section 26 11 13-unit sub-stations.pdf

MINISTRY OF HOUSING Western Sector Projects Sitework & Infrastructure OMRANIA and ASSOCIATES Project Specification

UNIT SUBSTATIONS SECTION 26 11 13 - 1

SECTION 26 11 13

UNIT SUBSTATIONS

PART 1: GENERAL

1.01 SECTION INCLUDES

A Factory assembled 13.8 kV unit substations with all associated equipment and accessories including, but not limited to, the following:

1. Skid, enclosure and compartments.

2. MV termination box.

3. Power transformer.

4. LV compartment.

5. Concrete foundation.

1.02 RELATED SECTIONS

A Section 01 31 00 Project Management and Coordination.

B Section 0133 00 Submittal Procedures.

C Section 01 61 00 Common Product Requirements.

D Section 01 75 00 Starting of Systems.

E Section 01 77 00 Contract Close-out.

F Section 01 78 36 Warranties.

G Section 03 30 00 Cast in Place Concrete.

H Section 26 05 00 Common Work Results for Electrical.

I Section 26 05 53 Electrical Identification.

J Section 26 27 00 LV Power Distribution Boards.

K Section 26 05 26 Earthing System.

L Section 26 08 00 Testing and Commissioning of Electrical Systems.

1.03 REFERENCES

A SSA 421 Testing Methods for Power Transformers (SASO).

B SSA 422 Power Transformers (SASO).

C IEC 60044-1 Instrument Transformers - Current Transformers.

D IEC 60044-2 Instrument Transformers - Voltage Transformers.



E IEC 60076 Power Transformers.

F IEC 60114 Indicating Instruments.

G IEC 60137 Bushings for Alternating Voltages above 1 kV.

H IEC 60185 Current Transformers.

I IEC 60228 Conductors of Insulated Cables.

J IEC 60229 Test on Cable Over Sheath.

K IEC 60255 Electric Relays.

L IEC 60296 Mineral Insulating Oils for Transformers and Switchgear.

M IEC 60337 Control Switches (Low Voltage Switching Devices for Control and Auxiliary Circuits, including Contactor Relays).

N IEC 60354 Loading Guide for Oil Immersed Transformers.

O IEC 60364 Electrical Installations of Buildings.

P IEC 60376 Specification and Acceptance of New Sulphur Hexafluoride (SF6

Q IEC 60408 Low Voltage Air Break Switches, Disconnectors, Switch Disconnectors and Fuse Combination Units.

).

R IEC 60439 LV Switchgear and Control gear Assemblies.

S IEC 60502-2 Power Cables with Extruded Insulation and their Accessories from 1 kV up to 30 kV (Um

T IEC 60529 Degrees of Protection provided by Enclosures (IP code).

=36 kV).

U IEC 60551 Measurement of Transformer and Reactor Sound Level.

V IEC 60811 Common Test Methods for Insulating and Sheathing Materials of Electric cables.

W IEC 60947 Low Voltage Switchgear and Control gear.

X IEC 61330 High Voltage / Low Voltage Pre-fabricated Substations.

Y SEC DPS SEC Distribution Planning Standards.

Z SEC SDMS SEC Distribution Materials Specifications.

AA SEC SDCS SEC Distribution Construction Standards.

1.04 SUBMITTALS

A Comply with section 0133 00.

B Submit manufacturer's catalogues and data including schematic drawings, dimensioned layouts of equipment and accessories, technical specifications, installation instructions and general recommendations. Include data substantiating that the proposed unit substation



comply with project requirements.

C Submit list of tools, test equipment, spare parts and ancillary equipment.

D Submit factory test reports verifying that the unit substation and associated equipment have successfully passed all routine tests including tests for interruption of load and fault currents. Type tests results shall be submitted, when required by the Engineer.

E Include erection and assembly drawings, complete information regarding tightening and securing with bolts or studs. Information furnished shall include torque wrench settings or complete details of other tightening procedures recommended for bus joints, connector attachments and contact attachments.

F Submit all required documents to Saudi Electricity Company (SEC) and obtain their approval.

1.05 QUALITY ASSURANCE

A Manufacturer: Firms regularly engaged in the manufacture of unit substations including power transformers and LV distribution panels of types, sizes and ratings required, whose products have been in satisfactory use in similar service for not less than 5 years. Preference shall be given to the local manufacturers and agents/suppliers.

