Attachement_A_-_Specifications.pdf

P R E S E N T E D B Y

P R E P A R E D F O R

N E W B R A U N F E L S U T I L I T I E S

J U N E 2 6 , 2 0 2 6

S P E C I F I C A T I O N F O R S U B S T A T I O N P O W E R T R A N S F O R M E R S F M 3 0 0 9 , F R E I H E I T , S H E R I F F ’ S P O S S E , A N D H O R T O N T O W N

THE RELEASE OF THIS DOCUMENT WAS

AUTHORIZED BY:

STEVEN V. DEASES

P.E. #109821 06/09/2026

ISSUED

FOR BID PURPOSES

ONLY

06-09-2026

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NEW BRAUNFELS UTILITIES

SPECIFICATION FOR SUBSTATION POWER TRANSFORMERS

TABLE OF CONTENTS

1.00 ITEM

2.00 SCOPE

3.00 USE

4.00 APPLICABLE STANDARDS

5.00 GENERAL

6.00 RATINGS

7.00 CONSTRUCTION

8.00 DRAWINGS AND INSTRUCTION MANUALS

9.00 INSPECTIONS AND TESTS

10.00 SHIPPING

11.00 SERVICING AND ASSEMBLY

12.00 DISCLAIMER

13.00 SPARE PARTS

APPENDIX A

APPENDIX B

APPENDIX C

APPENDIX D

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NEW BRAUNFELS UTILITIES

SPECIFICATION FOR

SUBSTATION POWER TRANSFORMERS

MARCH 2026

1.00 ITEM: Power Transformer(s) conforming to this specification

2.00 SCOPE:

This specification covers the minimum requirements for design, materials, fabrication, construction, testing, inspection, shipping, installation, testing, performance and warranty of new three-phase power transformer(s) and accessories delivered to the address below and factory set to operate at the following voltages:

Item Substation Qty. MVA Rating (MVA) Voltage Range (kV)

1 FM 3009 1 20//26.667//33.33/37.33 138 – 13.09Y/7.56 with LTC

2 Freiheit 1 20//26.667//33.33/37.33 138 – 13.09Y/7.56 with LTC

3 Sheriff’s Posse 1 20//26.667//33.33/37.33 138 – 13.09Y/7.56 with LTC

Hortontown

(Optional Unit) 1 20//26.667//33.33/37.33 138 – 13.09Y/7.56 with LTC

Delivery dates shall be as per table below (Including Final Site Assembly and Testing). However, ultimate final delivery date will be based on stated lead time from the date the Purchase Order is issued. If this timeframe is not achievable, Vendor may propose an alternate delivery date. However, the bids will be evaluated as such and may be the cause of rejection of bid upon evaluation. An earlier delivery than the below-specified schedule may be considered during bid evaluation. Vendor shall propose a delivery date in Appendix A.

Delivery Coordinates and Addresses:

FM 3009 Substation Google Maps Coordinates:

[Pending Final Address]

Freiheit Substation Google Maps Coordinates:

29.70612, -98.08317

1451 FM 1101

New Braunfels, TX 78130

Sheriff’s Posse Substation Google Maps Coordinates:

29°39’52.9”N 98°09’46.8”W 29.664699, -98.162990

3955 IH 35 S

New Braunfels, TX 78132

Delivery Dates Table

Station Delivery Date

FM 3009 2/1/2029 +/- 30 days

Freiheit 11/20/2028 +/- 30 days

Sheriff’s Posse 12/1/2029 +/- 30 days

Hortontown (Optional Unit) ASAP

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Hortontown Substation Google Maps Coordinates:

29.712854, -98.098345 1242 Industrial St.

New Braunfels, TX 78130

Delivery Contact:

New Braunfels Utilities Jeff Morriss 830.608.8881 jmorriss@nbutexas.com and New Braunfels Utilities Michael Najera 830.660.0660 mnajera@nbutexas.com

2.01 NBU may choose to buy any number of transformers from any one bidder or buy one transformer each from different bidders or any other combination thereof. The bids shall reflect pricing as such. NBU may choose to buy any number of transformers, up to the amount of transformers noted in the specification.

3.00 USE:

This equipment is to be used for three phase, 60 Hz voltage conversion in an outdoor distribution substation in the Central – South Texas area.

4.00 APPLICABLE STANDARDS:

4.01 Industry Standards

Each of the following specific standards or the latest revision thereof shall become a part of this specification as well as any standard or part thereof referred to therein.

4.01.01 American National Standards Institute (ANSI) CGA V-1 – Standard for Compressed Gas

Cylinder-Valve Outlet and Inlet Connections

4.01.02 ANSI C29.9 – Wet Process Porcelain Insulators – Apparatus, Post Type

4.01.03 ANSI C57.12.00 – General Requirements for Distribution, Power, and Regulating Transformers

4.01.04 ANSI C57.12.10 – Requirements for Transformers 230,000 Volts and below, 833/958 through 8333/10,417kVA, Single Phase, and 759/862 through 60,000/80,000/100,000 kVA, Three Phase

4.01.05 ANSI C57.12.36 – Requirements for Liquid Immersed Distribution Substation Power Transformers

4.01.06 ANSI C57.12.70 (2000) - Terminal Markings and Connections for Distribution and Power Transformers

4.01.07 ANSI C57.12.80 – Terminology for Power and Distribution Transformers mailto:jmorriss@nbutexas.com mailto:mnajera@nbutexas.com

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4.01.08 ANSI C57.12.90 – Test Code for Distribution, Power, and Regulating Transformers

