exhibit 4 - lfpubweb.cityofdenton.com · web viewcmc/esp utility products: rls350-6i . for 5/8”...

CITY OF DENTONRFP FOR SUPPLY OF ELECTRIC UTILITY UNDERGROUND DISTRIBUTION

TRANSFORMERS

Exhibit 4SPECIFICATIONS FOR UNDERGROUND PADMOUNTED

TRANSFORMERS

PURPOSE Denton Municipal Electric (DME), in Denton, Texas is providing information that will allow prospective suppliers to prepare quotations to furnish new SINGLE-PHASE AND THREE-PHASE PADMOUNTED TRANSFORMERS equipped as set forth in this specification. Only new transformers and parts never before used will be accepted on this bid. Salvaged material or remanufactured parts from any source will not be acceptable. Manufacturer shall provide a statement with their bid that only new parts and materials will be used for all transformers supplied for this bid.

The new electric distribution, padmounted, compartmental type, Class ONAN, self-cooled, 60 Hz, mineral oil-filled, loop-feed, deadfront transformers shall be designed to operate on DME’s 13.2 kV Grounded Wye/7.62 kV electric distribution system. The transformer size in kVA, the low voltage ratings and types of HV & LV terminations shall be supplied as specified. All padmounted transformers (both single- and three-phase units) are to be quoted and provided with an externally mounted de-energized tap selector switch located in the HV compartment with full-load kVA rated taps, two 2.5% above and two 2.5% below the nominal voltage position (total of five tap positions). Three-phase units shall have liquid level and temperature gauges on all units 500 kVA and larger. Three-phase units shall have a 4-position T-Blade High Voltage Switch. All padmounted transformers shall have a stainless steel skirt on the front sill and entire bottom of the tank (all metal that contacts the transformer pad shall be stainless steel).

Where the manufacturer provides warranties or guarantees as a customary trade practice; the bidder shall furnish the City of Denton with copies of such warranties or guarantees upon request by the City of Denton.

PROPOSALSProposals shall be provided using the attached bid proposal forms. Additional information clarifying the supplier’s product may be attached to the bid form. Pricing shall include all costs to deliver complete, new, electric distribution padmounted, compartmental type, Class ONAN self-cooled, 60 Hz, mineral oil-filled, loop-feed, deadfront, single-phase and three-phase, transformers as defined in this specification. Any special fees or commissions, and all freight for delivery to the Spencer Pole Yard must be included in the quoted price. Item pricing shall be mutually exclusive, thus the City of Denton reserves the right to choose the lowest quoted item cost from different vendors. The City of Denton also reserves the right to order similar

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transformer units from other vendors to best fit the needs of the utility, or to meet special and/or fast paced project schedules.

EVALUATION AND AWARDThe City of Denton will award the purchase, if any, based solely on its evaluation of the bids. Subsequent to the initial evaluation, the owner, at their discretion, may elect to conduct discussions with any of the prospective suppliers to resolve questions related to the substance of their proposals. Alternate proposals may be considered only at the DME’s option. DME reserves the right to accept any alternate proposal that it deems to be in the City’s best interest. Transformers shall be evaluated on initial and lifetime operating cost based on both no-load and load losses in watts as detailed in the Loss Evaluation section.

DEVIATIONS TO SPECIFICATIONBidders quoting to this specification will indicate any areas where deviations are required by their design and will provide sufficient information to permit full evaluation of their product prior to bid opening. This data will reference the appropriate section number and be sent in letter format with their bid. Any alternate bid should be approved by the City of Denton prior to the bid opening date. Alternates may not be considered less than 10 days prior to opening date. Approved alternates will then be sent back out in an Addendum, for all vendors to know that the alternate is acceptable. Unless specifically noted by bidder as indicated above, each quotation shall meet and include all items as detailed in this specification.

SHIPMENT AND DELIVERYA delivery schedule after placing an order is required with the bid. The delivery lead-time for new single-phase and three-phase padmounted distribution transformers may be a consideration in evaluating this bid. All transformer deliveries shall go to Denton Municipal Electric’s Pole Yard at 1701C Spencer Road, Denton, Texas 76205. Delivery hours are from 7-11AM & 1-3:30PM. A delivery notice, 24 hours in advance, shall be made to (940) 349-7603.

GENERAL REQUIREMENTSThe supplier shall furnish all manufacture drawings and instructions that are necessary to completely and safely transport, store, install and maintain each distribution transformer.

