Download Standard: Substation Installation Technical

Standard: Substation Installation Technical
Requirements
Standard Number: HPC-9DJ-23-0001-2012
Document Control
Author
Name:
Digitally signed by
Anthony Seneviratne
Date: 2013.09.16
12:36:24 +08'00'
Anthony Seneviratne
Position: Senior Standards Engineer
Document Owner
(May also be the Process Owner)
Approved By *
Name:
Justin Murphy
Justin Murphy
2013.09.17
10:30:19 +08'00'
Position: Manager Asset & Works
Name:
Justin Murphy
2013.09.17
10:30:59 +08'00'
Justin Murphy
Position: Manager Asset & Works
Date Created/Last Updated
September 2013
Review Frequency **
3 yearly
Next Review Date **
September 2016
* Shall be the Process Owner and is the person assigned authority and responsibility for managing the whole
process, end-to-end, which may extend across more than one division and/or functions, in order to deliver agreed
business results.
** Frequency period is dependent upon circumstances– maximum is 5 years from last issue, review, or revision
whichever is the latest. If left blank, the default shall be 1 year unless otherwise specified.
Revision Control
Revision
Date
Description
0
10/09/2013
Initial Document Creation
STAKEHOLDERS
The following positions shall be consulted if an update or review is required:
Manager Assets & Works
Manager Engineering Services
Manager Engineering Systems Planning
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TABLE OF CONTENTS
1 PURPOSE .................................................................................................... 6 2 APPLICATION ............................................................................................. 6 3 NORMATIVE REFERENCES ....................................................................... 6 3.1 Legislation and Standards ........................................................................................ 6 3.2 Definitions ................................................................................................................ 7 4 SUBSTATION INSTALLATION REQUIREMENTS.................................... 10 4.1 General .................................................................................................................. 10 4.2 Instructions, Procedures and Standards ................................................................ 10 5 GENERAL CONCEPTS ............................................................................. 11 5.1 Types of Distribution Substations ........................................................................... 11 5.2 Modular Packaged Substations (MPS) .................................................................. 11 5.3 Non MPS Arrangements ........................................................................................ 12 5.4 Customer Owned Substations................................................................................ 12 6 MINIMUM REQUIREMENTS FOR SUBSTATION INSTALLATIONS........ 13 6.1 Access .................................................................................................................... 13 6.1.1 Substation Site Access ......................................................................................................... 13 6.1.2 Substation Gatic Cover Access ............................................................................................ 13 6.1.3 Equipment ............................................................................................................................. 13 6.1.4 Personnel Access ................................................................................................................. 13 6.1.5 Location from Street Front .................................................................................................... 13 6.2 Site Requirements and Preparation ....................................................................... 14 6.2.1 Sole Use and Customer Owned Substations ....................................................................... 15 6.3 Requirements for Buildings .................................................................................... 15 6.3.1 General Requirements .......................................................................................................... 15 6.3.2 Aisles and Escape routes ..................................................................................................... 16 6.3.3 Doors .................................................................................................................................... 16 6.3.4 Ventillation ..............................................................................Error! Bookmark not defined. 6.3.5 Cable Trenches..................................................................................................................... 17 7 POINT OF SUPPLY.................................................................................... 18 7.1 District and Sole Substations ................................................................................. 18 7.2 Customer Owned Substations................................................................................ 18 8 FIRE PROTECTION OF SUBSTATIONS ................................................... 19 DM# 3666797
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8.1 MPs and Non MPS Substations installed outdoors ................................................ 19 8.2 Substations Installed Indoors (Including Customer Owned Substation) ................ 19 8.3 Requirements for Fire Rated Enclosures ............................................................... 19 8.3.1 Fire Rating ............................................................................................................................ 19 8.3.2 Doors .................................................................................................................................... 20 8.3.3 Ventilation ............................................................................................................................. 20 8.3.4 Cables ................................................................................................................................... 20 8.3.5 Fire Alarms and Fire Suppression Systems (where required) .............................................. 20 9 SCREENING OF SUBSTATIONS .............................................................. 22 10 ELECTRICAL REQUIREMENTS AND RATINGS...................................... 24 10.1 Electrical Protection of Substations ........................................................................ 24 10.1.1 Requirement for a Contiguous Customer Switchboard ........................................................ 24 10.2 Cables .................................................................................................................... 25 10.2.1 Cable sizes ........................................................................................................................... 25 10.2.2 Substations supplied from the Overhead Network ............................................................... 26 10.2.3 Installation of Cable Ducts .................................................................................................... 26 11 EARTHING REQUIREMENTS ................................................................... 27 11.1 Design and Construction Objectives ...................................................................... 27 11.2 Combined Earthing System.................................................................................... 27 11.2.1 Connections to the Earth Terminal Bar................................................................................. 28 11.2.2 Sizing of Earth Conductors ................................................................................................... 28 11.2.3 Difficulty in getting the required Combined Earth Resistance .............................................. 29 11.3 Separate MV and LV Earthing Systems ................................................................. 29 11.4 Earth Electrodes and Connectors .......................................................................... 30 11.4.1 Earth Electrodes ................................................................................................................... 30 11.4.2 Earth Connectors .................................................................................................................. 30 11.5 Conductive Structures in the Vicinity of Substations .............................................. 31 11.6 Cases Requiring Detailed Earthing Design ............................................................ 31 12 LIGHTING AND POWER ........................................................................... 32 13 ENVIRONMENTAL REQUIREMENTS ....................................................... 33 13.1 Oil Containment ..................................................................................................... 33 13.1.1 Indoor Substations ................................................................................................................ 33 13.1.2 MPS and Non MPS Substations Installed outdoors ............................................................. 33 13.2 Noise ...................................................................................................................... 33 13.2.1 Noise Regulations ................................................................................................................. 33 DM# 3666797
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13.2.2 Compliance with the WA Noise Regulations ........................................................................ 35 14 REVISION INFORMATION ........................................................................ 36 DM# 3666797
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1
PURPOSE
This document describes the technical requirements to be met where a new
substation is to be installed or an existing substation is to be upgraded. In the
hierarchy of documents pertaining to distribution substations, this document sits
below the Distribution Design Manual Volume 3 – Supply to Large Customer
Installations and above the Distribution Substation Manuals, DSM-1 to DSM-9.
This document shall also be read in conjunction with one of the following
documents published by Horizon Power:
2

Underground Distribution Schemes Manual

West Australian Distribution Connections Manual

Western Australian Electrical Requirements (WAER)

Supply Extension Projects – General Conditions for Individual Customers –
DSB 95/5.
APPLICATION
All persons, including Horizon Power staff and contractors involved in the
installation of substations for connection to Horizon Power’s distribution network
shall comply with these requirements, except as otherwise approved.
3
NORMATIVE REFERENCES
The following documents contain provisions that, though referenced in the text,
constitute requirements of these Substation Installation Technical Requirements,
but not limited to these documents. At the time of publication, the editions
indicated were valid. All standards and specifications are subject to revision, and
parties to agreements based on this standard are encouraged to investigate the
possibility of applying the most recent editions of the documents listed below.
Information on currently valid national and international standards and
specifications can be obtained from SAI Global.
3.1
Legislation and Standards

AS/NZS 1170.0:2002 Structural Design Actions – General Principles;

AS/NZS 1668.1:1998 The use of Ventilation and Air Conditioning in
Buildings – Fire and smoke control in multi compartment buildings;

AS/NZS 1680 Series - Interior and Workspace Lighting.

