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1、BRITISH STANDARD BS EN 60255-8:1998 Electrical relays Part 8: Thermal electrical relays The European Standard EN 60255-8:1998 has the status of a British Standard ICS 29.120.70 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 07:50:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 60255-8:19
2、98 This British Standard, having been prepared under the direction of the Electrotechnical Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 November 1998 BSI 05-1999 ISBN 0 580 30468 X National foreword This British Standard is the English la
3、nguage version of EN 60255-8:1998. It was derived by CENELEC from IEC 60255-8:1990. The CENELEC common modifications have been implemented at the appropriate places in the text and are indicated by a side line in the margin. The UK participation in its preparation was entrusted to Technical Committe
4、e PEL/95, Measuring relays and protection systems, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related inte
5、rnational and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references Attention is drawn to the fact that CEN and CENELEC Standards normally include an annex which lists normative referen
6、ces to international publications with their corresponding European publications. The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence I
7、ndex”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself
8、 confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages 2 to 14, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporate
9、d. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 07:50:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 60255-8:1998 BSI 05-1999i Contents Page National forew
10、ordInside front cover Foreword2 Text of EN 60255-83 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 07:50:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 07:50:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME E
11、UROPENNE EUROPISCHE NORM EN 60255-8 January 1998 ICS 29.120.70 English version Electrical relays Part 8: Thermal electrical relays (IEC 60255-8:1990, modified) Relais lectriques Partie 8: Relais lectriques thermiques (CEI 60255-8:1990, modifie) Elektrische Relais Teil 8: berlastrelais (IEC 60255-8:1
12、990, modifiziert) This European Standard was approved by CENELEC on 1997-07-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists an
13、d bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the respon
14、sibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Ital
15、y, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-105
16、0 Brussels 1998 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 60255-8:1998 E Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 07:50:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 60255-8:1998 BSI 05-1999 2 Foreword The tex
17、t of the International Standard IEC 60255-8:1990, prepared by IEC TC 95, Measuring relays and protection equipment, together with the common modifications prepared by the CENELEC BTTF 63-5, Static measuring relays, was submitted to the Unique Acceptance Procedure and was approved by CENELEC as EN 60
18、255-8 on 1997-07-01. The following dates were fixed: Annexes designated “normative” are part of the body of the standard. Annexes designated “informative” are given for information only. In this standard, Annex ZA is normative and Appendix A, Appendix B and Appendix C are informative. Annex ZA has b
19、een added by CENELEC. Contents Page Foreword2 Section 1. General 1Scope and object3 2Definitions3 Section 2. Requirements 3Standard values4 4Accuracy7 Section 3. Test methods 5Tests related to operating characteristics and accuracy8 6Tests for thermal requirements9 Appendix A Characteristic curves,
20、cold curves11 Appendix B Characteristic curves, hot curves11 Appendix C Example for determining accuracy13 Annex ZA (normative) Normative references to international publications with their corresponding European publicationsInside back cover Figure 1 Test circuit for determining the minimum operati
21、ng current and the cold characteristic9 Figure 2 Test circuit for determining the hot characteristics10 Table 1 Reference conditions and test tolerances of influencing quantities and factors5 Table II Previous current values when measuring the effect of influencing quantities5 Table III Standard ref
22、erence conditions and test tolerances of correcting quantities when measuring the effect of influencing quantities6 Table IV Standard values of the limits of the nominal ranges of influencing quantities and factors6 Table V Standard values of the limits of the nominal range of previous current value
23、s6 Table VI Standard values of the limits of the nominal range of correcting quantities7 latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement(dop) 1998-08-01 latest date by which the national standards conflicting with
24、 the EN have to be withdrawn(dow) 1998-08-01 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 07:50:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 60255-8:1998 BSI 05-19993 Section 1. General 1 Scope and object This standard is applicable to dependent specified time electrical measuring rela
25、ys which protect equipment from electrical thermal damage by the measurement of current flowing in the protected equipment. 1.1 This standard covers the following two types of relays: a) thermal electrical relays having a total memory function of the load-current conditions before the conditions whi
26、ch caused the switching of the relay; b) thermal electrical relays having a partial memory function, i.e. of the overload current conditions only. 1.2 This standard also covers the particular requirements for thermal electrical relays used for motor protection. The object of this standard is to stat
27、e the particular requirements for thermal electrical relays. It is to be read in conjunction with higher level documents in the EN 60255 and IEC 60255 series. 2 Definitions For definitions of general terms not defined in this standard, reference should be made to the International Electrotechnical V
28、ocabulary (IEV) (IEC Publication 50) and higher level documents. For the purpose of this standard the following definitions shall apply: 2.1 hot curve for a thermal electrical relay with a total memory function, the characteristic curve representing the relationship between specified operating time
