BS 6907-4-1988 Electrical installations for open-cast mines and quarries - Recommendations for winning stacking and processing machinery pumps and low signal level and communicatio.pdf

1、BRITISH STANDARD BS 6907-4: 1988 Electrical installations for open-cast mines and quarries Part 4: Recommendations for winning, stacking and processing machinery, pumps and low signal level and communications systems UDC 622.3:622.271.3:622.812.2:621.31:622.663.4:622.271.482:6221/9:383/388BS6907-4:1

2、988 This British Standard, having been prepared under the directionof the Mining and Quarrying Requisites StandardsCommittee, was published under the authority ofthe Board of BSI and comes intoeffect on 30 September 1988 BSI 07-1999 The following BSI references relate to the work on this standard: C

3、ommittee reference MQE/23 Draft for comment 86/75883 DC ISBN 0 580 16371 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Mining and Quarrying Requisites Standards Committee (MQE/-) to Technical Committee MQE/23, upon which the followin

4、g bodies were represented: Associated Offices Technical Committee British Coal China Clay Association Electric Cable Makers Confederation Electrical Contractors Association Engineering Equipment and Materials Users Association Federation of Civil Engineering Contractors Federation of Manufacturers o

5、f Construction Equipment and Cranes Health and Safety Executive Independent Engineering Insurers Committee Institution of Mining and Metallurgy Amendments issued since publication Amd. No. Date of issue CommentsBS6907-4:1988 BSI 07-1999 i Contents Page Committees responsible Inside front cover Forew

6、ord ii Section 1. General 1 Scope 1 Section 2. Winning, stacking and primary and secondary processing machinery 2 Protection against direct and indirect contact 2 3 External power supply systems 2 4 Self-contained power systems 2 5 Cable types 2 6 Control circuits and control devices 3 7 Emergency s

7、topping and emergency devices 4 8 Provision for supply isolation 4 9 Potentially explosive atmospheres 4 10 Static electricity 4 11 Electrostatic precipitators 5 12 Radioactive sources 5 13 Rail-mounted equipment 5 14 Hazards from electromagnetic induction 5 Section 3. Deep-well submersible type pum

8、ps 15 Protection against direct and indirect contact 6 Section 4. Low signal level systems and communication systems 16 General 7 17 Assessment of general characteristics 7 18 Protection of personnel against the transfer of unsafe voltages 7 19 Protection of low signal level against malfunction due

9、to interference 8 Publications referred to Inside back coverBS6907-4:1988 ii BSI 07-1999 Foreword This Part of BS6907 has been prepared under the direction of the Mining and Quarrying Requisites Standards Committee. BS6907 is based on the International Electrotechnical Commissions publication IEC621

10、 “Electrical installations for outdoor sites under heavy conditions (including open-cast mines and quarries)” and, like that publication, is published in Parts as follows. Part 1: Glossary; Part 2: General recommendations for protection against direct contact and electric shock; Part 3: Recommendati

11、ons for equipment and ancillaries; Part 4: Recommendations for winning, stacking and processing machinery, pumps and low signal level and communications systems; Part 5: Recommendations for operation. BS6907 sets out the guiding principles for the installation and operation of electrical equipment s

12、o as to ensure safety of persons, livestock, property and the proper functioning of the plant. It applies to the installation and operation of electrical apparatus and systems associated with outdoor sites under heavy conditions, including open-cast mines, quarries, stockpiles, etc. It applies parti

13、cularly to electrical apparatus and systems used for the following: a) winning, stacking and primary processing machinery; b) secondary processing machinery; c) conveyor systems; d) pumping and water supply systems; e) movable railway systems; f) control, signal, supervisory and communication system

14、s. BS6907 does not cover temporary and provisional places of work in the open, such as building sites and earth-moving sites, unless the equipment used is similar to that used in surface mining applications. It takes account of British practice, electrical regulations and law and thereby differs in

15、several respects from the IEC publication. Both cover a subject not previously the subject of an international standard or a British Standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct appli

16、cation. 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, pages i and ii, pages 1 to 10, an inside back cover and a back cover. This standard has been updated (see copyright dat