B Installer: Firms regularly engaged and qualified with at least 5 years of successful installation experience on projects with electrical installation work similar to that required for the project.

C All equipment for unit substations shall be from the same manufacturer and comply with the requirements of SASO, IEC and Saudi Electricity Company (SEC) having jurisdiction and shall be approved for use by SEC.

1.06 DELIVERY, STORAGE AND HANDLING

A Comply with section 01 61 00.

B Handle unit substation carefully to prevent breakage, denting or scoring the finish. Store equipment at an indoor location and protect from weather. When outdoor storage is necessary, elevate well above ground and enclose with durable, waterproof wrapping and protect from direct sun.

C Unit substations shall be protected, handled and stored in accordance with manufacturers instructions.

1.07 WARRANTY


1.08 SEC/MUNICIPALITY COMPLIANCE

A Contractor shall comply with all applicable SEC distribution material specification, construction and planning standards for power distribution networks and municipality specification for road lighting. Some of the specifications and standards are attached with the contract documents for guidance, however contractor shall obtain copy of all applicable specification and standards from the concerned authorities as required on site or instructed by the Engineer.

B Any conflict found between this project specification and SEC or municipality



specification/standards shall be immediately brought to the notice of Engineer for final decision.

PART 2: PRODUCTS

2.01 ACCEPTABLE MANUFACTURERS

Not Used.

2.02 GENERAL

A A unit substation combines power transformer and LV distribution panel in a single transportable unit ready for operation on being fixed in position on prepared plinth or foundation and connected to the power system. The MV switchgear/RMU is not an integral part of the unit substation.

B All materials used in the manufacture and installation of unit substations shall be of high quality and of proven suitability for the functions they will perform and the conditions they will meet in service.

C All materials shall be suitable for the climatic conditions given in section 26 05 00. Provide and apply any current de-rating due to ambient temperature, if required.

D Unit substations shall be installed on concrete foundations, as shown on the drawings, as a complete unit comprising power transformer, LV distribution panel and all required accessories in one metal enclosure.

E Metal enclosure or hut for unit substations shall have lighting, small power, ventilation and other miscellaneous requirements as per SEC standards and approved by the Engineer.

2.03 SKID, ENCLOSURE AND COMPARTMENTS

A All the components of unit substation such as power transformer with MV termination box and detachable LV compartment shall all be mounted on a common galvanized steel skid and housed in an enclosure.

B The enclosure shall mechanically have arrangement to be de-assembled or assembled at site or in workshop by technicians using simple tools.

C Enclosure and skid shall have adequate mechanical strength for lifting, mounting, and transportation of the unit substation as one unit. Lifting provision of unit substation shall be an integral part of the skid.

D The MV termination box and LV compartment shall be weatherproof and of robust construction and shall be provided with watershed top. It shall be manufactured from galvanized sheet steel or aluminium-zinc alloy of at least 3 or 2 mm thickness respectively.

E Adequate ventilation on the back side of MV termination box and LV compartment of unit substation shall be provided to permit natural circulation of air. The ventilation apertures shall be screened with galvanized steel or aluminium-zinc alloy double mesh to prevent entry of vermin and other foreign bodies.

F Galvanizing and surface protection of enclosure and skid against corrosion, painting and finish color (Cement gray RAL 7033) shall comply with the requirements as given in SEC material specifications.



G Access doors of LV compartment and power transformer shall be integrated as a part of the enclosure body. These doors shall be hinged, press fit type gasketed and fitted with a heavy-duty locking bar to secure it at the top and bottom. A central handle, locking bar, handle integral lock and pad locking provision shall be provided as given in the SEC material specifications.

H All doors shall be provided with door stoppers and locking at open position to protect from swinging in order to avoid accident.

I All door hinges shall be concealed and made of stainless steel or brass.

J All doors shall be bonded to the framework (enclosure) by a bolted removable 35 mm2

K All parts of equal size and shape shall be interchangeable. The general design shall be made with minimum number of joints.

tinned copper braid.

L All insulating materials shall be non-hygroscopic and resistance to tracking.

M All bolted electrical joints shall be secured by means of corrosion proof steel fasteners. These fasteners (bolts, nuts, and washers) shall be galvanized in compliance with SEC material specifications.

N All fasteners except the transformer shall not be accessible from outside of the enclosure of unit substation.

