Attachment 3 - 261214 MEDIUM-VOLTAGE TRANSFORMERS.pdf

JUBA ELECTRICAL UPGRADE DEVELOPMENT July 13, 2020

JUBA SOUTH SUDAN Issued for Bid

MEDIUM-VOLTAGE TRANSFORMERS SECTION 261214 - 1

SECTION 261214 - MEDIUM-VOLTAGE

TRANSFORMERS

PART 1 - GENERAL

1.1 SUMMARY

A. This Section includes the following types of transformers with medium-voltage primaries rated from 601 V up to 35 kV:

1. Dry-type distribution and power transformers.

2. Pad-mounted, liquid-filled transformers.

B. Related Sections include the following:

1. Section 033000 “Cast-in-Place Concrete.”

2. Section 260508 “Common Work Results for Electrical, Communications, and

Electronic Safety,” including for electrical safety accessories.

3. Section 260518 “Low-Voltage Electrical Power Conductors and Cables.”

4. Section 260525 “Grounding and Bonding for Electrical Systems.”

5. Division 26 Section on Identification for Electrical Systems.”

6. [Division 26 Section on “Vibration and Seismic Controls for Electrical Systems.”]

7. Section 260573 “Overcurrent Protective Device Coordination Study.

1.2 DEFINITIONS

A. NETA ATS: Acceptance Testing Specification.

1.3 SUBMITTALS

A. Product Data: Include rated nameplate data, capacities, weights, dimensions, minimum clearances, installed devices and features, location of each field connection, and performance for each type and size of transformer indicated.

B. Shop Drawings: Diagram power signal and control wiring.

C. Coordination Drawings: Floor plans, drawn to scale, on which the following items are shown and coordinated with each other, based on input from installers of the items involved:

1. Underground primary and secondary conduit stub-up location.

2. Dimensioned concrete base, outline of transformer, and required clearances.

3. Ground rod and grounding cable locations.

D. Qualification Data: For testing agency.

MEDIUM-VOLTAGE TRANSFORMERS SECTION 261214 - 2

E. Field quality-control test reports including Power-Factor Tests, Insulation Resistance Tests, and

Insulation Power Factor (Doble) Tests. Final test reports shall be provided to the Contracting

Officer/COR for forwarding to OBO/PDCS/DE/EE for approval, and to OBO/CFSM/FAC for inclusion in the Maintenance Database. Refer to Article on FIELD QUALITY CONTROL.

Identify the following:

1. Test procedures used.

2. Test results that comply with requirements.

3. Test results that do not comply with requirements and corrective actions taken to achieve compliance with requirements.

F. Certifications:

1. PCBs in Oil-Filled Units: As applicable, certification that, in accordance with OBO

Building Code Section 414, the oil contains no PCBs; see Article on QUALIFICATION

TESTING.

2. Certification of compliance with NETA ATS, Section 7.2 test parameters; see Article on

FIELD QUALITY CONTROL.

G. Follow-up service reports in accordance with Article on FOLLOW-UP SERVICE.

1. Record of Infrared Scanning: Prepare certified report that identifies switchgear checked and that describes infrared-scanning results. Include notation of deficiencies detected, remedial action taken, and observations after remedial action.

H. Operation and Maintenance Data: For transformer and accessories to include in emergency, operation, and maintenance manuals.

1. Include safety Standard Operating Procedures (SOP), including de-energization and isolation procedures.

1.4 QUALITY ASSURANCE

A. Independent Testing Agency Qualifications: Testing agency that is member company of

InterNational Electrical Testing Association (NETA) or that is acceptable to Contracting

Officer/COR based upon input from OBO/PDCS/DE/EE.

1. Testing Agency's Field Supervisor: Person currently certified by NETA or the National

Institute for Certification in Engineering Technologies (NICET) to supervise on-site testing specified in this Section.

