AS NZS 4871.3:2002 pdf free download.Electrical equipment for coal mines, for use underground Part 3: Substations.
2.1 GENERAL REQUIREMENTS
Substations shall he of rugged construction and shall he capable of withstanding the arduous conditions of handling to which they may be subjected. They shall comply with the following requirements:
(a) Each sub-assembly of the substation shall he securely fixed to a frame in a manner which shall prevent detrimental flexing of the substation.
(b) Appropriate lifting facilities shall be provided, for individual sub-assemblies and for the complete substation.
(c) Where a liquid-filled transformer is used, a means of containing the total volume of liquid in case of leakage shall he provided.
A base in the form of a tray capable of containing 110% of the total volume of liquid in the substation and designed to facilitate easy cleaning would fulfil this requirement.
2.2 PRIMARY SWITCHGEAR
The primary side of the substation shall be fitted with a switching device.
2.3 SECONDARY SWITCHGEAR
Where by design. circuit interruption of the secondary side of the substation is desired, it shall be fitted with a switching device.
2.4 TRANSFORMERS
2.4.1 General
The transformer of a substation shall be either of the dry sealed, encapsulated. gas filled (pressurized) type or contain an insulating liquid as the coolant.
The transformer shall comply with AS 2374 and, unless otherwise specified by the purchaser, its design shall comply with short circuit currents listed in ASINZS 4871.1 Table 4.1.
The core and coils of the transformer shall be securely clamped in order to ensure that the whole assembly is sufficiently rigid to withstand any electrical or mechanical stresses, caused by the arduous cyclic duty. which may occur in service and when being transported around the mine.
2.4.2 Lifting and anchoring of core
Guides, locating lugs or a combination of both, with adequate fixing bolts shall be mounted
inside the tank to register the location of the core.
Means for attaching lifting tackle shall be provided on the core frame.
2.4.3 Off-load tap changing
A tap changing device, having all positions clearly marked and with provision for locking in all positions, should be provided.
Where a hand-wheel operated tap changer is used, it shall be designed to suit the rated temperature and have provision to ensure it cannot be left in any position other than one of the tap positions.
Where bolted links are used, they shall be arranged to avoid incorrect connection.AS NZS 4871.3 pdf download.