Chapter 17 - NT PWC SDM Substation Layouts and Facilities - Outdoor Section Rev 2 - 17-1-2012

8/13/2019 Chapter 17 - NT PWC SDM Substation Layouts and Facilities - Outdoor Section Rev 2 - 17-1-2012

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SUBSTATION DESIGN MANUAL

CHAPTER 17

Substation Layouts and Facilities - Outdoor

Power & Water Corporation

Power Networks


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Substation Design Manual

Chapter 17 Substation Layouts and Facilities Outdoor

Document Number

D2010/287838

Document Control

Revision History

Changes made to this manual since the last revision are highlighted in yellow.

Disclaimer

The information contained in this document has been carefully compiled but Power & Water

Corporation takes no responsibility for any loss or liability of any kind suffered by any party, not

being the intended recipient of this document, in reliance upon its contents whether arising

from any error or inaccuracy in the information or any default, negligence or lack of care in

relation to the preparation of the information in this document.

Title Substation Design Manual

Section Substation Layouts and Facilities Outdoor

Document ID D2010/287838

Prepared Hydro Tasmania Consulting 09/10/2009

Reviewed Hydro Tasmania Consulting 09/10/2009

Revision RevisionDate

Details Authorised

Name / Position Signature

Draft 09/10/2009 For client review and input

Final Draft 4/12/2009Revised following client comments Brendon Gannon

Specialist Engineer

Rev 1 2/11/2010

Doc No & Doc Id InsertedSLD Initial & Ultimate DrawingNos insertedReference Docs [38] to [41] DocNos added17.2 second last paragraph

switchyard added, last paragraphof the 11kV Switchboard added17.7 changed to aggregate shallbe installed17.8 last paragraph added

Greg BrandManager Contracts& Projects

Rev 2 17/01/2012Revised to suit client comments Luke Whitehouse/

Entura


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Reference documents

Documents listed below are relevant to this chapter of the Power & Water Corporation (PWC)

Substation Design Manual. Each reference shall be followed by its list number E.g.: [1]. Anylisted reference which has a later edition will take precedence unless indicated otherwise.

[1] AS 2067 Substations and high voltage installations exceeding 1 kV a.c.

[2] ESAA National Guidelines for Prevention of Unauthorised Access toElectricity Networks

[3] ENA EG1 Substation Earthing Guide

[4] ESAA Substation Earthing Guide

[5] AS 1940 The storage and handling of flammable and combustible liquids

[6] ESAA (series) Guidelines for Oil Containment in the Electrical Supply Industry

[7] IEEE 980 IEEE Guide for Containment and Control of Oil Spills in Substations

[8] AS 1379 Specification and supply of concrete

[9] AS 1478.1 Chemical admixture for concrete, mortar and grout - Admixturesfor concrete

[10] AS 3600 Concrete structures

[11] AS 3610 Formwork for concrete

[12] AS 3799 Liquid membrane - forming curing compounds for concrete

[13] AS 3972 Portland and blended cements

[14] AS/NZS 4671 Steel reinforcing materials

[15] AS 1726 Geotechnical site investigations

[16]AS/NZS 3725 Design for installation of buried concrete pipes

[17] AS 1597.2 Precast reinforced concrete box culverts - Large culverts (from1500 mm span and up to and including 4200 mm span and4200 mm height)

[18] AS 4198 Precast concrete access chambers for sewerage applications

[19] AS 2758 Aggregates and rock for engineering purposes (Series)

[20] AS 1939 Degrees of protection provided by enclosures for electricalequipment (IP Code)

[21] AS 4282 Control of the obtrusive effects of outdoor lighting


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[22] AS/NZS 3000 Electrical Installations - Wiring Rules

[23] IEC 61936-1 Power Installations exceeding 1 kV a.c. Part 1: Common rules

[24] AS/NZS 2312 Guide to the protection of structural steel against atmosphericcorrosion by the use of protective coatings

[25] AS/NZS 2373 Electric cables - Twisted pair for control and protection circuits

[26] AS 2650 Common specifications for high-voltage switchgear andcontrolgear standards (IEC 60694)

[27] AS 2870 Residential slabs and footings

[28] AS/NZS 3008.1.1 Electrical Installations - Selection of cables - Cables for alternating

voltages up to and including 0.6/1 kV - Typical Australianinstallation conditions

