Guidelines Sub Station

8/11/2019 Guidelines Sub Station

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AREA ENGG. DEPT. (SAS) DOCUMENT TITLE:

GUIDELINES FOR THE DESIGN OF SUBSTATIONS

ORIGINATOR DOC No.SP0014/SAKKA DATE : JAN. 2000 REV. 3ADCO DOC. No.30.99.90.019 PROJECT No. PAGE No. 2 of 22

REVISION RECORD

Rev Date ORIGINATOR REVIEWED APPROVED DESCRIPTION

1 09/02/96 MT/MS MT/MS First Issue

2 J AN. 97 MT/MS MT/MS

3 2ndJan

2000

MS ALL HE (SAS) Revised with comments to

reflect ADCOs experience.

4 12.02.200 M.Darwish Issued to FEED Contractors ofUBPF Project


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TABLE OF CONTENTS

1. INTRODUCTION

2. CODES AND STANDARDS

3. LOCATION AND LAYOUT

3.1 Location

3.2 Layout

3.2.1 General3.2.2 Switch Room3.2.3 Battery Room3.2.4 Transformer Bays3.2.5 Other Rooms

4. DESIGN CONSIDERATIONS

4.1 Civil Work

4.1.1 Size of the Substation building

4.1.2 Material

4.1.3 Basis of Design

4.1.4 Design Assumptions

4.1.5 Design of Foundation

4.1.6 Reinforced and Precast Concrete

4.1.7 Type of Reinforcing Bars


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4.1.8 Shear Reinforcement

4.1.9 Continuity of Stress

4.1.10 Steel work

4.1.11 Roads Footways and Site Surfacing

4.1.12 Tanking and Water Proofing

4.1.12.1 Materials

4.1.13 Wire Screens

4.1.13.1 Windows4.1.13.2 Transformer Bay Screens and Doors

4.1.14 Doors

4.1.14.1 Access Doors4.1.14.2 Equipment Doors

4.1.15 Flooring

4.1.16 Wall and Ceilings

4.1.16.1 Wall Tiles4.1.16.2 Wall and Ceiling Finishes

4.1.17 Miscellaneous Civil Requirements

4.2 ELECTRICAL INSTALLATION

4.2.1 Lighting and Small Power

4.2.2 Substation Earthing and Lightning Protection


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4.2.3 Cabling System

4.3 FIRE DETECTION AND FIRE PROTECTION SYSTEM

4.3.1 Fire Detection System

4.3.2 Fire Protection System

4.4 SAFETY

4.4.1 Fire Extinguishers

4.4.2 Emergency Doors/Exists

4.5 TELECOMMUNICATION

4.6 HVAC WORKS

4.6.1 General

4.6.2 Small Substation

4.6.3. Large Substation


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1. INTRODUCTION

This document aims at describing the appropriate considerations thathave to be taken in locating, design and construction of a substation inorder to safely operate the equipment located within the substation,minimise the damage in the event of an explosion caused byequipment failure or due to incorrect operation of a plant and haveconvenience in day to day operation and maintenance of theequipment within the substation. These guidelines are applicable forpower distribution substation of voltage not above 33 kV and handling apower range of one to 25 MVA.

The scope of this document is to provide guidelines for the design ofsubstation building and allied building services for onshore oil, gas andchemical production facilities. It is not applicable to offshore fac ilities.

2. CODES AND STANDARDS

The design and Engineering of electrical installations shall be inaccordance with the latest issue of the "Regulation for the electricalinstallation" published by the Institution of Electrical Engineer (IEE),

International Electrotechnical Commission (IEC), British standards (BS),and the Code of Practice (CP) published by the British StandardsInstitution.

This document is required to be supplemented by the latest edition ofthe following DEPs :

Electrical Engineering guidelines : DEP : 31-10-00-31-GenPlant Telecommunication : DEP : 32-71-00-10-GenFire Fighting System : DEP : 80-47-10-11-GenReinforced Control Buildings/FieldAuxiliary Rooms : DEP : 34-17-10-30-GenMinimum Requirement for Design &Engineering of Buildings,Laboratories : DEP : 34-17-00-32-Gen


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Heating, Ventilating and air

conditioning for Plant Buildings : DEP : 31-76-10-30-GenNoise Control : DEP : 31-10-00-31-Gen

Where a particular subject is not addressed in this document the aboveDEPs shall be followed. Where there is a conflict between thisdocument and the above DEPs the former shall prevail.

