Model 413 ELF Magnetic Field Meter
Contents
1. Analog to Digital Converter ADC A Variable Buffer Amp Gain Amp Amp Bx A AN x A Gain Adjust A Variable Buffer Amp Gain Amp Amp By AZ Ay LZ TI Gain Adjust A Variable Buffer Amp Gain Amp Amp Bz A vz 7 a Gain Adjust Microprocessor Display n Driver On Off Switch P ower oe Supplies 9Qvolt Battery Refer ence Low a Battery Detect Figure 2 Model 413 Block Diagram 11 Model 413 ELF Magnetic Field Meter User s Manual SPECIFICATIONS Ranges 199 9 mG 1999 mG Autoranging Resolution 0 1 mG on 199 9 mG Range 1 mG on 1999 mG Range Accuracy 1 1 digit typical from 50 to 60 Hz The instrument is RMS responding and calibrated to sine wave at 60 Hz Accuracy Over Expanded Frequency Range gt 60 Hz but lt 300 Hz 5 40 50 Hz and 300 400 Hz 10 20 40 Hz and 400 2000 Hz 10 to 30 Analog Output Z Axis waveform only 5 mV mG 1 volt full scale at 199 9 mG Output impedance is 4 kQ DC Output 10 mV mG 2 volts full scale at 199 9 mG Output impedance is 4 kQ Directionality 1 typical for all measurement angles triaxial mode Sensor Type 3 x 750 turns of 38 Copper 0 29 inch diameter air core Display 3 digit Liquid Crystal Display LCD Battery Type 9 volt Alkaline Battery R2. User s Manual Model 413 ELF Magnetic Field Meter lL akeShore 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 Rev 1 2 P N 119 022 27 Sept 2000 Model 413 ELF Magnetic Field Meter User s Manual LIMITED WARRANTY Lake Shore Cryotronics Inc henceforth Lake Shore the manufacturer warrants this product to be free from defects in material or workmanship for a period of twelve 12 months from the date of shipment During the warranty period under authorized return of instruments or component parts to Lake Shore freight prepaid the company will repair or at its option replace any part found to be defective in material or workmanship without charge to the Owner for parts service labor or associated customary shipping cost Replacement or
3. repaired parts are warranted for only the unexpired portion of the original warranty All products are thoroughly tested and calibrated to published specifications prior to shipment Calibration Certifications are offered for six month periods only Where such documentation must be updated a re certification service is offered by Lake Shore at a reasonable cost LIMITATION OF WARRANTY This warranty does not apply to defects resulting from improper or inadequate maintenance unauthorized modification or misuse operation outside of the environmental specifications for any product or part or buyer supplied software interfacing This warranty is in lieu of any other warranties expressed or implied including merchantability or fitness for a particular purpose which are expressly excluded The owner agrees that Lake Shore s liability with respect to this product shall be set forth in this warranty and incidental or consequential damages are expressly excluded CERTIFICATION Lake Shore certifies that this product has been inspected and tested in accordance with its published specifications and that this product met its published specifications at the time of shipment The accuracy and calibration of this product at the time of shipment are traceable to the United States National Institute of Standards and Technology NIST formerly known as the National Bureau of Standards NBS Copyright 1996 1997 and 1999 by Lake Shore Cryotron
4. until the display blanks release and the display indicates Bz Finally press it once more to reset the instrument and enter triaxial mode In normal triaxial operation the unit indicates the correct magnetic field value regardless of physical orientation However single axis readings depend on the coil angle in relation to the magnetic field Maximum output occurs when the flux vector is perpendicular to the plane of the coil The greater the deviation from from right angles in either of three axes the larger the error of the reading For example a 5 variance on any one axis causes a 0 4 error See the illustration below 29 3 B 45 13 4 30 6 0 20 3 4 15 1 5 19 0 4 5 0 0 Error Deviation from Perpendicular 0 Effect of angular variations on percentage of reading error where Error 1 cos 8 100 Model 413 ELF Magnetic Field Meter User s Manual COMMON OPERATIONAL QUESTIONS What does 3 Axis mean The Model 413 displays the sum vector magnitude of magnetic readings taken simultaneously in three axes at right angles to each other The three axis measurement method provides all the information needed to calculate the actual magnetic field A single axis gaussmeter requires individual readings in all three orientations with the sensor aligned at exactly 90 angles at the same point in space and vector magnitude calculation to equal what the Model 413 does automaticall
5. ble single axis mode to display the individual vector components analog output DC recorder output and an optional display in microtesla uT The instrument comes with a padded imitation leather case and a one year warranty covering both parts and labor Model 413 ELF Magnetic Field Meter User s Manual Single Axis Mode Analog Outputs Pushbutton A D Approximate Location and Orientation of 3 Axis Sensors 3 Axis ELF Electromagnetic Field Meter Figure 1 Model 413 Front Panel Model 413 ELF Magnetic Field Meter User s Manual Features e Hand held Compact and Light Weight e 3 Axis Operation e Autoranging 199 9 and 1999 mG e 0 1 mG Resolution e Wide Frequency Response e Low Battery Indicator e Single Axis Mode e Two Analog Outputs e One Year Warranty CONTROLS Power Controls power to the unit Turn switch On up to power the unit Turn switch Off down to turn power off Single Axis Pushbutton Activates single axis mode Push button once for X axis reading again for Y axis again for Z axis and again to return to normal display DISPLAY milligauss The numeric display is in milligauss mG A milligauss mG is 1 1000 of a gauss G The unit measures in two ranges 0 to 199 9 mG or 0 to 1999 mG The decimal point automatically moves to the best field range BAT The BAT symbol displays when the 9 volt battery needs replacement NOTE The term magnetic