QUALITY CONTROLThe manufacturer shall be responsible for the quality control of the manufacturing processes to assure all requirements of these specifications are met. However, the purchaser reserves the right to observe, inspect, and require additional quality control investigations, either by its personnel or an independently employed quality control investigator, at any or all stages of fabrication at

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the manufacturer’s facilities. Failure to adequately maintain quality of fabrication until completion shall be grounds for cancellation of the order or any part thereof.

Field failure or field repairs required due to quality control failures or manufacturing procedures shall be the responsibility of the manufacturer.

WRITTEN WARRANTY and GUARANTEESWritten guarantees shall include any limitations as to the nature of failure or time limitations. The guarantee shall begin upon receipt of the accepted units, not the date of manufacture. Guarantees shall indicate whether or not it is made on a full replacement basis or a prorated basis, and if prorated, then what are the terms. Manufacturer/supplier guarantees the new single-phase and three-phase padmounted distribution transformers furnished under this specification are of high quality and agrees to replace any new padmounted distribution transformers that are found to be defective during inspection, installation, or service for a minimum period of 12 months after the unit is delivered to Denton. All replacements by the manufacturer/supplier shall be free of charge F.O.B. at the same delivery point called for in the original order. Replacements must be handled in a professional and timely manner and in no case shall a replacement unit take longer than 60 days to arrive in Denton after first being submitted for replacement.

Any material repaired or replaced under the terms of the above guarantee shall itself be covered by those terms as if it were a new product. The vendor shall state the expected service life and failure mode of the product in its intended application. This should also include documentation explaining how expected service life was determined. Any transformers that fail after the warranty, but before the expected service life, may be subjected to an engineering failure analysis to determine the cause of failure. This analysis will be performed by the vendor and DME engineers, or any other contractor or lab chosen by DME engineering. The vendor shall, if requested, supply the required resources for the analysis at no cost to DME.

Manufacturer shall notify DME of any manufacturing changes or defects that have been found that may potentially impact units delivered to or scheduled to be delivered to DME. Manufacturer shall be proactive on informing the customer of known product defects and any manufacturing changes from the original product quoted and delivered. Discovery of the manufacturer’s failure to inform DME shall be grounds for immediately canceling the bid award and any transformer orders already placed but not yet delivered and it may also affect the manufacturer’s or vendor’s ability to quote on future bids.

The bidder must be an approved distributor by the manufacturer of these products, and authorized to sell the products to the City of Denton. The bidder also guarantees the City will be

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represented by the Manufacturer, should an issue arise, and that all manufacturer’s warranties will be in effect for the life of the contract.

TECHNICAL SPECIFICATIONS: SINGLE & THREE-PHASE PADMOUNTED TRANSFORMERS:

Anchoring Provisions: The bottom edges of the compartment shall be so constructed as to provide for use of hold down devices accessible only from the inside of the compartment. Construction of the unit shall be such that it can be lifted, skidded, slid or any combination of these, into place on the mounting surface without disturbing the high voltage or low voltage cables or damaging the unit.

Basic Impulse Level (BIL): The high voltage basic impulse insulation level shall meet or exceed 95 kV.

Bushing Gasket: Shall be a neoprene gasket or equivalent for a leak free oil seal.

Coils: All insulating paper used as layer insulation in transformer coils shall be bonded type, coated on both sides with a thermosetting adhesive and properly cured prior to impregnating with oil. Coils shall be wound with copper primary and secondary conductors containing a thermosetting adhesive that when properly cured will form an effective bond, both turn-to-turn and layer-to-layer.

Core: The core shall be clamped and braced to resist distortion caused by short-circuit stresses within rating or transportation handling and to prevent the shifting of core laminations. The core shall be constructed of high-grade, grain oriented, silicon steel laminations or amorphous core, with high magnetic permeability.

Core shall include step-lap mitered joints to keep core losses, excitation current and noise level at a minimum. There shall be three primary and three secondary windings wound on a five-legged or equivalent core design.

All insulating paper used as layer insulation in transformers coils shall be coated on both sides with a thermosetting adhesive and properly cured prior to impregnating with oil. The transformer shall be designed and constructed to be completely self-protected by its ability to withstand external short-circuits, as defined by IEEE C57.12.00.

De-Energized Tap Selector: A manually operated, de-energized tap selector shall be provided for changing the primary winding taps on all padmounted transformers. The tap selector shall be

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capable of carrying the full transformer short-circuit current without damage or contact separation, gang-operated from a single operating point, and have a position indicator clearly marked with provisions to lock or secure the tap position. The tap selector operating mechanism shall include provisions for padlocking each tap position. The tap changer switch shall be an externally operated within the cabinet enclosure. It shall be a snap action switch capable of hotstick operation that does not require opening the oil-filled tank. The tap changer shall be clearly labeled to reflect that the transformer must be de-energized before operating the tap changer.