4.01.09 ANSI C57.13 – Requirements for Instrument Transformers

4.01.10 ANSI C57.19.00 – General Requirements and Test Procedure for Outdoor Power Apparatus Bushings

4.01.11 ANSI C57.19.01 – Standard Performance Characteristics and Dimensions for Outdoor Apparatus ` 1Bushings

4.01.12 ANSI C57.92 – Guide for Loading Oil Immersed Distribution and Power Transformers

4.01.13 ANSI C57.98 – IEEE Guide for Transformer Impulse Test

4.01.14 ANSI C57.106 – Guide for Acceptance and Maintenance of Insulating Oil in Equipment

4.01.15 ANSI C57.148 – IEEE Standard for Control Cabinets for Power Transformers

4.01.16 ANSI C62.11 – Standard for Metal-Oxide Surge Arresters for Alternating Current Power Circuits

4.01.17 ANSI C62.22 – Standard Guide for the application of Metal-Oxide Surge Arresters for Alternating-Current Systems

4.01.18 IEEE 4 – IEEE Standard for High-Voltage Testing Techniques

4.01.19 IEEE 80 – Guide for Safety in Substation Grounding

4.01.20 IEEE C2 – National Electric Safety Code (NESC)

4.01.21 NEMA TR-1 – Transformers, Regulators and Reactors

4.01.22 NEMA 250 – Enclosures for Electrical Equipment

4.01.23 NEMA CC1 – Electric Power Connectors for Substations

4.01.24 NEMA ICS2 – Standards for Industrial Control Devices, Controllers and Assemblies

4.01.25 NFPA 70 – National Electric Code (NEC)

4.01.26 ASTM A153-95 – Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products

4.01.27 ASTM D877 – Di-electric Breakdown Voltage of Insulating Liquids Using Disk Electrodes

4.01.28 ASTM D923 – Sampling Electrical Insulating Liquids

4.01.29 ASTM D1816 – Di-electric Breakdown Voltage of Insulating Oils of Petroleum Origin using VDE Electrodes

4.01.30 ASTM D3487 – Mineral Insulating Oil Used in Electrical Apparatus

5.00 GENERAL:

5.01 Design

5.01.01 The requirements specifically stated herein shall govern should there be any conflict with the above standards or the references therein.

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5.02 Service Conditions

The transformer shall be suitable for operation at its rated kVA for the usual temperature and altitude service conditions as defined in ANSI C57.12.00 and as stated below.

Elevation: <3300 feet above Mean Sea Level

Maximum Ambient Design Temperature: 40 °C

Minimum Ambient Design Temperature: -20 °C

Seismic Rating: As per geological and geographical location of New Braunfels, TX

Service: Continuous

5.03 Losses

5.03.01 The design shall be for the most economical loss ratio (conductor loss/core loss).

5.03.02 The guaranteed maximum losses will be used in an economic evaluation of the

Manufacturer's proposal. The criteria for evaluation may be found in Section 12.00.

5.04 Rating

Specific ratings will be found in Section 6.00 of this specification. The following general conditions apply.

5.04.01 The transformer shall be rated at 55°C average winding temperature rise and use thermally upgraded insulation that is capable of operating continuously at a 65°C temperature rise. The transformer nameplate shall indicate all capacity ratings.

5.04.02 The kVA capability of transformer at a 65°C rise shall be 112% of the 55°C rise rating.

The transformer shall be rated for full capacity in reverse power flow conditions.

5.05 Loading

Transformer shall be capable of emergency overload conditions per ANSI C57.92. The appurtenances such as bushings, bushing leads and load tap changer shall not limit this overload capacity. It is understood that there will be some loss of life associated with this overload condition. That loss of life should be approximated using ANSI C57.92.

5.06 Short Circuit Strength

5.06.01 The transformer shall meet or exceed the requirements in Section 7 of ANSI

C57.12.00, Short-Circuit Characteristics, limited to two seconds.

5.06.02 The Manufacturer shall also show evidence that their design will meet or exceed the requirements stated in 5.06.01 by either:

(1) Submitting certified test reports covering two fully offset shorts per phase at rated voltage with the short circuit current limited only by the transformer impedance on a prototype unit, or

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(2) Submitting data and drawings showing that the successful short circuit strength design has been accomplished.

The transformer shall be self-protecting without the aid of external impedance from a through fault standpoint. These design criteria shall apply to all transformer windings.

5.06.03 The audible sound level of the transformer shall not exceed the average sound levels specified in Table O-2 of NEMA Standard TR1-1993 or latest revision.

6.00 RATINGS:

6.01 Voltage Rating

The specific voltage ratings for transformers covered by this specification are to be provided according to Table 6.1.

6.02 Capacity Rating

6.02.01 The capacity ratings for transformers included in this specification are to be provided according to Table 6.1.

TABLE 6.1 - POWER TRANSFORMER RATINGS

Item H X Xo

1, 2 and 3

Voltage (kV) 138 Delta 13.09Y /7.56

Winding BIL (kVp) 550 150 150

Bushing BIL (kVp) 650 150 150

CTs One (per phase)

Top 600:5 Relaying N/A

600:5 Relaying

Middle Top 600:5 Relaying 1000/2000:5 Metering

Middle Bottom

2000:5 Relaying 2000:5 Relaying

Bottom 2000:5 Relaying 2000:5 Relaying

Arresters, MCOV (kV) 88 8.4

ONAN/ONAF/ONAF

(MVA) at 55/65 C rise 20 / 22.4 / 26.667 / 29.867 / 33.333 / 37.333

Design Impedance at 20

MVA

Standard as per IEEE / ANSI Standards

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Notes to Table 6.1:

1. Relaying Current Transformers shall be Multi-Ratio, C800 accuracy class. All CTs, Relaying or Metering, shall have a minimum TRF of 2.0 at all taps unless specified otherwise.

2. Dual Ratio Metering Current Transformers shall be 0.3B – 1.8 accuracy class with a minimum TRF of 2.0 for 1000:5 tap and a minimum TRF of 2.0 for 2000:5 tap.

3. NBU’s auxiliary voltages shall be 120/240 VAC, 3 wire, single phase and 125 VDC, unless otherwise Specified.

6.03 Bushing Current Transformers

6.03.01 All relaying current transformers shall be multi-ratio (five tap) and the proper ratio of the bushing current transformers corresponding to each voltage and capacity shall be provided according to Table 6.1, of this specification.