As a general rule, the requirements of the National and/or localregulations shall be adhered to, but if these are less stringent than the

requirements of this specification, the latter shall prevail.

3.0 LOCATION AND LAYOUT

3.1 Location

The location of the building shall comply as far as practicable withthe considerations listed below in order of importance.

DEP 34.17.00.32-Gen. gives guidance on the safety distance to be

considered when locating substation buildings.

The building including possible future extensions, shall be locatedin an area classified as non-hazardous by the IP Model Code ofSafe Practice, Part 15 (1990 edition).

The distance between the building and equipment containingflammable substance shall be at least 15 m. Depending on size,pressure and contents of this equipment, the minimum distancecan be up to 30 m, i.e. installations handling light hydrocarbonsunder elevated pressure eg:- process facilities. The distancebetween the building and any pipe rack shall be at least 6 m.Sufficient emergency exit routes shall be designed. Exit routesshall be provided in minimum two directions.


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Available data shall be reviewed to determine the requirements,if any, for survey for soil and underground services.

There shall be no underground utilities below the envisagedlocation of the building.

The building shall be located upwind of the prevailing winddirec tion. It shall be located away from vibrating or noiseproducing equipment.

The building shall preferably be located close to electrical loadcentre, centres of major operational importance, and whereappropriate, central with regard to future extensions. In that case,

space shall be reserved for possible extension of the building itself.The building shall preferably be located close to activitiesrequiring regular local supervision.

Reserved parking space next to the substation shall be provided.

Deviations from these considerations, and the final dec ision on thesubstation location, shall be discussed with ADCO.

3.2 LAYOUT

3.2.1 General

The substation will normally comprise :

- Switch gear room(s)- Battery room and the- Transformer compound

Depending on the project requirements, the followingadditional rooms may be required to be annexed to thesubstation.

- Process control room- Interface panels and relay panels room for

PLC/SCADA system


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- Store/workshop- Toilet & safety shower

3.2.2 Switch Gear Room

Switch gear room (s) shall be adequately sized to extend theswitch room by at least 30% of the original design for 415Vswitchboard. Space required for extension of High voltageswitchboard depends on the project requirement. Approval shallbe obtained from the Company before deciding the space forextension of High voltage switchgear.

A minimum space of 2 meters shall be provided in front of 415V

switchboards. A minimum space of 2.5 meters shall be providedin front of high voltage switchboard.

If two 415V switchboards are placed face to face, a minimumclearance of 3 meters shall be provided between them. If a 415Vswitchboard and High voltage switchboard is placed face toface, a minimum clearance of 4.0 meters shall be providedbetween them.

RCC columns shall not be provided between two rows of

switchboards.

In addition to the space allowed for future extension, a c learspace of 1.0 meter shall be left at the far ends for 415V M.V.switchboards. The above c learance shall be 1.5 meters for Highvoltage switchboards.

A clearance of 1.0 meter shall be provided at the rear of theswitchboard for rear access switchboards.

3.2.3 Battery Room

Batteries shall be located in a separate room for 110V and 125VDC system. Batteries shall be located in separate room for 24Vand 48V DC system if the battery capacity is more than 7500 VAH.


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Batteries shall be installed on steel or wooden racks. At least 1.0meter access space shall be provided at the front and sides ofthe battery rack.

If more than one DC system is provided in the substation, they shallbe located in a separate battery room irrespective of the batterycapacity. A c learance of 1.5 meters shall be provided betweentwo battery racks.

- Washing basin to be provided in the battery rooms togetherwith proper drain system.

3.2.4 Transformer Bays

Transformers shall be installed on concrete plinth. For transformerof size up to 2500 kVA a clear space of 1.25 meter shall beprovided around the transformer. For transformers above 2.5MVA, a clearance of 1.5 meters shall be provided around thetransformer. 5000 kVA transformer bays and above shall beprovided with one common oil pit to accommodate at least 150%of oil volume of one transformer.

Transformer bays shall be provided with cable trenches for access

to the transformer. The trenches shall be so arranged for easyreplacement of transformer from the transformer bay.

3.2.5 Other Rooms

Size of any other rooms, if required, shall be decided on theproject requirements.

