibration error.

  • Page 64: Status Byte And Service Request (Srq)

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 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 buffer. The status byte is used to generate a service request (SRQ). The selection of summary bits that will generate an SRQ is controlled by the Service Request Enable Register.

  • Page 65: Service Request Enable Register

    The bus controller can, for example, send a query command to the Model 642 and then wait for MAV to set. If the MAV bit has been enabled to initiate an SRQ, the user’s program can direct the bus controller to look for the SRQ leaving the bus available for other use.

  • Page 66: Using Operation Complete (*Opc) And Operation Complete Query (*Opc?)

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 5.1.4.4.6 Using Operation Complete (*OPC) and Operation Complete Query (*OPC?) The Operation Complete (*OPC) and Operation Complete Query (*OPC?) are both used to indicate when pending device operations complete. However, the commands operate with two distinct methods.

  • Page 67: Gpib0 Setting Configuration

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual Figure 5-7. GPIB0 Setting Configuration Figure 5-8. DEV 12 Device Template Configuration Computer Interface Operation 5-15...

  • Page 68: Visual Basic Ieee-488 Interface Program Setup

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 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 recommended, running Windows 95 or better. It assumes your IEEE-488 (GPIB) card is installed and operating correctly (refer to Paragraph 5.1.5.1).

  • Page 69: Ieee-488 Interface Program Control Properties

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual Table 5-4. IEEE-488 Interface Program Control Properties Current Name Property New Value Label1 Name lblExitProgram Caption Type “exit” to end program. Label2 Name lblCommand Caption Command Label3 Name lblResponse Caption Response...

  • Page 70: Visual Basic Ieee-488 Interface Program

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 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...

  • Page 71: Typical National Instruments Gpib Configuration From Ibconf.exe

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual à à é é ê ê é é à à ê ê IBCONF.EXE.eps Figure 5-9. Typical National Instruments GPIB Configuration from IBCONF.EXE Computer Interface Operation 5-19...

  • Page 72: Program Operation

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 5.1.5.3 Program Operation Once the 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 program. The word [term] indicates the required terminators included with the response.

  • Page 73: Serial Interface Overview

    SERIAL INTERFACE OVERVIEW The serial interface used in the Model 642 is commonly referred to as an RS-232C interface. RS-232C is a standard of the Electronics Industries Association (EIA) that describes one of the most common interfaces between computers and electronic equipment.

  • Page 74: Hardware Support

    Hardware Support The Model 642 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 part of each character so the transmitter and receiver can be resynchronized between each character.

  • Page 75: Message Flow Control

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual Message Strings (Continued) A query string is issued by the computer and instructs the instrument to send a response. The query format is: <query mnemonic><?><space><parameter data><terminators>. Query mnemonics are often the same as commands with the addition of a question mark. Parameter data is often unnecessary when sending queries.

  • Page 76: Visual Basic Serial Interface Program Setup

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 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 recommended, running Windows 95 or better, with a serial interface. It uses the COM1 communications port at 9600 Baud.

  • Page 77: Serial Interface Program Control Properties

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual Table 5-7 Serial Interface Program Control Properties Current Name Property New Value Label1 Name lblExitProgram Caption Type “exit” to end program. Label2 Name lblCommand Caption Command Label3 Name lblResponse Caption Response...

  • Page 78: Visual Basic Serial Interface Program

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual Table 5-8. 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...

  • Page 79: Program Operation

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 5.2.7.2 Program Operation Once the 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 program. The word [term] indicates the required terminators included with the response.

  • Page 80: Command Summary

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 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 5-9. All the commands are detailed in Paragraph 5.3.1, which is presented in alphabetical order.