B. Comply with ANSI C57.12.28, IEEE C57.12.10, IEEE C57.12.70, and IEEE C57.12.80.

MEDIUM-VOLTAGE TRANSFORMERS SECTION 261214 - 3

C. Comply with requirements of the OBO Electrical Code (NFPA 70, “National Electrical Code” as amended by OBO).

1. Electrical Components, Devices, and Accessories: Listed and labeled in accordance with

Chapter 1 of the OBO Electrical Code by testing agency acceptable to Contracting

Officer/COR based upon input from OBO/PDCS/DE/EE, and marked for the intended use.

1.5 DELIVERY, STORAGE, AND HANDLING

A. Store transformers protected from weather so condensation will not form on or in units. Provide temporary heating according to manufacturer's written instructions.

1.6 PROJECT CONDITIONS

A. Service Conditions: IEEE C37.121, usual service conditions except for the following:

1. Altitudes above 1000 m.

2. Exposure to fumes, vapors, or dust.

3. Exposure to hot and humid climate or to excessive moisture, including steam, salt spray, and dripping water.

4. Exposure to seismic shock or to abnormal vibration, shock, or tilting.

5. Exposure to excessively high or low temperatures.

6. Unusual transportation or storage conditions.

7. Unusual grounding-resistance conditions.

B. Lightning and Surge Protection:

1. Main transformers serving compound buildings shall have distribution class lightning arresters on primary side, and surge protectors on secondary side of transformer.

2. Provide surge protection at service entrance to each building.

1.7 COORDINATION

A. Coordinate size and location of concrete bases. Cast anchor-bolt inserts into bases. Concrete, reinforcement, and formwork requirements are specified in Section 033000 “Cast-in-Place

Concrete.”

B. Coordinate installation of louvers, doors, spill retention areas, and sumps. Coordinate installation so no piping or conduits are installed in space allocated for medium-voltage transformers except those directly associated with transformers.

MEDIUM-VOLTAGE TRANSFORMERS SECTION 261214 - 4

1.8 QUALIFICATION TESTING

A. Expand transformer manufacturer’s standard tests to include; insulation power factor (Doble) tests, insulation oil tests, and dielectric tests. For oil-filled units manufacturer shall certify that, in accordance with OBO Building Code Section 414, oil contains no PCBs, and shall affix label to that effect on transformer tank and on each oil drum containing insulating oil.

B. Added oil condition (acidity, water, power factor, dissolved gas, and dielectric), and insulation power factor test (Doble Test). Maximum acceptable insulation power factor test value is five percent. Tests shall be conducted in accordance with IEEE C57.12.90, IEEE Std. 62, ASTM D

3612, and ASTM D 3487. Manufacturer shall certify that insulating oil contains no PCBs, and shall affix label to that effect on transformer tank, and on each oil drum containing insulating oil.

PART 2 - PRODUCTS

2.1 PAD-MOUNTED, LIQUID-FILLED TRANSFORMERS

A. Description: ANSI C57.12.13, IEEE C57.12.00, IEEE C57.12.22 IEEE C57.12.26, pad-mounted, 2-winding transformers. Stainless-steel tank base and cabinet.

B. Insulating Liquid: Mineral oil, complying with ASTM D 3487, Type II, and tested according to

ASTM D 117; or less- flammable type, fire-resistant biodegradable seed oil (Envirotemp FR3 or equal).

C. Insulation Temperature Rise: 80 deg C when operated at rated kVA output in 40 deg C ambient temperature. Transformer shall be rated to operate at rated kilovolt ampere in average ambient temperature of 30 deg C over 24 hours with maximum ambient temperature of 40 deg C, without loss of service life expectancy.

D. Basic Impulse Level: 95 kV.

E. Full-Capacity Voltage Taps: Four 2.5 percent taps, two above and two below rated medium-voltage; with externally operable tap changer for de-energized use and with position indicator and padlock hasp.

F. Medium-Voltage Switch: Make-and-latch rating based on calculated short circuit available, symmetrical, arranged for radial feed with 3-phase, 2-position, gang-operated, load-break switch that is oil immersed in transformer tank with hook-stick operating handle in primary compartment.

G. Primary Fuses: Fuse assembly with fuses complying with IEEE C37.47. Rating of current-limiting fuses shall be 50-kA RMS at specified system voltage.

