Manual - ETS
Contents
1. 12 4 0 Theory of Operation Before operating any components follow the safety information in the ETS Lindgren Product Information Bulletin included with your shipment The basic premise of a Helmholtz coil is that it produces a homogeneous magnetic field in its center which is directly proportional to the number of turns in the coils and the current applied to them A Helmholtz coil is a parallel pair of identical circular coils spaced one radius apart and wound so that the current flows through both coils in the same direction The winding results in a very uniform magnetic field between the coils with the primary component parallel to the axes of the two coils The uniform field is the result of the addition of the two field components parallel to the axes of the two coils and the difference between the components perpendicular to the axes The primary purpose of this device is to provide a uniform low frequency magnetic field for susceptibility testing of electronic equipment The magnetic field strength H produced by a given AC or DC current through the coil pair is given approximately by the formula H zx 0 899 R e His the magnetic field in oersteds e Nis the number of turns per coil e is the coil current in amperes e Ris the coil radius in centimeters 13 14 In SI Units this becomes the formula where H x agis R e His the magnetic field in amperes per meter e Nis the number of turns per coil e is the c2. and other product marking information 1 0 Introduction ETS Lindgren Model 6400 Helmholtz Coils create an extremely uniform low frequency magnetic field between and in the center of the coils The generated field can be applied as a magnetic field immunity test system or a low frequency calibrator The strength of the magnetic field generated is directly proportional to the number of turns in the coils and the current applied to them The coils are wound in series so that the magnetic field produced by current flowing in one coil aids the field in the other coil The windings on all standard Helmholtz coils are wound of insulated magnet wires The wire gauge varies depending upon the model of the coil system and details are found in the Specification section of this manual The maximum current of a custom Helmholtz coil is determined by the wire gauge Several of the Helmholtz coils are equipped with a rotatable adjustable height pedestal capable of supporting equipment under test EUT in the center of the assembly base Equipment which is exposed to the homogenous magnetic field should be placed on the equipment test table with the height adjusted so that the center of the equipment is closely aligned with the axis of the coils Ferromagnetic objects within the cylindrical volume of the coil tend to distort the magnetic fields in areas near the object The coil system has been constructed with minimal metallic components limited to the copper co
3. Model 6400 Series Helmholtz Coil User Manual S ETS LINDGREN An ESCO Technologies Company ETS Lindgren L P reserves the right to make changes to any product described herein in order to improve function design or for any other reason Nothing contained herein shall constitute ETS Lindgren L P assuming any liability whatsoever arising out of the application or use of any product or circuit described herein ETS Lindgren L P does not convey any license under its patent rights or the rights of others Copyright 2001 2011 by ETS Lindgren L P All Rights Reserved No part of this document may be copied by any means without written permission from ETS Lindgren L P Trademarks used in this document The ETS Lindgren logo is a trademark of ETS Lindgren L P Revision Record 6400 Series Helmholtz MANUAL Part 399273 Rev B Revision Description ae Initial Release December 2001 Updated title to reflect series June 2009 Revise to current style standards Removed filter addendum add filter information as a numbered section Update table format in Section 3 April 2011 Specifications Update measurement in Section 5 Operation from 2 45 cm to 2 54 cm Table of Contents Notes Cautions and WarningS ccccscesssseeseeeeeeeeneseeeeeees iv 1 0 INULOGUCTIONT aiina eee ae eee ea 5 Model 6406S or Split Base Helmholtz Coils 0 0 0 0 ceecceceeeeeeeeeeseeeeeeaees 6 ETS Lindgren Product Info
4. eneity of magnetic fields within the test volume gt Push the coil assemblies into position by holding the coil section of each assembly Do not push the coil assemblies using the thermoplastic support rods Helmholtz Coil EUT Table For units equipped with an adjustable table the table should be set at the desired height before placing the test item on it To adjust the table height first loosen the clamp screw s and then move the table height up or down to the desired level Hand tighten the clamp screw s The table can be lifted off of the platform to accommodate larger EUTs Simply remove the plastic support screws on the floor of the coil platform that attach the table and gently lift and remove the table gt The marks on the support column are spaced 2 54 cm 1 inch apart for reference A mechanical stop limits the table travel within its lowest and highest position gt The top of the table is within 2 54 cm 1 inch of the coil system axis when the lowermost inch mark is at the top of the base column 17 Limit the weight of the equipment placed on the table to the coil specifications in the chart that follows Center the EUTs mass over the center of the base Do not lubricate the support column but keep the column clean by periodically cleaning with a clean damp cloth C e e 6404 34 75 b 6406 34 kg 75 Ib 6406S Split base no rr ae 6408 34 34kg 75Ib 75 b With the exception of the wi