6.03.02 The bushing current transformers required shall be internal to the tank and shall meet the requirements of Section 7.13 of this specification.

6.04 Basic Impulse Level (BIL) Rating

6.04.01 The BIL corresponding to each voltage rating included in this specification shall be as specified in Table 6.1.

6.04.02 The BIL for the Neutral lead and bushing for shall be the same as that for the respective phase windings and bushings for that transformer.

6.05 Surge Arrester Ratings

6.05.01 The following Station class Metal-oxide gapless surge arresters have been approved for use on NBU’s 60 Hz, three-phase electric transmission and distribution system:

TABLE 6.2 SURGE ARRESTERS

System Voltage (kVrms)

Manufacturer Duty Rating

(kVrms)

MCOV

(kVrms) Type

ABB

GE

Hubbell

EXLIM-Q / XPS

TRANQUELL

EVP / MVN

13.09

ABB

GE

Hubbell

8.4 8.4 8.4

EXLIM-Q / XPS

TRANQUELL

EVP / VL

(1) The Station class arrester pressure relief capability shall be 65 kA RMS (symm.) minimum.

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(2) The surge arresters shall be provided with an Anderson TLS-42 connector for grounding purposes. No substitutions permitted on the ground connector.

6.05.02 Ratings of surge arrester corresponding to each voltage rating included in this specification shall be as specified in Table 6.2.

6.06 Additional Tap Voltages

6.06.01 De-energized Tap Changer

(1) The High Voltage windings of all transformers shall have a full capacity De-energized Tap Changer unless otherwise specified. This shall be provided according to Section

7.11 of this specification.

(2) The tap changer shall have two (2) 2 1/2% steps above and two (2) 2 1/2% steps below nominal rated voltage. It should have positive indication of position without requiring use of tools to read tap position.

(3) The tap changer shall be capable of carrying the full transformer short circuit current without damage or contact separation.

6.06.02 Load Tap Changer (LTC)

(1) The Low Voltage windings of all transformers shall have a Reinhausen RMV-II Load Tap Changer unless otherwise specified. This shall be provided according to Section

7.12 of this specification.

(2) The LTC shall have sixteen (16) 5/8% taps above and sixteen (16) 5/8% taps below nominal rated voltage.

(3) LTC shall be full capacity rated at all taps below Nominal voltage.

7.00 CONSTRUCTION:

The transformer shall be constructed with the following features:

7.01 Bushings

The insulation class of the bushings required shall be as specified in Section 6.04 and Table 6.1.

7.01.01 The electrical and dimensional characteristics of apparatus bushings shall be as specified for the appropriate insulation class in ANSI C76.1 and C76.2.

7.01.02 Bushings shall be cover mounted and located as specified in Figure 7.1.

7.01.03 Each bushing shall be provided with a stud connector having a NEMA 4” x 4” four hole cadmium, silver or tin plated pad.

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7.01.04 A neutral bushing shall be furnished for all Wye connected three-phase windings for connecting to the neutral of the windings.

7.01.05 All bushings shall be ANSI Sky Gray #70 colored.

7.01.06 All bushings of the same voltage class provided on the same order shall be electrically and mechanically identical.

FIGURE 7.1 BUSHING LAYOUT

7.01.07 All bushings shall be manufactured by ABB type “O Plus Dry” and have C1 and C2 test taps. C1 power factor shall not exceed 0.5% and the C2 power factor shall not exceed 1%. Test results shall be recorded as referenced in specification item 9.01.01 paragraph m.

Bushings shall be: LV Bushings – 25kV Class 3000A HV Bushings – 138kV Class 800A

7.01.08 The minimum phase-to-phase spacing of any two bushings shall not be less than 24", unless approved by NBU.

7.01.09 Transformer pad dimensions shall not exceed 15’6’ (W) X 12’ (D). Overall transformer assembled dimensions shall not exceed 21’ (W) X 19’ (D).

7.02 Liquid-Level Indicator

A magnetic liquid-level indicator shall be readable while standing at the base level, and shall be manufactured by Qualitrol.

7.02.01 The indicator shall have a dark face dial with light colored markings and a light colored indicating hand.

7.02.02 The diameter of the dial (inside bezel) shall not be less than:

(D)

(W)

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(1) 3 1/4", when the center of the indicator dial is 96" or less above the base.

(2) 5 1/2", when the center of the indicator dial is more than 96" above the bottom of the base.

7.02.03 Dial markings shall show the 25 °C level and the "Hi-Lo" levels.

7.02.04 The words "liquid level" shall be on the dial or on a suitable nameplate adjacent to it.

7.02.05 The 25 °C liquid level shall be indicated by suitable permanent markings on the tank or by indicating the distance from the liquid level to the highest point of the hand-hole or manhole flange surfaces on the nameplate.

7.02.06 The change in liquid level per 10 °C change in temperature shall be indicated on the nameplate.

7.02.07 Liquid level indicators mounted above 96” from Transformer base shall have their dial face tilted downwards for ease of viewing, unless specified otherwise.

7.02.08 Alarm contacts shall be available for one ‘HI’ and two ‘LOW’ oil levels – Low and

Critically low.

7.02.09 Alarm Contacts

(1) Non-grounded Form ‘C’ alarm contacts which are suitable for interrupting, at 250V DC, a maximum of the following currents shall be provided:

(a) 0.02 amperes direct-current inductive load.

(b) 0.20 amperes direct-current non-inductive load.

(2) These alarm contacts and any additional or spare contacts shall be brought out as individual alarms and terminated in the control cabinet on a properly labeled terminal block (with description) for alarms. See section 7.06.09 and 7.06.10 herein.

(3) The terminal block shall meet the requirements of Section 7.06.13 herein.

(4) The wiring for the alarm contacts shall meet the requirements of Section 7.18, Auxiliary Wiring, herein.