AS 1682.1:1990 Fire Dampers – Specification;

AS 1905.1:2005 Components for the protection of openings in fire-resistant
walls – Fire-resistant door sets;

AS 1940:2004 The Storage and Handling of Flammable and Combustible
Liquids

AS 2067:2008 Switchgear assemblies and ancillary equipment for
alternating voltages above 1 kV ;

AS 2419.1:2005 – Fire Hydrant Installations- System design, installation
and commissioning;

AS/NZS 3000 :2007 Wiring Rules – published by Australian Standards;
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3.2

AS 4799-2000 Installation of underground utility services and pipelines
within railway boundaries;

Dial Before You Dig Service for lodging an enquiry and requesting a plan;

Horizon Power Underground Distribution Schemes (UDS) Manual;

Horizon Power FIPSM (Field Instruction Procedures & Standards Manual);

Horizon Power Network Standard: Testing & Commissioning – Technical
Requirements;

Western Australian Electrical Requirements - (WAER 2008) – published by
Energy Safety, WA;

Western Australian Distribution Connections Manual (WADCM – 2012);

Traffic Management for Works on Roads - Code of Practice, Main Roads,
WA
Definitions
The definitions and abbreviations below apply:
Architect
A qualified person who is engaged by the Customer to prepare
drawings to comply with Uniform Building Bylaws and Local
Government Authority requirements.
Cluster Substation
A District or Sole Use substation where all equipment is
“clustered” on a single site and where the installation of
screening or an enclosure is at the Customer’s discretion.
Conductive
structures
Shall include metallic and any reinforced or prestressed concrete
parts of an installation.
Contiguous
Applicable to Customer’s main switchboard location with respect
to a Substation. Contiguous means adjoining or very close to the
Substation enclosure to ensure that cable/s connecting the
substation equipment to the main switchboard has zero
probability of being damaged with consequent risk to safety and
reliability. In the case of Sole Use Substations, contiguous
means also visible means of isolation.
Customer Owned
Substation
A substation where the Customer is on a Medium Voltage tariff
and owns and is responsible for all electrical equipment other
than Horizon Power’s metering equipment and any medium
voltage switches connecting the substation to the Horizon Power
network.
Distribution
System
Any apparatus, equipment, plant or buildings used, or to be used
for, or in connection with, the transportation of electricity at a
nominal voltage of less than 35 kV.
District Substation
A substation that has LV connections to the street mains.
Horizon Power owns and is responsible for all electrical
equipment within the substation.
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Electrical
Consultant
A qualified person who is engaged by the Customer to design
and prepare the electrical technical and regulatory
documentation for the project.
Fire Rated
A minimum fire rating Level of 120/120/120
Fire Resistant
Surface
A surface having a fire rating Level of 120/120/120
Construction
Project Manager
The Officer appointed by Horizon Power as Horizon Power’s
representative to whom all site contractual and technical matters
are referred.
Gatic Cover
Gas Air Tight Inspection Cover.
Guideline
A set of recommendations indicating how something should be
done or what sort of action should be taken in a particular
circumstance.
MEN
Multiple Earthed Neutral Installation
Low Voltage (LV)
Low Voltage is defined as steady state voltages less than 1 kV
Medium Voltage
(MV)
Steady state voltages equal to or greater than 1 kV and less than
or equal to 35 kV
Modular Packaged
Substation (MPS)
A District or Sole Use substation where the transformer and/or
medium voltage switchgear and/or low voltage switchgear is
housed in a self contained metal enclosure/s connected as a
single package.
Policy
A brief, straightforward statement indicating intention and
direction, and enabling the decision-making process.
Procedure
Prescribed means of accomplishing policy through a series of
steps or processes
Site
All parts of the works that are the subject of the offer and
acceptance between Horizon Power and the Customer for the
provision of electrical services.
Sole Use
Substation
A substation established for a single customer and which has no
LV interconnection with the street mains. Horizon Power owns
and is responsible for all electrical equipment within the
substation.
Structural
Engineer
A qualified person who is engaged by the Customer to design
and prepare structural documentation for the substation
enclosure to resist loads and forces as outlined in AS 1170
where relevant.
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Substation
(Distribution
Substation)
A collection of switchgear and/or a transformer/s on a single site
(which may or may not be screened or enclosed) connected to
the Distribution System.
Suitably qualified
and competent
engineer.
Professionally qualified electrical engineer with adequate
experience to be competent in earthing design
WADCM
Western Australian Distribution Connections Manual
WAER
Western Australian Electrical Requirements
Works
The electricity works associated with the provision of electrical
supplies to the installation that is the subject of the offer
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4
SUBSTATION INSTALLATION REQUIREMENTS
4.1
General
All works shall be carried out in compliance with the following Horizon Power
documented requirements and all works shall cease if the safety of workers or
the public cannot be assured:
4.2
a)
Training and Authorisation;
b)
Job Planning and Risk Assessment (Work Planning);
c)
Personal Protective Equipment (PPE);
d)
Contractor Responsibilities;
e)
Traffic Management; and
f)
Related Instructions, Procedures and Standards (see Clause 2.2 below)
Instructions, Procedures and Standards
Horizon Power and Service Providers shall comply with Horizon Power
Instructions, Procedures, Standards and Construction Drawings when engaged
in the installation of substations on Horizon Power networks.
This includes but not limited to the following Horizon Power documents:
a)
Selected Horizon Power Field Instructions and Work Procedures;
b)
Electrical Safety Standards (ESS);
c)
“Fit for Work” Policy;
d)
Minimum Personal Protective Clothing and Footwear Standard;
e)
Job Risk Assessment Procedure;
f)
Hazard Incident Reporting Notification and Investigation;
g)
Guidelines for Excavation Work near Horizon Power’s underground and
h)
overhead electrical networks;
i)
Project Flow and Quality Assurance Procedure for all work types;
j)
Underground Cable Installation Manual;
k)
Testing and Commissioning Standard; and
l)
Distribution Equipment and Labelling Standard.
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5
GENERAL CONCEPTS
The standard substation types installed by Horizon Power are given below.
5.1
Types of Distribution Substations
Horizon Power may require that the supply arrangement to an installation be via
a particular "type" of substation, i.e.:

"District" Substation (With LV street feeds to/from the substation);