O Maximum overall dimensions of unit substations with enclosures shall be as given below:

Unit Substation Ratings Maximum Overall Dimensions (mm)

kVA Low Voltage (V) Length Width Height 300 400/230 1800 500 400/230 1800 1500 2200 1000 400/230 2000 1500 400/230 2400 1800

P Two gasketed openings of 250 mm x 250 mm on the front of LV compartment door shall be provided for the provision of connecting cables from a mobile generator in emergency situation. These openings shall be provided with M8 size, round, non-slotted bolted cover with nuts and washers. Unbolting of these covers shall be accessible from inside of the unit substation only. The gasket of these openings shall be pressure fit type.

Q Two (2) holes for unit substations up to 500 kVA and four holes (4) for substations exceeding 500 kVA, each 13 mm diameter for installation of mobile generators cables shall be provided on vertically extended LV bus-bars.

R Aluminum name plates for the transformer and the low voltage compartment with information as required in SEC material specifications including item identification for the unit substation shall be fixed inside the left door of the low voltage compartment.

2.04 MV TERMINATION BOX

A Medium voltage termination box shall be part of transformer and shall be located as per SEC material specifications and standard practices.



B Medium voltage termination box shall enclose cable clamps, grounding connectors and medium voltage bushings.

C The MV cable clamps shall be wooden conforming to SEC material specifications.

D Medium voltage termination box shall have adequate size for terminating three single core or one three core MV cables as per SEC material specifications, sizes as shown on drawings (e.g. 50 to 70 mm2

E The design of protection of MV termination box shall be IP-54.

aluminium or copper) with heat/cold/pre-mold termination. This box shall have single gasketed cover with removable bolts. Bottom plate shall be in two halves and cable entry with steel knockouts suitable for above cables. Loose rubber bushings shall be provided inside of this box for these knockouts.

2.05 POWER TRANSFORMER

A Power transformers shall be suitable for unit substation, outdoor ground-mounted type, having two separate mineral oil immersed copper windings in hermetically sealed mild steel tanks and generally comply with all applicable clauses of SEC material specifications.

B MV bushings shall be located horizontally on the right hand side (facing unit substation from the front) in a cable termination box. Bushing shall be suitable for M16 bolted type connection with heat/cold shrinkable or pre-moulded termination with separable elbow connectors.

C MV and LV bushings shall be identified, labeled and printed with black paint as follows:

1. MV bushings: U V W.

2. LV bushings: u v w n.

D The no-load and load losses of power transformers shall not exceed the maximum acceptable values given in SEC material specification. The values of losses submitted in the manufacturers catalogues for approval shall be treated as guaranteed values and any increase in these values at the time of testing shall not be accepted.

E The cooling of transformer shall be by natural circulation of oil internal to the transformer and external air i.e. ONAN.

F The transformer shall be supplied initially filled with Class 1 un-inhibited transformer mineral oil complying with IEC 60296.

G Oil level & temperature indicators and off-load tap changer operating knob shall easily be accessible / readable and operate-able from LV panel compartment with adequate safety. Oil temperature indicator shall be equipped with tripping contact if requested and specified in the tender / data schedule.

H Oil drainage / sample and pressure relief valves shall on the transformer and easily accessible from the transformer compartment.

I Transformer shall be fitted with a lockable 5 positions, manual, off-load tap changer having taps at + 5 %, 0 %, + 2.5 %; unless otherwise mentioned on the drawings or elsewhere in the tender documents.

J Electrical characteristics of the power transformer shall be as follows:

1. Primary rated on-load voltage: 13800 V.



2. Secondary rated on-load voltage: 400/230 V.

3. Short circuit current that transformer should withstand for two (2) seconds is:

a. 25 times full load current for ratings of 50, 100, 200, 300 kVA. b. 20 times full load current for ratings of 500 kVA. c. 17 times full load current for ratings of 1000 and 1500 kVA.

4. Winding connections: Primary Delta; Secondary Star.

5. Vector group: Dyn ll.

6. Impedance voltage at normal tap: 4 % (upto 300 kVA), 5 % (500 kVA), 6 % (> 500 kVA).

7. Insulation Level:

a. System highest voltage: Primary - 17.5 kV; Secondary - 1.0 kV. b. Power frequency test voltage (applied): Primary - 38.0 kV;

Secondary - 3.0 kV. c. Impulse test voltage full wave (peak value): Primary - 95.0 kV.