17、e) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6907-4:1988 BSI 07-1999 1 Section 1. General 1 Scope This Part of BS 6907 gives recommendations for the safe and efficient installation of winning, stacking and primary and secondar

18、y processing machinery, pumps and low signal level and communication systems. It both supplements and gives specific exemptions to the recommendations given inBS6907-2 and BS6907-3 and should, therefore, be read in conjunction with those Parts. NOTE 1A glossary of terms used in this standard is give

19、n inBS6907-1. NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover.BS6907-4:1988 2 BSI 07-1999 Section 2. Winning, stacking and primary and secondary processing machinery NOTEThe recommendations of BS6907-2 and BS6907-3 apply, except where specific ex

20、emptions are stated. 2 Protection against direct and indirect contact 2.1 Mounting of components Protective conductors are not required for the exposed conductive parts of individual components provided that: a) each component is mounted on a conductive part which is either 1) a protective conductor

21、, or 2) directly connected to a protective conductor; and b) the conductance between each component and the part on which it is mounted is at least equal to that resulting from the application of11.5.2 of BS6907-2:1988; and c) the electrical continuity is assured, either by construction or by suitab

22、le connections, in such a way as to be protected against mechanical, chemical or electrochemical deterioration. Where the equipment is required to operate under corrosive atmospheric conditions or extreme vibrating conditions, a separate protective conductor should be connected to the components. 2.

23、2 Off-board mobile and movable auxiliary equipment For off-board mobile and movable auxiliary equipment (e.g.welding equipment, vulcanizing transformers) which require the provision of a protective conductor, either the protective conductor should be visible throughout its length or one or more of t

24、he following measures should be adopted. a) The protective conductor should be monitored for continuity. b) Sensitive earth leakage protection should be provided. c) A visible equipotential bonding-conductor should be provided between the off-board mobile or movable auxiliary equipment and the plant

25、 from which it is supplied. 3 External power supply systems 3.1 System design The supply system should meet the requirements of cyclic or periodic loads, motor starting, and inherent a.c.motor oscillations due to transient load changes, taking account of power factor, harmonic currents and any restr

26、ictions imposed by the electricity supplier. 3.2 Overcurrent protection Overload and short-circuit protection for transformers, cables, etc. should take into consideration the starting requirements and fluctuating nature of the load. 3.3 Automatic reclosing or transferring Where regeneration may del

27、ay the operation of undervoltage devices, automatic reclosing or transferring devices should not be used in the power distribution system unless: a) such devices have sufficient time delay to allow motor disconnection (see6.2); or b) the device is fitted with “out of step” protection; or c) the comb

28、ination of supply system and motor design is such as to permit automatic re-energization. 3.4 System voltage Recognition should be taken of the difference in voltage between full load and no load conditions. Where large variations in load can occur, it may be necessary to regulate the supply voltage

29、 to the installation. 4 Self-contained power systems 4.1 System design The power generation systems should meet the requirements of motor starting, regeneration, peak load, r.m.s.load, power factor and frequency stability. 4.2 Fire protection Consideration should be given to the need for special and

30、/or additional fire protection due to the fuels used, seeBS6907-3. 4.3 Earthing When the supply of electrical energy is self-contained within stationary, mobile, or movable items of equipment and there is no external supply, such equipment need not be connected to the general mass of the earth. Expo

31、sed and extraneous conductive parts should be equipotentially bonded. 4.4 Supply to off-board equipment When power is supplied to off-board mobile and movable equipment the recommendations of2.2 apply. 5 Cable types Where cables are exposed to physical damage, they should be protected by enclosures,

32、 armouring or other suitable means.BS6907-4:1988 BSI 07-1999 3 Cables should be installed and terminated in such a manner that they are protected from damage resulting from corona or from physical and environmental conditions. Where installed in areas prone to corrosive atmospheres, steam, extreme h

33、eat, ultraviolet radiation, material build-up, etc.additional protection may be necessary. 6 Control circuits and control devices 6.1 Shock, vibration and voltage fluctuations The effect of shock, vibration or voltage fluctuations on control devices should be taken into consideration, ensuring that

