26_13_24_Medium_Voltage_Switchgear_(15_kV).pdf

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DIVISION 26

ELECTRICAL

SECTION 26 13 24

MEDIUM VOLTAGE SWITCHGEAR (15 kV)

PART 1 GENERAL

1.01 WORK INCLUDED

A. This Section includes requirements for dead-front medium voltage rated switchgear for switching of 12.47kV underground primary distribution circuits installed for this

Contract.

1.02 REFERENCES

A. The publications listed below, current as of the date of this solicitation, form a part of this specification to the extent referenced. The publications are referred to in the text by designation only:

1. National Electrical Manufacturers Association - NEMA

2. American National Standards Institute - ANSI

a. ANSI C37.71/IEEE - Standard for Three-Phase, Manually Operated

Subsurface Load Interrupting Switches for Alternating-Current

Systems

b. ANSI C37.72 - Manually Operated, Dead Front Pad-Mounted

Switchgear with Load Interrupting Switches and Separable Connectors for Alternating Current Systems

c. ANSI C37.73/IEEE - IEEE Standard Requirements for Pad-Mounted

Fused Switchgear

d. ANSI Standard Z55.1 for No. 61 - Gray Finishes for Industrial

Apparatus and Equipment

e. IEEE C37.112 - IEEE Standard Inverse-Time Characteristic Equations for Overcurrent Relays

f. IEC 56 - Medium-Voltage Circuit-Breaker Interrupting Ratings-

Unstated Short-Circuit Considerations

g. IEC 265-1 (Class A) - Specifications for SF6 Gas Filled Pad Mounted

Switchgear

h. ANSI 495 - Refrigerant Liquid Receivers

i. ANSI C119.2 - Separable Insulated Connector Systems for Power

Distribution Systems above 600 V

j. ANSI C57.12.28/IEEE - Standard for Pad-Mounted Equipment-

Enclosure Integrity

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3. American Society for Testing and Materials (ASTM)

a. ASTM B 117 - Standard Practice for Operating Salt Spray (Fog)

Apparatus

b. ASTM D 714. - Standard Test Method for Evaluating Degree of

Blistering of Paints

c. ASTM D 523 - Standard Test Method for Specular Gloss

d. ASTM D 659 - Method of Evaluating Degree of Chalking of Exterior

Paints (

e. ASTM D 1645 - ASTM D1645 Method of Test for Print Resistance of

Varnishes

f. ASTM D2472 - Standard Specification for Sulfur Hexafluoride

g. ASTM D 2794 - Standard Test Method for Resistance of Organic

Coatings to the Effects of Rapid Deformation (Impact)

h. ASTM D 3359 - Standard Test Methods for Measuring Adhesion by

Tape Test

i. ASTM 4060 - Standard Test Method for Abrasion Resistance of

Organic Coatings by the Taber Abraser

j. ASTM D 4585 - Standard Practice for Testing Water Resistance of

Coatings Using Controlled Condensation

k. ASTM G 53 - Standard Practice for Operating Light-and Water-

Exposure Apparatus (Fluorescent UV-Condensation Type) for

Exposure of Nonmetallic Materials

1.03 SUBMITTALS

A. Prior to obtaining any material in connection with this Section, detailed shop drawings of each medium voltage switchgear shall be submitted, including, but not limited to:

1. Overall outline dimensions, base details and weight.

2. Nameplate data.

3. Material list with manufacturers’ data describing the switchgear and showing compliance with specifications.

4. Microprocessor equipment.

5. Load-interrupter switches.

6. Fault interrupters.

7. SF6 system.

8. Plan showing exact location and details of channel sill, anchor bolts and termination of power bus and control cables.

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PART 2 PRODUCTS

2.01 GENERAL

A. The 15kV switchgear shall be configured in accordance with the Contract Drawings, One-Line Diagrams and shall conform to these Specifications.

B. The switchgear shall consist of a single self-supporting enclosure with base spacer, containing load-interrupter switches, fault interrupters, microprocessor-based over-current control, SF6 and with the necessary accessory components, all completely factory assembled and operationally checked. The interrupter switches and fault interrupters shall be enclosed within an inner grounded steel compartment for electrical isolation and for protection from contamination. Switch terminals shall be equipped with bushings rated 200 or 600 amps continuous, and bus terminals shall be equipped with bushing wells rated 200 amps continuous to provide for elbow connection.

Bushings and bushing wells shall be mounted on the walls of the inner compartment and shall extend into a termination compartment. Refer to power one-line diagrams for individual switchgear ratings, bus and bushing well ratings, and configurations.