29、and current, taking account of the thermal effect of a specified steady-state load current before the overload occurs 2.2 cold curve for a thermal electrical relay, the characteristic curve representing the relationship between specified operating time and current, with the relay at reference and st
30、eady-state conditions with no-load current flowing before the overload occurs 2.3 correcting quantity (compensating quantity) a quantity modifying the specified characteristics of the relay in a specified manner. Such quantities can be oil temperature, etc. 2.4 basic current the specified limiting v
31、alue of the current for which the relay is required not to operate NOTEThe basic current serves as a reference for the definition of the characteristics of thermal electrical relays. Settings of a thermal electrical relay are made in terms of this current. 2.5 constant k the constant by which the ba
32、sic current is multiplied to obtain the current value to which the accuracy of the minimum operating current referred 2.6 previous load ratio the ratio of the load current preceding the overload to basic current under specified conditions Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 07:50:
33、32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 60255-8:1998 4 BSI 05-1999 Section 2. Requirements 3 Standard values 3.1 Characteristic curves The characteristics of time with respect to current can be stated either by equations or by graphical methods. The equations for a simple thermal model are
34、given below under Sub-clauses 3.1.1 and 3.1.2. Other characteristic curves are permitted and should be declared by the manufacturer. As an example, see Appendix A. NOTE 1For practical purpose, e.g. testing, it is convenient to give the characteristic curve as a combination of current and time values
35、. NOTE 2The time constant used in an equation should be as declared by the manufacturer. 3.1.1 Cold curve A general curve for thermal electrical relays, based on the heating effect and on the time constant, is given by the following formula: where t E IB k I = operating time; = time constant; = basi
36、c current; = constant; = relay current. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 07:50:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 60255-8:1998 BSI 05-19995 3.1.2 Hot curve With regard to preheating on a relay with a total memory function, the hot curve is relevant. For example, t
37、he equation obtained by modification of the general cold curve is given by the following formula which is derived in Appendix B: where Ip is the specified load current before the overload occurs. 3.2 Nominal ranges of auxiliary energizing quantities For other nominal ranges than the preferred 80 % t
38、o 100 % the limits of the nominal range shall be as declared by the manufacturer. 3.3 Standard reference values of influencing quantities and factors The standard reference values and test tolerances of influencing quantities and factors, previous current values and correcting quantities are given i
39、n Table 1, Table II and Table III, respectively. Table 1 Reference conditions and test tolerances of influencing quantities and factors Table II Previous current values when measuring the effect of influencing quantities Influencing Quantity or factor Reference conditionTest tolerances GeneralPositi
40、onAs for normal service condition For static relays 5 in any direction or as declared by the manufacturer Characteristic quantities and input energizing quantities Setting of basic currentRated current or as declared by the manufacturer As declared by the manufacturer Magnitude (reference for determ
41、ination of variations) As declared by the manufacturer. For motor protection, two times and six times basic current. As declared by the manufacturer. For motor protection: 1 % D.C. transient component in a.c. ZeroWhere necessary as declared by the manufacturer TimeSettingAs declared by the manufactu
42、rer As declared by the manufacturer Setting parameter(s) of the curve As declared by the manufacturer As declared by the manufacturer Auxiliary energizing quantities VoltageRated value(s)As declared by the manufacturer D.C. component in a.c.ZeroWhere necessary as declared by the manufacturer Quantit
43、yReference conditionTest tolerances Specified load current before overload occurs For cold curve: zeroNot applicable For hot curve: as declared by the manufacturer As declared by the manufacturer Previous load ratio for motor protection For hot curves: 1.0 or 0.9 as chosen by the manufacturer 1 % Li
44、censed Copy: sheffieldun sheffieldun, na, Fri Nov 10 07:50:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 60255-8:1998 6 BSI 05-1999 Table III Standard reference conditions and test tolerances of correcting quantities when measuring the effect of influencing quantities 3.4 Standard values of the l
45、imits of the nominal range of influencing quantities and factors The standard values of the limits of the nominal range of influencing quantities and factors, previous current values and correcting quantities are given in Table IV, Table V and Table VI respectively. Table IV Standard values of the l
46、imits of the nominal ranges of influencing quantities and factors Table V Standard values of the limits of the nominal range of previous current values Correcting quantityReference conditionTest tolerances Unbalance current in a sinusoidal polyphase system BalancedSee note 8b and c of Table II of EN
47、 60255-6 Speed of protected rotating machine As declared by the manufacturer As declared by the manufacturer Temperatures of different parts of the protected equipment (see Note 1) Temperature of cooling medium of the protected equipment 20 C or as declared by manufacturer (see Note 2) 2 C NOTE 1The
48、se values of correcting quantities represent steady-state thermal conditions of the protected equipment before overload occurs. Their application depends on the principle of the relay used. NOTE 2To be declared by the manufacturer mainly when a cooling medium other than air is used. Influencing Quan
49、tity or factorNominal range GeneralRate of change of ambient temperature As declared by the manufacturer Relative humidity Position For static relays 10 in any direction or as declared by the manufacturer External magnetic fieldAs declared by the manufacturer Characteristics quantities and input energizing quantities Magnitude As declared by the manufacturer For motor protection see 4.1.1 WaveformAs declared by the manufacturer D.C. transient component in a.c. TimeSetting parameter(s) of the curveAs declared by the man