All transformers shall be provided with an externally mounted de-energized tap selector switch located in the HV compartment with full-load kVA rated taps, two 2.5% above and two 2.5% below the nominal voltage position (total of five tap positions). The tap changer shall be set at the factory to the neutral or nominal tap position.

Dielectric Oil: Shall be free of measurable quantities of Polychlorinated Biphenyl’s (PCB’s). Only dielectric mineral oil will be accepted, Envirotemp® FR3™ fluid will NOT be accepted. The permanent nameplate attached by the factory must indicate the type of oil and contain the words “NO PCB”. All invoices and certified test reports must include a statement certifying that the equipment indicated therein contains no PCB’s as defined by the United States EPA (less than 2 PPM).

Dimensions: Transformer overall dimensions shall not exceed DME’s standard pad dimensions, which are as follows:

a.) 1-Phase, all sizes: 48” W X 48” Db.) 3-Phase, 75 to 500 kVA: 84” W X 84”c.) 3-Phase, 750 to 2500 kVA: 96” W x 102” D

Any proposed deviations from these specifications shall be submitted to DME Engineering for evaluation.

Internal Fault Detector:

Each transformer shall be equipped with a non-resettable device which detects and provides external indication of internal transformer faults, and also incorporates pressure relief functionality. The approved device is manufactured by IFD Corporation or approved equal (See Appendix A).

HV Bushing Insert: The manufacturer shall supply “Elastimold #1601A4” Loadbreak, 15 kV, 200 amp, bushing inserts only and conform to IEEE 386. The bushings shall be removable, externally clamped, and arranged for loop-feed deadfront operation. The bushings inserts shall IFB # 6778Exhibit 4


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have a hex-broached base to accommodate torque tool for installation assistance. A latched elbow indicator ring shall be provided. The current carrying path will be all copper/copper alloy. The bushing inserts shall have a torque-limiting feature between 7-14 ft-lbs to eliminate bushing well stud breakage. The bushing inserts must be capable of rotating clockwise continuously without loosening the current interchange.

Lifting Provisions: All transformers shall have two lifting supports on each side of the tank (four total). Each lifting lug shall be designed to provide a minimum safety factor of five. These lifting provisions shall be used to lift the complete oil-filled transformer without bending, cracking, or deforming the tank or lifting structure. The lifting lugs shall be arranged on the tank to provide a distributed and balanced lift in the vertical direction. Lifting lugs may come uninstalled for shipping but must be provided with each transformer.

Locking Provisions: Shall utilize a recessed, captive, 1/2" penta-head bolt with NC Class 2 threads, separate from the locking device. The penta-head bolt shall be threaded into a blind hole. The penta-head device shall be coordinated such that the padlock cannot be inserted into hasp until the access door is fully latched and all penta-head devices are securely engaged per IEEE C57.12.28. The diameter of the hole for the padlock shall be a minimum of 1/2”. The padmounted equipment shall meet the requirement for tamper resistance as set forth in IEEE C57.12.28.

Loss Evaluation: Transformers will be evaluated on initial and lifetime operating costs based on the following formula:

Evaluated cost = Unit initial cost + $4.50/Watt * TNLL + $/Watt * TLL

Where:Unit initial cost = Transformer’s cost in dollarsTNLL = Transformer’s no-load losses in wattsTLL = Transformer’s load losses in watts

For evaluation purposes, the following data shall be provided with all bids: Manufacturer’s name Catalog numbers of each item bid Guaranteed average transformer no load losses in watts @ 85°C Guaranteed average transformer load losses in watts @ 85°C

If the manufacturer delivers transformers whose certified test reports show that the loss factors exceed the guaranteed watt loss figures in the bid with tolerances greater than 10% core loss or 6% total loss, then those units will be rejected and all costs associated with promptly replacing IFB # 6778Exhibit 4


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the aforementioned units with ones that meet the guaranteed figures shall be the full responsibility of the manufacturer. If the value of actual losses exceeds the quoted value then credit shall be issued for the difference per the quoted $/watt evaluation provided.

All certified test reports shall be submitted to DME Engineering prior to each transformer shipment. Payment will not be authorized for any transformer until certified test reports have been received, reviewed and verified for compliance with the specification.

