AS NZS 4871.4:2010 pdf free download – Electrical equipment for mines andquarries Part 4: Mains powered electrical mobilemachines

AS NZS 4871.4:2010 pdf free download – Electrical equipment for mines andquarries Part 4: Mains powered electrical mobilemachines.
2.2 ELECTRICAL ISOLATION
Every machine shall be provided with an isolating facility by means of which all power to the machine can be isolated for the purpose of carrying out electrical work.
The main switching device shall be manually operated and capable of being locked in the isolated position.
The isolator shall be either in a separate compartment or remote from the machine to isolate the supply cable.
The main isolating device shall isolate all electrical circuits within the confines of the machine unless such circuits are ELV or for equipment operating in hazardous areas, all circuits arc classified as intrinsically safe.
2.3 ISOLATION FOR MECHANICAL MAINTENANCE
Every machine shall be equipped with an isolating device by means of which all power to the machine can be isolated for the purposes of carrying out non-electrical work on the machine. The main isolating device shall isolate all electrical power circuits that may effect movement.
On the load side of the isolating device, functional switching devices may be used for individual drives or groups of drives.
2.4 LIGhTING SYSTEMS
Machines shall be provided with a lighting system that is appropriate for the machines operation.
2.5 AUTOMATIC GAS MONITORING SYSTEM
Where an explosive gas monitoring system is provided, the following requirements and recommendations apply:
(a) The trip mechanism should isolate the power supph’ to the machine.
(b) The monitor should give a visual warning that a predetermined concentration of explosive gas has been reached.
(c) The monitor should be configured to cease operation of parts of the machine when the explosive gas concentration setpoint has been reached.
(d) A lockout mechanism that will prevent the restoration of power to a machine until the trip mechanism is reset should be fitted. Following an explosive gas trip it should not be possible to apply power to the machine until the explosive gas concentration has fallen to safe levels.
(e) There should be a visual indication of the gas level.
2.11 MAChINE INTERLOCK CONTROLS
2.11.1 Conveyor reversing
The reversing of a machine conveyor shall he controlled by a switching device so the reverse operation will not occur inadvertently.
2.11.2 Cable interlock
For applications here the trailing cable machine anchor point may not be directly supervised by an operator or has a risk of overtension (such as with shearers on longwall applications), the supply cable shall be prevented from being over tensioned by a system that automatically stops any dangerous motion associated with the over tension.
2.11.3 Trailing cable attachments
Attachments should be provided for anchoring trailing cables where the cable attaches to the machine.
The design should allow for all machine movements to minimize the risk of cable damage.
Where the cable is secured to allow reeling of the cable, means should he provided to reduce shock loading on the cable in excess of the safe working load of the cable.
2.11.4 Pilot control
Where pilot control switching is fitted on a machine, the switch device shall be spring return from the ‘start’ position to the ‘run’ position. Trip functions may be connected in the pilot circuit. The pilot circuit should not allow restoration of power unless it is in a healthy state. For example, if there is iio power on a machine and the switch is stuck in RUN, theit the pilot relay should not operate.
Refer to Clause 3.2.1.4 of AS/NZS 4871.1 for hazardous zone applications.
2.11.5 Electrical braking
Electrical dynamic braking, where fitted, shall not be used for safety or parking brake applications.
2.11.6 Over-speed protection
Where it is possible for the operator of the machine to inadvertently over-speed a mobile machine, an over-speed protection device shall he provided.