4.0 DESIGN CONSIDERATIONS

4.1 Civil Works

4.1.1 Size of the Substation Building

The substation shall be of elevated floor type. The height ofthe building shall be limited to one storey above the raised


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ground floor . As a consequence the air-conditioning unitshall be located either on the grade level or on the roof.

The transformer rooms shall be built as a one storey building,at grade level without basement.

The shape of the building shall be rec tangular with noprotruding canopies etc.

A general arrangement drawing showing the internal layoutof the building shall be prepared in close consultation withADCO.

4.1.2 Materials

The building shall be designed with reinforced monolithicconcrete frames and concrete block in fill.

- Transformer bay / compound shall be structural steelframed structure.

The Reinforced Concrete Works shall be in accordance

with the requirements of BS 8110.

All materials used shall be in accordance to BritishStandards unless an alternative National Standard is offeredto and approved by ADCO. The standards referred

throughout in this document do not present an exhaustivelist of the standards applicable.

4.1.3 Basis of Design

- Bottom of raised floor slab to be elevated 1.80 m fromfinished ground level.


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- Block walls shall be made 200 mm thick solidconcrete block or of 300mm thick as applicable andapproved by ADCO.

- Roofing shall be protected by appropriate waterproofing system with laps laid on primed screed andriged closed cell extruded polystyrene foaminsulation 50mm.

4.1.4 Design Assumptions

The building and its components shall be designed to resistwind loads calculated in accordance with British Standard

Code of Practice CP3 Chapter-V, Part 2. A basic windspeed (3 sec gust 1-in 50 yr return period) of 45 m/s at aheight of 10 m above ground level be assumed.

Floor live load shall be taken as the actual equipment loadprovided by supplier or 6.25 KN/m2whichever is greater.

Roof live load shall be taken equal to 2.0 KN/m2in additionto any HVAC equipment and plinth loads

All structural and secondary elements shall be designedassuming a basic horizontal seismic coefficient of 0.075 andan importance factor of 1.25 in accordance with division IVof the Uniform Building Code (UBC) chapter 16.

Walls and roofs shall be designed to provide a minimum

thermal insulation 'U' value of 0.6 W/m2K.

4.1.5 Design of Foundations

Foundations shall be designed to British Standard BS 8004"Code of Practice for Foundations", and based on specificsoil investigations ot be carried out in the building location.


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Where ground improvement methods are adopted theseshall be approved by ADCO.

In weak soils an allowance is to be made for the provision ofpiles. Preliminary test piles will be placed and tested beforeany construction and during the design, in order to obtainsuitable working loads for the proposed piles.

n Transformers shall be installed on a separate concretefoundation raised 150 mm above grade.

n Oil pit shall be provided around transformers and shallbe filled with single size gravel (20 - 40 mm) pit concretefloors shall be sloped to a sump (see section 3.2.4).

4.1.6 Reinforced and Precast Concrete

Reinforced and precast concrete designs shall be carriedout in accordance with BS 8110 with particular reference tothe alternative loading condition.

Mild steel shall not be used except for dowel bars atmovement joints.

4.1.7 Type of Reinforcing Bars

High strength deformed bars type II shall be of yield strength460 N/mm

2.

Mild steel shall be plain bars of yield strength 240 N/mm2.

4.1.8 Shear Reinforcement

Shear reinforcement shall be as recommended by BS 8110.

4.1.9 Continuity of Stress

In general, special attention shall be paid to ensurecontinuity and a minimum of local stress concentration.Adequate lapping of reinforcement is required.


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4.1.10 Steelwork

Structural steel shall comply with the requirements of BSEN

10025.

Structural steel design shall be in accordance with BS 5950.

4.1.11 Roads Footways and Site Surfacing

Roads shall be suitably designed and constructed inaccordance with shell standards for vehicles carrying thelargest/heaviest items of plant and shall be of sufficientdurability to require the minimum of maintenance during

the design life of the substation. Site Roads shall beconstructed of heavy traffic duty concrete blocks. All roadsshall be laid at slopes to assist site drainage. Non pavedareas shall be stabilised by gravel spread layer.

- Under the basement - Gravel to be surfaced and thesize to be agreed with ADCO.

4.1.12 Tanking and Water Proofing

4.1.12.1 Materials

Mastic asphalt shall conform to either BS 6577 or BS6925 for undercoating and BS 1466 or BS 1467 fortop coating.