1. Manufacturer: S & C Electric Company Vista Model or approved equal. Refer to contract drawings for individual switchgear configuration model numbers and locations.

2.02 CERTIFICATION OF RATINGS

A. The manufacturer shall be completely and solely responsible for the performance of the switches, fault interrupters; microprocessor and SF6 system as well as the complete integrated pad mount gear assembly as rated.

B. The Contractor shall furnish upon request certification of ratings of the basic switch and interrupter components and/or the integrated gear assembly consisting of the switchgear components in combination with the enclosure.

2.03 ENCLOSURE DESIGN

A. To ensure a completely coordinated design, the switchgear shall be constructed in accordance with the minimum construction specifications of the switch and interrupters manufacturer to provide adequate electrical clearances. The enclosure shall conform to

ANSI C57.12.28.

B. In establishing the requirements for the enclosure design, consideration shall be given to all relevant factors such as controlled access, tamper resistance, corrosion resistance, and resistance to entry of foliage, animals and airborne contaminants.

2.04 SWITCHGEAR RATINGS

A. Ratings for the integrated pad mount assemblies identified, as shown on the Contract

Drawing One-Line Diagram, shall be as designated below:

kV, Nominal 12.47 kV, Maximum 15.5

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Main Bus Continuous, Amperes 600

Three-Pole Interrupter Switches

Continuous, Amperes 600

Load Dropping, Amperes 600

Short-Circuit Ratings, Amperes Rms Asymmetrical 12,50025,000

Fault Interrupter

Maximum, Amperes 600

Load Dropping, Amperes 600

Short-Circuit Ratings

Amperes Rms Symmetrical 12,50025,000

The momentary and two-time duty-cycle fault-closing ratings of switches, momentary rating of bus and interrupting ratings of fault interrupters shall equal or exceed the short-circuit ratings of the switchgear. Refer to power one-line diagrams for additional information.

2.05 SF6-GAS INSULATION

A. The SF6 gas shall conform to ASTM D2472.

B. The switchgear shall be filled with SF6 gas to a pressure of 7 psig at 68º F.

C. The gas-tight tank shall be evacuated prior to filling with SF6 gas to minimize moisture in the tank.

D. The switchgear shall withstand system voltage at a gas pressure of 0 psig at 68º F.

E. A gas-fill valve shall be provided.

F. A temperature-compensated pressure gauge shall be provided that is color coded to show the operating range. The gauge shall be mounted inside the gas-tight tank (visible through a large viewing window) to provide consistent pressure readings regardless of the temperature or altitude at the installation site.

2.06 GAS-TIGHT TANK

A. The tank shall be submersible and able to withstand up to 10 feet of water over the base.

B. The tank shall be of welded construction and shall be made of stainless steel.

C. A means of lifting the tank shall be provided.

2.07 VIEWING WINDOWS

A. Each load-interrupter switch shall be provided with a large viewing window at least 6 inches by 12 inches to allow visual verification of the switch-blade position (closed, open, and grounded) while shining a flashlight on the blades.

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B. Each fault interrupter shall be provided with a large viewing window at least 6 inches by

12 inches to allow visual verification of the disconnect-blade position (closed, open, and grounded) while shining a flashlight on the blades.

C. Viewing windows shall be located on the opposite side of the gear from the bushings and bushing wells so that operating personnel shall not be required to perform any routine operations in close proximity to high-voltage elbows and cables.

D. A cover shall be provided for each viewing window to prevent operating personnel from viewing the flash which may occur during switching operations.

2.08 HIGH-VOLTAGE BUS

A. Bus and interconnections shall withstand the stresses associated with short-circuit currents up through the maximum rating of the switchgear.

B. Before installation of aluminum bus, all electrical contact surfaces shall first be pre-pared by machine-abrading to remove any oxide film. Immediately after this operation, the electrical contact surfaces shall be coated with a uniform coating of an oxide inhibitor and sealant.

2.09 PROVISIONS FOR GROUNDING

A. One ground-connection pad shall be provided on the gas-tight tank of the switchgear.

B. The ground-connection pad shall be constructed of stainless steel and welded to the gas-tight tank, and shall have a short-circuit rating equal to that of the switchgear.

C. When an enclosure is provided, no less than one enclosure ground pad shall be provided.

D. One ground-connection pad per way shall be provided.

2.10 CONNECTIONS

A. For gear rated 12.5 kA short circuit, load-interrupter switches shall be equipped with

200 or 600-ampere bushings, and fault interrupters shall be equipped with 200-ampere bushing wells.

