1、Copyright 1998 IEEE All Rights Reserved 1IEEE Std 1140-1994 (R2006)IEEE Standard Procedures for the Measurement of Electric and Magnetic Fields From Video Display Terminals (VDTs) From 5 Hz to 400 kHzSponsorElectromagnetic Compatibility Society Standards Committeeof theIEEE Electromagnetic Compatibi
2、lity SocietyApproved March 17, 1994Reaffirmed September 14, 2006IEEE Standards BoardAbstract: Procedures for the measurement of electric and magnetic fields in close proximity to video displayterminals (VDTs) in the frequency range of 5 Hz to 400 kHz are provided. Existing international measurementt
3、echnologies and practices are adapted to achieve a consistent and harmonious VDT measurement standard fortesting in a laboratory controlled environment.Keywords: electric field, magnetic field, video display terminal (VDT)The Institute of Electrical and Electronics Engineers, Inc.345 East 47th Stree
4、t, New York, NY 10017-2394, USACopyright 1994 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published 1994. Printed in the United States of AmericaISBN 1-55937-423-3No part of this publication may be reproduced in any form, in an electronic retrieval system or o
5、therwise, without theprior written permission of the publisher.IEEE Standardsdocuments are developed within the Technical Committees of theIEEE Societies and the Standards Coordinating Committees of the IEEE StandardsBoard. Members of the committees serve voluntarily and without compensation.They ar
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12、eived the concurrenceof a balance of interests. For this reason IEEE and the members of its technical com-mittees are not able to provide an instant response to interpretation requests except inthose cases where the matter has previously received formal consideration. Comments on standards and reque
13、sts for interpretations should be addressed to:Secretary, IEEE Standards Board445 Hoes LaneP.O. Box 1331Piscataway, NJ 08855-1331USAIEEE standards documents may involve the use of patented technology. Theirapproval by the Institute of Electrical and Electronics Engineers does not mean thatusing such
14、 technology for the purpose of conforming to such standards is authorizedby the patent owner. It is the obligation of the user of such technology to obtain allnecessary permissions.iiiAt the time this standard was completed, the Working Group had the following membership:D. Moongilan,ChairD. Traver,
15、Vice ChairS. Berger A. Light S. A. RobertsJ. Chubb M. Misakian R. A. SuttonR. Justice D. Moongilan D. WittersR. C. PetersonThe following persons were on the balloting committee:IntroductionThis introduction is not part of IEEE Std 1140-1994, IEEE Standard Procedures for the Measurement of Electric a
16、ndMagnetic Fields From Video Display Terminals (VDTs) From 5 Hz to 400 kHz.The purpose of this standard is to establish uniform procedures for the measurement of electric and magneticfields from video display terminals (VDTs). The measurement practices in this standard follow the princi-ples and pro
17、cedures of MPR (National Board for Measurement and Testing) published in Sweden. The num-ber of test points required, calibration levels, instrumentation and calibration procedures used, grounded andungrounded system test methods, and calculation of measurement uncertainty are different from MPR. Th
18、emeasurement procedures outlined in this standard are for testing in a laboratory-controlled environment. Themeasurement distances indicated in this document are based on approximate human operator and VDT inter-action distance. The electric field measurements attempt to approximate the field that i
19、s perturbed by humanoperator interaction. Due to insufficient information defining safe or unsafe electric or magnetic field levelsfor human operators, this document does not assume any human factors other than test distance.This standard was revised 12 times to incorporate the comments of balloting
20、 members.The first working draft was completed in February 1991 by an ad hoc group with the following membership:C. AbernathyR. AshleyD. BaronH. BassenS. BergerW. BolvinE. BronaughF. BuckleyM. BurtonJ. ButlerC. CampD. CapplesH. DennyR. ElmserW. FloodD. GeorgeB. HanrahanD. N. HeirmanA. HoolihanB. Hun
21、terR. MacyS. MillendorfM. MisakianD. MoongilanS. NilssonT. NilssonJ. OsepchikJ. ParkerR. C. PetersonB. RhodesR. SatoR. ShowersD. StaggsR. TellD. TraverA. WilsonD. WittersS. A. RobertsJ. ChubbD. GeorgeK. GullicksonD. HanttulaL. HillJ. HowardA. LightD. MoongilanS. RobertsonJ. TinsmanJ. YenickPaul Zahr