34、the safety of personnel and equipment is not endangered by inadvertent operation of control devices. (Seealso2.5 of BS6907-3:1988.) When mechanically latched switching devices are used and re-energization following loss of supply power would endanger personnel or equipment, means should be provided

35、to automatically unlatch the switching device on loss of supply power. The device should also be unlatched on operation of protective devices. 6.2 Synchronous motor control 6.2.1 Automatic discharge of field energy. Where synchronous motors are used provision should be made for automatic discharge o

36、f the field energy upon disconnection of the motor. 6.2.2 Automatic field excitation control. Where synchronous motors are used to drive periodic or cyclic loads, an automatic field excitation control is recommended. 6.2.3 Power loss protection. Where synchronous motors are used to drive loads which

37、 may be regenerative, means should be provided to trip the motor starting switch or incoming line switch upon loss of power supply. Frequency-sensitive devices are recommended. When automatic reclosing or transferring devices are used in the distribution system, the recommendations of3.3 apply. 6.3

38、Stop controls 6.3.1 Use of stop controls. The devices described in6.3.2 to 6.3.4 inclusive should not be used for purposes of isolation or immobilization to allow work to be carried out on parts which would otherwise be electrically energized or moving, except where permitted inBS6907-5. 6.3.2 Stop

39、control circuits. The circuits of stop controls and of other safety protection devices should be as simple, reliable and direct acting as is practicable. 6.3.3 Location of stop controls. A stop control should be located near each start control, except for lift call controls. Additional stop controls

40、 may be provided. 6.3.4 Pullwire stop controls. Stop controls operated by a pullwire should be arranged so that a pull on the wire in any direction transverse to the conveyor axis or breakage of the wire will stop the controlled equipment.The stop controls should be of a type in which the contacts a

41、re actuated by a positive mechanical action and can be reset only by a further mechanical action. 6.3.5 Stopping sequence. It is essential that the operation of a stop control for a piece of equipment should initiate stopping of that equipment and where required: a) stop all upstream equipment to a

42、controlled loading point, or cause the material from all upstream equipment to be diverted to an alternative route; b) initiate braking to stop the equipment in a safe time; c) prevent run back. On very long conveyor systems, however, the operation of a stop control within one stop zone need not sto

43、p all upstream conveyors beyond that zone, provided that the conveyor upstream of the zone is proved to be unloaded, for example by sensors. Although the stop control may be reset automatically, restarting should be by manual initiation. 6.4 Start controls Where equipment is started manually from on

44、e or more locations, audible and/or visual warning devices, together with appropriate notices, should be provided to give advance warning of equipment starting unless one or more of the following conditions apply: a) personnel access to hazardous parts is prevented; b) danger to personnel does not e

45、xist from equipment starting; c) the hazardous parts of the equipment being started are in full and clear view from all starting locations. Where equipment is started automatically, an audible and/or visual warning system should be provided unless conditions a) and/or b) apply. For sequential starti

46、ng of a localized plant group, a single warning system may be sufficient.BS6907-4:1988 4 BSI 07-1999 6.5 Interlocking of start controls Where equipment can be started from more than one location, the control system should permit operation from only one nominated location at any one time. Safe operat

47、ion may require that: a) pre-start warning is used; or b) the equipment is in sight for all starting locations; or c) the equipment is guarded against inadvertent access. 6.6 Protection against unauthorized starting Provision should be made to guard against unauthorized starting. 7 Emergency stoppin

48、g and emergency devices 7.1 Emergency stopping Effective means should be provided for stopping drives under emergency conditions. Consideration should be given, not only to disconnection of supply as the primary means of safe stopping, but also to other effective means where available, such as elect

49、rical braking. Emergency stopping may be accomplished by means other than disconnection of power, provided that such means otherwise are in accordance with6.3. For example, when rotating converters are used, disconnection of the external excitation is permitted if protection against self-excitation is provided. 7.2 Emergency devices Emergency stop controls should be provided for all equipment which is accessible to personnel and which can present a hazard to them. The emergency stop controls should be readily accessible and located in a suitable position for