6. del 413 ELF Magnetic Field Meter User s Manual Normal Operation Bring the instrument into the vicinity of ELF magnetic fields and note the magnetic field level The three internal magnetic field sensors are located just below the LCD display The display indicates the magnetic field level at that point in space Instrument rotation about that point results in no changing field indication as long as the magnetic field is constant across the dimensions of the internal sensors Some degree of directionality occurs in near fields where the magnetic field level changes rapidly over distances comparable to the dimensions of the instrument In far fields where the magnetic field is essentially constant directionality of the instrument is typically less than 1 Single Axis Mode The Model 413 can display the vector components of the magnetic flux density By By and Bz in mG When placed in the single axis mode an arrow symbol appears in the upper left area of the LCD It disappears when the Model 413 is returned to triaxial default mode To activate single axis mode without moving the instrument press the pushbutton on the top panel firmly until the display blanks then release After blanking for about 0 5 seconds the display indicates the Bx component Model 413 ELF Magnetic Field Meter User s Manual Press the pushbutton a second time until the display blanks release and the display indicates By Press it a third time
7. eplace only with an alkaline battery Duracell MN1604 Eveready 522 or equivalent Battery Life 50 hours typical use to 5 2 volts minimum using standard 9 volt alkaline battery Operating Temperature Range 10 to 50 C 14 to 122 F Operating Relative Humidity 90 at 40 C 104 F Storage Temperature Range 20 to 85 C 4 to 185 F Storage Relative Humidity 95 up to 60 C 140 F Dimensions 15 2 cm x 8 3 cm x 3 6 cm 6 x 3 3 x 1 4 inches Weight 200 grams 7 ounces The unit is not waterproof 12 Model 413 ELF Magnetic Field Meter User s Manual BATTERY REPLACEMENT The unit normally provides about 50 hours of continuous use with a 9 volt alkaline battery When the battery level falls below 5 5 volts BAT appears in the display indicating a low battery About 1 hour of measurement time remains before accuracy degrades Replace the battery as soon as possible To remove the battery turn the Power switch OFF turn the unit over Use a small screwdriver to remove the bottom door in the enclosure Carefully disconnect the old battery connect a new battery then replace the back cover IN CASE OF TROUBLE If the instrument fails to turn on or behaves unpredictably replace the battery This usually solves most problems There are no locally serviceable parts in the Model 413 If you are experiencing problems contact the factory at the phone numbers or e mail addresses on the bac
8. field is used loosely throughout the manual All references to magnetic field levels in this manual actually refer to the magnetic flux density which has CGS units of milligauss mG Model 413 ELF Magnetic Field Meter User s Manual ANALOG OUTPUTS Z Axis Output Jack Labeled A Provides 5 mV mG output corresponding to Z axis only with 1 volt full scale at 199 9 mG DC Output Jack Labeled D Provides 10 m V mG output with 2 volts full scale at 199 9 mG Output corresponds to whatever currently displays and updates every 400 msec 2 5 times per second The 3 Axis Advantage The Model 413 3 axis measurement method prevents measurement errors due to improper instrument orientation a problem associated with single axis instruments With the Model 413 it is virtually impossible to get an erroneous reading of the magnetic field Inexperienced and non technical users benefit from the ease of use of the Model 413 while experienced users appreciate the ability to make accurate measurements and field surveys quickly and confidently WARNING Never extend your hands or the instrument into live high voltage circuits Turning the Instrument On To operate the Model 413 first turn the ON OFF switch ON up The instrument performs a self test and displays 188 8 for about 2 seconds verifying proper operation After the power on sequence finishes the display indicates the magnetic field reading in mG 4 Mo
9. ics Inc All rights reserved No portion of this manual may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photocopying recording or otherwise without the express written permission of Lake Shore A Model 413 ELF Magnetic Field Meter User s Manual INTRODUCTION The Lake Shore Model 413 3 Axis Extremely Low Frequency ELF Magnetic Field Meter is a battery powered hand held Gaussmeter that measures a variety of ELF sources e AC Power Lines Video Display Terminals e Appliances e Office Equipment e Computers e Other Electrical Equipment The Model 413 uses three internal sensors at right angles to each other to evaluate and display a wide range of ELF magnetic fields independent of measurement angle The instrument uses an analog to digital converter and microprocessor to accurately compute and display the vector magnitude of the magnetic flux density in milligauss It automatically adjusts to the measurement range offering the best resolution yielding a wide dynamic measurement range of 0 1 to 1999 mG with a typical accuracy better than 2 sufficient for characterizing most electrical and electronic equipment Normally the unit provides 50 hours of continuous use with a standard 9 volt alkaline battery A low battery indicator signals users when about 1 hour of measurement time is available before the battery needs replacing Features include a switcha
