1、 IEC/TR 62750 Edition 1.0 2012-02 TECHNICAL REPORT Unified fluorescent lamp dimming standard calculations IEC/TR 62750:2012(E) THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2012 IEC, Geneva, Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduce
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9、N R ICS 29.140 PRICE CODE ISBN 978-2-88912-939-3 Registered trademark of the International Electrotechnical Commission Warning! Make sure that you obtained this publication from an authorized distributor. 2 TR 62750 IEC:2012(E) CONTENTS FOREWORD . 3 1 Scope . 5 2 Explanation of the dimming requireme
10、nts . 5 2.1 General . 5 2.2 Additional heating 5 2.3 Cathode heating limits . 6 2.4 Substitution resistors for electronic controlgear qualification 7 3 Determination of limit values 8 3.1 General . 8 3.2 Minimum sum-of-squares SoS min(I D30 I D I Dtrans ) 9 3.2.1 Lamp and electronic controlgear syst
11、ems SoS min9 3.2.2 Electronic controlgear qualification limits SoS min. 11 3.3 Minimum cathode voltage CV min(I Dmin I D I D30 ) . 12 3.3.1 Lamp and electronic controlgear systems CV min12 3.3.2 Electronic controlgear qualification limits CV min12 3.4 Maximum cathode voltage CV max(I Dmin I D I Dtra
12、ns ) 13 3.4.1 Lamp and electronic controlgear systems CV max. 13 3.4.2 Electronic controlgear qualification limits CV max. 14 4 Example of calculation for 54W HO lamps 14 4.1 General . 14 4.2 Calculation of lamp and ECG systems SoS min. 15 4.3 Calculation of lamp and ECG systems CV min. 15 4.4 Calcu
13、lation of ECG qualification limits CV min16 4.5 Calculation of lamp and ECG systems CV max16 4.6 Calculation of ECG qualification limits CV max. 16 5 Glossary of symbols . 17 Bibliography 20 Figure 1 Fundamental circuit for SoS test 10 Table 1 SoS parametric values 9 Table 2 Fitted power law paramet
14、ers . 11 Table 3 Informative parameters for lamp and controlgear systems . 13 Table 4 Datasheet parameters . 14 TR 62750 IEC:2012(E) 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ UNIFIED FLUORESCENT LAMP DIMMING STANDARD CALCULATIONS FOREWORD 1) The International Electrotechnical Commission (IEC) is
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26、 different kind from that which is normally published as an International Standard, for example “state of the art“. IEC 62750, which is a technical report, has been prepared by subcommittee 34A: Lamps, of IEC technical committee 34: Lamps and related equipment. The text of this technical report is b
27、ased on the following documents: Enquiry draft Report on voting 34A/1511/DTR 34A/1546/RVC Full information on the voting for the approval of this technical report can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Direc
28、tives, Part 2. 4 TR 62750 IEC:2012(E) The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication will be reco
29、nfirmed, withdrawn, replaced by a revised edition, or amended. A bilingual version of this publication may be issued at a later date. TR 62750 IEC:2012(E) 5 UNIFIED FLUORESCENT LAMP DIMMING STANDARD CALCULATIONS 1 Scope This Technical Report applies to fluorescent lamp dimming systems. It deals with
30、 the interface of fluorescent lamps and dimming electronic controlgear. A unified framework for standardization of fluorescent lamp dimming systems and the associated parameter calculation method are described in this Technical Report. Dimming of fluorescent lamps is becoming increasingly important
31、as a strategy for conserving global energy resources. This report is the result of many years of effort by global experts to understand and test fluorescent dimming systems with the objective of standardizing these systems to grow confidence and reliability in the marketplace. Two theoretical framew
32、orks have been merged to create this unified dimming standardization method: the SoS (sum of squares of lead-in-wire currents) and CV (cathode voltage) models. The application of dimming to actual fluorescent lamp and electronic controlgear (ECG) systems is the primary concern for reliability in the
33、 application and end-user confidence. Characteristics of the dimming parameter limits described in this report and observed in real system applications such as in situ field diagnostics are offered as informative. The practical need to use substitution resistors for ECG qualification is described in
34、 this report and also given as normative parameters in the lamp and ECG standards. No attempt to treat the informative real lamp-ECG system parameters as normative will be made in either the lamp or the controlgear standards. 2 Explanation of the dimming requirements 2.1 General This clause gives a
