《BS-7749-1994 IEC-60397-1972 IEC-60397A-1975.pdf》由会员分享，可在线阅读，更多相关《BS-7749-1994 IEC-60397-1972 IEC-60397A-1975.pdf（22页珍藏版）》请在三一文库上搜索。
1、BRITISH STANDARD BS 7749:1994 IEC 397:1972 including supplement IEC 397A:1975 Guide to Test methods for batch furnaces with metallic heating resistors Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:43:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7749:199
2、4 This British Standard, having been prepared under the direction of the Power Electrical Engineering Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 August 1994 BSI 10-1999 The following BSI references relate to the work on this stand
3、ard: Committee reference PEL/87 Draft for comment 70/20132 DC ISBN 0 580 23398 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Power Electrical Engineering Standards Policy Committee (PEL/-) to Technical Committee PEL/87, upon which th
4、e following bodies were represented: Association of Manufacturers Allied to the Electrical and Electronic Industry (BEAMA Ltd.) British Glass Manufacturers Confederation British Industrial Furnace Constructors Association British National Committee for Electroheat British Steel plc Electric Trace He
5、ating Industry Council (ETHIC) Electricity Association Energy Industries Council Engineering Equipment and Materials Users Association Engineering Industries Association Health and Safety Executive Induction and Dielectric Heating Manufacturers Association Institution of Electrical Engineers Lightin
6、g Industry Federation Ltd. Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:43:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7749:1994 BSI 10-1999i Contents Page Committees responsibleInside front cov
7、er National forewordii Section 1. General 1Scope1 2Object1 3Definitions1 Section 2. Technical tests 4Types of tests and general test conditions3 Section 3. Description of technical tests 5Procedure of tests and technical measurements4 Appendix A Analogous electric model of accumulated heat9 Appendix
8、 B List of symbols14 Figure A.1 Temperature curve plotted during cooling11 Figure A.212 Figure A.313 Figure A.4 Analogous electric model of accumulated heat14 Figure 1 Wiring diagram for leakage current measurement in hot-state in a single-phase furnace15 Figure 2 Wiring diagram for leakage current
9、measurement in hot-state in a three-phase furnace15 Figure 3 Wiring diagram for leakage current measurement using the differential current method16 Table I8 List of referencesInside back cover Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:43:32 GMT+00:00 20
10、06, Uncontrolled Copy, (c) BSI BS 7749:1994 ii BSI 10-1999 National foreword This British Standard has been prepared under the direction of the Power Electrical Engineering Standards Policy Committee. It is identical with IEC 397:1972 Test methods for batch furnaces with metallic heating resistors,
11、including supplement IEC 397A:1975, published by the International Electrotechnical Commission (IEC). It is being published at the request of the British Technical Committee on Electroheat (PEL/87), taking into account that IEC 519-1:1984 General requirements has been ratified by CENELEC and publish
12、ed as a European Standard (EN), and has been published as BS EN 60519-1:1993 Safety in electroheat installations Part 1: General requirements. The text of IEC 397A:1975, first supplement to IEC 397:1972, is marked by a sideline in the margin. A British Standard does not purport to include all the ne
13、cessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-reference International StandardCorresponding British Standard IEC 398:1980BS 7684:1993 Gene
14、ral test conditions for industrial electro-heating equipment (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 16, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendment
15、s incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:43:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7749:1994 BSI 10-19991 Section 1. General 1 Scope This recommendation
16、applies to industrial furnaces heated indirectly with metallic heating elements (e.g., for heat-treatment, hot-forming, etc.) in which the internal atmosphere is composed of air not intentionally modified. This recommendation applies to batch chamber, bell, elevator, shaft, carriage, or to furnaces
17、of any similar construction. These furnaces may be constructed either with or without forced air circulation. This recommendation covers furnaces of low and very low voltage categories (below 500 V). 2 Object The object of this recommendation is the standardization of testing conditions and methods
18、to determine the essential parameters and technical data of the above-mentioned furnaces. This recommendation does not contain a list of mandatory tests, and is not restrictive. According to need, tests necessary for the assessment of a furnace can be chosen at will from among those specified in the