"Sole Use" Substation (With no LV street feeds); or

"Customer Owned" Substation (Supplied at distribution MV voltage levels).
The decision as to which type is selected depends on several factors, including:
a)
Size of customer's load;
b)
Location of customer's load centre on the property, and distance of the
same from the street boundary;
c)
Type and nature of loads within the installation (disturbing, passive, etc.);
d)
Nature of Horizon Power's existing distribution network and loading levels
on other substations in the vicinity;
e)
Horizon Power's need to connect LV street feeds to/from the substation;
etc.
LV street feeds may be required to/from a substation for the following reasons:
a)
The customer requires a "back-up" LV supply to the installation;
b)
There will be future developments and load growth in the immediate area;
c)
The customer's load is expected to increase in the future;
d)
Ease of maintaining equipment in the substation (e.g. with street feeds into
the substation, the customer's load can be partly met while the MV
switchgear is being maintained); etc.
Consideration may also be given to installing a pad-mount or Integrated Package
Substation (IPS) in lieu of the more common brick enclosure substations. There
may be cost advantages as well as land/space advantages with this option.
5.2
Modular Packaged Substations (MPS)
A Modular Package Substation comes complete with a single transformer and
LV switchgear. It is housed in a self contained metal enclosure and is installed
on an inverted, direct buried concrete culvert. If MV switchgear is required, this is
also housed in a self-contained metal enclosure which is installed adjacent to the
transformer on a direct buried steel mounting frame.
Modular Package Substations are used only as District Substations. They are
not used as Sole Use substations. In addition, they are not fire rated and they
are not designed for installation in a fire rated enclosure.
Therefore, MPS is the preferred arrangement for a District substation with a
maximum load of 630 kVA after allowing for future load growth, and the
substation does not require being fire rated.
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5.3
Non MPS Arrangements
A non MPS arrangement comprises a combination of one or more transformers
plus LV switchgear and MV switchgear as required. Each of these items is a
separate component housed in a self contained metal enclosure. The
transformer is installed on an inverted, direct buried concrete culvert. The LV and
MV switchgear enclosures are installed on direct buried steel mounting frames.
Non MPS components are not installed as a single package. They can be
installed either as a “cluster” substation or in a fire rated enclosure (see
Section 6). In the latter case, the culvert and switchgear mounting frames are not
required.
Non MPS arrangements can comprise multiple transformers, with 1000 kVA
being the largest individual transformer size. They can be used as both District
and Sole Use substations.
A non MPS arrangement shall be used where;
5.4

A Sole Use substation is required; or

Multiple transformers are required; or

The maximum load is greater than 630 kVA after allowing for future load
growth; or