Markings: Terminal designations shall be as defined by ANSI Standard Terminal Marking and Connections for Distribution and Power Transformers, IEEE C57.12.70. Terminal designations shall be painted on the unit with oil resistant, yellow paint. The identification of terminal connections shall be shown on the instruction nameplate. The vendor shall stencil the transformer voltage and kVA in yellow paint on both the inside and outside of the door or hood. The fuse size shall be stenciled only on the inside of the door.

Nameplates: Transformer shall be furnished with a non-corrosive diagrammatic metal, high-contrast, low glare laser-engraved finish for readability. The nameplate shall be permanently attached with non-corrosive hardware. The diagrammatic nameplate shall include the name of the manufacturer of the equipment. The nameplate shall contain all connection, impedance, and rating information in accordance with IEEE C57.12.00, Nameplate C.

Packaging & Shipping: Each transformer shall be fastened to skids or to a two-way entry, disposable pallet of the vendor's own design. This pallet must be of such dimension as to provide two inch (2") clearance of the transformer at its widest outside measurements, on all four sides. Skids or pallets must provide with a minimum of 2.25” of fork underclearance.

Paint: Transformer shall be thoroughly cleaned and phosphatized, then painted with a least one coat of corrosion inhibiting primer. The tank finish shall be of high grade paints employing a controlled baking process that will insure a protective coating in accordance with the requirements of IEEE C57.12.28, paragraph 5, "Enclosure Coating System." The materials and process used shall be designed to protect against the effects of abrasion, sunlight, rural and industrial atmosphere, and humidity. The color shall be Munsell 7GY 3.9/1.5 olive green. Paint thickness on all exterior surfaces shall be a minimum of 2.5 mils. Interior tank coating shall be white or similar light color to enhance visibility during repair and maintenance.

Ratings: All ratings shall be based on not exceeding a 65°C winding temperature rise.High Voltage: 13.2 kV Grd Y/7.62 kV Typical Transformer Low Voltage (kVA):

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240/120: 25, 50, 75, 100, 167480/240: 25, 100, 167208Y/120: 75, 112.5, 150, 225, 300, 500, 750, 1000, 1500480Y/277: 112.5, 150, 225, 300, 500, 1000, 1500, 2000, 2500240/120 Δ: 50, 225, 300

Safety Labels & Warnings: Bilingual English/Spanish WARNING and DANGER labels shall be applied in accordance with NEMA standards Publication Number 260, latest revision and shall be attached to individual cabinets of pad mounted transformers as follows:

WARNING label, “Warning…High Voltage Keep Out”, shall be centered on the outside of the latched HV compartment door two inches below the top.

DANGER label, “Danger…Hazardous Voltage…Keep Out…Qualified Persons Only”, shall be mounted inside each compartment and centered on the face of the transformer directly above the HV bushings so it is visible when the door is in the open position.

Security: The transformer tank and compartments shall be constructed so as to limit disassembly, breakage, prying open any doors, panels and sills with the door or cover in the closed and locked positions. There shall be no openings through which foreign objects such as sticks, rods or wires might be inserted to contact live or energized parts. Enclosure security shall conform to the requirements of Section 4 of IEEE C57.12.28.

Short-circuit: All transformers shall be capable of withstanding short-circuits in accordance with IEEE C57.12.00 and IEEE C57.12.90.

Sound: Sound levels shall be within the limits specified in NEMA TR-1.

Stainless Steel Fasteners & Parts: All surfaces that are in contact with the pad and the base sill shall be made of 400CB, 409 or 304L stainless steel. Stainless steel hardware shall be used to fasten stainless steel surfaces. Doors, hood hinges, and their assemblies shall also be stainless steel.

Testing: Each transformer shall receive all tests in accordance with the latest revision of the Test Code IEEE C57.12.91 and performed as specified by IEEE 57.12.00 and IEEE C57.12.90. Short-circuit withstand capability shall be verified by full short-circuit tests on similar or larger units in accordance with the latest revision of IEEE C57.12.00 and IEEE C57.12.90. Short-circuit withstand verification shall be submitted to DME prior to shipment of the transformers.

A certified test report shall be submitted with or prior to each transformer shipment and delivery and shall contain the test data for each transformer serial number manufactured. The certified IFB # 6778Exhibit 4


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test report shall as a minimum contain the data as in IEEE C57.12.90. The test reports, PCB reports, and other drawings or documentation shall be provided electronically upon request in an Excel, Word, PDF or AutoCAD format to DME at no additional cost.

