Location 1. Substations at customer premises must be at the GL and personnel and plant access also to be in the same level 2. All indoor TFs shall be dry or K-class oil with flash point above 250°C 7.5.3 Access requirements 7.5.4 Building walls, floors, ceilings and basements 1. The building shall be suitable to withstand an internal pressure of minimum 2.0 kPa. 2. Waterproofing 3. Below ground parts must include vertical and horizontal moisture barriers. 7.5.4.2 Walls 7.5.4.3 Floors 1. Floors shall be made of reinforced concrete 2. Trenches or penetrations shall be provided with aluminium tread plate covers to dimensions and quantities as specified on the drawings. Roofing (as a standalone building) 1. Roof can be concrete, metal decking, timber framework. 2. Roof garden or landscape are not permitted 7.5.4.5 Cable basements 3. Substation with cable bases are not permitted. 7.5.5 Doors Any ventilation opening adjacent to any door lock shall be fitted with a suitable barrier to prevent unauthorised opening of the door lock and prevent vandalism to the door lock. 7.5.5.4 Personnel door Open to outside, quick release emergency panic lock with single action escape door 7.5.5.5 Equipment door Minimum clearance to be maintained is 2000mm wide x 2700mm high, means to provide pressure release. 7.5.6 Conduits, cable supports and enclosures 7.5.6.1 General Minimum cover to the top of HV conduits from ground level shall be 750mm. If this dimension cannot be achieved, concrete encasement will be required. All conduit bends are to be minimum 1000mm radius Conduits between substation rooms shall be concrete encased and sealed to prevent fire travelling between rooms or inflicting damage to adjacent cables when a fault occurs in any one of the cables. A clear area of at least one (1) metre is required in front of cable riser doors. 7.5.7 Drainage 7.5.7.1 General Substation basements, HV trenches and substation floors are to be gravity drained to a point free from risk of surcharge. HV trenches shall be drained in straight runs by minimum 50mm diameter copper or rigid PVC pipe. Drainage openings in basements and trenches shall be provided with grates to prevent blockage. LV trenches shall not be connected to the drainage system unless connect by a flame trap. 7.5.7.2 Basements and trenches below potential water table Underfloor shall be made from permeable material Drain to point free of surcharges or sump external to substation Automatic discharge pump shall be fitted 7.5.12.2 Floor Except tiled floors Sealer to minimise dust formation Prevent formation of concrete dust Abrasion resistant Non-slip Non-flammable Concrete penetrating type, not just a surface coating Resistant to oil and grease Chemically stable with concrete floor The sealant colour required is golden yellow or similar. 7.5.13 Telephone Telephone to be installed at customers’ expense Telecommunication authority approved conduit of 20mm diameter to be installed. 7.5.14 Anti-vibration pads Provision must be made for lifting transformers onto anti-vibration pads. This can be in the form of a lifting beam or jacks. 7.5.15 Rollers and jacking pads All transformers shall be either fitted with bi-directional rollers or jacking pads to aid relocation inside the substation. Rollers shall be lockable to prevent unwanted movement. 7.5.16 Wall anchors Wall anchors and/or pulling ring sockets shall be installed in the floor or walls, in the position shown on the layout drawings and in a manner to achieve any working load specified. 7.5.17 Ventilation/pressure relief 7.5.17.1 General - To heat removal and overpressure develop at faults - Corrosion and Vandal proof proof louvres - Galvanized steel mesh ventilation opening must be weatherproof - Max natural ventilation in or absence of forced ventilation - Forced ventilation system shall be able to be supply, install and maintained without entering the substation - Ventilation must be forced in to the room not extracted out and sufficient to maintain max temp of 5°Cabove air intake. Ventilation system design Design shall demonstrate max temperature with and without forced ventilation, and shall have following items, - The maximum temperature inside the room at approx.1.8m above ground level at various external ambient temperatures. The ambient temperature shall be based on meteorological data associated with the area the substation is installed ie. no. of days over 30 degrees and maximums. Area of natural ventilation provided (the max natural ventilation shall be installed even when forced is being installed so that fans only run on rare occasions) A statement that the design is based on the 2-stage louvre actually being installed Calculations of air turn over If fans are installed how many days they may be in operation based on thermostat settings. Based on the above a statement advising if forced or natural ventilation is required. Filters to be installed from outside to prevent dust ingress prevent impair the operation Louvre are 4m2 for pressure relief 7.5.17.2 Equipment losses The full load equipment losses to be provided for are 16kW for each oil filled transformer or 20kW for each dry type transformer. The ventilation system shall be designed to cater for the maximum number of transformers the room can accommodate. 7.5.17.3 Location of ventilation openings