  • Page 81: Interface Commands (Alphabetical Listing)

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual Table 5-9. Command Summary Command Function Page Command Function ............Page *CLS Clear Interface Cmd ........29 INTWR? Internal Water Mode Query ......33 *ESE Event Status Enable Cmd......29 KEYST? Keypad Status Query ........33 *ESE? Event Status Enable Query......30...
  • Page 82 Lake Shore Model 642 Electromagnet Power Supply User’s Manual *ESE? Standard Event Status Enable Register Query *ESE?[term] Input: Returned: <bit weighting>[term] (Refer to command for description) Format: *ESR? Standard Event Status Register Query *ESR?[term] Input: Returned: <bit weighting> Format: Bits in this register correspond to various system events and latch when the event occurs. When an Remarks: event bit is set, subsequent events corresponding to that bit are ignored.
  • Page 83 Input: *TST?[term] Returned: <status>[term] Format: <status> 0 = No errors found, 1 = Errors found The Model 642 reports status based on test done at power up. Remarks: *WAI Wait-to-Continue Command Input: *WAI[term] This command is not supported in the Model 642.
  • Page 84 Lake Shore Model 642 Electromagnet Power Supply User’s Manual DFLT Factory Defaults Command Input: DFLT 99[term] Sets all configuration values to factory defaults and resets the instrument. The instrument must be at Remarks: zero amps for this command to work. The "99" is included to prevent accidentally setting the unit to defaults.
  • Page 85 Lake Shore Model 642 Electromagnet Power Supply User’s Manual ERSTR? Error Status Register Query Input: ERSTR? [term] Returned: <hardware errors>, <operational errors> [term] nnn,nnn Format: The integers returned represent the sum of the bit weighting of the error bits. These error bits are Remarks: latched when an error condition is detected.
  • Page 86 IEEE Interface Mode Command Input: MODE <mode>[term] Format: <mode> 0 = Local, 1 = Remote, 2 = Remote with local lockout. MODE 2[term] – Places the Model 642 into remote mode with local lockout. Example: MODE? IEEE Interface Mode Query Input: MODE?[term] Returned: <mode>[term]...
  • Page 87 Lake Shore Model 642 Electromagnet Power Supply User’s Manual OPST? Operational Status Query Input: OPST? [term] Returned: <bit weighting> [term] Format: The integer returned represents the sum of the bit weighting of the operational status bits. Refer to Remarks: Paragraph 5.1.4.2.2 for a list of operational status bits.
  • Page 88 Lake Shore Model 642 Electromagnet Power Supply User’s Manual RDGV? Output Voltage Reading Query Input: RDGV? [term] Returned: <voltage> [term] Format: ±n.nnnn <voltage> Actual output voltage measured at the power supply terminals. RSEG Ramp Segments Enable Command Input: RSEG <enable> [term]...
  • Page 89 XPGM <mode>[term] Format: <mode> 0 = Internal, 1 = External, 2 = Sum. XPGM 1[term] – Places the Model 642 into external program mode where the output current is set by Example: an external voltage. XPGM? External Program Mode Query...
  • Page 90 Lake Shore Model 642 Electromagnet Power Supply User’s Manual This Page Intentionally Left Blank 5-38 Computer Interface Operation...

  • Page 91: Options And Accessories

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual CHAPTER 6 OPTIONS AND ACCESSORIES GENERAL This chapter provides information on accessories available for the Model 642 Electromagnet Power Supply. ACCESSORIES INCLUDED Part Number Description MAN-Model 642 Model 642 Electromagnet Power Supply User’s Manual.
  • Page 92 Lake Shore Model 642 Electromagnet Power Supply User’s Manual This Page Intentionally Left Blank Options and Accessories...

  • Page 93: Service

    RETURNING PRODUCTS TO LAKE SHORE If it is necessary to return the Model 642 for recalibration, repair or replacement, a Return Authorization (RA) number must be obtained from a factory representative or from the Lake Shore web site. Do not return a product to Lake Shore without an RA number.

  • Page 94: Line Voltage Selection

    LINE VOLTAGE SELECTION The Model 642 may be configured for four basic AC power configurations: 208 VAC, 230 VAC, 380 VAC and 415 VAC. Proper voltage selection must be made before connection to the power mains. Each configuration requires the appropriate wiring within the power wiring access panel on the rear of the instrument.