Materials for mastic asphalt shall be obtained fromsuppliers approved by ADCO. Bitumen sheetmembranes shall conform to BS 743.


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4.1.13 Wire Screens

4.1.13.1 Substation Building Wire Screens

Wire screens shall be mounted below substation torestrict access to the cable tray area.

All wire shall comply with BS 4102. The screens shallbe woven from minimum 3.55 mm diameter wire toform a mesh size of 25 mm x 25mm.

Each panel shall be framed with MS bars. The jointsin the framing bars are to be welded and the mesh

attached to form a rigid panel.

The whole screen is to be galvanised aftermanufacture to comply with the requirements of BS729.

4.1.13.2 Transformer Bay Screens and Doors

Wire screens and doors for transformer bays shallbe manufactured from rectangular or circular

hollow sections complying with BS 4848 and wiremesh complying with BS 4102.

The wire for mesh shall be a minimum of 3.55 mmdiameter and the mesh size shall be 25 mm x 25mm.

4.1.14 Doors

4.1.14.1 Access Doors

Outward opening doors shall be provided at twosides of the substation building for ease of access.The doors shall be provided with automatic doorclosures.


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Switch gear room(s) shall have two doors one forthe access of equipment and the other foraccess of personnel/emergency exit doors.

Battery room shall have one access door. Thisaccess door shall lead to a separate entranceto the substation.

Doors shall have minimum 1 hour fire rating unlessotherwise specified for the project.

All doors shall have a good seal between doorand frame to maintain the different pressure

between the various rooms and the outside of thebuilding.

4.1.14.2 Equipment access Doors

Equipment access doors shall be bolted to thesteel door frame and the seal shall be air-tight.Equipment door for switch room(s) shall have aheight of 2.75meters.

4.1.15 Flooring

Flooring shall be of concrete with a layer of epoxy toppingfor all rooms except the battery room and toilets. Batteryroom shall be provided with anti-acid type tiled flooring.Toilet shall be provided with normal ceramic tiles.

4.1.16 Wall and Ceilings

4.1.16.1 Wall Tiles

Wall tiles in battery room and toilets (if provided)shall be glued to the wall with spec ial tileadhesive recommended by the manufacturer.


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Tiles used in the battery room shall be anti-ac idtype.

4.1.16.2 Wall and Ceiling Finishes

All surface finishing materials for walls and ceilingsin the substation shall be fire-resistant or non-combustible and shall have no loose fibers.

If the substation is provided with a Packaged Air-condition System, false ceiling shall be providedexcept for the battery rooms.

4.1.17Miscellaneous Civil Requirements

Natural light shall be provided by using glass blocks, asapplicable.

Access ladders for roof slabs shall be provided. Battery room shall be provided with an eyewash basin,

sink, safety shower & drain. The ground level under raised floor slab should be

stabilised by 75 mm thick of 20 dia single sized washedgravel grading.

Doors & Windows

Access doors shall be insulated Sandwich 2 HR provided with cylinder lock panic bar. Toilet doors to be of timber sandwich with level catch

and shall be provided with viewing window and airlouver.

Windows shall be aluminium type.

- Air lock shall be provided at the access door of processcontrol room if it is annexed to the substation.


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Fire walls Requirements

- 2 hours for the walls (solid block walls) between twotransformers.

4.2 ELECTRICAL INSTALLATION

4.2.1 Lighting and Small Power

Lighting within the substation shall be of fluorescent lightfixture. Light shall be ceiling mounted. If the substation has

a false ceiling the light fixtures shall be of recessed type.

Lighting, small power and exhaust fans for battery roomshall be explosion proof type suitable for EExd II CT2 duty.

Self contained self maintained type exit lights shall beprovided at all access doors.

25% of the lights provided within the substation shall be selfcontained self maintained type.

Perimeter lighting shall be provided on the substation wallsusing HPMV bulk head fitting.

Access lighting shall be provided by HPSV light fittingmounted on lighting poles.

Following minimum lux levels shall be considered whiledesigning the lighting.

Location Lux Level

Switchgear room 300 LuxBattery room 150 LuxTransformer bay 150 Lux


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Process control room 500 LuxInterface & Relay panel room 300 LuxStore/ workshop 300 Lux

Toilets and access ways 100 LuxOutdoor access ways 50 Lux

Convenience small power outlets shall be of industrial type.At least 20 % of the small power outlets shall be of 3ph-3wire type.