The certified test report shall contain the following information: Date of Test No-Load Loss @ 85°C Load Loss @ 85°C Total Loss @ 85°C Percent Impedance @ 85°C Percent Exciting Current @ 100% Voltage

The City of Denton will reject transformers not meeting these specifications or exceeding the guaranteed losses as stated in the original bid by more than 10% and credit on units less than 10% per IEEE C57.12.00. The city shall have the option of rejecting transformers up to 60 days after receiving reports. The city will make no payments until the vendor satisfies all conditions stated above and has delivered the certified test results.

Vent Sign: A label on the tank indicating, “Vent Before Operating Fuse” shall be attached above the fuse holder and clearly readable.

TECHNICAL SPECIFICATIONS: SINGLE-PHASE PADMOUNTED TRANSFORMERS:

The single-phase padmounted distribution transformers shall conform to the latest revisions of IEEE C57.12.38 (Pad-Mounted-Type, Self-Cooled, Single-Phase Distribution Transformers 250 kVA and Smaller: High Voltage, 34 500 GrdY/19 920 V and Below; Low Voltage, 480/240 V and Below), IEEE C57.12.00; 12.28; 12.38; 12.70; 12.80; 12.90 and other applicable ANSI, IEEE, and OSHA standards.

Hood/Door: Hood shall be flip-top and made with heavy duty 3/8” removable stainless steel hinge pins and a sill of 6” height. The roof shall be crowned to prevent standing moisture. The flip-top hood shall open a minimum of 180, and rest securely on the tank top. The padlock mechanism shall be designed such that the penta-head bolt must be thoroughly engaged prior to the padlock being closed. Padmounted transformers shall meet the cabinet security provisions of IEEE C57.12.28.

DME prefers the rounded type hood arrangement (as shown in Appendix A) on single-phase pad-mounts instead of a welded square corner hood or door. DME may consider a square or

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welded corner hood, provided that it is reinforced, built to tight tolerances, and designed to prevent door closing and latching problems. If the total evaluated low bidder on any individual item happens to be a square hood design then it will be DME’s sole consideration whether or not to accept that design or quote after careful review of the actual hood design, hands-on operation and visual inspection of an evaluation unit that shall be delivered to Denton Municipal Electric’s Pole Yard at 1701C Spencer Road, Denton, Texas 76205 for inspection. The basis for DME’s decision will be whether or not the manufacturer can adequately assure DME that their square door or hood design can consistently be easily opened and closed and latched with the captive penta-head bolt installed. Any square hood design that is evaluated as the low bid and accepted will have an initial probationary trial period for three months. If DME detects any problems or issues then those units must be promptly replaced to DME’s full satisfaction. DME shall have the final decision in determining whether or not to accept any particular manufacturer or transformer hood or door design. DME considers the door design to be an operational and safety related issue.

Manufacturer shall provide outline drawings with their bids, post on the Internet, or FedEx to DME for evaluation, prior to bid award. The manufacturer shall only supply the accepted type of unit throughout the bid period and not change the hood or door design, or make any other transformer or manufacturing process changes without notifying DME in writing. The manufacturer shall promptly replace any unit that is delivered or found upon initial installation to have a hood or door that will not properly open, close or that cannot easily be locked closed with the captive penta-head bolt installed.

Fuse Unit: The fuse unit shall be an oil-immersed Bayonet fuse holder and fuse link. The fuse shall be designed to be located within the transformer and installed in a bayonet fuse holder. The bayonet-type fuse link shall be able to remove the transformer from the distribution system in case of an internal fault (fault sensing), secondary short, or overload (overload sensing). This fuse shall be draw-out design and supplied in series with an internal isolation link and external drip shield guard. The fuse holder shall include a flapper valve on each bayonet to seal the fuse well when the bayonet fuse is removed. Each new transformer shall come fused from the manufacturer with a Dual-Sensing fuse sized for the rated kVA.

HV Arrangement: The high voltage connector arrangement shall be according to IEEE C57.12.34, Section 8.

HV Bushing Well & Insert: The manufacturer shall supply “Elastimold #1601A4” Loadbreak, 15 kV, 200 amp, bushing inserts only that conform to IEEE 386. The bushings shall be removable, externally clamped, and arranged for loop-feed deadfront operation. The bushing

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inserts shall have a hex-broached base to accommodate torque tool for installation assistance. A latched elbow indicator ring shall be provided. The current carrying path will be all copper/copper alloy. The bushing inserts shall have a torque-limiting feature between 7-14 ft-lbs to eliminate bushing well stud breakage. The bushing inserts must be capable of rotating clockwise continuously without loosening the current interchange.