7.03 Thermometer (Top-Oil)

A bulb-type thermometer for indicating the top liquid temperature shall be mounted in a thermometer well as shown in ANSI C57.12.00, Figure 3. Thermometer shall be manufactured by Qualitrol.

7.03.01 The indicator shall be remote mounted at eye level height. All capillary tubing shall be protected from mechanical damage.

7.03.02 The thermometer shall have a dark face dial with light colored markings, a light colored indicating hand, and an orange-red maximum indicating hand with provisions for resetting.

7.03.03 The diameters of the dial (inside bezel) shall be 3 ½” minimum.

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7.03.04 Switch settings shall be visible and accessible for adjustment from the bezel face after removal of the cover glass. The indicator shall be ambient temperature compensated and have a 2% accuracy over the dial range.

7.03.05 The dial markings shall cover a minimum range of 0 degrees Centigrade to 160 degrees Centigrade with a minimum of 5 degrees Centigrade graduations.

7.03.06 The words "liquid temperature" shall be on a suitable nameplate mounted adjacent to the thermometer.

7.03.07 Non-grounded alarm contacts shall be provided per Section 7.02.09 of this specification.

7.03.08 Words identifying the function of the indicator shall be on a suitable nameplate, mounted adjacent to the indicator.

7.03.09 Gauge capillary shall be protected with a continuous Stainless Steel armor.

7.04 Sudden Pressure Relay

7.04.01 A Qualitrol Sudden Pressure relay shall be furnished to detect the occurrence of a fault in the transformer which produces an abnormal rise of pressure.

7.04.02 This relay shall consist of a pressure tight containing a bellows operated micro-switch, an equalizer and a test plug.

7.04.03 A Qualitrol seal-in relay shall be provided. The voltage rating of the seal-in relay shall be 125 VDC. Sudden (fault) pressure relay circuits will be powered with 125 VDC from customer’s lockout relay circuit. Non-grounded alarm contacts shall be provided per Section 7.02.09 of this specification. The reset button or switch and seal-in relay shall be mounted in the control cabinet and properly labeled. An overcurrent automatic-trip manual reset circuit breaker shall be furnished for protecting each seal-in relay circuit.

7.04.04 A disconnecting valve shall also be supplied for ease of removing the Sudden Pressure

Relay for maintenance, with the relay mounted no higher than 5 feet above the base of the transformer and the electrical connector plug oriented toward the ground.

7.05 Auxiliary Cooling Equipment

7.05.01 Devices for automatic control of single or double-stage cooling equipment shall be provided with the following:

(1)

(a) Thermally operated control device with thermal element mounted in a well (as described in ANSI C57.12.00).

(b) The device shall be responsive to winding temperature of the transformer and responsive to the current derived in phase.

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(c) The current transformer to furnish this current is to be in addition to those required in Section 6.03.02 herein and shall be shown along with its ratio on the main transformer nameplate.

(d) There shall be an ammeter test jack with a switchblade in the secondary circuit of this current transformer designed to accommodate a Superior test plug, Cat.

No. 3614 or equivalent. This test jack shall be located in the main control cabinet for calibration and testing and shall be clearly labeled. If the above mentioned test jack cannot be provided, the manufacturer may, after NBU’s approval, provide an alternate test jack. The manufacturer shall also furnish the test plug suitable for the alternate test jack.

(e) The calibration resistor, if present, shall be located adjacent to the test jack and properly labeled.

(f) The device shall include a temperature indicator mounted remotely on the side of the transformer at eye level. Device capillary shall be protected with a continuous Stainless Steel armor.

(g) Words identifying the function of the indicator shall be on a suitable nameplate, mounted adjacent to the indicator.

(h) The instruction books shall define a procedure for field calibration of the thermometer giving test curves on points.

(2) The device shall have four sets of contacts as follows:

Contact Function

(a) Supply power to the first bank of cooling either directly or by control of an auxiliary relay. This same contact should also supply power to the second bank of cooling either directly or by control of an auxiliary relay.

(b) Supply power to the second bank of cooling either directly or by control of an auxiliary relay. This contact should be provided however need to be left as a spare.

(c) Two sets of contacts to initiate an alarm or actuate a relay with non-grounded contacts provided per Section 7.02.09 of this specification.

(3) A switch for automatic and manual control of both cooling banks shall be located in the control cabinet. The switch is to control both stages of cooling simultaneously.

Stage one and two cooling shall become powered when winding temperatures reach the threshold for the first stage of cooling.

(4) An electronic loss of voltage relay (or relays) shall be incorporated in the wiring to indicate loss of power to both fan stages and fan control circuit, have a thirty-second time delay before contact closure to eliminate false indication and shall have non-grounded alarm contacts per Section 7.02.09 herein.

(5) Automatic-trip manual-reset circuit breakers shall be furnished for each bank of cooling equipment and fan control circuit in the control cabinet.

(6) Automatic-trip manual-reset circuit breaker shall be furnished for each individual fan motor.

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7.05.02 The following shall apply to cooling fans and fan motors:

(1) All fan blades shall have OSHA type side and rear guards enclosing them for personnel safety. The fans shall also have front guards to prevent birds and other animals from entering the fan housing.

(2) All fan motors shall have sealed permanently lubricated ball bearings. Fans must be rated for continuous operation.

(3) Fans shall be manufactured by Krenz Vent.

(4) All connections to fan motors shall be watertight and weatherproof plug and receptacle connections.

(5) Fan motors shall be TENV with automatic reset thermal protectors, and connectors shall be oriented downward.

(6) Fans shall be mounted to the side of the radiators. Cooling fans shall not be mounted directly on the radiators but on a removable support structure adequately supported from the main tank.

(7) Fan wiring shall be neatly routed around the fan to fan receptacles with proper wire management. The use of plastic tie-wraps is not acceptable.