The substation requires being fire rated.
Customer Owned Substations
Typically, for loads greater than 4 MVA, a Customer Owned substation shall be
provided. Neither the MPS nor the non MPS arrangements are suitable for
Customer Owned Substations. Horizon Power shall provide extensible MV
switchgear necessary for connection to the network. The equipment shall be
installed in a switch room constructed by the customer, along with the customer’s
own MV switchgear (See DSM-3-22 for details).
Where a customer’s load is less than 4 MVA, MV outdoor ground mounted
switchgear can be considered. (See DSM-3-23 for details). A Customer Owned
Outdoor Ground Mounted Substation cannot be upgraded for loads above
4 MVA. In the event that the customer’s load increases above 4 MVA, the
substation shall be converted to a MV Indoor Ground Mounted Substation, which
will require a switch room to be built.
In areas with overhead networks only, MV outdoor aerial mounted switchgear
may be used (See DSM-3-24 for details).
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6
MINIMUM REQUIREMENTS FOR SUBSTATION
INSTALLATIONS
6.1
Access
6.1.1
Substation Site Access
Access to the substation site shall be suitable for heavy vehicles to enable the
construction, maintenance and operation of the substation. The maximum
allowable slope of the access road / driveway to the substation is 1:10. It is
essential that the immediate area around the substation is level to facilitate
removal or replacement of the transformer/switchgear.
6.1.2
Substation GATIC Cover Access
GATIC covers provide access from the top, when a substation is in an
underground location (e.g. building car parks) to facilitate installation and
removal of equipment.
If Gatic covers are to be installed:
a) And access to the substation is via ‘gatic’ cover, the clear opening dimensions
shall to be 2500 mm x 2000 mm.
b) Inside the substation building, the minimum clear ceiling height above the
‘gatic’ cover shall be 3.3 m. Lifting eyes or a monorail shall be designed and
installed to allow for the installation of Horizon Power plant. See Horizon
Power drawing DSM-6-05 for details.
c) Outside the substation building, there shall be access for a crane from the
street or right of way with no obstructions above the ‘gatic’ cover.
6.1.3
Equipment
Access to the substation shall be suitable for heavy plant. If a transformer is to
be installed, consideration shall be given to installation constraints (i.e. size and
weight). The general dimensions of a 1000 kVA, 33 kV transformer are,
1600 mm high x 2100 mm wide x 1800 mm long, with a mass of 5 tonnes.
Equipment foundations shall be capable of holding the loads of all equipment to
be installed.
The method of lowering or raising large items of equipment shall be considered
at the design stage.
6.1.4
Personnel Access
Horizon Power shall be provided direct access to all substations, 24 hours per
day, 7 days per week. This is required even where the substation is located
within a building or more than 30 metres from a property boundary.
6.1.5
Location from Street Front
District substations shall be located not more than 30 m from the street boundary
to limit voltage drop.
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6.2
Site Requirements and Preparation
There are a range of variables that may impact on the finished ground levels
around a substation site including but not limited to the following geographical,
environmental and climatic factors:
a)
Soil types, content, compaction and stabilisation;
b)
Position of the site in terms of elevation above flood levels and location in
relation to coastal or inland environments;
c)
Weather conditions
precipitation;
d)
Drainage;
e)
The existence of or use of existing or introduced vegetation/natural ground
cover;
f)
The use or need for retaining walls; and
g)
The size and overall weight of the structure in terms of the prevailing
ground conditions.
including
ambient
temperature
and
levels
of
The following conditions shall apply to all substation sites:
a)
The site shall not be lower than the finished level of surrounding lots and
adjacent road carriageways. In rural areas, the finished level of
carriageways may be higher than the surrounding areas to allow for natural
drainage from the carriageway;
b)
Substations shall not be built in water courses and shall be located 1 metre
above the 100 year flood level, pegged, compacted and levelled to an out
of plane tolerance of ±10 mm. ( In certain locations, where the built up area
is below the 100 year flood level, pad-mount substations may not be
suitable);
c)
No other services including telecommunications, water and gas services
shall be installed either on or under or in close proximity to the site;
d)
The site shall be suitably prepared and the ground stabilised by the
removal of any vegetation and a layer of top soil to the depth of 100 mm
and then backfilling with a layer of sand. If the site contains materials other
than sand (e.g. rock, clay or building materials) the site shall be excavated
and back filled with clean compacted sand to a depth of 1 metre;
e)
The site shall be compacted to a blow count of 8 per 300 mm using a
Standard Penetrometer or a Perth Penetrometer.
f)
In the event that the site is higher than the finished levels of neighbouring
areas, retaining walls, access steps and drainage complying with the
relevant Australian Standards and the requirements of the Local
Government Authority shall be provided;
g)
If batters are required, they shall be provided with a finish that prevents
wind and water erosion, including kerbing or similar low profile retaining
structures around the lower edge to maintain batter material. Where
retaining walls, access steps, screens and /or batters are installed, the land
requirements shall be increased to accommodate these associated
features and any associated footings. Footings for such structures, or
adjacent properties shall not encroach into the substation area;
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h)
Where a substation is located in a trafficable area such as car parks, there
is a likelihood of vehicles damaging or blocking access to the substation. In
such situations bollards, concrete kerbing or other protective structures
shall be installed to protect the substation and maintain the ability to
operate equipment safely. Bollards with a non-conductive surface are
preferred, to prevent touch voltage hazards. (see Clause 9.5 when
installing conductive bollards). Concrete kerbing shall be 150 mm high with
a barrier profile around the site boundary;
i)
Following the installation of all substation equipment, exposed surface
areas at the site shall be stabilised to mitigate against the effects of