22、aD. Moongilan,ChairivWhen the IEEE Standards Board approved this standard on March 17, 1994, it had the followingmembership:Wallace S. Read,ChairDonald C. Loughry,Vice ChairAndrew G. Salem,SecretaryGilles A. Baril Donald N. Heirman Joseph L. Koepnger*Bruce B. Barrow Richard J. Holleman D. N. Jim Log
23、othetisJos A. Berrios de la Paz Jim Isaak L. Bruce McClungClyde R. Camp Ben C. Johnson Marco W. MigliaroJames Costantino Sonny Kasturi Mary Lou PadgettStephen L. Diamond Lorraine C. Kevra Arthur K. ReillyDonald C. Fleckenstein E. G. Al Kiener Ronald H. ReimerJay Forster* Ivor N. Knight Gary S. Robin
24、sonRamiro Garcia Leonard L. Tripp*Member EmeritusAlso included are the following nonvoting IEEE Standards Board liaisons:Satish K. AggarwalJames BeallRichard B. EngelmanDavid E. SoffrinStanley I. WarshawStephen J. HuffmanIEEE Standards Project EditorvContentsCLAUSE PAGE1. Scope 12. Definitions 13. G
25、eneral conditions . 23.1 General. 23.2 Background electric field levels. 33.3 Background magnetic field (magnetic flux density) 34. Electric field test equipment 44.1 Electric field measuring probe. 44.2 Probe filters and signal processing 54.3 Calibration 55. Electric field strength measurement pro
26、cedure 65.1 VDT test setup . 65.2 Measurement procedure. 65.3 Measurement uncertainty. 76. Magnetic field test equipment 96.1 Magnetic field measuring probe 96.2 Probe filters and signal processing 106.3 Calibration 107. Magnetic flux density measurement procedure . 117.1 VDT test setup . 117.2 Meas
27、urement procedure. 117.3 Measurement uncertainty. 138. Bibliography 15viANNEXESA (normative) Electric eld measuring probeprinciple of operation 16B (normative) VDT characterizationtypical data recording format 19C (normative) Measurement uncertaintytypical data recording format . 20D (normative) Mea
28、surement instrumentation used. 211IEEE Standard Procedures for the Measurement of Electric and Magnetic Fields From Video Display Terminals (VDTs) From 5 Hz to 400 kHz1. ScopeThis standard provides procedures for the measurement of electric and magnetic elds in close proximity tovideo display termin
29、als (VDTs) in the frequency range of 5 Hz to 400 kHz. This standard adapts existinginternational measurement technologies B71and practices to achieve a consistent and harmonious VDTmeasurement standard for testing in a laboratory controlled environment. Such measurements are needed forinvestigative
30、studies that rely on the knowledge of electric and magnetic eld levels near electronicequipment.The requirements of the controlled laboratory test environment in which the characteristics specied in thisstandard are to be tested are difcult to establish at a users installation. Therefore, it is reco
31、gnized that theresults obtained in the laboratory may be difcult to reproduce in the on-site environment.This standard does not provide measurements at specic frequencies, but does provide one measurement foreach of two frequency bands: 5 Hz to 2 kHz and 2 kHz to 400 kHz.2. Denitions2.1 band I:The f
32、requency band 5 Hz to 2 kHz.2.2 band II:The frequency band 2 kHz to 400 kHz.1The numbers in brackets preceded by the letter B correspond to those of the bibliography in clause 8.IEEEStd 1140-1994 IEEE STANDARD PROCEDURES FOR THE MEASUREMENT OF ELECTRIC AND MAGNETIC22.3 background elds:Any electric o
33、r magnetic eld that does not originate from the VDT under test.2.4 calibration:The process of determining the numerical relationship, within an overall stated uncertainty,between the observed output of a measurement system and the value, based on standard sources, of the phys-ical quality being meas
34、ured. (In terms of this standard, the physical quality being measured is electric andmagnetic elds.)2.5 center-center point:A point on a VDT screen cathode ray tube (CRT) face panel that is both the hori-zontal and vertical mid-point. The center-center point is represented by the bisector of the hor
35、izontal andvertical center lines on the VDT screen.2.6 Class I equipment:Equipment in which protection against electric shock is achieved by: a) using basicinsulation, and b) providing a means of connecting the conductive parts, which are otherwise capable of assum-ing hazardous voltages if the basi
