1、BRITISH STANDARD BS6705:1987 Specification for Electrical measuring instruments for use on intrinsically safe circuits in coal mines UDC 622.33:621.317.7.019.3:622.81BS6705:1987 This British Standard, having been prepared under the directionof the Mining and Quarrying Requisites StandardsCommittee,
2、was published under the authorityofthe Board of BSI andcomes into effect on 28August1987 BSI12-1999 The following BSI references relate to the work on this standard: Committee reference MQE/25 Draft for comment84/70935 DC ISBN 0 580 15173 5 Committees responsible for this British Standard The prepar
3、ation of this British Standard was entrusted by the Mining and Quarrying Requisites Standards Committee (MQE/-) to Technical Committee MQE/25, upon which the following bodies were represented: Association of British Mining Equipment Companies British Coal Council for Electrical Equipment for Flammab
4、le Atmospheres (BEAMA) Health and Safety Executive National Union of Mineworkers Amendments issued since publication Amd. No. Date of issue CommentsBS6705:1987 BSI 12-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 General 1 3 Limiting parameters for electrical
5、 measuring circuits 1 4 Marking 1 5 Documentation 1 Publications referred to Inside back coverBS6705:1987 ii BSI 12-1999 Foreword This British Standard has been prepared under the direction of the Mining and Quarrying Requisites Standards Committee. It is applicable to portable electrical measuring
6、instruments used for testing intrinsically safe equipment installed in coal mines. In testing intrinsically safe equipment in hazardous areas it is imperative that neither any testing instrument used nor the method of testing adopted adversely affect the intrinsic safety of the circuit under test. W
7、hile a testing instrument may have been considered, and perhaps certified, separately as intrinsically safe under specified conditions, the intrinsic safety of the system formed by the test instrument and the equipment to which it is connected will depend upon the combined effects of voltage, curren
8、t, inductance and capacitance of the test instrument and equipment. To maintain intrinsic safety of the system, therefore, the certification documentation for the equipment has either to specify the exact type of instrument(s) that can be used for testing or to specify, in general terms, limits for
9、relevant input/output circuit parameters of the instrument, as seen by the circuit under test. This standard specifies the limits for such circuit parameters, thereby enabling intrinsically safe equipment to be designed which is capable of being tested by a range of instruments without the intrinsic
10、 safety of either the equipment or the test instrument being impaired. Guidance on the use of instruments complying with this standard is given in section4 of BS6704:1987. Attention is drawn to the Health and Safety at Work etc. Act1974, the Factories Act1961, the Mines and Quarries Act1954, the Reg
11、ulations made under these Acts, and also any other appropriate statutory requirements or bye-laws. These place responsibility for complying with certain specific safety requirements on the manufacturer and the user. The address of the recognized certification authority in the UK for Group I (coal mi
12、ning) apparatus for intrinsic safety purposes is as follows: Health and Safety Executive HSE (M) Certification Support Unit Harpur Hill Buxton Derbyshire SK179JN A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for
13、their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and 2, an inside back cover and a back cover. This standard has been updated (s
14、ee copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6705:1987 BSI 12-1999 1 1 Scope This British Standard specifies limiting parameters for input/output circuits of portable electrical measuring instruments for testin
15、g intrinsically safe circuits used in coal mines. It applies to the following types of test circuits when connected to intrinsically safe circuits having a voltage not exceeding60V peak at the point of test. a) Voltage dependent circuits. These are high impedance circuits contained in instruments su
16、ch as voltmeters, oscilloscopes, frequency meters and similar instruments that depend upon voltage for their operation. b) Current dependent circuits. These are low impedance circuits contained in instruments such as ammeters, and similar instruments that depend upon current for their operation. c)
17、Current injection circuits. These are circuits which inject a current into the circuit under test generally for the purpose of measuring resistance or impedance. This standard is not applicable to intrinsically safe instruments that provide a high voltage for testing insulation nor to instruments us
18、ed to measure the resistance or continuity of shot-firing circuits. Nor does it specify operational performance requirements of testing instruments. Instruments specified in this standard are intended for use in accordance with BS6704 and with any condition of the applicable certification to either
19、the instrument or the circuit to which it is connected for test purposes. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 General The circuits associated with the test leads shall be in accordance with BS5501-7 for category “ia” apparatus. When
20、used in hazardous areas, the electrical measuring instrument shall have a recognized type of protection. 3 Limiting parameters for electrical measuring circuits 3.1 General In addition to the requirement for the electrical measuring circuit, at its terminals, to comply with BS5501-7, the maximum inp
21、ut/output parameters under countable fault conditions for category “ia” apparatus shall be as specified in3.2, 3.3 or3.4. 3.2 Voltage dependent circuits 3.2.1 The minimum resistance shall be10007/V and the minimum resistance in any range shall be10007. 3.2.2 The maximum inductance shall be20mH. 3.2.
22、3 The maximum capacitance shall be0.74F. 3.3 Current dependent circuits 3.3.1 The maximum inductance shall be164H unless the effect of the inductance is limited by the use of infallible shunts, e.g.diodes. 3.3.2 The maximum voltage drop shall be1.2V. NOTEMaximum capacitance is not specified because
23、capacitance is normally insignificant in relation to intrinsic safety at the value of voltage drop specified. 3.4 Current injection circuits 3.4.1 The maximum open circuit voltage shall be2.0V. 3.4.2 The maximum short circuit current shall be2.5mA. NOTEMaximum capacitance and inductance are not spec
24、ified because capacitance and inductance of the internal circuits of the instrument are normally insignificant in relation to intrinsic safety at the values of voltage and current specified. 4 Marking In addition to any marking required by a certification authority, electrical measuring instruments
25、containing circuits in accordance with this standard shall be marked with the number of this standard, i.e.BS6705:1987 1) , together with the types of measurements for which the instrument can be used. 5 Documentation The supplier of an electrical measuring instrument complying with this standard sh
26、all produce and make available a) such information as is necessary for its safe and correct use; and b) descriptive documents which specify the maximum capacitance and maximum inductance of the circuits that may be connected to the instrument. 1) Marking BS6705:1987 on or in relation to a product is
27、 a claim by the manufacturer that the product has been manufactured in accordance with the requirements of the standard. The accuracy of such a claim is therefore solely the manufacturers responsibility. Enquiries as to the availability of third party certification to support such claims should be a
28、ddressed to the appropriate authority for other certification marks.2 blankBS6705:1987 BSI 12-1999 Publications referred to BS5501, Electrical apparatus for potentially explosive atmospheres. BS5501-7, Intrinsic safety “i”. BS6704, Code of practice for selection, installation and maintenance of intr
29、insically safe electrical equipment. BS6705:1987 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international level. It is incorporated
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