MEDIUM-VOLTAGE TRANSFORMERS SECTION 261214 - 5

1. Current-limiting type in dry-fuse holder wells, mechanically interlocked with liquid-immersed switch in transformer tank to prevent disconnect under load.

2. Internal liquid-immersed cartridge fuses.

3. Bay-O-Net liquid-immersed fuses which are externally replaceable without opening transformer tank.

4. Bay-O-Net liquid-immersed fuses in series with liquid-immersed current-limiting fuses.

Bay-O-Net fuses shall be externally replaceable without opening transformer tank.

5. Bay-O-Net liquid-immersed current-limiting fuses which are externally replaceable without opening transformer tank.

H. Surge Arresters: Distribution class, one for each primary phase; complying with IEEE C62.11 and NEMA LA 1; support from tank wall within medium-voltage compartment. Transformers shall have three arresters for radial-feed circuits.

I. Medium-Voltage Terminations and Equipment: Live front with externally clamped porcelain bushings and cable connectors suitable for terminating primary cable.

J. Medium-Voltage Terminations and Equipment: Dead front with universal-type bushing wells for dead-front bushing-well inserts, complying with IEEE 386 and including the following:

1. Bushing-Well Inserts: One for each medium-voltage bushing well.

2. Surge Arresters: Dead-front, elbow-type, metal-oxide-varistor units.

3. Parking Stands: One for each medium-voltage bushing well.

4. Portable Insulated Bushings: Arranged for parking insulated, medium-voltage, load- break cable terminators; one for each primary feeder conductor terminating at transformer.

K. Accessories:

1. Drain Valve 25 mm, with sampling device.

2. Dial-type thermometer.

3. Liquid-level gage.

4. Pressure-vacuum gage.

5. Pressure Relief Device: Self-sealing with an indicator.

6. Mounting provisions for low-voltage current transformers.

7. Mounting provisions for low-voltage potential transformers.

8. Busway terminal connection at low-voltage compartment.

9. Alarm contacts for gages and thermometer listed above.

L. Size transformer according to that indicated on Drawings or size calculations in accordance with

OBO Electrical Code Chapter 2. If size must be adjusted to accommodate load different from that in calculations, provide 20 percent spare capacity over actual demand. Include provisions for future addition of fans to extend capacity 20 percent beyond self-cooled OA rating for future growth.

MEDIUM-VOLTAGE TRANSFORMERS SECTION 261214 - 6

M.

N.

Include provisions for future addition of fans to extend capacity 20 percent beyond self-cooled

OA rating for future growth.

Transformer impedance should be selected to limit fault current to 65kA.

2.2

IDENTIFICATION DEVICES

A. Nameplates: Engraved, laminated-plastic or metal nameplate for each transformer, mounted with corrosion-resistant screws. Nameplates and label products are specified in Division 26 Section on

"Identification for Electrical Systems."

2.3

SOURCE QUALITY CONTROL

A. Factory Tests:

1. General: Perform design and routine tests according to standards specified for components. Conduct transformer tests according to ANSI and IEEE Standards.

2. Perform the following factory-certified tests on each transformer:

a. Resistance measurements of all windings on rated-voltage connection and on tap extreme connections.

b. Ratios on rated-voltage connection and on tap extreme connections.

c. Polarity and phase relation on rated-voltage connection.

d. No-load loss at rated voltage on rated-voltage connection.

e. Excitation current at rated voltage on rated-voltage connection.

f. Impedance and load loss at rated current on rated-voltage connection and on tap extreme connections.

g. Applied potential.

h. Induced potential.

i. Temperature Test: If transformer is supplied with auxiliary cooling equipment to provide more than one rating, test at lowest kilovolt-ampere Class OA or Class AA rating and highest kilovolt-ampere Class OA/FA or Class AA/FA rating.

1) Temperature test is not required if record of temperature test on an essentially duplicate unit is available.

j. The Government, at its option, may witness all required factory tests. Notify

Contracting Officer/COR at least 14 days before date of tests and indicate their approximate duration.