K At the rated power, the transformer shall comply with the following maximum temperature rise limits:

1. Top oil: 45 C. 2. Windings: 50 C. 3. Hot spot: 98 C. 4. Average temperature due to short circuit: 250 C.

L The noise level emitted by a transformer at full load shall not exceed 48 dB. Measurements shall be in accordance with IEC 60551.

M The power transformers shall be supplied with all necessary fittings required for the satisfactory operation of the transformers as per SEC requirements and material specifications and shall include, but not limited to, the following:

1. Temperature indicator. 2. Pressure relief vent. 3. Oil level indicator. 4. Lifting lugs. 5. Tank earthing points. 6. Oil filling and drain facility. 7. HV and LV cable support clamps. 8. Engraved name plate with all details. 9. Skid base.

2.06 LV COMPARTMENT

A Low voltage (LV) compartment shall comply with SEC material specifications and the applicable requirements of section 26 27 00.

B LV distribution panel shall contain incoming transformer connections, bus-bars, instruments panel, 400 A moulded case circuit breakers (MCCBs) for outgoing circuits, earthing terminals and the provision for mobile generator connection.

C As an option if shown on tender drawings, LV distribution panel for bulk power supply shall be



equipped with main circuit breaker without outgoing MCCBs and provision for direct connection of customer cables on the bus-bar.

D The LV distribution panel shall be enclosed with lockable doors. All live metal shall be insulated and the operator shall not be able to accidentally come into contact with live connections or bus-bars when energized. All cable terminations shall be easily accessible from front, fully shrouded and shall permit connections to be made with adjacent circuits live.

E All insulating material shall be non-hygroscopic and resistant to tracking and cracking.

F LV distribution panel complete with all its fittings and attachments shall be capable of withstanding the effects of direct solar radiation at their installed locations. The temperature of metal surfaces exposed to direct solar radiation shall be regarded as 75 C, plus the effect of any internal heating.

G All parts shall of equal size and shape shall be interchangeable. The general design shall be made with minimum number of joints.

H For unit substations, incoming transformer connections shall be through LV bus-bars. Removable copper links shall be provided to enable disconnection of incoming transformer bus-bar connections from LV bus-bars.

I Holes of 13 mm diameter for connection of mobile generator cables shall be provided 50 mm center to center apart. The holes shall be suitable to accommodate NEMA type lugs. Holes shall be two (2) for LV distribution panel upto 1600 A rating and four (4) for LV panels exceeding 1600 A.

J Three (3) current transformers conforming to IEC 60185 shall be installed at the incoming bus-bars of LV distribution panel for metering purpose. CT secondary neutral point shall be earthed. The current ratings of CTs shall be selected according to the power transformer rating as indicated in SEC material specifications.

K Following items related to LV distribution panel shall be provided and installed in compliance with the requirements given in SEC distribution material specifications and distribution construction standards:

1. Ratings of transformer LV phase links. 2. Main / incomer CT rating. 3. Transformer connection with LV panel. 4. Number of outgoing circuits/MCCBs. 5. Clearances between outgoing circuits. 6. Bus-bar sizes / ratings. 7. Indicating instruments and meters. 8. Fault level. 9. Provision for installing CT for revenue metering part of the panel. 10. Grounding facility. 11. Internal lighting of panel. 12. Auxiliary supply. 13. LV cable supports. 14. Labels and danger plates. 15. Enclosure specifications and dimensions.

L Provide an aluminium name plate fixed inside of left door of the LV panel, engraved with all required information in Arabic and English as mentioned in SEC material specifications.

2.07 CONCRETE FOUNDATION



A Prefabricated steel reinforced concrete foundation shall be used for the installation of unit substations. This foundation shall be unified suitable to accommodate 300, 500, 1000 and 1500 kVA substations.

B The concrete foundation shall be constructed in accordance with SEC standard details. Cast in situ concreting shall not be done without prior approval of SEC.

C Agree with and obtain approval of SEC for the suitability of the dimensions of foundations, trenches, openings and all other civil works details of the concrete foundation before fabrication.

PART 3: EXECUTION

3.01 INSPECTION


B Examine the area for unit substations and the conditions under which they are to be installed, and correct any unsatisfactory conditions detrimental to the proper and timely completion of the work. Do not proceed with the work until unsatisfactory conditions have been corrected in a manner acceptable to the Engineer.