LV Neutral: The low voltage neutral shall be a fully insulated terminal. A ground pad shall be provided on the outer surface of the tank. A removable ground strap, suitably sized for the short-circuit rating of the transformer shall be provided and connected between the low voltage neutral terminal and the ground pad as defined in IEEE C57.12.00.

Parking Stand: A single high-side parking stand located between the high-side bushing wells shall be provided for the attachment of bushing accessories for each high-side position. Two parking stands will also be acceptable.

Secondary Terminal or Connector: a.) Transformers less than 75 kVA shall come standard with a 5/8” copper stud and contact

nuts. Any transformer 75 kVA and larger shall come standard with a 1” copper stud and contact nuts.

b.) Shall have a disconnectable secondary, screw-on style, 6 position connector installed with a clear PVC insulating boot, self-sealing wrench outlets and self-adjusting cable outlets.

c.) Cable range shall be #10-350 MCM for units with 5/8” stud and #10-500 MCM for units with 1” stud. Both shall include an oxide inhibiting compound.

d.) Dual rated for use with both aluminum and copper conductors.e.) The connector length shall not exceed 8”. f.) Shall meet or exceed ANSI C119.4 specifications.g.) The approved secondary connector is: (See Appendix A)

CMC/ESP Utility Products: RLS350-6I for 5/8” stud and RLS500-6I for 1” stud.

Single-Phase Tank: Shall be constructed of heavy gauge steel (a minimum of 12 gauge). The transformer shall be all-welded, sealed-tank construction of sufficient strength to withstand a constant pressure of 7 PSI without permanent distortion or deformation per IEEE C57.12.38. All welds on the exterior of the tank are to be full welds. Spot, tack or skip welds are not acceptable for attaching hinges, brackets, etc. There shall be no exposed screws, bolts or other fastening devices which are externally removable. The top shall be pitched to facilitate water run-off.

The Transformer shall be quoted with a Stainless Steel (“Mini-Skirt”) located around the base of the tank and the front sill. The stainless steel assists by providing additional corrosion resistance from typical lawn fertilizers, water sprinklers and humid environments. The full stainless steel IFB # 6778Exhibit 4


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sill and tank construction shall be included in the standard unit base cost quoted for each transformer.

Single Phase transformers shall also be supplied with:a.) Oil level/fill plug b.) Oil drain plug and valve made of brass, minimum 1/2” diameter with hand-valve, located

in the low voltage areac.) The transformer shall be equipped with a replaceable pressure relief valve that complies

with the requirements of IEEE C57.12.38 latest revision, including the following: i. The body of the valve shall be brass, bronze or stainless steel.

ii. The venting port, on outward side of valve head seat, shall be protected to prevent entry of dust, moisture and insects before and after valve has actuated.

iii. The device shall have a pull ring for manual or hot stick activation.d.) Two steel grounding pads with 1/2”-13 NC tapped hole, minimum thread depth of 7/16”

deep per IEEE C57.12.38.

APPROVED MANUFACTURERS FOR SINGLE-PHASE PADMOUNTED TRANSFORMERS :

a.) ABBb.) Cooperc.) General Electricd.) Howard Industries

Alternative manufacturer products may be considered that meet specifications per the Deviations to Specification section listed above and that DME approves.

TECHNICAL SPECIFICATIONS: THREE-PHASE PADMOUNTED

TRANSFORMERS:The three-phase padmounted distribution transformer shall meet or exceed the latest applicable ANSI and IEEE standards. The three-phase padmounted distribution transformers shall conform to the latest revisions of IEEE C57.12.00; 12.28; 12.34; 12.70; 12.80; 12.90; NEMI TR1; WUG 2.13 Rev. 4 and other applicable ANSI, IEEE and OSHA standards.

Current Transformers (CT’s): The low voltage bushings shall be of such length to allow mounting of current transformers thereon. The low voltage bushings shall have a minimum of 2.5” for the mounting of current transformers. The low voltage neutral shall be a fully insulated terminal. (See Appendix A for CT details.)

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Doors: Unlocking the padlock and disengaging the penta-head bolt shall permit access to both the high and low voltage terminations when the compartment doors are removed or opened. There shall be a steel barrier between the high voltage and low voltage compartments.

Two 1/2” penta-head bolts must be removed from the flange formed on the steel HV/LV barrier before the HV door can be opened. In addition to the regular locking provisions, all access doors shall be secured by a recessed, captive, penta-head bolt which threads into a blind hole. A penta-head bolt shall be considered “captive” so the retention scheme will prevent it from being readily removed during normal operation of the door(s). The recess is to be non-rotating. The dimensions of the penta-head bolt and non-rotating recess shall comply with IEEE C57.12.28. Stainless steel hinges and hinge pins shall be provided.