5. gidly supported by a nonmetallic nonmagnetic framework The supplied cable assembly and proper orientation of the coils insures that the Helmholtz coil system is arranged in the series aiding configuration ETS Lindgren Product Information Bulletin See the ETS Lindgren Product Information Bulletin included with your shipment for the following Warranty information e Safety regulatory and other product marking information Steps to receive your shipment e Steps to return a component for service ETS Lindgren calibration service ETS Lindgren contact information 2 0 Maintenance CAUTION ht 4 WARRANTY Before performing any maintenance follow the safety information in the ETS Lindgren Product Information Bulletin included with your shipment Maintenance of the Helmholtz coil is limited to external components such as cables or connectors Clean the exterior of the coil using a damp cloth and mild cleaner Always unplug the unit before cleaning If you have any questions concerning maintenance contact ETS Lindgren Customer Service Maintenance Recommendations Maintenance is limited to periodically cleaning the coil with a clean damp cloth Annual Calibration See the Product Information Bulletin included with your shipment for information on ETS Lindgren calibration services Service Procedures For the steps to return a system or system component to ETS Lindgren for
6. nductors the electrical connectors and the caster frames The casters however are outside of the coil cylinder and cause practically no field disturbance Precision in the manufacture of the coils and their support assembly are well within a design tolerance of 0 5 cm 0 2 in in both radius and axial separation The limit of this tolerance would produce a maximum error of 0 55 in the accuracy of the magnetic field constant under the worst conditions For this reason the Helmholtz coil is considered a standard and produces a magnetic field whose accuracy is governed by the accuracy of the current monitoring equipment Model 6406S or Split Base Helmholtz Coils A standard ETS Lindgren Helmholtz coil consists of two identical circular coils placed in parallel and spaced one radius apart The coils are both mounted to a single base with an adjustable pedestal placed in the center to position the EUT Some EUT s however do not fit conveniently on the pedestal In these instances a split base option may be ordered Each coil is mounted on a separate wheeled base for positioning on either side of the EUT such as an automobile The Model 6406S Helmholtz Coil consists of two coils secured on separate base mounts in the Helmholtz configuration which can be used as a low frequency calibrator The coil provides a magnetic field which is essentially homogenous throughout the volume of a 0 60 meter 2 foot cylinder in its center The coil forms are ri
7. necessary to series resonate the coil if high driving current is required at a high frequency If this is the case take precautions to avoid shock or burn from the high voltages developed across the reactive elements 19 This page intentionally left blank 20 Appendix A Warranty gt See the Product Information Bulletin included with your shipment for the complete ETS Lindgren warranty for your Helmholtz Coil System DURATION OF WARRANTIES FOR A HELMHOLTZ COIL SYSTEM All product warranties except the warranty of title and all remedies for warranty failures are limited to two years Product Warranted Duration of Warranty Period 21 This page intentionally left blank 22 Appendix B Conversion Table for Magnetic Units To Convert From ma EO S System Memes je HBB Quantity E ca turn m a a a e e Multiply by above value t Assumes w 1 if 1 multiply by value of u to convert from H to B Assumes y 1 if 1 divide by value of u to convert from B to H 1 tesla 1 weber m For example 1 tesla 10 gauss 1 gauss 79 6 ampere turns m in an unloaded coil u 1 If u 2 50 1 tesla 7 96 x 10 2 50 3 18 x 10 amp turns m 23 This page intentionally left blank 24