10. k of this manual To return a unit obtain a Return Goods Authorization RGA number from a factory representative Lake Shore requires the following information before attempting any repair 1 Instrument model and serial number 2 Name company address amp phone number 3 Malfunction symptoms 4 RGA number Ship unit to Lake Shore at Customer expense Lake Shore will pay for shipping to return units under warranty If possible use original packing material for reshipment If not available consult Lake Shore for packing instructions 13 Model 413 ELF Magnetic Field Meter User s Manual EL akeShore Lake Shore Cryotronics Inc 575 McCorkle Blvd Westerville Ohio 43082 8888 USA E Mail Addresses sales lakeshore com service lakeshore com Visit Our Website www lakeshore com Fax 614 891 1392 Phone 614 891 2243
11. ords electric appliances TVs vacuum cleaners etc Remember the iron filings on paper with a magnet underneath experiment The filings would line up corresponding to the magnetic field shape What type of field does the unit measure The Model 413 measures only the magnetic portion of an extremely low frequency ELF AC field It does not measure electric fields or DC magnetic fields Model 413 ELF Magnetic Field Meter User s Manual What is the difference between DC amp AC DC stands for Direct Current DC fields are unchanging such as those produced by a permanent magnet or by DC currents For example the Earth generates a DC field which is typically 500 mG AC stands for Alternating Current AC fields are always changing such as those generated by AC currents The Model 413 is calibrated only for continuous sine wave fields The electricity running to your home is AC Inside a home or office the normal ambient background reading is about 0 4 milligauss What is a Gauss The gauss G is a unit of magnetic flux density often refered to as the B field A gauss is defined as 10 teslas or 1 maxwell per square centimeter Named for Karl Fredrich Gauss 1777 1855 What are some typical readings Appliance At 4 in At12in At 36 in Gan Ocener 1300 to 30 to 0 5 to p 4000mG_ 300mG 7mG Computer 50 to 3to lt 1 to Monitor 600 mG 30 mG 2mG Microwave 600 mG 90 mG 5mG Oven Tele
12. vision 5to 0 4 to lt 0 1 to 100 mG 20 mG 1 5mG 10 to 0 6 to Toaster 60mG 7mG lt 0 1 mG Vacuum 230 to 20 to 1to Cleaner 1300 mG 200 mG 20 mG Model 413 ELF Magnetic Field Meter User s Manual CIRCUIT DESCRIPTION See Figure 2 ELF Amplification Detection Circuitry Three independent ELF amplifier detection chains provide AC voltages proportional to the vector components of the RMS magnetic field for ELF sine waves Each chain consists of an air wound sensing coil followed by three stages of AC amplification and filtering Analog to Digital ADC Conversion A 4 channel Analog to Digital Converter ADC converts AC voltages to a 12 bit digital data word In addition to the x y z components of the magnetic field the fourth channel of the ADC senses the battery voltage Microprocessor and Support Circuitry The heart of the Model 413 is a CMOS microprocessor During each measurement cycle it initiates data transfer from the ADC computes the vector magnitude of the magnetic field and transfers results to the LCD via the display driver The micro processor also senses over and under range conditions and adjusts AC amplifier gains accordingly It recognizes entry into single axis mode and displays only the appropriate vector component of the magnetic field Timing circuitry synchronizes the measurement cycle to repeat every 400 msec 10 Model 413 ELF Magnetic Field Meter User s Manual
13. y What is Autoranging Autoranging means the display automatically places the decimal point of the reading in the correct position There are two ranges 199 9 mG and 1999 mG The automatic change between ranges occurs at about 160 mG Where are the sensing coils The Model 413 has 3 internal sensing coils Their approximate position and orientation is indicated on the front panel Looking at the top of the unit the x axis sensor is aligned across the meter face from left to right The y axis sensor is aligned across the meter face from bottom to top The z axis sensor alignment is through the meter from front to back These coils work best in large low gradient magnetic fields Model 413 ELF Magnetic Field Meter User s Manual Does movement affect the reading Yes The Model 413 must be stationary to take a reading Moving the Model 413 couples the 500 mG field of the Earth into the coils and gives erroneous readings Does orientation affect the reading Under normal triaxial operation field rotation has only minor effect on the resulting reading However in Single Axis Mode orientation is critical MAGNETIC TERMINOLOGY QUESTIONS What is an Electromagnetic Field Although you cannot see it there is an electric field around everything with an applied voltage and a magnetic field around everything that conducts current The combined effect is called the electro magnetic field This includes power lines electric c
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