35、general explanation of the dimming requirements found in the fluorescent lamp and controlgear standards. Subclause 2.2 provides an overview of the theoretical framework for the unified dimming standard. Subclause 2.3 provides an explanation of informative limits for the cathode heating based on phys
36、ical lamp and ECG systems. Subclause 2.4 provides the basis for normative controlgear qualification using substitution resistors. In this Technical Report, the use of primed quantities will signify values obtained when measuring on actual fluorescent lamp and ECG systems. Unprimed quantities refer t
37、o standardised quantities when testing ECG on substitution resistors. Although lead wire and lamp discharge currents pertain to actual lamps, they will remain unprimed quantities in this report. 2.2 Additional heating It is a well-known fact that, when lowering the lamp current to decrease the lumin
38、ous flux (dimming) below a certain current value, the cathode is not heated sufficiently any more by the lamp current. At these dimmed conditions without added ohmic heating, the cathode fall will increase to sustain the lamp current and this results in an increased sputtering of the cathode and the
39、reby a decrease in lamp life. So additional cathode heating is necessary to keep the cathode at a sufficiently high temperature for thermionic emission. The amount of this additional heating current through the cathodes as a function of the lamp current is however dependent on the controlgear circui
40、t layout. There may be a phase shift between these currents like in circuits with a capacitor parallel to the lamp. In other circuits, the additional heating current is delivered by separate heating sources, in which case it is not clear through which lead-in wire which part of the lamp current flow
41、s. For a generalized description, these different circuits are included when describing the controlgear requirements. 6 TR 62750 IEC:2012(E) It has been found that measuring the root mean square (r.m.s.) currents through the two lead- in wires to the cathode and calculating the sum of the mean squar
42、es of these two currents as a function of the discharge current can estimate the cathode heating. The sum of squares, SoS, needed to keep the cathode at a sufficient temperature, is found to have a linear dependence on the root mean square (r.m.s.) discharge current: SoS = I 2 LH + I 2 LL = X 1 Y 1
43、I Dwhere I Dis the discharge current; I LHis I lead high, which is the highest current through either lead-in wire; I LLis I lead low, which is the lowest current through either lead-in wire. Alternatively, it has also been found that it is possible to describe cathode heating in terms of root mean
44、square (r.m.s.) voltage applied across the cathode, CV, while dimming. To a reasonable approximation in the deep dimming range, the voltage necessary to keep the cathode at a sufficient temperature is also a linear function of the root mean square (r.m.s.) discharge current, CV = X 3 Y 3 I D , where
45、 the coefficients X 3and Y 3are constants, different from X 1and Y 1in the SoS expression. The dimming range of discharge currents for which additional heating is necessary is given by a maximum value, I Dtrans , which defines the transition between normal and dimming operation, and a minimum value,
46、 I Dmin , specified in the lamp standard. These values are expressed relative to the cathode test current, I test , designated in the relevant IEC datasheets. This cathode test current is defined in the relevant IEC standard as the current to be applied when measuring the cathode hot resistance. An
47、indirect measure related to the overall cathode temperature is the ratio, R h /R c , where R his the “hot” resistance during operation and R cis the “cold” resistance at 25 C. For a nominally performing filament, the measured hot resistance will usually correspond to a hot-to-cold resistance ratio,
48、R h /R c , of 4,75. The range of discharge currents, I Dmin I D I Dtrans , specified for dimming is typically 10 % of I test I D 80 % of I testfor many lamp designs 1 . For discharge currents above the dimming range, I D I Dtrans , additional cathode heating is not required, but not forbidden as lon
49、g as the value for the maximum current in any lead, I LHmax , is observed. Explicit values for the dimming range of discharge current and cathode test current are specified in the lamp datasheets. 2.3 Cathode heating limits The SoS model is developed from assumptions about the cathode hot spot. This is the location where the discharge arc attaches to the electron-emitting region of the cathode. As the discharge current is lowered into the dimming region, a h