19、 suggested list. When needed, supplementary tests can also be made, though preferably in compliance with the standards in use in the countries concerned. 3 Definitions The following definitions apply for the purpose of this recommendation. For definitions of fundamental and general terms in the fiel
20、d of electro-heating, the reader should refer to Chapter 05: Fundamental definitions, and Chapter 40: Electro-heating applications, of IEC Publication 50: International Electrotechnical Vocabulary (IEV). 3.1 indirect resistance electric furnace furnace in which the heat evolved by the Joule effect i
21、n the heating elements is transferred to the material to be heated 3.2 charge total of materials to be heated at the same time in the furnace (IEV 40-10-005) 3.3 heating element electric conductor with ohmic resistance, connected to the source of electric energy, in which the electric energy is tran
22、sformed to thermal energy by the Joule effect 3.4 heating assembly assembly of heating elements controlled, regulated or switched jointly 3.5 furnace temperature Fi (C) the temperature at one or more specified points in the heated space of the furnace 3.6 rated maximum furnace temperature Fn (C) the
23、 rated operating temperature in normal service of the furnace for which the furnace is designed. It is indicated on the nameplate of the furnace 3.7 external surface temperature of the furnace Fs (C) the temperature measured at one or more determined points on the outer surface of the furnace Licens
24、ed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:43:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7749:1994 2 BSI 10-1999 3.8 ambient temperature Fa (C) the temperature of air surrounding the furnace at a point where thermal radiation and natural convection from
25、the furnace do not exert any influence 3.9 reference ambient temperature Fr (C) ambient temperature, to which all furnace characteristic data are referred. The reference ambient temperature is fixed at 20 C 3.10 temperature-time variation (C) the temperature variation at a given point in the furnace
26、 plotted against time 3.11 surface temperature of the furnace at thermal steady-state Fso (C) the temperature reached at thermal steady-state at a predetermined point on the external surface of the furnace 3.12 rated furnace voltage(s) Un (V) the voltage(s) for which the furnace is designed. It (the
27、y) is (are) given on the nameplate 3.13 furnace power P (kW) power consumed by the heating elements of the furnace at a given time 3.14 furnace rated power Pn (kW) power consumption of the furnace at the rated furnace voltage, rated current, rated frequency and rated temperature 3.15 mean no-load in
28、put loss Po (kW) the energy loss in kWh in unit time (in hours) at the rated temperature of the empty furnace in normal operating conditions in thermal steady-state. In this case, the power demand of auxiliary devices, determined for the heating assembly (e.g. fan), should be added to the furnace ra
29、ted power 3.16 electric power input of furnace switched on in cold state Pf (kW) the input power at the moment of switching on the cold furnace 3.17 heating-up time tp (h) the time necessary to heat a dried, empty, closed furnace from 20 C at rated voltage so that the temperature measuring equipment
30、 indicates the rated furnace temperature 3.18 connected load Ptot (kW, kVA) maximum furnace power input measured at rated voltage 3.19 time for attainment of thermal steady-state tth (min/h) the time between switching on the furnace in the cold state and attainment of thermal steady-state 3.20 therm
31、al steady-state of furnace the thermal condition when all energy input is used to cover heat losses Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:43:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7749:1994 BSI 10-19993 3.21 cold furnace condition the ther
32、mal condition in which the temperature of the assembly of constructional elements of the furnace equals the ambient temperature 3.22 hot furnace condition the thermal condition when the rated temperature is reached 3.23 energy consumption E (kWh) the quantity of energy consumed by the furnace during
33、 a given time without charge 3.24 heating-up energy consumption EA (kWh) the quantity of energy absorbed by the empty furnace between switching on the cold furnace and attainment of the thermal steady-state without charge 3.25 leakage current leakage current is the current which in normal operation
34、flows from live parts of the installation or apparatus through or over the functional insulation to conducting parts not forming part of the working circuit when these last-mentioned parts are electrically connected to the middle point of the power system or to a directly earthed point of the networ