Each unit shall have provisions for latching doors fully-open while performing work on the unit, making terminations or performing switching operations.

Grounding Provisions: All non-energized metallic components of the transformer shall be grounded. Tank grounding provisions shall consist of two ground pads, welded to the base or tank wall near the base on diagonal corners. Ground pads shall be copper-faced or stainless steel with two holes spaced horizontally on 1.75” centers and tapped for 1/2” 13-UNC thread. The minimum thickness of the copper-facing shall be 0.02” (0.5 mm) and the minimum thread depth of the holes shall be 7/16”.

HV Compartment: The transformer shall be furnished with a high voltage compartment located on the left of the centerline when facing the doors. The HV compartment shall be provided with an interlocked door, which can only be opened after the LV compartment door has been opened. Parking stands for each phase of the loop-feed shall be provided for the attachments of bushing accessories.

HV Switch: Three-phase pad-mounted units shall have a four-position T-Blade (A, B, AB (Secondary Closed), AB (Secondary Open)) high voltage switch located in the high voltage compartment on all transformers. Each position shall be clearly marked with a schematic diagram. Special notes, instructions and any warnings must be listed either on or adjacent to the high voltage switch. Switch must be capable to switch full rated kVA loads of the unit.

Liquid Level Gauge: (500 kVA and larger) This gauge shall have a vertical face and is gasket mounted to the front plate of the transformer, inside the low-voltage compartment above the secondary terminals. The liquid level indicator shall be shipped mounted on the transformer as indicated and require no maintenance.

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Liquid Temperature Gauge: (500 kVA and larger) The temperature gauge is to indicate the top liquid temperature in the tank. The device shall be furnished with a red pointer to show the highest temperature attained since the last reset. The device shall have the capability to reset the maximum indicator.

LV Compartment: The transformer shall be furnished with a low voltage compartment located on the right of the centerline when facing the doors. The LV compartment shall be arranged per IEEE C57.12.34, Figure 4(A). The low voltage compartment shall be furnished with a three-point latch with provisions for padlocking. The LV compartment shall include all indicating devices and fittings that are to be supplied, along with a stainless steel diagrammatic nameplate. The LV cabinet must allow adequate room to make terminations without being cramped and shall not require a double-hinged side-door on the cabinet that can be opened to make connections after LV cables are in-place and ready to be terminated.

LV Ground Strap: Removable ground straps suitably sized for the short-circuit rating of the transformer as defined in IEEE C57.12.00, latest revision, shall be provided and connected between the low voltage neutral terminal and the ground pad. The ground strap shall utilize only one spot on the NEMA LV Spade Pad, closest to the tank and shall not encroach upon the other holes on the spade pad.

LV Terminations: The externally clamped low voltage bushings shall be epoxy with threaded studs meeting IEEE C57.12.34. The low-voltage bushing terminal shall be spade-type and arranged for vertical-takeoff of outgoing cables. The X0/Neutral bushing shall have a removable copper-grounding strap.

The LV terminal spade pads shall be in a staggered arrangement meeting IEEE C57.12.34. The vendor shall include LV terminal spade pads installed on threaded studs with transformers and provisions for dielectric bracing as required per the list below.

NEMA LV Spade PadsXFMR Voltage 8-Hole 10-Hole 12-Hole Dielectric Bracing

208Y/120 75 kVA - 300 kVA --- --- ---208Y/120 --- 500 kVA - 1500 kVA --- Required480Y/277 112.5 kVA - 500 kVA --- --- ---480Y/277 --- 750 kVA - 1500 kVA --- Required480Y/277 --- --- 2000 kVA & Larger Required

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Overcurrent Protection: The fuse unit shall be an oil-immersed current limiting bayonet fuse. The fuse shall be installed in a bayonet fuse holder. The bayonet type fuse link shall be used in series with an internally mounted isolation link. Overcorrect protection shall be provided by a Bayonet expulsion Dual-Sensing fuse. Units 2000 kVA and larger shall utilize high-ampere overload-type bayonets. All units shall come equipped with a manufacturer recommended Dual-Sensing fuse sized for the rated kVA.

Three-Phase Tank: The tank shall be constructed of heavy gauge steel (a minimum of 12 gauge). The transformer shall be all-welded, sealed tank construction of sufficient strength to withstand a constant pressure of 7 psig without permanent distortion or deformation and 15 psig without rupturing or affecting cabinet security per IEEE C57.12.34, paragraph 8.10.1. All welds on the exterior of the tank are to be full welds. Spot, tack or skip welds are not acceptable for attaching hinges, brackets, etc. There shall be no exposed screws, bolts or other fastening devices which are externally removable. The top shall be pitched to facilitate water run-off.