2.4 COILS

A. For transformers to be installed in high fault current areas, aluminum and sheet windings should be avoided.

MEDIUM-VOLTAGE TRANSFORMERS SECTION 261214 - 7

2.5 INSULATING OIL

A. Neutralization Number shall not be greater than 0.03 gm KOH/ml when measured in accordance with ASTM D 974. Emulsified water shall not exceed 25ppm at 20 deg C. When measured in accordance with ASTM D 1553. Power factor shall not exceed 0.5 percent at 20 deg C when measured in accordance with ASTM D 924.

2.6 AVR AND MEDIUM VOLTAGE TRANSFORMERS

A. AVR and Medium Voltage Transformer Configurations: Without exception, all medium voltage automatic voltage regulators shall be delta connected. Without exception, all medium voltage transformers shall have delta connected primaries and wye connected secondaries.

2.7 PAINTING

A. For all outdoor applications and all indoor applications in harsh environment refer to Division 09

Section on “High Performance Coatings.” After fabrication, all exposed ferrous metal surfaces of transformer and component equipment shall be cleaned and painted.

PART 3 - EXECUTION

3.1 EXAMINATION

A. Examine areas and conditions for compliance with requirements for medium-voltage transformers.

B. Examine roughing-in of conduits and grounding systems to verify the following:

1. Wiring entries comply with layout requirements.

2. Entries are within conduit-entry tolerances specified by manufacturer and no feeders will have to cross section barriers to reach load or line lugs.

C. Examine walls, floors, roofs, and concrete bases for suitable mounting conditions where transformers will be installed.

D. Verify that ground connections are in place and that requirements in Section 260525 "Grounding and Bonding for Electrical Systems" have been met. Maximum ground resistance shall be 10 ohms at location of transformer.

E. Proceed with installation only after unsatisfactory conditions have been corrected.

3.2 INSTALLATION

A. Install transformers on concrete bases.

MEDIUM-VOLTAGE TRANSFORMERS SECTION 261214 - 8

1. Anchor transformers to concrete bases according to manufacturer's written instructions, seismic codes at Project, and requirements in Division 26 Section on "Vibration and

Seismic Controls for Electrical Systems."

2. Construct concrete bases of dimensions indicated, but not less than 100 mm larger in both directions and 100 mm high.

3. Use 20.7-MPa , 28-day compressive-strength concrete and reinforcement as specified in

Section 033000 "Cast-in-Place Concrete."

4. Install dowel rods to connect concrete bases to concrete floor. Unless otherwise indicated, install dowel rods on 450-mm centers around full perimeter of base.

5. Install epoxy-coated anchor bolts, for supported equipment, that extend through concrete base and anchor into structural concrete floor.

6. Place and secure anchorage devices. Use supported equipment manufacturer's setting drawings, templates, diagrams, instructions, and directions furnished with items to be embedded.

7. Tack-weld or bolt transformers to channel-iron sills embedded in concrete bases. Install sills level and grout flush with floor or base.

B. Maintain minimum clearances and workspace at equipment according to manufacturer's written instructions and the OBO Electrical Code.

3.3

IDENTIFICATION

A. Identify field-installed wiring and components and provide warning signs as specified in

Division 26 Section on "Identification for Electrical Systems."

3.4

CONNECTIONS

A. Ground equipment according to Section 260525 "Grounding and Bonding for Electrical

Systems."

B. Connect wiring according to Section 260518 "Low-Voltage Electrical Power Conductors and

Cables."

3.5

FIELD QUALITY CONTROL

A. Perform the following field tests and inspections:

1. After installing transformers but before primary is energized, verify that grounding system at substation is tested at specified value or less.

2. After installing transformers and after electrical circuitry has been energized, test for compliance with requirements.

3. Perform electrical test and visual and mechanical inspection stated in NETA ATS, Section 7.2.

4. Test and adjust controls and safeties.

MEDIUM-VOLTAGE TRANSFORMERS SECTION 261214 - 9

B. Upon satisfactory completion of insulation resistance test, perform insulation power factor test and an excitation test on transformer windings. Added oil tests to be performed after electrical tests of the transformer. Transformer shall not be energized until recorded test data have been approved by Contracting Officer/COR.