7.06 Controls Cabinet

The control cabinet shall be furnished as follows:

7.06.01 There shall be only one controls cabinet to which NBU's wiring is to be connected.

7.06.02 The cabinet shall be weatherproof NEMA Type 4 with suitable breather and drain kits.

7.06.03 The door(s) of the cabinet shall swing in the horizontal plane, have a 3 point latch mechanism and provisions for padlocking.

7.06.04 The door shall have a device for keeping it open during operation at the cabinet by a workman.

7.06.05 The door shall have a compartment for holding the Instruction Manual and one set of drawings.

7.06.06 The cabinet shall be at a convenient working height from the base of the transformer.

Cabinet door hinges shall be Stainless steel.

7.06.07 The cabinet shall contain the following:

(1) Terminals for all NBU provided sources such as AC and DC power and LTC sensing voltage.

(2) Shorting type terminal blocks for all current transformer leads. Terminal blocks shall be labeled with CT identification. See figure 7.2 for the typical alarm and shorting type terminal block layout.

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(3) All alarm terminals brought to terminal blocks and labeled.

(4) Sudden-pressure relay reset switch.

(5) Cooling equipment selector switches.

FIGURE 7.2 ALARM AND SHORTING TERMINAL BLOCK LAYOUT (TYPICAL)

(6) Terminals for connecting NBU’s wires (from NBU-furnished type ‘a’ contact from NBU’s 52 device) for interrupting automatic control action of LTC for loss of load (see Section 7.12.07 (12) of this specification).

(7) Automatic-tap-changer control equipment which shall be panel mounted and capable of being removed without disturbing the current shorting switch for the compensator circuit.

(8) A 130 V, 100 W incandescent light or equivalent with a door switch, and a 120 V GFCI duplex receptacle, both protected by automatic-trip manual-reset circuit breakers. A second 120 V standard duplex receptacle shall also be furnished on a separate circuit protected by an automatic-trip manual-reset circuit breaker.

(9) Thermostatically controlled heater, protected by an automatic-trip manual-reset circuit breaker, for control of humidity. The thermostat shall be set to cut-off when temperature rises above 90 °F.

(10) All other accessories called for in this specification which are to be located in the Controls cabinet.

7.06.08 Alarms and Annunciation

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(1) All wiring specified shall be in accordance with Section 7.18.

(2) NBU requires, at a minimum, the following alarms to be wired to the terminal blocks and the annunciator(s), if applicable.

• Transformer sudden pressure

• LTC sudden pressure

• Winding temperature (110°C)

• Winding temperature (100°C)

• Liquid Temperature (95°C)

• Liquid Temperature (85°C)

• Main tank critical low oil level

• Main tank low oil level

• LTC tank critical low oil level

• LTC tank low oil level

• Main tank pressure relief

• LTC tank pressure relief

• Main tank Nitrogen pressure high/low

• Nitrogen System low bottle pressure

• Cooling system loss of AC power

• LTC control loss of AC power

• LTC motor loss of AC power

• LTC voltage backup module

• LTC vacuum bottle failure

• Dehydrating Breather

7.06.09 Transformer Communications and Control

(1) The manufacturer shall provide and install terminal blocks in the main control cabinet to facilitate remote control and indication with NBU’s SCADA system.

(2) The manufacturer shall provide wiring using copper alarm cables from the following devices to the terminal blocks:

a. Transformer alarm outputs (All alarms described above in Section 7.06.08.

b. LTC remote control

c. LTC and transformer accessory lock out provisions connected as remote controls

(3) Terminal blocks shall be wired to all outputs of the annunciator panels, if applicable.

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(4) Sufficient quantity of terminal blocks are to be provided so that all available annunciator and control points are connected, including 10% spares.

7.06.10 The bottom of the cabinet shall consist of a bolt-in removable gasketed steel plate a minimum of 270 square inches in area and of a gauge similar to that of the main cabinet material. The plate shall be of such dimension that NBU can remove and cut sufficient number and size of conduit holes for the connection of NBU's wiring.

7.06.11 All terminals and equipment shall be legibly and indelibly identified. Factory wiring will contain both location and destination labels for both ends of the wire.

7.06.12 All connecting terminal blocks shall be similar to General Electric type EB-25.

7.06.13 All current transformer leads shall be individually terminated onto a short-circuiting terminal block equivalent to General Electric type EB-27.

7.06.14 There shall be no manufacturer connection on the side of the terminal blocks allocated for NBU’s connections. All NBU’s connections need to be labeled by manufacturer with the correct device label.

7.06.15 The cabinet shall have a grounding connector for safety grounding.

7.06.16 All terminal blocks for NBU's connections shall be accessible to NBU's control cable entering the bottom of the cabinet without overlapping other control components in the cabinet.

7.06.17 All wiring shall be bundled or contained and shall meet the requirements of Section

7.18 of this specification.

7.06.18 All Controls wiring installed by the Transformer manufacturer shall not be smaller than 14 AWG.

7.07 Oil

Oil for insulating and cooling the transformer shall be provided in steel drums by the Manufacturer for all transformers according to the following. Oil required for topping off after installation at the final destination shall be included.

7.07.01 General:

The oil furnished under this specification shall be Type II Mineral Oil as described in ASTM D3487 (Latest Revision).

The oil furnished under this specification shall meet the characteristics stated in the aforementioned industry standards or the references therein.

The requirements specifically stated within this specification shall govern should there be any conflicts with the above standards or the references therein.

7.07.02 Characteristics:

The physical properties of the insulating oil as received shall meet the requirements set forth in Table 7.1.

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7.07.03 Oil Inspections and Tests:

The Manufacturer shall perform a chemical analysis and submit a certified chemist's report to NBU on the contents of each refinery storage tank used for filling each truck to show that the requirements of the characteristics chart above have been met or exceeded.

Oil Transport truck

Oil shipments made in transport trucks shall meet the following requirements unless otherwise approved by NBU.