The cooling equipment and compartments subject to pressures shall be designed to withstand, without permanent deformation, pressures of at least twenty five percent greater than maximum operating pressures. The maximum design withstand pressure shall be indicated on the nameplate. Tank design shall include sufficient expansion volume to allow operation under specified load conditions.

Tanks without cooling fins are preferred. If required, cooling fins shall be designed so that no sharp points or edges exist on any part of the fins or where they attach to the tank. Cooling fins shall have a 5" clearance from the ground. External corners and edges shall be rounded and smoother. Cooling fins shall be arranged to minimize their protrusion from the tank.

Temperature Rise Limits: The design shall be such that excessive tank heating will not occur. The winding temperature rise above ambient temperature shall not exceed 65°C when tested in accordance with their rating. The hottest spot temperature shall not exceed 80°C when tested in accordance with their rating. The temperature rise of the insulating oil shall not exceed 65°C when measured near the top of the tank.

Three-Phase Transformers shall also be supplied with:a.) Oil level/fill plugb.) Oil drain plug and valve made of brass, minimum 1/2” size with hand-valve, located in

the low voltage areac.) The transformer shall be equipped with a replaceable pressure relief valve that complies

with the requirements of IEEE C57.12.38 latest revision, including the following: i. The body of the valve shall be brass, bronze or stainless steel.

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ii. The venting port, on outward side of valve head seat, shall be protected to prevent entry of dust, moisture and insects before and after valve has actuated.

iii. The device shall have a pull ring for manual or hot stick activation.d.) Two steel grounding pads with 1/2”-13 NC tapped hole, 7/16” deep (1 in HV, 1 in LV)

per IEEE C57.12.38.e.) Liquid temperature Gauge (500 kVA and up)f.) Liquid level oil Gauge (500 kVA and up)g.) 4-Position T-Blade High Voltage Switch

APPROVED MANUFACTURERS FOR THREE-PHASE PADMOUNTED TRANSFORMERS :

a. ABBb. Central Moloneyc. Cooperd. General Electrice. Howard Industriesf. Pauwels

Alternative manufacturer products may be considered that meet specifications per the Deviations to Specification section listed above.

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Appendix A

IFD Fault Detector

CURRENT TRANSFORMERS – GE ENCOMPASS JAB-0W (For Three-Phase Transformers Only)

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IFB # 6778Exhibit 4


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LV Spade Pad - Dimensions(For Three-Phase Transformers Only)

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LV Bushing & Terminal Stud (For Three-Phase Transformers Only)

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(For Single-Phase Only)

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CONNECTOR MANUFACTURING COMPANY 501 Symmes Road

Hamilton, Ohio 45015-1369

Telephone: 513-860-4455


TRANSFORMERS

Single-Phase Padmounted Transformer

Typical single-phase transformer with disconnectable, secondary, screw-on style, CMC secondary connectors with clear PVC insulating boots that have self-sealing wrench outlets, self-adjusting cable outlets, and an oxide inhibiting compound.

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Typical single-phase transformer with disconnectable secondary screw-on style CMC secondary connectors with clear PVC insulating boots that have self-sealing wrench outlets and self-adjusting cable outlets.

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Example of the Rounded corner style that DME prefers on single-phase door or hood.This style allows much easier opening and closing and allows for quick and proper engagement of the penta-head bolt and padlock without having to manually flex or pop out the handle and locking mechanism.

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Hood: Example of the DANGER sign attached inside the flip-up hood of single-phase transformers.

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Three-Phase Padmounted Transformer

High Voltage Compartment: Typical three-phase loop-feed deadfront transformer with de-energized tap selector, three Bayonet oil-immersed fuses and parking stand mounting devices.DME also requires oil temp and T-blade 4 position HV switch on new 3-phase units.

Low Voltage Compartment: Typical staggered terminal arrangement with the pads that are dielectrically braced on 500 kVA and larger transformers to support the secondary cables and termination weights. Minimum criteria for LV terminal spade pads is mandatory as listed in the table on page 14 of this specification. Liquid level gauge is shown.

IFB # 6778Exhibit 4


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Front and Side View

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Side and rear View

IFB # 6778Exhibit 4

exhibit 4 - lfpubweb.cityofdenton.com · web viewcmc/esp utility products: rls350-6i . for 5/8”...

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