36、c insulation fails, to the protective ground conductor in the building wire.2.7 Class II equipment:Equipment in which protection against electric shock does not rely on basic insula-tion only, but also on the provision of additional safety precautions, such as double insulation or reinforcedinsulati
37、on. There is no provision for protective grounding or reliance upon installation conditions.2.8 eld measuring instrument:A device used to sense and read out the electric or magnetic eld intensi-ties surrounding a VDT under test. (For this standard, this instrumentation consists of three parts: probe
38、;readout detector, where the signal from the probe is processed and the data displayed; and any leads betweenthe probe and readout detector.)2.9 measurement uncertainty:The limits of error for a measured value, between which the true value willlie with the condence stated. (For this standard, measur
39、ement uncertainty is associated with measuring theabsolute value of the electric and magnetic elds.)2.10 tangential plane:The plane that is tangential to the surface of the VDT screen at the center-centerpoint.2.11 video display terminal (VDT):A device for the presentation of information by controll
40、ed excitation ofa CRT screen for visual observation designed for interactive use by an operator. For the purposes of thisstandard, the keyboard will not be included as part of VDT and is removed from the test area. This standardexcludes liquid crystal display (LCD) terminals.3. General conditions3.1
41、 General3.1.1 Location of VDT under test and measuring probeThe VDT under test, the measuring eld sensor (probe), and the signal processor/display (readout device ordetector) shall be positioned at least 1 m from all metallic structures and objects.The VDT under test shall be connected to the mains
42、supply with the power cord/cable supplied by the man-ufacturer as part of the equipment. The power cord/cable shall be positioned as follows: Horizontally for0.1 m from the test object, and then vertically down for at least 1 m.The power cord of the VDT under test shall be connected to the phase and
43、 neutral conductors of the mainspower network. If the power plug permits an interchange of the phase and neutral conductors, measurementsshall be taken with the connection that gives the highest Band I reading. If the VDT under test is designed toIEEEFIELDS FROM VIDEO DISPLAY TERMINALS (VDTs) FROM 5
44、 Hz TO 400 kHz Std 1140-19943be grounded, then the ground connection of the power cord shall be connected to ground. If the power cordof the VDT under test has a grounded neutral, then the neutral shall be connected to the ground.Additional units that are not part of the testsuch as the central proc
45、essing unit (CPU), video test patternsignal generators, and connecting cables necessary for the operation of the VDTshall be positioned sotheir elds do not exceed the required ambient levels (see 3.2 and 3.3). It is acceptable to add shielding andcables to these additional units as a long as a clear
46、ance of 1 m is maintained from the closest metallic part ofVDT under test or the measuring probe.The cables between the measuring probe and the readout (detector) shall be positioned so that they do notinuence the measured electric eld values. The cables will not affect the magnetic eld measurements
47、. 3.1.2 Power line voltageThe power line voltage of the VDT under test shall be within 3% of its nominal value, as stated on the man-ufacturers name plate. The nominal value of the power line voltage shall be specied in the test report andthe actual measured value shall be recorded. If a voltage ran
48、ge is specied, the test shall be performed at thecenter of the specied range. For this latter case, the power line voltage and the range shall be recorded in thetest report.3.2 Background electric eld levelsBackground electric eld levels in the test area, including power line transmitted disturbance
49、s and internallygenerated noise in the measuring system, shall not together exceed 2 V/m in Band I and 0.2 V/m in Band II.The background electric eld levels shall be measured with the VDT in place prior to beginning the VDTelectric eld measurements. All signal, power, and peripheral equipment cables required for operation shallbe on and terminated at the VDT. The VDT power cable shall be de-energized (otherwise the power cablewill radiate an electric eld) when making background measurements. If grounding and shielding of periph-eral