(a) The tanks, including the lower valves and piping, shall be thoroughly cleaned, dried, and flushed with oil before filling for shipment.

(b) The oil shall not be placed in the tanks if there is any moisture contamination in the tank, valves, and/or piping.

(c) A dry nitrogen (10 ppm H2O max) positive pressure blanket shall be placed above the oil in the tanks.

(d) Oil shall be shipped in dedicated tankers capable of pressuring off oil with dry nitrogen. Only oil shipped in this manner will be accepted when shipped in Oil tankers.

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TABLE 7.1 INSULATING OIL CHARACTERISTICS

Characteristic Value Related Standard

Aniline point 63-78oC ASTM D611

Color 0.5, max ASTM D1500

Chlorides and Sulfates None ASTM D878

Corrosive Sulfur Noncorrosive ASTM D1275B

Dielectric Breakdown Voltage @ 0.10 in @ 1 mm @ 2 mm

30 kV min 28 kV min 56 kV min

ASTM D877

ASTM D1816

ASTM D1816

Dielectric Breakdown Voltage, Impulse Conditions

145 kV, minimum ASTM D3300

Flash Point 145oC, min ASTM D92

Furanic Compounds 25 µG/L max ASTM D5837

Gassing Tendency at 80°C (µL/min) +30 max ASTM D2300B

Interfacial Tension at 25°C (dynes/cm) 40 min ASTM D971

Moisture Content 25 ppm max ASTM D1533

Neutralization Number 0.03 mg KOH/g of Oil, max ASTM D974

Oxidation Inhibitor (% by weight) 0.3% ASTM D2668

Oxidation Stability (rotating bomb test) 195 minutes, minimum ASTM D2112

Polychlorinated Biphenyl Not Detectable ASTM D4059

Pour Point -40oC max ASTM D97

Power Factor

0.05 max @ 25 oC

0.3 max @ 100oC

ASTM D924

Saturation Concentration 60 ppm H2O @ 25oC, max

Specific Gravity 0.91 @ 15oC/15oC, max ASTM D1298

Viscosity (SSU/cSt) 36/3 @ 100oC, max 62/11 @ 40oC, max 350/76 @ 0oC, max

ASTM D88/D445

Visual Examination Clear and Bright ASTM D1524

Weight 7.5 lb/gal

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7.08 Oil Preservation Systems

7.08.01 The Manufacturer shall supply an inert gas pressure system in accordance with ANSI C57.12.10, C57.12.30, and C57.12.80. Conservator or expansion tank systems are allowable on EHV transformers only.

7.08.02 The inert gas pressure system is one in which the interior of the transformer (by means of a positive pressure of inert gas maintained from a separate inert gas source and reducing valve system) is sealed from the atmosphere throughout a top-oil temperature range of 100 °C, and the internal pressure does not exceed 8 psi gauge.

(1) The inert gas shall be dry nitrogen with less than 0.5 percent by volume of impurities and less than 0.03 percent by weight of moisture.

(2) The nitrogen shall be supplied in 200 cubic foot cylinders equipped with connection No. 580 of ANSI B57.1, a minimum working pressure of 2,015 psi, and the appropriate transfer of NBU ship documentation for refilling. Cylinders shall conform to regulations of the United States Department of Transportation (DOT) and Texas Department of Transportation (TxDOT) and appropriately marked as such.

(3) The nitrogen bottle shall be in a weatherproof cabinet at base level.

(4) The gauges shall monitor, display and regulate the gas pressure of the transformer tank and monitor and display the gas pressure of the nitrogen bottle.

(5) All transformers shall have a provision for sampling tank gas. This provision shall consist of a valve and fitting designed to accommodate one-quarter inch I.D. "Tygon"-type tubing. This shall be located inside the nitrogen bottle cabinet. The gas sample location on the transformer tank shall be valved and shall be located at an opposite end of the tank from the gas filling location. All rigid gas tubing shall be Stainless Steel.

(6) Non-grounded alarm contact shall be provided per Section 7.02.09 herein for detection of Main tank low and high gas pressure and low Nitrogen bottle pressure.

7.09 Pressure Relief Device

A pressure relief device shall be located on the main tank cover and on each oil filled compartment isolated from the main tank. Electric alarm contact and mechanical target operation of the device are both required.

7.09.01 Non-grounded electrical alarm contact shall be provided according to Section 7.02.09 of this specification. The contact leads shall be terminated in the control cabinet.

7.09.02 The mechanical target shall be capable of being viewed from ground level.

7.09.03 Pressure relief device shall be manufactured by Qualitrol and sited in accordance with manufacturer's recommendations for the transformer ratings.

7.10 Tanks

7.10.01 Design

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(1) The main transformer tank and any attached compartment that is subjected to operating pressures shall be designed to withstand, without permanent deformation, pressure 25 percent greater than the maximum operating pressures resulting from the system of oil preservation used.

(2) The maximum operating pressures (above and below standard atmospheric pressure) that the transformer tank is designed to withstand shall be indicated on the nameplate.

(3) Tanks shall be designed for vacuum filling (essentially full vacuum) in the field.

Auxiliary compartments, when not designed for vacuum filling, shall be so designated and valves shall be provided to isolate them from the main tank. Specific instructions concerning vacuum procedures shall be defined in the instruction manual.

(4) Main cover shall be of welded construction with a single-pitch slope design for positive water drainage. A 1-1/2" NPT coupling shall be welded at each corner on the top cover for installation of a temporary rope/pipe safety fence during maintenance on the transformer, with additional provisions provided for personnel tie-off points for maintenance access.

(5) CT and core junction boxes and similar top-mounted appurtenances shall be designed to prevent water penetration.

Note: All plugs in this specification shall have external heads. No Allen-head fittings are allowed. Also, cast type plugs are not acceptable.

(6) One or more manholes shall be provided in the cover:

(a) Removable bolted covers with gaskets shall be provided.

(b) The manhole covers should be flat with a minimum diameter of 18 inches.