C Agree with the manufacturer for the suitability of the civil works for foundations which shall be compatible with equipment and all sizes and details shall be checked and confirmed before concrete is poured, or revised with the approval of the Engineer where necessary.

D It is the contractor's sole responsibility to supply all materials required for the construction of concrete base in the correct location and to the specified dimensions, level and grade and to connect all incoming and outgoing cables.

3.02 INSTALLATION

A Install unit substations in accordance with the requirements given in SEC distribution material specifications, SEC distribution construction standards, manufacturer's written instructions, recognized industry practices and comply fully with SASO and IEC.

B Install unit substations on concrete foundations using the appropriate lifting gear to ensure that no damage occurs. When correctly located, the units shall be anchored in position and tested before and after connecting the incoming and outgoing cables.

C Provide foundation bolts and grout them in cement concrete floor using non-shrinkable material approved by the Engineer. All installation materials for physically erecting the unit substations such as anchor bolts, nuts, washers, supporting steel, etc. shall be provided and installed by the contractor. Install the unit upright and in level. It shall be firmly and rigidly bolted on the floor and concrete supports.

D Tighten all bolts and studs in accordance with the torque wrench settings and procedures as recommended by the manufacturer. Provide calibrated hand torque wrenches, necessary platforms, equipment and personnel for checking by Engineer when required.

E Earthing of substations shall be carried out in accordance with the requirements given in SEC material specifications, SEC distribution construction standards and section 26 05 26.

3.03 FIELD QUALITY CONTROL




B Perform dielectric strength or insulation resistance test of all equipment in unit substations and the substation as a complete unit after installation and fixation in place.

C Carry out tests to prove the operation of all LV switches and circuit breakers. Simulate fault on protective relays and devices.

D Perform current injection test of all protective devices and relays.

E Perform ratio test and other field tests of all current and voltage transformers according to SASO and IEC requirements.

F Testing of power transformers including the following tests as a minimum shall be performed:

1. Ratio tests on rated voltage connection and all tap connections.

2. Polarity and phase rotation tests the rated voltage connection.

3. No-load loss at rated voltage on the rated voltage connection.

4. Exiting current at rated voltage on the rated connection.

5. Impedance and load loss at rated current on the rated voltage connection at each unit and on the top extremes of one unit.

3.04 ADJUSTMENTS

A Comply with sections 01 75 00 and 01 77 00.

B Adjust transformers taps to provide acceptable voltage at utilization equipment connected to unit substation.

C Adjust protective relays and devices to provide adequate over current protection and selective tripping with downstream devices according to short circuit and protection coordination study and after proper coordination with the protection settings of the Saudi Electricity Company (SEC) having jurisdiction.

3.05 TRAINING


B Provide instruction and training to the Owners staff for the operation and maintenance of equipment. Provide a minimum of twenty four (24) hours training to be divided between classroom and hands-on training as required by the Owner.

C Agree the training schedule (dates, time, duration of each class, etc.) with the owner at least one month before the actual training programme is scheduled.

3.06 OPERATION AND MAINTENANCE PROGRAMME


END OF SECTION

SECTION 26 11 13Comply with section 0133 00.Submit manufacturer's catalogues and data including schematic drawings, dimensioned layouts of equipment and accessories, technical specifications, installation instructions and general recommendations. Include data substantiating that the proposed un...Submit list of tools, test equipment, spare parts and ancillary equipment.Submit factory test reports verifying that the unit substation and associated equipment have successfully passed all routine tests including tests for interruption of load and fault currents. Type tests results shall be submitted, when required by th...Include erection and assembly drawings, complete information regarding tightening and securing with bolts or studs. Information furnished shall include torque wrench settings or complete details of other tightening procedures recommended for bus joi...Agree with the manufacturer for the suitability of the civil works for foundations which shall be compatible with equipment and all sizes and details shall be checked and confirmed before concrete is poured, or revised with the approval of the Enginee...It is the contractor's sole responsibility to supply all materials required for the construction of concrete base in the correct location and to the specified dimensions, level and grade and to connect all incoming and outgoing cables.Provide foundation bolts and grout them in cement concrete floor using non-shrinkable material approved by the Engineer. All installation materials for physically erecting the unit substations such as anchor bolts, nuts, washers, supporting steel, etc...

section 26 11 13-unit sub-stations.pdf

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