[29] AS/NZS 3947.3 Low voltage switchgear and controlgear - Switches, disconnectors,switch-disconnectors and fuse-combination units

[30] AS 4100 Steel Structures

[31] AS/NZS 61000 Electromagnetic compatibility (Series)

[32] AS 62271.200 High-voltage switchgear and controlgear - A.C. metal-enclosedswitchgear and controlgear for rated voltages above 1 kV and up

to and including 52 kV (IEC 62271-200, Ed. 1 (2003) MOD)

[33] AS 62271.201 High-voltage switchgear and controlgear - AC insulation-enclosedswitchgear and controlgear for rated voltages above 1 kV and upto and including 52 kV

[34] AS 62271.301 High voltage switchgear and controlgear - Dimensionalstandardization of terminals

[35] AS 2791 HV switchgear and controlgear - use and handling of SF6in HVswitchgear and controlgear

[36] AS/NZS 1768 Lightning protection

[37] D2010/287823 Chapter 1 - 11 or 22 kV Metal Clad Switchgear

[38] D2010/287831 Chapter 6 - HV Cables and Conductors

[39] D2010/287859 Chapter 15 - Earthing

[40] D2010/287840 Chapter 19 - AC Supply

[41] D2010/287847 Chapter 25 - Substation Signage

[42] D2010/287851 Chapter 28 - Security

[43] XXX Chapter 30 - 66 kV Gas Insulated Metal Enclosed Switchgear


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Table of Contents

17.1 Single Line Diagram - Initial Development ................................................................. 617.2 Single Line Diagram - Ultimate Development ............................................................. 717.3 Fencing and Gates ................................................................................................... 717.4 Switchyard Lighting ................................................................................................. 817.5 Switchyard Civil Works ............................................................................................. 817.6 Ducts and Trenches ................................................................................................. 917.7 Transformer Bunding ............................................................................................. 1017.8 Oil Containment .................................................................................................... 1017.9 Fire Walls ............................................................................................................. 1117.10 Transformer Spacing ............................................................................................. 1117.11 Switchyard AC Supply ............................................................................................ 1217.12 Fire Protection ...................................................................................................... 12


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17.1 Single Line Diagram - Initial Development

The typical initial development single line diagram of the substation is shown in the drawing

B10-12014.

The 66 kV plant shall be an outdoor air insulated switchyard arrangement. The initial

development shall comprise:

Two (2) 66 kV line circuits

A single 66 kV busbar with two (2) 66 kV bus section circuit breakers and

disconnectors to form three (3) bus sections, Bus A, Bus B and Bus C

Two (2) 66/11 or 66/22 kV power transformers, with provision for a third transformer

For further details on 66 kV indoor Gas Insulated Metal Enclosed Switchgear refer to[43].

The 11 or 22 kV plant shall be an indoor metal clad switchboard arrangement. For further

details refer to[37].Initial development shall consist of a single busbar with two (2) sections.

Each 11 or 22 kV bus section shall have:

o One (1) incoming circuit breaker

o Five (5) outgoing feeder circuit breakers

o One (1) capacitor banks circuit breaker

o One (1) auxiliary transformer/outgoing feeder circuit breaker

One (1) bus section circuit breaker on the right hand side of each bus when viewed

from the front

A cable connection chamber shall be installed at the left hand end of Bus 1, when viewed from

the front, to facilitate future connection of ring bus cables.

As w e l l as the above req u i reme nts the re may a l so be a need to supp ly f ac il i t ie s toc onne c t a Nom ad s ubs t a t io n i n t h e e ven t o f a t r an s fo rme r and equ i pmen t f a i l u reRe fe r to the s cope o f w o rks f o r f u r the r de ta i l sThe designer shall consider all aspects of civil and primary construction and installation of the

future equipment in the design as described in section17.2.The initial substation design shall

not impede on the ease of the installation of the future equipment.


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17.2 Single Line Diagram - Ultimate Development

The typical single line diagram of the ultimate substation is shown in drawings B10-12015 and

B10-12016.

Provision for installation of a third incoming transmission line and a third 66 kV transformer

shall be made as indicated on the SLD. This will enable PWC to increase the capacity of its

substation with minimal disruptions to the operation of the existing equipment.