B. For gear rated 25 kA short circuit, load-interrupter switches and fault interrupters shall be equipped with 200 or 600-ampere bushings.

C. Bushings and bushing wells shall be located on one side of the gear to reduce the required operating clearance.

D. For gear rated 12.5 kA only, the following optional features shall be included:

1. Fault interrupters shall be equipped with 200-ampere bushings.

2 Load-interrupter switches shall be equipped with 200 or 600-ampere bushing wells.

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2.11 BUSHINGS AND BUSHING WELLS

A. Bushings and bushing wells shall conform to ANSI/IEEE Standard 386.

B. Bushings and bushing wells shall include a semiconductive coating.

C. Bushings and bushing wells shall be mounted in such a way that the semiconductive coating is solidly grounded to the gas-tight tank.

D. Bushings rated 600 amps continuous shall have a removable threaded stud so that the bushings are compatible with all 600 amp elbow systems - those requiring a threaded stud, as well as those that do not.

2.12 LOAD-INTERRUPTER SWITCHES

A. The three-phase, group-operated load-interrupter switches shall have a three-time and ten-time duty-cycle fault-closing rating as specified under "Ratings." This rating defines the ability to close the switch the designated number of times against a three-phase fault with asymmetrical (peak) current in at least one phase equal to the rated value, with the switch remaining operable and able to carry and interrupt rated current. Certified test abstracts establishing such ratings shall be furnished upon request.

B. The switch shall be provided with an integral ground position that is readily visible through the viewing window to eliminate the need for cable handling and exposure to high voltage to ground the equipment.

C. The ground position shall have a three-time and ten-time duty-cycle fault-closing rating.

D. The switch shall be provided with an open position that is readily visible through the viewing window to eliminate the need for cable handling and exposure to high voltage to establish a visible gap.

E. The open gaps of the switch shall be sized to allow cable testing through a feed thru bushing or the back of the elbow.

2.13 FAULT INTERRUPTERS

A. Fault interrupters shall have a three-time and ten-time duty-cycle fault-closing and fault interrupting rating as specified under "Ratings." This rating defines the fault interrupter's ability to close the designated number of times against a three-phase fault with asymmetrical (peak) current in at least one phase equal to the rated value and clear the resulting fault current, with the interrupter remaining operable and able to carry and interrupt rated current. Certified test abstracts establishing such ratings shall be furnished upon request.

B. The fault interrupter shall be provided with a disconnect with an integral ground position that is readily visible through the viewing window to eliminate the need for cable handling and exposure to high voltage to ground the equipment.

C. The ground position shall have a three-time and ten-time duty-cycle fault-closing rating.

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D. The disconnect shall be provided with an open position that is readily visible through the viewing window, eliminating the need for cable handling and exposure to high volt-age to establish a visible gap.

E. The fault interrupter, including its three-position disconnect, shall be a single integrated design so that operation between the closed and open positions or the open and grounded positions is accomplished with a single, intuitive movement.

F. The open gaps of the disconnect shall be sized to allow cable testing through a feed thru bushing or the back of the elbow.

G. An internal indicator shall be provided for each fault interrupter to show when it is in the tripped condition. The indicator shall be clearly visible through the viewing window.

2.14 OPERATING MECHANISMS

A. Load-interrupter switches and fault interrupters shall be operated by means of a quick-make, quick-break mechanism.

B. The manual handle shall charge the operating mechanism for closing, opening, and grounding of the switches and fault interrupters.

C. A single, integrated operating mechanism shall fully operate each fault interrupter or load interrupter switch in a continuous movement, so that additional operations are not required to establish open or grounded positions.

D. Operating mechanisms shall be equipped with an operation selector to prevent inadvertent operation from the closed position directly to the grounded position, or from the grounded position directly to the closed position. The operation selector shall require physical movement to the proper position to permit the next operation.

E. Operating shafts shall be padlockable in any position to prevent operation.

F. The operation selector shall be padlockable to prevent operation to the grounded position.

G. The operating mechanism shall indicate switch position which shall be clearly visible from the normal operating position.

2.15 OVERCURRENT CONTROL

A. A microprocessor-based overcurrent control shall be provided to initiate fault interruption.

B. For pad-mounted style switchgear, the control shall be mounted in a watertight enclosure. The control shall be removable in the field without taking the gear out of service.

C. Control settings shall be field-programmable using a personal computer connected via a data port to the control. The data port shall be accessible from the exterior of the enclosure. Neither external power nor energization of the gear shall be required to set or alter control settings.