  • Page 95: Voltage Change Detail

    Use the following procedure to verify or change the circuit breaker current setting. 1. Identify the power wiring access panel on the rear of the Model 642. 2. Turn the front panel line power switch OFF (O). 3. Disconnect the power cable at the plug end for safety.

  • Page 96: Power Line Fuse Replacement

    The start-up supply is energized any time the three-phase power input voltage is connected to the Model 642. This section deals with the fuses for this supply. If the power line fuses for this supply are open, the Model 642 internal three-phase contactor will not close and normal operation will not be possible.

  • Page 97: Error Messages

    Cold Plate temperature is over 45° C. The output setting is set to 0 A and no current Internal Temperature Fault entry will be allowed. The error message will flash for 10 seconds then the Model 642 will turn itself off.

  • Page 98: Electrostatic Discharge

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual Table 7-3. Operational Errors The Remote Enable connection loop is not closed. The output setting is set to 0 A and Remote Enable Fault no current entry will be allowed. Once the loop is closed, the error is cleared by pressing Detected the STATUS key or sending “ERCL”...

  • Page 99: Handling Electrostatic Discharge Sensitive Components

    7.8.2 Installation 1. Replace the top panel on the Model 642 with the folded lip of the panel toward the front of the unit. 2. Replace and secure the 17 flat-headed Phillips screws. Do not use excessive torque. 3. Replace the two Phillips head screws securing the top panel lip to the top edge of the front panel.
  • Page 100 Lake Shore Model 642 Electromagnet Power Supply User’s Manual Firmware Replacement (Continued) 4. Disconnect the ribbon cable to the Analog Board assembly from J-2. 5. Disconnect the cable to the fan from J-3. 6. Disconnect the ribbon cable to the Keypad Board assembly from J-4.

  • Page 101: Board Locations

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual DIGITAL BOARD Figure 7-5. Board Locations (top view) Service...

  • Page 102: Digital Board Parts Locations

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual CR15 CR16 CR10 CR11 MOUNTING SCREWS C126 C113 C123 C127 C114 IRDG GND2 VRDG A/D 2 IN C104 C112 JMP1 TEST C117 C118 C122 C121 C102 C119 +5(1) GND 1 111-278 /A...

  • Page 103: Connector And Cable Definitions

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual 7.10 CONNECTOR AND CABLE DEFINITIONS All non-power electrical connections to the rear of the Model 642 are detailed in this section. 7.10.1 Analog I/O Connector The Analog I/O connector provides the connections for the External Programming voltage as well as Analog representations of the current and voltage output levels.

  • Page 104: Auxiliary Connector

    The Auxiliary Connector provides connections for three functions: 1. Emergency Stop – This normally-closed circuit turns off power to the Model 642 just as if the OFF (O) button was pressed on the front panel when opened. Normal operation requires a closed connection between the pins.

  • Page 105: Power Supply Connector

    The Power Supply connector provides the means to connect a water control valve (24 VAC) and an associated water flow switch (closed during flow) to protect the Model 642 from loss of water flow. Pins 1 & 2 must be closed for normal operation.

  • Page 106: Serial Interface Cable Wiring

    The total length of cable allowed in a system is 2 meters for each device on the bus, or 20 meters maximum. The Model 642 can drive a bus of up to 10 devices. A connector extender is required to use the IEEE-488 Interface and Relay Terminal Block at the same time.

  • Page 107: Ieee-488 Connector Details

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual Symbol Description DIO 1 Data Input/Output Line 1 DIO 2 Data Input/Output Line 2 DIO 3 Data Input/Output Line 3 DIO 4 Data Input/Output Line 4 End Or Identify Data Valid...

  • Page 108: Calibration

    Uncalibrated (default) values for gains are 1 while offsets are 0. Operation with these values is possible but the accuracy will be reduced to as much as ±2% of full scale, generally. If the Model 642 is used in closed loop operation and programmed through the external input, regular calibration may not be required.