(c) Covers weighing more than 45 pounds shall be hinged and removable.

(d) All covers shall have handles.

(7) All joints for tank and manhole covers, bushings, and other bolted covers shall be gasketed. These joints shall be designed so gaskets will not be exposed to the weather, and shall be provided with mechanical stops to prevent crushing. Gaskets shall be recessed and machine grooved. One set of spare gaskets shall be provided with each unit.

(8) Tank shall not have corner welds. All Tank welds shall be continuous, both inside and outside.

(9) Use of Plastic tie-wraps to secure or support wires, tubes or components at Transformer exterior is not acceptable.

(10) Any tubing more than 6” in length shall be adequately supported at regular intervals.

This criteria also applies to Conduits, gauge probes, capillaries and Nitrogen tubing.

(11) All external hardware shall be Stainless Steel.

(12) Any auxiliary compartments, such as reactor pockets or others, shall have welded top covers. Bolted covers on such compartments are not acceptable.

7.10.02 Grounding

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Grounding for the transformer should be accomplished through the use of a grounding halo. Grounding halo shown on typical drawing in Figure 7.3 shall consist of 2” x ¼” copper busbar. Grounding halo consisting of looped conductor is not acceptable. A grounding halo as shown on the typical drawing should be installed on both back and front of the transformer. Additionally, two copper busbars shall be run from front to back of transformer to connect both front and back halos. They shall be run on the side wall.

(1) Tank Ground Pads

A NEMA 2-hole or 6-hole threaded copper faced steel pad shall be welded to the tank in each of the following locations (see Figure 7.3):

(a) Adjacent to the Xo bushing on top of tank (one 2-hole pad).

(b) Six inches up from the bottom on left and right corners, on both high voltage and low voltage sides of the transformer (four 6-hole Type-N pads).

(c) Approximately one-third of the vertical distance from the pads mounted on the lower left and lower right corners of the transformer to the top of the transformer, on both high voltage and low voltage sides of the transformer (four 2-hole pads).

(d) Approximately two-thirds of the vertical distance from the pads mounted on the lower left and lower right corners of the transformer to the top of the transformer, on both high voltage and low voltage sides of the transformer (four 2-hole pads).

(e) Thread protection for these ground pads during shipment shall consist of a flanged cup of a non-corrosive material suitable for press fitting into threaded openings.

(2) Neutral Bushing Grounding

(a) The X0 bushing shall have a stud to NEMA 4-hole pad copper connector.

(b) A suitably sized Copper cable with enough slack shall be furnished from the Xo terminal to the adjacent tank ground pad.

(c) A suitably sized copper bar, separate from Ground Halo Copper bus-bars, shall be installed from the tank ground pad of 7.10.02(1)(a) to the pad of 7.10.02(1)(b).

The bus bar shall have suitable supports to tank.

(3) Surge Arrester Grounding

The surge arresters furnished on the transformer shall be grounded to all four tank ground pads listed in 7.10.02 (1)(b) above through the ground halo copper bus bars with suitable supports on tank for all bars.

(4) Core Ground

(a) The location of core ground(s) shall be indicated on the outline drawing.

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(b) Transformers shall have the core ground(s) terminate through the tank wall by means of a suitably rated porcelain bushing for proper core insulation. Each core shall have a separate ground and bushing (main, series, reactor, etc.).

(c) The bushing(s) shall be housed in a weather resistant protective metal housing.

(d) The ground bushing terminal(s) shall be connected by Copper cable with enough slack to an adjacent dedicated ground pad, dedicated to that bushing, welded to the transformer tank wall. The cable or strap shall be easily removable for core ground resistance testing. These grounding pads shall have a continuous electrical connection to the transformer grounding pads listed in 7.10.02(1)(b) through the ground halo with adequate supports to the tank.

(5) NBU shall connect tank ground pads to substation ground grid to complete adequate transformer grounding protection. Two holes shall be maintained on the tank ground pads of 7.10.02 (1) (b) and (c) for NBU's use.

FIGURE 7.3 TRANSFORMER TANK GROUNDING PADS AND HALO (TYPICAL)

COPPER BUS BAR HALO

2-HOLE NEMA PAD

6-HOLE NEMA PAD

TRANSFORMER CASE

GROUND TO GROUNDING GRID

CONNECTION FOR HALO TO

GROUNDING GRID.

CONNECTION FOR HALO TO

GROUNDING GRID.

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7.10.03 Drain and Filter Valves

(1) A combination drain and lower filter valve of the globe type shall be provided.

(2) This valve shall provide for complete drainage of the liquid and for outlet to oil filtering means.

(3) The size of the drain valve should be 2-inches and it should have 2-inch female NPT threads with a brass plug in the open end.

(4) The drain valve shall NOT have a built-in sampling port device between the main valve seat and the pipe plug. NBU uses custom port/device.

(5) An upper filter valve of the globe type, located in the same segment of the drain valve, should be located below the 25 degrees Centigrade liquid level, suitable for the return of filtered oil.

(6) The size of the upper filter valve shall be 2-inch and shall have 2-inch female NPT threads with a brass plug in the open end.

7.10.04 Lifting Facilities

(1) Means for lifting the complete transformer by overhead crane shall be provided. No accessories shall be installed that would interfere with rigging used to lift transformer.

(2) The bearing surfaces of the lifting means shall be free from sharp edges. Facilities for guying the transformer during transport shall be provided.

(3) Lifting means shall be provided for removing the lid and untanking the transformer.

7.10.05 Moving Facilities

(1) The base shall permit rolling or sliding in the directions of both centerlines of the transformer and attachment holes in base structure shall be provided for pulling the transformer in these directions.

The base shall be so designed that the center of gravity of the transformer, as normally prepared for shipment, shall not fall outside the base support members for a tilt of base of 15 degrees from the horizontal, with or without oil in the transformer.