The designer shall consider the construction of transformer foundations, bund walls and all the

other components of the transformer circuit.

The space allowed on site for the future equipment shall be sufficient to install equipment of

the same type as the equipment being installed.

Foundat i ons f o r f u tu re sw i t chyard equ ipment f o rm ing par t o f the u l t imatedeve lopment sha l l no t be i n s ta l l ed un le s s ca l l ed fo r i n the s cope o f wo rks f o r thespec i f i c pro jec tUltimate development of the 11 or 22 kV Switchboard will include the installation of a third bus

section (No. 3) and connection of cable from this section to No. 1 section to form a ring bus.

17.3 Fencing and Gates

Due to the high voltages within the PWC substations, any access by unauthorised personnel

can result in loss of life or serious injury and damage to plant items. To prevent unauthorised

access PWC substations shall have adequate fencing and locked gates. Refer to AS2067 [1]

Section 5.2. An emergency door/gate shall be provided adjacent to the main gate for the use in

emergency evacuation. This door shall have a quick release button that can only be activated

from the inside and shall not allow personal to enter into the site.

All security fences and gates shall be designed in accordance with[1] and[2].

To reduce the risk associated with step and touch potentials during a fault, fences and gates

shall be earthed to the main earth grid in accordance with[1], [3],and[4].

The type of fence shall be TG/CE anti climb, 4 barbed cyclone fence.

Othe r se cu r i t y m easu re s sha l l be se l e c ted i n ac co rdance w i th the c r i t e r i a s e t ou t i nthe s cope o f wo rks f o r the par t i cu l a r s i t e , also refer to [42] for further details onsubstation security.


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17.4 Switchyard Lighting

Switchyards and substations shall have sufficient lighting to allow personnel to move around

the switchyard and operate equipment safely at night.

The designer shall perform lux level calculations to ensure that 20 lux is maintained throughout

the switchyard at ground level.

Additional lighting shall be provided at places where particular hazard existed such as stairs or

step changes in ground level.

The outdoor lights shall be of industrial type, and illumination shall cover the entire switchyard

area and the property boundary fence.

The lighting shall be designed such that the light spill does not disturb neighbouring areas.

Substation yard lights shall have High Pressure Sodium bulbs and a minimum of IP56 rating

and comply with[20] and[21].

If hinged mast lights are used, the designer shall ensure that the light does not impinge on the

clearances around any of the equipment while in motion.

The outdoor lighting shall not be on a single circuit. Lighting shall also be on a separate circuit

to the outdoor GPOs.

Switchyard lighting shall not be mounted on lightning protection masts.

17.5 Switchyard Civil Works

Fo r fu l l de s c r i p t i on o f s i t e c i v i l r equ i rements re fe r to p ro je c t spec i f i c t e chn i ca ldo cumen ta t i o n and s c ope o f wo r kThe civil works that shall be undertaken for construction of new substations or switchyards shall

cover, but not be limited to:

Full geotechnical investigation shall be performed at all new sites in accordance with[15]

Permanent datum points shall be installed on the site based on geotechnical

investigations

The site shall be cleared of any vegetation and other materials

Earth works

Slopes, crowns and ditches shall be excavated and filled to ensure satisfactory storm

water drainage of the site. The installation and design of pipes, culverts and pits shall

be in accordance with[16], [17] and [18].PWC has a preference for a near level site

where possible. Where a gradient is required for drainage a fall of 1:50 shall be used.


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The site shall be compacted to achieve appropriate soil strength. Consideration shall be

given to operation and maintenance equipment that shall be driven onto the site when

designing the switchyard civil works.

Substation base layer and finishing - installation of loose crushed granite or other form

of rock to a nominal depth of 100 mm, using a maximum of 20 mm aggregate size on

the switchyard surface to provide acceptable step and touch voltages. The layer shall be

designed in accordance with[19].Refer to[39] for earthing design details.