8. oil current in amperes e Ris the coil radius in meters If instead of magnetic field intensity H the magnetic flux density B is the parameter of interest the equation when expressed in CSG units becomes B uH x 0 899 e Bis the magnetic flux density in gauss e pis the relative permeability e Nis the number of turns per coil e is the coil current in amperes e Ris the coil radius in centimeters In SI units the relationship is given by B wu H 8 99 x 107 u2 e Bis the magnetic flux density in teslas e pis the relative permeability e pois the permeability constant e Nis the number of turns per coil e is the coil current in amperes e Ris the coil radius in meters For the unloaded coil the relative permeability u is one so that B H in CGS units and B LH in SI units Refer to Appendix B Conversion Table for Magnetic Units for more unit conversions 15 This page intentionally left blank 16 5 0 Operation Before operating any components follow the safety information in the ETS Lindgren Product Information Bulletin included with your shipment If high driving current is required at a high frequency take precautions to avoid shock or burn from the high voltages developed across the reactive elements CAUTION Helmholtz Coil Placement Place the Helmholtz coil in a space relatively free of metal objects and structures This will insure a minimum of distortion and the best possible homog
9. re connectors and casters if equipped the entire coil structure is made of non conductive non magnetic materials Handle the structure carefully at all times taking precautions to avoid subjecting it to thermal or mechanical shock Adding Power to the Helmholtz Coil When connecting the AC or DC current source for driving the Helmholtz coil magnetic field generator coil be sure the connecting leads are of sufficiently heavy gauge to handle the required current For example AWG 10 wire is required for 20 amperes based on a rule of thumb of 500 circular mils per ampere Also be certain that there is good mechanical bonding between connecting leads to both the current source and the Helmholtz coil input connector The coils are wound with 10 AWG copper wire so that they may be driven with 20 amperes continuously for generating magnetic fields up to 10 gauss Lower intensity fields may be generated by using a calibrated current supply or by monitoring the voltage across a series resistor The Models 6402M 6406S and certain custom coils are not wound with 10 AWG therefore power should be applied to correlate with the wire gauge 18 Magnetic fields greater than one gauss may be generated at frequencies from DC to 200 Hz However if higher frequencies are required the coil impedance will require fairly high driving voltages to drive enough current through the coil in order to reach the desired field intensity In certain cases it may be
10. rmation Bulletin cccccceceseeeeeeeeeeeeeeeeeeeeeeees 6 2 0 Maintenance asssssnsnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnennnnnnnnnnnnnnnnnnnn nnmnnn 7 Maintenance Recommendations c ccceecccceececeeeeeceeeeeeeeeesseeeesseeesseeeessaees 7 Annaa AID ATION 555 8 oa ance 2h ed decd E E E A NS 7 SEVICE Procedur S iia sutras cece eh Beare teste a oe eon eee us 7 3 0 SDeCCIICALIONS ieee ie eee 9 4 0 Theory of Operationnc cei ee sed eek 13 5 0 Operat ON chinese ee eee eee 17 Helmholtz Coil Placement cccccccssscccsseeceeseeceeseeseusesseseeseueeesausessueeeees 17 Helmholtz Com Tale is icc ried chica eect da odes civ Snnte dvncaivadhcdskcoaca AG 17 Adding Power to the Helmholtz Coll ccccccceccseeeeeeeeeeeeeeeeeeeeeeeeeeseseaeeees 18 Appendix A Warranty ccccccsseceeeeesseeeeeeeeeeeeeeeeeeneseneesanes 21 Appendix B Conversion Table for Magnetic Units 23 Notes Cautions and Warnings CAUTION Note Denotes helpful information intended to provide tips for better use of the product Caution Denotes a hazard Failure to follow instructions could result in minor personal injury and or property damage Included text gives proper procedures Warning Denotes a hazard Failure to follow instructions could result in SEVERE personal injury and or property damage Included text gives proper procedures See the ETS Lindgren Product Information Bulletin for safety regulatory
11. service see the Product Information Bulletin included with your shipment This page intentionally left blank 3 0 Specifications gt Currents higher than the Maximum Current Input listed may be used if the appropriate duty cycles are applied gt See table in Appendix B for conversion to Gauss Ampere Coil Radius 30 5cm 30 5cm 12 0 in 12 0 in Coil Factor 84 3 11 14 Amperes Meter Ampere l Coil Factor 1 06 0 14 Gauss Amperes 3 5 70 Max Continuous Field 21 2 1 5 Gauss Max Current Input 20 10 Amperes Continuous Homogeneity 10 within a 10 within a 19 8cm cylinder 25 4cm cylinder Mating Connector MS3106 A 20 09S Coil Radius 45 7cm 60 9cm 17 9 in 23 9 in Coil Factor 39 79 65 25 Amperes Meter Ampere Coil Factor 0 50 0 83 Gauss Amperes Max Continuous Field 10 16 5 Gauss 20 20 Max Current Input Amperes Continuous Homogeneity 10 within a 10 within a 23cm cylinder 40cm cylinder Mating Connector MS3106 A 20 MS3106 A 20 23S 09S 10 ee wosa mwm o e e Coil Factor 50 06 86 04 39 79 Amperes Meter Ampere l Coil Factor 0 63 1 08 0 50 Gauss Amperes Max Continuous Field Gauss Max Current Input Amperes Continuous Homogeneity 10 within a 10 within a 10 within a 0 6m cylinder 0 6m cylinder 0 7m cylinder Mating Connector MS3106 A 24 MS3106 A 24 MS3106 A 24 09S 09S 09S 11 This page intentionally left blank
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