erosion. Crushed limestone or blue metal (10 -25 mm aggregate) shall be
laid around each item of equipment to a depth of 50 mm and to a width not
exceeding 450 mm. Any such laid materials shall be easily removable to
allow access to cables and equipment and shall be clear of the earth
grading ring by a minimum of 300 mm;
j)
AS 2419.1:2005 – Fire Hydrant Installation requirements are that fire
hydrants and brigade booster assemblies be located in a position at least
10 metres from any substation;
k)
Substations shall be located away from noise sensitive premises as per
Section 13; and
l)
Based on conservative worse case scenarios, a minimum 8 m clearance
from petroleum/gas storage or dispensing facilities (refer to WADCM
Clause 14.4.2.4 for more details).
Refer to DSM-3 for minimum land area requirements.
6.2.1
Sole Use and Customer Owned Substations
A suitable site and building shall be provided by the customer in accordance with
the conditions stipulated in Clauses 6.2 and 6.3, at no cost to Horizon Power.
The customer shall provide architectural drawings of the proposed site, including
areas adjacent to it, for approval by Horizon Power, prior to commencing
construction of the substation.
The entire area as shown in drawings approved by Horizon Power shall be
retained for Horizon Power’s sole use, unhindered by any obstructions that may
affect normal operations and maintenance.
6.3
Requirements for Buildings
As a minimum, substation buildings shall comply with the requirements of the
Building Code of Australia and with the requirements of the Local Government
Authority of the area in which the substation is to be located. Structural design
shall be in accordance with AS/NZS 1170 series of standards.
6.3.1
General Requirements
a)
Load carrying structural members, partition walls, claddings, enclosures
etc, shall be selected to achieve the appropriate fire rating;
b)
Electrical operating areas shall be designed to prevent water ingress and
to minimise condensation;
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c)
Materials used for walls, ceilings and floors on the ground shall not be
damaged by water penetration or leakage;
d)
All penetrations shall be sealed with a fire rated material;
e)
The building design including foundations shall take into account the
expected mechanical loading (weight of transformers and other equipment)
and internal pressure caused by an arc fault;
f)
The design strength of the building shall be sufficient to withstand all static
and dynamic loads due to normal operation of the installation and
abnormal conditions associated with equipment failure, not limited to but
including internal pressure caused by an arc fault or oil vapour explosion;
g)
Floors shall be flat and stable and able to support the static and dynamic
loads;
h)
Ceilings shall be a minimum height of 2.5 m above floor level;
i)
The external walls and roof of the building shall have sufficient design
strength for the environmental conditions (rain, wind, sun etc.); and
j)
An outdoor substation shall comply with the fire protection requirements in
Clause 8.1. If these requirements cannot be met, an indoor substation shall
be considered.
Fire protection of Indoor substations shall be as per Clause 8.2.
6.3.2
6.3.3
6.3.4
Aisles and Escape routes
a)
Aisles shall be at least 750 mm wide and shall not be reduced even where
equipment projects into aisles;
b)
Space for evacuation shall be 600 mm (minimum), even when removable
parts or open doors, which are blocked in the direction of escape, intrude
into escape routes; and
c)
There shall be at least two points for egress.
Doors
a)
Access doors shall be secured to prevent unauthorised access;
b)
Access doors shall open outwards and be provided with safety signs in
accordance with HPC-2AA-07-0001-2012: Guideline - General Application
of Signs Used on Distribution Equipment;
c)
Doors shall be positioned such that they do not create a personnel hazard
or allow blockage by parked vehicles;
d)
Emergency exit doors shall have panic release bars fitted to facilitate
opening in an emergency from the inside, even when they are locked from
the outside;
e)
The minimum dimension of doors shall be 2040 mm high and 820 mm wide
for single doors and 2040 mm high and 1720 mm wide for double doors.
Ventilation
Ventilation is required to assist air circulation and help cool transformers. The
preferred method for aerating fully enclosed substations is by natural cross flow
ventilation. This methodology minimises the risk of transformer or equipment
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failure caused by overheating due to mechanical and electrical malfunction of
installed ventilation systems.
Adequate openings shall be provided for ventilation and pressure relief for
gaseous products to prevent structural damage in the event of an explosion in
roofed enclosures. In substations where a transformer is installed, the normal
transformer ventilation will meet this requirement.
Where natural cross flow ventilation for transformers cannot be achieved, and
forced draught ventilation is required, fans, ducting and weather proof outlet
grilles shall be installed. Individual ducts are required for each transformer and
grilles shall be of robust construction and with low resistance to air flow. Refer to
DSM-6-02 for exhaust fan details and DSM-06-03 for the associated sub
distribution board schematic.
If the ducting passes over the top of the transformer, the ceiling height of the
enclosure shall be increased to a minimum of 3 metres.
6.3.5
Cable Trenches
Trenches shall be 1200 mm x 1200 mm with trench walls and floors painted with
Silicon Glaze S50 waterproof paint. Trench covers shall be steel grated with
Webforce C253MP or equivalent (Refer to DSM-6-10 and DSM-3).
Access to trench from the outside shall be via conduits only. Once cables have
been installed, conduits shall be completely sealed with fire retardant material
(Refer to DSM-6-01).
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7
POINT OF SUPPLY
The customer shall provide and install the consumer mains cable from the
customer’s main switchboard to Horizon Power’s designated point of supply.
These cables shall:
a)
Take the shortest possible route across Horizon Power’s site;
b)
Not cross underneath any Horizon Power equipment;
c)
Be installed in Heavy Duty PVC conduits; and
d)
Preferably be copper cables due to the smaller lug sizes.
Consumer mains including neutral conductors, switchboards, main switches and
service protective devices shall comply with the WA Electrical Requirements
(WAER), WADCM and AS/NZS 3000.
7.1
District and Sole Substations
Where the point of attachment is within a District or Sole Use substation, the
Consumer’s Mains shall connect the Customer’s Main Switchboard to:

Horizon Power’s LV switchboard in a District substation; and

Horizon Power’s transformer LV terminals in a Sole Use substation.
The maximum size of consumer mains that can be terminated within a District or
Sole Use Substation is shown in DSM-1.
7.2
Customer Owned Substations
The Customer shall supply and install adequately rated medium voltage main
switches and busbars suitable for connection to Horizon Power’s MV metering
unit/s. Although the use of switchgear identical with Horizon Power’s is preferred,
Customers may purchase and install switchgear of a different make. In such
cases, to enable connection of the Customer’s switchgear to Horizon Power’s
switchgear, the Customer shall provide a suitable arrangement acceptable to
Horizon Power. The type of switchgear Horizon Power uses will be advised on
application (see DSM-3-22A/22B).
If a recloser is used by the customer as the main switch, it must be set to one
shot to lock out operation (see DSM-1-10 and DSM-3-24 for details).
To ensure the integrity of Horizon Power and Customer equipment and the
safety of operators, such an arrangement shall be designed and constructed with
adequate clearances, rating, etc and verified by type testing in accordance with
the relevant Australian Standard.
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8
FIRE PROTECTION OF SUBSTATIONS
Transformers used in Horizon Power’s substations have a potential fire risk zone
that extends in every direction and fire protection requirements are outlined
below.
8.1
MPs and Non MPS Substations installed outdoors
Minimum separation requirements are given in Table 1.
Table 1: - Minimum Separation Distance – Substations Installed Outdoors
Transformer Capacity
Clearance to other similar
capacity transformers or
Fire Resistant Surfaces
Up to 630 kVA
Clearance to Non Fire
Rated building surfaces
1m
6m
3m
7.5 m
(< 1000 L oil)
630 kVA (> 1000 L oil)
Substation enclosures not fully enclosed, with open roof, shall maintain
clearance to non fire rated building surfaces in accordance with Table 1. (See
details in DSM-5).
8.2
Substations
Substation)
Installed
Indoors
(Including
Customer
Owned
All Substations installed indoors (inside buildings) shall be fire rated to a FRL not
less than 120/120/120. This applies if the Substation building houses a single
transformer rated lower than 630 kVA or contains several transformers with
capacity 630 kVA or greater.
Where there are more than two transformers, transformer pairs shall be fire
segregated to a FRL not less than 120/120/120.
8.3
Requirements for Fire Rated Enclosures
This clause describes the additional conditions to those specified in Clause 6.3
where the substation requires being fire rated.
8.3.1
Fire Rating
Fire rated enclosures such as Indoor substations shall be fire rated, with a
minimum FRL 120/120/120 fire rating.
FRL 120/120/120 fire rated walls are deemed to comply if they constructed in
accordance with AS 3700 as follows:
(a)
Double clay brick on a concrete footing; or
(b)
150 mm thick solid concrete blocks.
Reinforced concrete floors and roofs/ceilings shall be built to be not less than
100 mm thick at the point of minimum cross section in order to achieve a
FRL 120/120/120 fire rating.
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8.3.2
Doors
Fire rated enclosures such as Indoor substations shall be fitted with self-closing
fire doors having a FRL not less than 120/120/120 when;
(a)
An enclosure door opens to any part of a building; or
(b)
Where there is any other structure within its fire risk zone (see DSM-5-02
DSM-5-04 and DSM-5-05 for details).
Fire resistant doors shall be fitted with panic release bars, complying with
AS 1905.
8.3.3
Ventilation
Ventilation and pressure relief device openings in indoor substations shall be
fitted with self closing dampers having a FRL not less than 120/120/120 when:
(a)
Fire exits or areas set aside for fire escape purposes are within 6 m of such
openings (although there shall be no opening to a fire isolated stairwell); or
(b)
An opening is not more than 2 m from any other part of a building housing
the substation or any other adjacent building.
(See DSM-5-04 and DSM-5-05 for details).
The requirement of the fitting of self-closing dampers will not apply when
ventilation ducts of a suitable length are installed external to the enclosure and
such ducts have a FRL not less than 120/120/120. For details of fire rated
dampers refer to AS 1682 and AS/NZS 1668.
For substations where only switchgear is installed, pressure relief vent/s shall be
installed and all vents shall be fitted with external louvers for security. Fire
dampened vents shall be installed as shown in DSM-6-02. They shall be fitted
with rotating type blades held in the open position by two thermal links in parallel
and shall conform to AS 1682 and AS/NZS 1668.
8.3.4
Cables
Cables located within a building and supplying an indoor substation shall be
enclosed or otherwise protected by an enclosure constructed to an FRL of not
less than 120/120/120.
Cables in trenches and buildings shall be laid in such a way that the fire safety of
the building is not adversely affected. Trench covers shall not exceed 1 metre in
length and shall be steel grated with Webforce C253MP or equivalent (Refer to
DSM-6-10 and DSM-3). To avoid fire propagation, ducts through which cables
pass from one room to another shall be sealed with suitably fire resistant
(minimum 2 hrs) material.
Power and control circuits shall be physically separated or routed differently to
preserve the integrity of control circuits for as long as possible following possible
damage to power circuits.
(Refer to DSM-6 and DSM-3)
8.3.5
Fire Alarms and Fire Suppression Systems (where required)
For substations installed within buildings, there may a need to specify fire alarms
and automatic fire suppression protection. Local authority requirements in this
regard vary and these need to be verified.
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Fire alarm systems shall be dual activation systems including both thermal (rate
of rise detectors) and smoke detectors.
Fire suppression systems shall be capable of containing the fire and be of the
sprinkler type with foam (dry head). Water sprinklers are not permitted. The foam
released shall not damage equipment within the substation or interfere with their
operation.
In addition to the requirements of clause 8.3.1, automatic fire suppression
protection should be considered when transformers with capacity 630 kVA or
more are installed.
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9
SCREENING OF SUBSTATIONS
Where a MPS or non MPS cluster arrangement is to be installed, Horizon Power
has no requirement for screening around the site. However, the Customer may
elect to install screening around the site (e.g. for aesthetic reasons). The erection
of such screening is at the Customer’s discretion and is the Customer’s
responsibility.
If the Customer proposes to install screening, this shall be stated in the
Customer’s application to Horizon Power. The following conditions relating to
screening shall apply:
a)
In general, any type of screening is permissible (e.g. vegetation, fencing,
masonry walls, etc.). Horizon Power will provide a drawing showing
indicative
permissible
screening
arrangements
for
the
site.
(see DSM 6-13);
b)
Screening shall comply with the separation requirements in Table 1.
(Clause 6.1.1);
c)
Where full screening is proposed, two openings are required with
dimensions as shown on the Horizon Power drawings. The openings do
not require doors. However, if the Customer elects to install doors at these
openings, the doors are to be hinged to open both inwards and outwards,
with no self locking. The outward opening of the doors shall be
unobstructed with no physical barriers within a 2 metre radius of an opened
door. If locking is required, Horizon Power padlocks are to be used. These
are available from the Construction Project Manager for the project. Doors
do not need to be fitted with labels;
d)
Where screening is to be roofed, liaison with Horizon Power is required to
ensure
issues
such
as
ventilation
and
future
equipment
removal/replacement are addressed;
e)
The screening shall be installed only after Horizon Power has completed all
work on site. This is to ensure that the screening does not interfere with
installation work nor become undermined by any Horizon Power trench
excavation;
f)
No part of the screening or associated foundations or supports shall
intrude within the Horizon Power site area as shown on the appropriate
drawing. The Customer shall be responsible for ongoing maintenance of
the screening;
g)
Unless specifically negotiated otherwise with Horizon Power, the screening
and any associated foundations or supports shall not extend more than
550 mm below finished ground level. This is to protect Horizon Power
cables entering and exiting the site;
h)
The use of metallic screen fencing is not recommended.
i)
Where metallic screening is installed within the 2 metre restricted zone
(DSM-6-13) it shall be bonded by suitable earthing connections to the
substation earthing system. In addition, it shall be connected to a grading
wire buried at a depth not less than 500 mm below ground and not more
than 550 mm below ground at a distance of 1000 mm outside the
screening; and
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j)
Metallic screens installed outside the 2 metre restricted zone (DSM-6-13)
may not need to be bonded to the substation earthing system or grading
ring (earthing designs and calculations may show that they need to be
bonded).
k)
Horizon Power reserves the right to remove a screen, if required, when it
has to work on a substation.
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10
ELECTRICAL REQUIREMENTS AND RATINGS
Equipment installed in substations including protective devices and cables shall
have the capability to withstand, without damage, the maximum fault currents at
the substation location. Fault level drops when a substation is located farther
away from the source of supply, (e.g. a generating station).
System design fault levels may be more or less than typical values shown
in Table 2. The maximum system design fault level for any particular
location must be obtained from Horizon Power.
LV fault levels will depend on the number of transformers used to supply the
installation.
Table 2: - Typical MV System Design Fault Levels (1 second)
SYSTEM DESIGN FAULT LEVEL
SYSTEM VOLTAGE
10.1
(kV)
(MVA)
(kA)
6.6
200
18.1
11
350
18.1
22
500
13.1
33
750
13.1
Electrical Protection of Substations
Protective devices shall be installed in substations to ensure that:

faults are safely disconnected; and

discrimination is provided to prevent fault impact on network and
customers.
Suitably rated fuses and circuit breakers shall be used to achieve this objective.
The ratings, length and exposure to damage of cables downstream of protective
devices shall be considered, to ensure that cables are adequately protected.
Other downstream protective devices such as customer’s main switch shall
grade with substation fuses.
Details of fuses and circuit breakers are provided in DSM-1 - Customer Supply
Arrangements. Where circuit breakers are specified, they shall be of the current
limiting type.
10.1.1
Requirement for a Contiguous Customer Switchboard
Where a customer is supplied from a fused low voltage circuit emanating from a
District Substation, the customer’s switchboard can be remote from the
substation. In such case, the consumer’s mains’ is protected by a fuse that
grades with the customers’ main switch, which is dependent on the customer’s
load. This is not always possible because the maximum fuse size on the low
voltage circuit depends on the transformer rating/voltage and may also depend
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on whether the transformer is protected by a drop out fuse or RMU fuse switch.
(DSM-1-02, DSM-1-03, DSM-1-04).
Where a customer is supplied from a District Substation and the magnitude of
the load is such that the customer’s main switch cannot grade with the maximum
size LV fuse which can be used with the transformer, the customer shall be
supplied either via LV links or LV disconnects. In such case, the customer’s
switchboard shall be contiguous with the substation. (DSM-1-05, DSM-1-06).
Where a customer is supplied from a Sole Use Substation and consumer’s
mains is connected directly on to the low voltage bushing of the transformer with
no protection, the customer’s main switchboard shall be contiguous with the
substation, to limit the amount of unprotected cable that may be exposed to
damage. (DSM-1-07, DSM-1-08, DSM-1-09).
Where the requirement for a contiguous customer switchboard exists as per
above and where:
10.2
(a)
The substation is screened, the customer’s main switchboard shall be
against the exterior of the screen.
(b)
There is a substation enclosure constructed, the customer’s main
switchboard shall be against the exterior wall of the enclosure.
(c)
There is no screen or enclosure, the customer’s main switchboard shall be
immediately adjacent to the edge of the substation site boundary but not
more than 1 metre from the point of supply.
Cables
Cables to be used in substation installations shall:
10.2.1
a)
Be capable of carrying the maximum load currents and fault currents
expected during the life (65 years) of the cable without mechanical damage
or chemical deterioration;
b)
Be Installed such that the possibility of inadvertent mechanical damage
and interference is minimised;
c)
Have insulation appropriate for the nominal voltage;
d)
Have termite protection;
e)
Have safe separation clearance from other cables and services; and
f)
Have appropriate mechanical protection when laid below ground and when
located above ground, up to a height of 2400 mm from any surface on
which a person can stand to the point where the cable enters the ground.
Cable sizes
Standard cable sizes used are given in Table 3.
Table 3: - Standard Cable Sizes
LV
22 kV
33 kV
16, 25, 185, 240, 630 mm2
35, 185, 240, 400 mm2
50, 95, 185 mm2
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3.3 kV, 6.6 kV and 11 kV installations shall be equipped with 22 kV cables.
Refer to HPC-5DJ-03-0001-2012: Standard - Underground Cable InstallationTechnical Requirements, for details about installing cables associated with
substations.
10.2.2
Substations supplied from the Overhead Network
Substations supplied from the overhead network via drop out fuses shall be
through an appropriate cable termination installed on a pole.
10.2.3
Installation of Cable Ducts
Cable ducts shall be installed during civil construction of substations to facilitate
cable installation at a later stage. Installation details for cable ducts associated
with substations are provided in DSM-6-01 and DSM-6-02.
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11
EARTHING REQUIREMENTS
11.1
Design and Construction Objectives
The design and construction of the earthing system shall ensure that:
a)
All conductive parts consisting of metalwork and equipment that is within
the reach of a person standing on the ground (i.e. up to 2.4 m above
ground) are effectively earthed;
b)
Hazardous touch, step and transfer voltages that can occur during fault
conditions are mitigated;
c)
A low impedance earth is available to effectively carry to earth transient
currents that are imposed due to lightning and switching surges; and
d)
Future modifications, particularly below ground require minimal alteration.
Earth conductors, electrodes and connections (joints) shall be designed and
constructed to ensure that:
11.2
a)
Fault currents are carried to earth without damage to these components;
b)
Possibility of inadvertent mechanical damage and interference is
minimised; and
c)
Corrosion is minimised.
Combined Earthing System
For distribution substations, a combined earthing system shall be used, where
the MV and LV earthing systems are interconnected at ‘an earth terminal bar’
(DSM-6-11 and DSM-6-12) or a ‘grading ring’. Details of earthing connections
are provided in DSM-6. The combined earthing system shall have a resistance
sufficiently low (≤ 1 ohm) to ensure that the design objectives of Clause 11.1 are
fulfilled.
A grading ring shall be installed in substation installations to mitigate against
touch voltages. The grading ring is installed around equipment that is earthed
and subject to hazardous voltage rise during fault conditions. It is installed
around the substation at a distance of 750 mm (with substation doors open) and
buried at a depth of 500 mm. The grading ring is connected to two earth
electrodes which are installed diagonally at opposite ends, which makes up the
earthing system.
Two electrodes shall be used to ensure that there is adequate redundancy in the
event that one electrode is disconnected from the grading ring for some reason
including testing. A maximum resistance of 10 ohms per electrode is permitted to
allow for upstream protection to operate correctly.
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11.2.1
Connections to the Earth Terminal Bar
The following shall be connected to the earth terminal bar separately using
appropriately sized conductors:
a)
Metallic substation enclosure (able sized to greater of MV or LV fault
current);
b)
Metallic MV switchgear frame (cable sized to MV fault current);
c)
MV surge diverters (if any - cable sized to MV fault current);
d)
Metallic sheath of MV cables (cable sized to MV fault current);
e)
Transformer earth lug (cable sized to greater of MV or LV fault current);
f)
Transformer neutral (cable sized to LV fault current);
g)
Earth bar of LV switchboard (cable sized to LV fault current);
h)
Grading ring to earth terminal bar (cable sized to MV fault current);
i)
Earth electrode system (if present);
j)
Metallic substation doors; and
k)
Steel reinforcement in substation structures (if present).
In MPS and non MPS substations, the MV and LV earth bars are permanently
connected (factory fitted) by a link. This allows the MV and LV earths to be
separated if required. Also, on the LV side, the neutral bar and earth bar are
connected by a solid link.
11.2.2
Sizing of Earth Conductors
The conductors referred to in a) to g) of Clause 11.2.1 shall be sized such that
they are not smaller than those values given in Table 4.
Table 4: - Size of Earth Conductor
Expected Earth Fault
Current (MV or LV) at
Substation during
Substation Life
For a) to h) of Clause
9.2.1
≤ 9.5 kA for 1 sec
70 mm2
>9.5 kA and ≤ 18 kA for 1
sec
150 mm2
or 2 x 70 mm2
>18 kA and ≤ 30 kA for 1
sec
3 x 70 mm2
>30 kA and ≤ 40 kA for 1
sec
2 x 150 mm2
>40 kA for 1 sec
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PVC Insulated Single
core copper conductor
Page 28 of 36
or 4 x 70 mm2
Determine size as per
AS 2067:2008
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The grading ring shall be connected to the earth terminal bar by two separate
PVC Insulated conductors sized in accordance with Table 4. Size of grading ring
conductor shall be as per Table 5.
Table 5: - Size of Grading Ring Conductor
Expected Earth Fault
Current (MV or LV) at
Substation during
Substation Life
≤ 12 kA for 1 sec
70 mm2
>12 kA and ≤ 25 kA for 1
sec
150 mm2
>25 kA and ≤ 40 kA for 1
sec
>40 kA for 1 sec
11.2.3
Bare copper conductor
or 2 x 70 mm2
2 x 150 mm2
or 4 x 70 mm2
Determine size as per
AS 2067:2008
Difficulty in getting the required Combined Earth Resistance
The number of customer installation electrodes associated with the LV MEN
system connected to the substation will influence the combined resistance.
Where there are an insufficient number of customers connected, it may be
difficult to get a combined resistance of less than 1 ohm.
Low resistance earths can be installed at pillars located away from the
substation, where the soil resistivity may be conducive to obtaining a low
resistance earth and may also be beyond the zone of influence of the substation
earth. For example, ‘deep earths’ (typically 30 m) where there is a lower
resistivity layer deep into the earth.
11.3
Separate MV and LV Earthing Systems
Where a common earthing configuration does not provide for safe touch, step
and transfer voltages, segregation of MV and LV earthing systems shall be
considered, but this is not the preferred option. A separate earthing system shall
require a detailed earthing design to be carried out by a suitably qualified and
competent engineer.
By separating the MV and LV electrodes, the transfer of EPR from the MV
system to the LV system can be controlled. However, the integrity of the
separated MV and LV earthing systems must be maintained during the life of the
installation. Therefore, they shall be captured in Horizon Power’s Geospatial
Information system (GIS). This will ensure that the possibility of other earthed
structures being installed within the physical separation distance will be
minimised.
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A minimum separation distance of 4 m has been suggested in AS 2067. The
required separation may need to be much larger for low/high resistivity layers
with a LV network of limited extent. (Refer also to Clause 9.6)
Separated MV and LV earthing systems may not be effective in controlling
hazardous step and touch voltages in the event of a MV line to LV line contact at
the distribution transformer, or on a conjoint MV/LV line section. The following
options may be considered for protecting against MV to LV contacts:

Ensuring the configuration of LV lines at the distribution transformer poles
is such that MV to LV contact is unlikely; and