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D. Power and sensing for the control shall be supplied by integral current transformers.

E. The minimum total clearing time (from initiation of the fault to total clearing) for fault interruption shall be 40 milliseconds (2.4 cycles) at 60 hertz or 44 milliseconds (2.2 cycles) at 50 hertz.

F. The control shall feature time-current characteristic (TCC) curves including standard E speed, K-speed, coordinating-speed tap, coordinating-speed main, and relay curves per

IEEE C37.112-1996. Coordinating-speed tap curves shall optimize coordination with load-side weak-link/backup current-limiting fuse combinations, and coordinating-speed main curves shall optimize coordination with tap-interrupter curves and upstream feeder breakers.

G. The standard E-speed curve shall have phase-overcurrent settings ranging from 25E through 400E. The standard K-speed curve shall have phase-overcurrent settings ranging from 25K through 200K. The coordinating-speed tap curve shall have phase-overcurrent and independent ground-overcurrent settings ranging from 50 amperes through 400 amperes. The coordinating-speed main curve shall have phase-overcurrent settings ranging from 100 amperes through 800 amperes and independent ground-overcurrent settings ranging from 100 amperes through 400 amperes.

H. Time-current characteristic curves shall conform to the following IEEE C37.112-1996

IEEE Standard Inverse-Time Characteristic Equations for Overcurrent Relays: U.S.

Moderately Inverse Curve U1, U.S. Inverse Curve U2, U.S. Very Inverse Curve U3, U.S. Extremely Inverse Curve U4, U.S. Short-Time Inverse Curve U5, I.E.C. Class A

Curve (Standard Inverse) C1, I.E.C. Class B Curve (Very Inverse) C2, I.E.C. Class C

Curve (Extremely Inverse) C3, I.E.C. Long-Time Inverse Curve C4, and I.E.C. Short-

Time Inverse Curve C5.

I. The control shall have field-adjustable instantaneous-trip settings (0.2 kA through 6 kA) and definite-time delay settings (32 ms through 96 ms for coordinating-speed tap and 64 ms through 128 ms for coordinating-speed main), to allow tailoring of the coordinating-speed tap and coordinating-speed main curves to the application.

J. Event records shall be easily extractable from the control using a personal computer connected to the data port.

2.16 VOLTAGE INDICATION

A. Voltage Indication with Provisions for Low-Voltage Phasing

1. Voltage indication with provisions for low-voltage phasing shall be provided for each load-interrupter switch and fault interrupter by means of capacitive taps on the bushings, eliminating the need for cable handling and exposure to high voltage to test the cables for voltage and phasing. This feature shall include a flashing liquid-crystal display to indicate the presence of voltage for each phase, and a solar panel to supply power for testing of the complete voltage-indication circuit and phasing circuit.

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2. The voltage-indication feature shall be mounted on the covers for the viewing windows, on the opposite side of the gear from the bushings and bushing wells, so that operating personnel shall not be required to perform any routine operations in close proximity to high-voltage elbows and cables.

2.17 ARC RESISTANCE

A. For gear rated 25 kA short circuit, the switchgear shall conform to or exceed the requirements of applicable portions of IEC 298, Appendix AA covering arc resistance, through 25 kA for 15 cycles.

2.18 ENCLOSURE

A. The switchgear shall be provided with a pad-mounted enclosure suitable for installation of the gear on a concrete pad.

B. The pad-mounted enclosure shall be separable from the switchgear to allow clear access to the bushings and bushing wells for cable termination.

C. The basic material shall be 14-gauge hot-rolled, pickled and oiled steel sheet.

D. The enclosure shall be provided with removable front and back panels, and hinged lift-up roof sections for access to the operating and termination compartments. Each roof section shall have a retainer to hold it in the open position.

E. Lift-up roof sections shall overlap the panels and shall have provisions for pad-locking that incorporate a means to protect the padlock shackle from tampering.

F. The base shall consist of continuous 90-degree flanges, turned inward and welded at the corners, for bolting to the concrete pad.

G. Panel openings shall have 90-degree flanges, facing outward, that shall provide strength and rigidity as well as deep overlapping between panels and panel openings to guard against water entry.

H. For bushings rated 600 amperes continuous, the termination compartment shall be of an adequate depth to accommodate encapsulated surge arresters mounted on 600-ampere elbows having 200-ampere interfaces.

I. For bushing wells rated 200 amperes continuous, the termination compartment shall be of an adequate depth to accommodate 200-ampere elbows mounted on feed thru inserts.