  • Page 109: Calibration Equipment

    This resistor must withstand the full current of the Model 642 and do so with a minimum of heating that can easily change the resistance and therefore the current measurement. At 70 A, this resistor only dissipates 4.9 W. Even so, it is highly recommended to mount the resistor on a heat sink with forced air-cooling to minimize temperature rise and related value changes during calibration.

  • Page 110: Calibrate Output Voltage Reading Zero

    3. Get the Model 642 external programming voltage reading. NOTE: To get this reading from the Model 642, press and hold the Status key on the front panel until the display goes dark ( 3 seconds). When the key is then released, a diagnostics display will be seen. The upper right reading, “EXT PROG”, is the reading needed for this step.
  • Page 111 31. Recalibrate Current Output Zero (refer to Section 7.13.3.1). 32. Recalibrate Current Reading Zero (refer to Section 7.13.3.2). 33. Set the Model 642 output current to 65 A (ramp rate 30 A/s nominal). 34. Wait 30 seconds. 35. Measure the actual voltage across the shunt and record (V shunt 36.

  • Page 112: Calibrate Current Reading Gain

    11. Verify the gain factor to be 1, ±0.02. 12. Send “CALG 5, gain constant”. 13. Verify the Model 642 output voltage reading to match the actual output voltage within, ±0.001 V. 14. Set the Model 642 output current to 0 A.

  • Page 113: Calibrate External Current Programming Voltage Reading Gain

    NOTE: To get this reading from the Model 642, press and hold the Status key on the front panel until the display goes dark (~3 seconds). When the key is then released, a diagnostics display will be seen. The upper right reading, “Ext Prog”, is the reading needed for this step.
  • Page 114 Lake Shore Model 642 Electromagnet Power Supply User’s Manual Gain Calibration Constant Query CALG? Input: CALG? <type>[term] Format: nn <type> 0 – 10. Returned: <value>[term] Format: ±nnnnnnn (Refer to command for description) Calibration Save Command CALSAVE Input: CALSAVE[term] Saves all CALZ and CALG calibration constants in non-volatile memory.

  • Page 115: Appendix A - Glossary Of Terminology

    Lake Shore Model 642 Electromagnet Power Supply User’s Manual APPENDIX A GLOSSARY OF TERMINOLOGY accuracy. The degree of correctness with which a measured value agrees with the true value. electronic accuracy. The accuracy of an instrument independent of the sensor.
  • Page 116 Lake Shore Model 642 Electromagnet Power Supply User’s Manual 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 measurement or comparison with a standard, the correct value of each scale reading on a meter or other device, or the correct value for each setting of a control knob.
  • Page 117 Lake Shore Model 642 Electromagnet Power Supply User’s Manual 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.
  • Page 118 Lake Shore Model 642 Electromagnet Power Supply User’s Manual 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 water (273.16 K), the equilibrium temperature that pure water reaches in the presence of ice and its own vapor.
  • Page 119 Lake Shore Model 642 Electromagnet Power Supply User’s Manual 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 temperature sensing material fabricated from pure platinum to make the Lake Shore PT family of resistance temperature sensor elements.
  • Page 120 Lake Shore Model 642 Electromagnet Power Supply User’s Manual Seebeck effect. The development of a voltage due to differences in temperature between two junctions of dissimilar metals in the same circuit. self-heating. Heating of a device due to dissipation of power resulting from the excitation applied to the device. The output signal from a sensor increases with excitation level, but so does the self-heating and the associated temperature measurement error.
  • Page 121 Lake Shore Model 642 Electromagnet Power Supply User’s Manual APPENDIX B UNITS FOR MAGNETIC PROPERTIES Table B-1. Conversion from CGS to SI Units Gaussian Conversion SI & Quantity Symbol & CGS emu Factor, C Rationalized mks Magnetic flux density, tesla (T), Wb/m...
  • Page 122 Lake Shore Model 642 Electromagnet Power Supply User’s Manual Table B-2. Recommended SI Values for Physical Constants Quantity Symbol Value (SI units) µ Permeability of Vacuum 4 × 10 Speed of Light in Vacuum 2.9979 × 10 Permitivity of Vacuum 8.8542 ×...

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