Road works to ensure that access roads and substation roads are suitable for transport

of power transformers and crane as the largest onsite equipment and suit the turning

radius of low loader for road used to transport transformers

Power transformer foundations and bunds - The power transformer foundations and

bund walls shall be connected to the oil containment system. Refer to17.7 and17.9

Control building and its foundations

Cable ducts/trenches - The main cable duct shall be installed from the substation control

building to the outdoor yard equipment. Refer to17.6.Below ground basement cable

ducts shall use, as a minimum, water tight rubber membranes to maintain a seal from

external water ingress. Additional concrete admixtures to increase the concrete

waterproofing may also be applied if the designer considers the benefits advantageous

and economical, however, this does not preclude the use of the rubber membrane.

Modular buildings may be used as long as they are designed to a similar standard.

17.6 Ducts and Trenches

A main cable duct shall be installed from the outside of the control room to the switchyard

outdoor equipment. Subsidiary cable ducts shall be installed along each bay of equipment. The

ducts shall be constructed from inverted precast concrete box culverts with appropriate checker

plate covers and be adequate to support all types of cables including control. LV cables shall be

supported on the walls of the duct by means of a cable tray assembly. Buried PVC conduit shall

connect the concrete duct to individual items of equipment.

Ducting shall be designed to allow stormwater to be drained away from the switchroom via

gravity. In situations where gravity draining is not possible, such as a basement, a sump and

sump pump may be provided. The duct shall have a sufficient width to allow for a person to

stand inside the duct as well as room for mounting two sets of cable trays. Refer to drawings

XXX for an example of a typical installation. Also refer to[38] for cabling segregation details.

Transformer 11 or 22 kV cabling shall also be installed in concrete ducts or conduits, using

separate ducts or conduits for each transformer.

The duct covers shall have sufficient strength to withstand the load of heavy vehicles when the

trench crosses a substation road or accessway.


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Bund drainage system

Oil/water separator

An environmental risk/impact assessment shall be undertaken for every new oil/water separatorat a zone substation site to assess the risk of off-site impacts arising from discharge of water

from the oil/water separator and must be designed to trap oil on site. PWC has a preference for

passive oil/water separators. The units shall:

be suitable for a 1 in 50 year storm

allow a maximum of 30 ppm suspended solids at its outlet

allow a maximum of 10 mg/L of oil at its outlet

17.9 Fire Walls

[1] suggests that designers use ENA 18-2008 as a guideline for fire protection of HV

substations. This standard establishes that the Building code of Australia (BCA) class 8

requirements can be used as a guide for buildings used for HV installations. Table 6.1 of[1]

provides a guide for outdoor transformer segregation.

Where a fire hazard exists, HV substation enclosures within or adjacent to buildings must be

designed with a minimum FRL 120/120/120 fire rating. Fire barriers providing FRL 120/120/120

are to be used where this minimum cannot be met. Where a transformer fire is part of the riskassessment, then a fire rating greater than 120 minutes needs to be considered.

Sufficient space shall be provided around the transformer to the walls of the enclosure or fire

wall for the purpose of operation and maintenance access.

The structural adequacy, integrity of barrier material and insulative materials must be

maintained in the event of a fire for the FRL period.

The FRL applies in the same way for the enclosure and any penetrations or opening in the

enclosure.

Flame traps shall be provided inside the bund of the transformer through the use of a non-

flammable pipe within a pit in the bund.

17.10Transformer Spacing

There shall be sufficient spacing between the power transformer bunds to provide safety

clearances and service access to equipment in the HV busbar areas, the lines circuits and

transformer circuits.

Transformers access shall be free from line crossings to allow the transporting and lifting of

transformers and buildings without the restrictions presented by overhead lines.


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17.11Switchyard AC Supply

A 3 phase 300 A weatherproof junction box shall be installed adjacent to transformers for

supplying power to transformer oil filtering equipment.

15 A outlets shall be strategically positioned throughout the yard to provide power for operation

and maintenance. Refer to[40] for further details for AC Supply.

17.12Fire Protection

Fire hydrants shall be strategically located around the switchyard and transformer bays.

Thermal detectors shall be installed in the transformer area and connected to the substation

fire incident panel (FIP).

Chapter 17 - NT PWC SDM Substation Layouts and Facilities - Outdoor Section Rev 2 - 17-1-2012

Documents

Transcript of Chapter 17 - NT PWC SDM Substation Layouts and Facilities - Outdoor Section Rev 2 - 17-1-2012