J. An instruction manual holder shall be provided.

K. Non-removable lifting tabs shall be provided.

2.19 ENCLOSURE FINISH

A. All exterior welded seams shall be filled and sanded smooth for neat appearance.

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B. To remove oils and dirt, to form a chemically and anodically neutral conversion coating to improve the finish-to-metal bond, and to retard underfilm propagation of corrosion, all surfaces shall undergo a thorough pretreatment process comprised of a fully automated system of cleaning, rinsing, phosphatizing, sealing, drying, and cooling, before any protective coatings are applied. By utilizing an automated pretreatment process, the enclosure shall receive a highly consistent thorough treatment, eliminating fluctuations in reaction time, reaction temperature, and chemical concentrations.

C. After pretreatment, protective coatings shall be applied that shall help resist corrosion and protect the steel enclosure. To establish the capability to resist corrosion and protect the enclosure, representative test specimens coated by the manufacturer's finishing system shall satisfactorily pass the following tests:

1. 4000 hours of exposure to salt-spray testing per ASTM B 117 with:

a. Underfilm corrosion not to extend more than 1/32 in. from the scribe, as evaluated per ASTM D 1645, Procedure A, Method 2 (scraping);

and

b. Loss of adhesion from bare metal not to extend more than 1/8 in. from the scribe.

2. 1000 hours of humidity testing per ASTM D 4585 using the Cleveland

Condensing Type Humidity Cabinet, with no blistering as evaluated per ASTM

D 714.

3. 500 hours of accelerated weathering testing per ASTM G 53 using lamp UVB-

313, with no chalking as evaluated per ASTM D 659, and no more than 10% reduction of gloss as evaluated per ASTM D 523.

4. Crosshatch-adhesion testing per ASTM D 3359 Method B, with no loss of finish.

5. 160-inch-pound impact, followed by adhesion testing per ASTM D 2794, with no chipping or cracking.

6. 3000 cycles of abrasion testing per ASTM 4060, with no penetration to the substrate. Certified test abstracts substantiating the above capabilities shall be furnished upon request.

D. The finish shall be inspected for scuffs and scratches. Blemishes shall be touched up by hand to restore the protective integrity of the finish.

E. The finish shall be dark brown Federal Standard 595, Color #20040

2.20 OPTIONAL COMPONENTS

A. A USB cable kit shall be provided for connecting an overcurrent control to a user-furnished personal computer.

B. Two (2) cable connected remote operators shall be provided for remote operation, one for each project.

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2.21 LABELING

A. Hazard-Alerting Signs

1. The exterior of the pad-mounted enclosure (if furnished) shall be provided with

"Warning-Keep Out-Hazardous Voltage Inside-Can Shock, Burn, or Cause

Death" signs.

2. Each unit of switchgear shall be provided with a "Danger-Hazardous Voltage-

Failure to Follow These Instructions Will Likely Cause Shock, Burns, or Death" sign. The text shall further indicate that operating personnel must know and obey the employer's work rules, know the hazards involved, and use proper protective equipment and tools to work on this equipment.

3. Each unit of switchgear shall be provided with a "Danger-Keep Away-

Hazardous Voltage-Will Shock, Burn, or Cause Death" sign.

2.22 NAMEPLATES, RATINGS LABELS, AND CONNECTION DIAGRAMS

A. Each unit of switchgear shall be provided with a nameplate indicating the manufacturer's name, catalog number, model number, date of manufacture, and serial number.

B. Each unit of switchgear shall be provided with a ratings label indicating the following:

voltage rating; main bus continuous current rating; short-circuit rating; fault-interrupter ratings including interrupting and duty-cycle fault-closing; and load-interrupter switch ratings including duty-cycle fault-closing and short-time.

PART 3 EXECUTION

3.01 GENERAL

A. Prior to installation, verify that switchgear is in conformity with the specifications.

B. Inspect equipment for physical damage.

C. The switchgear shall be installed as shown on Contract Drawings, specified herein and recommended by the manufacturer.

3.02 INSTALLATION

A. The Contractor shall provide all equipment foundations pads complete with anchor bolts and mounting hardware as required.

B. The switchgear and base spacer shall be placed on the foundation and securely bolted in place.

C. Provide grounding grid around the switchgear as detailed, make all grounding connections.

D. Make all medium voltage cable terminations as specified.

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E. All doors, panels and sections shall be inspected for proper fit and alignment.

F. Perform insulation resistance test on switchgear using a 1000 volt megohm-meter.

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