Replacing bare LV conductors over conjoint MV/LV spans with LV buried
cable and LV ABC cable.
The transformer insulation level shall be rated to withstand the maximum EPR on
the MV earthing system, without breaking down to the LV side (e.g. via MV/LV
winding breakdown, or transformer tank to LV winding breakdown).
When the LV earthing system is segregated from the MV earthing system at a
distribution substation, the total earth impedance of the LV earthing system
(including associated MEN earths) shall be sufficiently low to ensure that the MV
feeder protection will operate in the event of a MV winding to LV winding fault.
11.4
Earth Electrodes and Connectors
11.4.1
Earth Electrodes
Copper clad steel rods (15 mm diameter, 1.4 m length) are used as standard on
the Horizon Power network for earthing. The rod is driven so that its top is
200 mm below surface level which provides adequate protective cover rod and
the cable connected to it and to minimise the effect of seasonal variation in the
upper layers of soil.
When joining earth electrodes vertically by driving earth electrodes into the
ground, the electrodes must be installed in drilled holes or mechanically driven to
minimise vibration and ensure good electrode to ground contact. Electrodes
must never be cut.
In rocky areas, driving earth rods mechanically may cause them to break. In
such cases bored earths shall be installed by boring a hole in the ground to the
required depth. Earth rods are then lowered into the hole and backfilled with a
suitable earthing enhancing material (e.g., gypsum). When joining electrodes
with couplings proper electrical connectivity shall be maintained by suitable
means such as scratch brushing and greasing.
More details about earthing electrode installation can be found in the Distribution
Line Earthing Standard: HPC-9DC-08-0001-2012.
11.4.2
Earth Connectors
a)
Connectors used must be either of the bolted or compression types;
b)
Normally accessible earthing terminations to equipment must be made with
compression lugs or bolted clamps;
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11.5
c)
All earthing connections to equipment and electrodes shall be so arranged
that they can be removed, permanently or temporarily, independently of
any other earth, so as not to compromise safety; and
d)
All services including water, sanitary drainage and gas shall maintain a
minimum separation and exclusion zone of 500 mm around LV earth
electrodes. This zone shall be extended to 600 mm for stormwater
drainage services. (WADCM Clause 12.5.5.3.)
Conductive Structures in the Vicinity of Substations
An Earthing design must take into consideration the close proximity of
continuous metallic objects that can give rise to transferred voltages. Transferred
voltage is the potential rise of an earthing system caused by a current to earth
transferred by means of a connected conductor (for example, a metallic cable
sheath, metallic pipelines, metallic fences or rail) into areas with low or no
potential rise relative to earth, resulting in potential difference occurring between
the connected conductor and its surroundings.
When the potential rise on the earthing system is transferred by metallic pipes
(water or gas), or a fence earthed at regular intervals along its length, such
conductive parts will rise to a potential somewhere between the maximum and
minimum potential rise affecting it.
Such conductive structures shall be separated from the substation earth grading
ring by at least 2 metres. Metal bollards installed outside substations shall be
located at least 2 metres away from the earth grading ring. If located within
2 metres, the bollard shall be bonded to the grading ring and included within the
grading ring.
Telecommunications plant, gas pipelines and metallic fences can be subject to
transfer voltages from substation installations. Refer to the Standard – Power
Lines and Cables in the Vicinity of Conductive Installations: HPC-9DC-07-00012012, which provides guidance on calculating the EPR and LFI (Low Frequency
Induction) on such conductive structures.
11.6
Cases Requiring Detailed Earthing Design
The following are some cases where detailed earthing design must be
undertaken as they are likely to result in unacceptable earthing:
a)
MEN systems where there is a small number of MEN connections (i.e. less
than 100 interconnected neutrals within a circular radius of 1 km);
b)
Commercial centres with no LV interconnections;
c)
Close proximity to swimming pools;
d)
Close proximity to Telecommunication pits;
e)
Close proximity to Rail traction corridors;
DM# 3666797
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12
LIGHTING AND POWER
Accessible indoor and outdoor substations shall be provided with suitable lighting
for routine operations.
Lighting levels required shall be considered during substation design. Guidance
on lighting levels is provided in the AS/NZS 1680 Series - Interior and
Workspace Lighting.
Lighting and Power circuits and outlets in substations shall be wired in
accordance with AS 3000.
In District Substations, Horizon Power shall supply and install all lighting fixtures,
GPO’s and wiring necessary.
In Sole Use and Customer owned Substations, the customer shall be
responsible for the above as Horizon Power has no LV supply within the
substation. Where the installation of a fan is required for ventilation, a suitable
GPO shall be provided.
Refer to DSM-06-03 for typical Indoor Substation Distribution Board.
DM# 3666797
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13
ENVIRONMENTAL REQUIREMENTS
13.1
Oil Containment
13.1.1
Indoor Substations
Indoor substations shall have provision for the containment of oil in transformers
by the erection of a suitable bund. A 2-course bund built of 230 x 100 x 76 mm
standard bricks shall suffice.
Other proven oil containment / absorption options such as using hydrocarbon
absorbents are acceptable, although oil bunds have been Horizon Power’s
standard practice.
All probable oil leakage points including cable entry points shall be suitably
sealed to prevent oil leakage.
13.1.2
MPS and Non MPS Substations Installed outdoors
Horizon Power’s standard practice does not require oil containment in
transformers installed outdoors.
Substations shall not be installed in environmentally sensitive sites, without
adequate oil containment facilities. This can be in the form of in-built oil holding
trays, oil bunds or other proven containment / absorption options such as using
hydrocarbon absorbents (Refer to DSM-9).
13.2
Noise
13.2.1
Noise Regulations
Noise limits are generally set by the Department of Environment and
Conservation (DEC) in Western Australia through Environmental Protection
(Noise) Regulations 1997.
The Noise Regulations define Noise Sensitive Premises as:
a)
Premises occupied solely or mainly for residential or accommodation
purposes;
b)
Rural premises
c)
Caravan parks and camping grounds;
d)
Hospitals with less than 150 beds;
e)
Rehabilitation centres, care institutions and the like;
f)
Educational institutions;
g)
Premises used for public worship;
h)
Hotels which provide accommodation to the public;
i)
Premises used for aged care or child care;
j)
Prisons and detention centres; and
k)
Any other promises not defined as industrial, utility or commercial premises
as per the Noise Regulations.
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The noise level limits for Noise Sensitive Premises are given in Table 6.
Table 6 – Noise Level Limits for Noise Sensitive Premises
Location of Substation
Assigned level (dB)
Within 15 m from Noise 45 +Road Noise Level
Sensitive Premises
Beyond 15 m from Noise 60 +Road Noise Level
Sensitive Premises
Beyond 450 m from Noise 0
Sensitive Premises
Road Noise Level is determined as follows:
1.
Major Road (more than 15,000 vehicles per day) within 100 m of Noise
Sensitive Premises = 6 dB
2.
Major Road (more than 15,000 vehicles per day) beyond 100 m of Noise
Sensitive Premises = 2 dB
3.
Secondary Road (6,000 - 15,000 vehicles per day) within 100 m of Noise
Sensitive Premises = 2 dB
4.
Secondary Road (6,000 - 15,000 vehicles per day) beyond 100 m of Noise
Sensitive Premises = 1 dB
5.
Any other Road
or any
Sensitive Premises = 0 dB
Road
beyond
450
m
from
noise
Horizon Power Transformers are designed to emit sound levels in accordance
with AS 2374.6 and the maximum levels are given in Table 7.
Table 7 – Maximum Transformer Sound Levels
Transformer Capacity
Sound level (dB)
1000 kVA
65 dB
630 kVA
63 dB
315 kVA
58.5 dB
≤ 200 kVA
56 dB
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13.2.2
Compliance with the WA Noise Regulations
To comply with the WA Noise Regulations, the Noise Level Limits for Noise
Sensitive Premises should not be exceeded. Where compliance is not achieved
by transformer location with respect to the concerned Noise Sensitive Premises,
the following options may be considered:
a)
Using sound attenuating enclosures or barriers; and
b)
Providing sufficient clearance to noise sensitive premises.
In the design of substations the following shall be considered:
a)
Impact on the local environment (Regulations/Guidelines);
b)
Impact on the working environment (Occupational Health & Safety
Regulations in WA); and
c)
Equipment Noise (from Horizon Power’s Transformer Specification and in
accordance with AS 2374.6 for transformers).
Refer to DSM-6-09 for setback requirements from sensitive premises.
DM# 3666797
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14
REVISION INFORMATION
(Informative) Horizon Power has endeavoured to provide standards of the
highest quality and would appreciate notification if any errors are found or even
any queries raised.
Each Standard makes use of its own comment sheet which is maintain
throughout the life of the standard, which lists all comments made by
stakeholders regarding the standard.
The following comment sheet DM: 3553660 can be used to record any errors or
queries found in or pertaining to this standard, which will then be addressed
whenever the standard gets reviewed.
Date
15/04/2013
Rev No.
0
Notes
Original Issue
DM# 3666797
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