1、BRITISH STANDARD BS 4145:1967 Specification for Glass mica boards for electrical purposesBS4145:1967 This British Standard, having been approved by the Electrical Industry Standards Committee and endorsed by the Chairman ofthe Engineering Divisional Council, was published under theauthority of the G
2、eneralCouncil on 31 March 1967 BSI 09-1999 The following BSI references relate to the work on this standard: Committee references ELE/16 and ELE/16/53/13 Draft for comment D65/8047 ISBN 0 580 04117 4 Co-operating organizations The Electrical Industry Standards Committee under whose supervision this
3、British Standard was prepared consists of representatives from the following Government departments and scientific and industrial organizations: Associated Offices Technical Committee Association of Consulting Engineers Association of Mining Electrical and Mechanical Engineers Association of Supervi
4、sing Electrical Engineers British Electrical and Allied Manufacturers Association* British Railways Board Crown Agents for Oversea Governments and Administrations Electric Cable Makers Confederation Electric Lamp Industry Council Electric Light Fittings Association Electrical Contractors Association
5、 (Incorporated) Electrical Contractors Association of Scotland Electrical Research Association* Electricity Council, the Central Electricity Generating Board and the Area BoardsinEnglandandWales* Electronic Engineering Association* Engineering Equipment Users Association Institution of Electrical En
6、gineers Ministry of Aviation* Ministry of Defence, Army Department* Ministry of Defence, Navy Department* Ministry of Labour (H.M. Factory Inspectorate) Ministry of Power Ministry of Public Building and Works Municipal Passenger Transport Association (Incorporated) National Inspection Council for El
7、ectrical Installation Contracting National Physical Laboratory (Ministry of Technology) Oil Companies Materials Association Post Office* Public Transport Association (Incorporated) South of Scotland Electricity Board The Government departments and scientific and industrial organizations marked with
8、an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: British Electro-Ceramic Manufacturers Association British Plastics Federation Glass Textile Association London Transport Board Radio the sal
9、t tray should, therefore, be emptied, washed all over, carefully dried and refilled with sufficient saturated solution or slurry at intervals of not more than2months. More frequent changes may be necessary if the chamber is used where conditions of severe contamination are experienced. To ensure uni
10、form conditions throughout the chamber circulate air, with a fan, over the surface of the saturated solution or slurry and around the test pieces. Free access of the conditioning atmosphere to all test pieces is essential. From time to time check that the humidity of the air in the chamber is correc
11、t. Appendix B Electric strength proof test in oil B.1 Test piece The test piece shall be of sufficient area to accommodate the electrodes and avoid flashover and of the thickness of the material under test. B.2 Conditioning Condition the test piece as described inAppendix A. B.3 Test temperature Mak
12、e the test at20 C with the test piece and electrodes immersed in oil complying with BS148 2) . B.4 Electrodes The upper electrode shall be a solid cylinder of brass approximately1 1 / 2in(38mm) diameter and not lessthan 1 1 / 2 in(38mm) high. The lower electrode shall be a brass block3 in (76mm) dia
13、meter and at least1in (25mm) high. The sharp edges shall be removed from the electrodes, but the radius at the edge shall not exceed 1 / 32 in(0.8mm). The electrodes shall be arranged coaxially as shown inFigure 1. B.5 Test voltage The test voltage shall be alternating and of a frequency in the rang
14、e48c/s to62c/s. It shall be of approximately sine wave form and the ratio of peak value to the r.m.s.value shall be within the limits of5%(1.341.48). The test voltage shall be expressed as its peak value divided by and shall be determined by means of a peak or other type of voltmeter connected acros
15、s the output winding of the transformer. Alternatively, it may be measured by means of the voltmeter connected across the input winding or across a portion of the output winding or across a special winding. Peak voltmeters, of types other than a sphere gap, may be subject to error if the waveform is
16、 re-entrant, or if there is a change in mains frequency, or if high frequencies are generated by brush discharges. It is preferable to calibrate any instrument used against a sphere gap, but calibration of an r.m.s.instrument against a peak voltmeter is permissible if there is adequate evidence, such as a certificate of calibration, that the peak voltmeter is free from error. 1) A suitable chamber is described in BS3718, “Laboratory humidity ovens (non-injection type)”. 2) BS148, “Insulating oil for transformers and switchgear”.