4.2.2 Substation Earthing and Lightning Protection

When substation has transformer(s), one earth well shall be

provided for each transformer. Earth resistance shall belimited to less than one ohm with all loops closed.Substation earthing shall always be connected to plantearthing. For remotely located substations, the main earthshall be connected to a dedicated earth well. All earthwells shall reach below the water table.

Lightning protection shall be provided if required to complywith the specified standards/regulations /code of practice.

4.2.3 Cabling System

Cable trays shall be of hot dip galvanised steel. AdequateTrays shall be provided below the floor openings in theswitch gear room. There shall be an offset between thecable trays and the floor opening for ease in termination.The floor opening shall be sealed by Aluminium plate. Fireretardant type Mastic sealant shall be provided at cableopening to avoid ingress of dust.


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4.3 FIRE DETECTION AND FIRE PROTECTION SYSTEM

4.3.1 Fire Detection System

In general smoke detection system shall be installed in allsubstations.

For substations where switchgears are not completedcompartmented normal roof mounted smoke detectorsshall be used.

While for substations with switchgears completely

compartmented ultra sensitivity smoke detectors in the A/Creturn duct shall be used.

Note : EX (d) extract fans and light fittings shall be used inthe battery rooms.

Temperature detection shall be installed in transformerbays.

A fire alarm annunciator panel shall be installed in the

substation to locate the zone of fault.

A common alarm shall be routed from each substationdirec t to central fire and gas alarm system.

If isolation of power (i.e. tripping of particular switchgear) isrequired due to detection of fire, confirmation by aminimum of two detectors should be implemented to avoidtripping of switchgears on faulty detectors/spurious alarms.

4.3.2 Fire Protection System

Portable hand held 9 kg capacity DPC cylinders shall beprovided at each entrance of substation. One cylinder


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shall be provided for every 10 sq.mt closed area of thesubstation.

Fire fighting water hose reel shall not be installed in thebuilding.

4.4 TELECOMMUNICATION

There shall be one telephone socket for every 40 sq.m closedarea of the substation or one telephone socket for every room,which ever is smaller. Telephone sockets are normally notprovided in the battery room.

All telephone outlets shall be master twin socket outlets providingtwo electrically separate female socket outlets each of which isconnected to an individual line. Parallel points shall not beprovided.

Telephone distribution boxes (TDB) shall be fitted with ten pairdisconnection type terminal block. Termination of cable into theTDB shall be by the IDC method.

Individual conductor diameter of the telephone cable shall be

0.6 - 0.9 mm

Steel trunking shall be used to house the internal telephonedistribution cables. The trunking shall be earthed at main stationearth only.

4.5 HVAC WORKS

4.5.1 General

Switchgear and battery charger rooms shall be airconditioned to 250C dry bulb. Temperature and 55% 5%

relative humidity. Heat gains from the electrical equipmentshall be considered in the cooling load calculations.


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If battery room contains hydrogen generating batteries shallequal to Q= 55 x h x I (where Q = Liters of air per hour, h =number of cells & I = 25% of the rated charge outputs) have

a ventilation rate of 12 air changes per hour. Two wallmounted explosion proof exhaust fans shall be used, oneacting as standby, with automatic changeover in case offailure of the duty fan. Rec irculation of battery room air isnot allowed.

If the battery room contains Alkaline sealed batteries 4changes per hour shall be considered.

HVAC system shall not contain CFC refrigerant. HFC or

HCFC should be used.

Toilet shall have a ventilation rate of 5L/S m2. A wall/glassmounted exhaust shall be used with make up air extractedfrom the adjacent conditioned spaces thru a door louver /under cut.

4.5.2 Small Substations

Substations of areas not exceeding 60M2 (excludingtransformer bays) shall be air conditioned by means of

window type A/C units. (One unit to be standby).

Multiple A/C units shall be sized and installed in suchmanner that the normal climatic requirements are meteven if one unit fails.

Make up for ventilation air of the battery room shall beprovided from the adjacent conditioned spaces through awall mounted backdraft damper.

4.5.3 Large Substations

Substations of areas larger than 60m2 (excludingtransformer bays) shall be air conditioned by means ofpackaged A/C units or chilled water system.


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