35、k Section 2. Technical tests 4 Types of tests and general test conditions 4.1 List of technical tests The following tests are to be carried out for the assessment of the electro-heating equipment containing a furnace: a) Electric breakdown test of furnace insulation (see Sub-clause 5.1); b) Measurem
36、ent of the power input of furnace switched on in cold-state (see Sub-clause 5.2); c) Furnace temperature measurement (see Sub-clause 5.3); d) Temperature measurement at the external surface of furnace (see Sub-clause 5.4); e) Total energy consumption measurement (see Sub-clause 5.5); f) Rated heatin
37、g input measurement (see Sub-clause 5.6); g) Heating-up time measurement (see Sub-clause 5.7); h) Mean no-load loss power determination (see Sub-clause 5.8); i) Determination of time necessary to reach the thermal steady-state (see Sub-clause 5.9); j) Temperature measurement of accessible furnace pa
38、rts (see Sub-clause 5.10); k) Determination of rated temperature change during the control cycle (see Sub-clause 5.11); l) Leakage current measurement (see Sub-clause 5.12); m) Determination of furnace temperature variation during the cooling period (see Sub-clause 5.13); n) Determination of accumul
39、ated heat (see Sub-clause 5.14). 4.2 General conditions of test performance See IEC Publication 398: General test conditions for electro-heating installations. 4.3 Particular conditions of technical tests a) Tests according to Sub-clause 4.1 are realized on a furnace without charge; b) Tests with ch
40、arge are to be agreed upon between manufacturer and user; c) When the furnace has a mechanical or electric regulation, appropriate test methods should be agreed upon between manufacturer and user. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:43:32 GMT+00:0
41、0 2006, Uncontrolled Copy, (c) BSI BS 7749:1994 4 BSI 10-1999 Section 3. Description of technical tests 5 Procedure of tests and technical measurements 5.1 Electric breakdown test of furnace insulation NOTETests to be performed are under consideration. 5.2 Measurement of the power input of furnace s
42、witched on in cold-state Pf The power of a furnace switched on in cold-state Pf (kW) is measured by means of wattmeters; this power corresponds to the maximum value likely to be encountered in operation. In case watt-meters cannot be used, the power input can be determined approximately from current
43、 measurement at constant voltage when the circuit may be assumed to have ohmic resistance only. NOTEIn case the connected load (Ptot) exceeds the power of furnace switched on in cold-state, the method of measuring this power should be agreed upon between manufacturer and user. 5.3 Furnace temperatur
44、e measurement Fi The furnace temperature measurement inside the furnace shall be made at the place (or places) according to either preliminary agreement between manufacturer and user, or in accordance with the diagram of temperature distribution, given by the manufacturer. The temperature variations
45、 are measured using a recording instrument or reading the values of temperature on an indicating instrument at regular time intervals of not longer than 1 h. When the furnace temperature is close to the required one., or close to the rated temperature, the time interval of readout must be reduced so
46、 as to allow an accurate determination of the moment of reaching the required temperature for the first time. The intervals should be not longer than 1 h or another value agreed upon between manufacturer and user. 5.4 Temperature measurement at the external surface of furnace Fs The measurement is m
47、ade at not less than three points, those being the points at which the highest and the lowest temperatures are expected, and a point in the centre of the side wall of the furnace. The measurement is performed at regular intervals until the temperature reaches a steady value. The time intervals shoul
48、d not be longer than 1 h or another value agreed upon between manufacturer and user. 5.5 Total energy consumption measurement EA The measurement is made by means of an electric energy meter, values being read out at regular time intervals until the temperature corresponding to that of the steady-sta
49、te is reached. Measurements must be made during a period not exceeding 0.5 h. 5.6 Rated heating input measurement Pn The measurement is made by means of a wattmeter (wattmeters) or any other analogous device agreed upon by the manufacturer and user at a temperature fixed by these parties. This temperature is such that the measurement is made outside periods of automatic temperature and power regulation. NOTE 1In case this measurement cannot be made by means of a wattmeter, the rated input power may be determined from the consumed energy as follows: The ene