1. Power Factor Testing: For transformer rated under 100KVA and less than 4160 volts on both primary and secondaries, power factor testing is optional acceptance test.

Transformers shall be tested in accordance with IEEE Std 62.

2. Dielectric Testing: Liquid filled transformers shall have insulating liquid dielectrically tested after installation and before being energized. Insulating liquid shall be tested in accordance with ASTM D 877, and breakdown voltage shall not be less than 2, 5, or 8,000 volts as specified.

3. Power Factor Tests: Liquid filled transformers shall have oil power factored at 20 deg C, per ASTM D 924 prior to being energized. Results shall not be greater than 0.5 percent at

20 deg C.

4. Insulation Resistance Tests: Additional industry test specifications.

5. Insulation Power Factor (Double) Tests: Perform insulation power factor test and winding excitation test on transformer windings in accordance with ANSI IEEE C57.12.90.

Insulation power factor shall not exceed 0.5 percent for new liquid filled units. New dry type units with power factors up to five percent are still be acceptable.

C. Remove malfunctioning units, replace with new units, and retest as specified above.

D. Acceptance: Final test reports shall be provided to Contracting Officer/COR for forwarding to

OBO/CFSM/FAC for inclusion in Maintenance Database.

E. Prepare test reports.

3.6 FOLLOW-UP SERVICE

A. Voltage Monitoring and Adjusting: If requested by Government, perform the following voltage monitoring after Substantial Completion but not more than six months after Final Acceptance:

1. During period of normal load cycles as evaluated by Government, perform seven days of three-phase voltage recording at secondary terminals of each transformer. Use voltmeters with calibration traceable to National Institute of Science and Technology (NIST) standards, and with chart speed of not less than 25 mm per hour. Voltage unbalance greater than one percent between phases, or deviation of any phase voltage from nominal value by more than plus or minus five percent during test period, is unacceptable.

2. Corrective Actions: If test results are unacceptable, perform the following corrective actions, as appropriate:

a. Adjust transformer taps.

b. Prepare written request for voltage adjustment by electric utility.

MEDIUM-VOLTAGE TRANSFORMERS SECTION 261214 - 10

3. Retests: After corrective actions have been performed, repeat monitoring until satisfactory results are obtained.

4. Report: Prepare written report covering monitoring and corrective actions performed.

B. Infrared Scanning: After Substantial Completion, but not more than 60 days after Final

Acceptance, perform infrared scan of each switchgear. Remove front and rear panels so joints and connections are accessible to portable scanner.

1. Follow-up Infrared Scanning: Perform additional follow-up infrared scan of each switchgear 11 months after date of Substantial Completion.

2. Instrument: Use infrared-scanning device designed to measure temperature or to detect significant deviations from normal values. Provide calibration record for device.

3.7 DEMONSTRATION AND TRAINING

A. Coordinate with Contracting Officer/COR and post Facility Manger to identify staff, including locally employed staff (LES) maintenance personnel, who may access transformer.

B. Train Government maintenance personnel in the following:

1. Coordinate training with training for other related equipment.

2. Training Topics:

a. Standard Operating Procedures (SOP) described in O&M Data Manual

b. Review data in manufacturer’s maintenance manuals, including interface with written SOP.

c. Review safety precautions and use of medium-voltage safety accessories with requirements in Section 260508 “Common Work Results for Electrical, Communications, and Electronic Safety” and Section 260573 “Overcurrent

Protective Device Coordination Study.”

d. De-energizing procedures to safely de-energize, isolate and lock-out transformers prior to any maintenance or repair work.

e. Features and construction of project equipment.

f. Routine testing and monitoring operations.

g. Interpretation of readings of indicating and alarm devices.

h. Routine inspection procedures.

i. Access control panel to maintain operations log in accordance with procedures of

OBO/CFSM/FAC.

j. Removal and replacement of control panel or components.

k. Cleaning of connections and conductors on basis identified by OBO/CFSM/FAC considering input from manufacturer.

C. Schedule training with Contracting Officer/COR with at least seven days' advance notice.

END OF SECTION 261214