(2) The transformer center of gravity for (a) shipment and (b) fully assembled transformer (including oil) shall be permanently marked and labeled on all four tank walls. Adhesive stickers used for this purpose are not acceptable.

7.10.06 Jacking Facilities

(1) Jacking facilities shall be located near the corners of the base.

(2) The jack ports or lugs shall be so designed that the jack can be inserted.

(3) Dimensions and clearances for jacking provisions shall be as shown below in Figure 7.4.

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FIGURE 7.4 JACKING PROVISIONS

7.10.07 Paint Requirements

(1) All metal surfaces shall be cleaned before applying primer.

(2) Two coats of primer shall be applied to all exposed metal surfaces using application methods recommended by paint Manufacturer.

(3) A minimum of two top coats shall be applied to all exterior primed surfaces using application methods recommended by paint Manufacturer.

(4) The top coat shall be ANSI No. 70, Sky Gray, Munsell #5.OBC7.0/0.04.

(5) The topcoat thickness shall be at least 3 mils at all points.

(a) The transformer tank top after application of the coating paint shall be skid resistant and its color shall match the rest of the tank.

(b) All top surfaces of the tank shall be skid resistant coated, including tank, manhole covers, CT and core junction boxes, bushing flanges and any other metal extension or attachment which protrudes from the tank top surface.

(6) The interior of the tank shall be painted white with a paint that is not affected by the transformer oil.

(7) Transformer base shall be coated with Coal Tar or an equivalent compound.

(8) A suitable warning label shall be affixed to the hatch covers listing appropriate procedures and precautions to be followed when removing the covers.

(9) Two 1-pint Aerosol spray touch-up paint cans of each color shall be supplied with the transformer.

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7.10.08 Radiators

(1) The transformers shall be equipped with unpainted, fully hot dipped galvanized steel, removable radiators. All radiators on the transformer must be interchangeable.

(2) Clearances shall be large enough to permit painting and maintenance of tank, tubes, and radiators.

(3) Radiators and coolers shall be designed to withstand the same maximum and minimum pressures required of the main tank.

(4) Removable radiators and coolers shall be fastened to transformer case with bolted gasketed flange connectors. Bolted flange connectors must not bear any weight of the Radiator assembly.

(5) Ball valves shall be provided to permit the ready installation and removal of radiators and drainage of oil from radiators without drawing oil from transformer tank.

Verification of valve shutoff capability shall be documented to NBU in final test reports that are submitted.

(6) There shall be no external valve levers or stops constructed of plastic or aluminum material.

(7) Radiators and coolers shall be equipped with lifting eyes, and so designed that they may be handled without the addition of special bracing.

(8) The top and bottom of each radiator assembly shall have a vent and drain coupling and plug. The coupling is to be American Pipe Standard with ¾” or 1” tapered plug.

(9) Cooling fans shall not be mounted directly on the radiators but on a removable support structure adequately supported from the main tank.

7.11 De-energized Tap Changer and Switches

7.11.01 High Voltage windings shall have a tap changer for de-energized operation with an operating handle located on the side of the tank at a height convenient for operation from the base level. (No more than 6 feet above ground level.)

7.11.02 Ratings for the de-energized tap changer shall meet the requirements of Section 6 of this specification.

7.11.03 The tap changer handle should have provisions for padlocking, consisting of a 3/8-inch minimum diameter hole, and shall provide visible indication of the tap position without unlocking or requiring use of tools to remove DETC cover. For a given winding, the number 1 or the letter A shall be assigned to tap having the greatest number of effective turns. All tap changer and series-parallel switch handle shall be clearly labeled near their mounting on the main tank with their own nameplate. This nameplate shall also have information on which winding they cater to, all tap and switch positions with corresponding voltages.

7.11.04 When more than one (1) de-energized mechanisms are required, the mechanisms shall be gang operated. All de-energized tap changing shall be accomplished by use of One (1) handle only.

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7.12 Load-Tap Changing Equipment (LTC)

7.12.01 Design

The load-tap changing equipment shall be a Reinhausen RMV-II LTC and shall include a motor-driven mechanism, a SEL-2414 LTC control and Beckwith M-2025D, or equivalent Current Loop Interface. The LTC shall regulate the secondary (low voltage) side of the transformer.

7.12.02 Rating

LTC ratings are per Section 6.00 of this specification.

7.12.03 Vacuum Interrupter

The Reinhausen vacuum interrupter-type LTC shall consist of the following:

(1) The vacuum interrupter shall consist of a stationary and moving contact enclosed in a vacuum tight bottle.

(2) An extension of the operating rod shall serve as an external wear indicator for the electrical contacts.

(3) The vacuum interrupter contact life shall be the same as the service life of the transformer.

7.12.04 N/A

7.12.05 Load Tap Changer Compartment

(1) The interrupting mechanism shall be housed in a compartment separate from the main transformer tank. Oil in the interrupting compartment shall be completely separated from oil in the transformer tank.

(2) Hinged covers shall be provided for access to the load tap changing compartment without opening the main tank or lowering the liquid in the main tank. Covers weighing more than 45 pounds shall be hinged and removable. Covers weighing 45 pounds or less shall have handles.

(3) A globe type drain valve shall be located in the bottom of each oil-filled compartment to provide complete oil drainage. The compartment shall have a sump or lip on the bottom to prevent oil from spilling out when the cover is opened. The size of the drain valve shall be 1-inch NPT (National Pipe Threads) female threads and a brass plug in the open end. The drain valve shall have a built-in sampling device which shall be located on the side of the valve between the main valve seal and the pipe plug.

The device shall be supplied with a 5/16-inch, 32 threads per inch, male connector equipped with a cap. A 1-inch filling plug with a brass plug shall be located in the top of each oil-filled compartment.

(4) A magnetic liquid-level gauge, as described in Section 7.02 of this specification, with a vertical face shall be mounted on the side of oil-filled LTC compartment.

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(5) A pressure-relief device, as described in Section 7.09 of this specification, shall be installed on the LTC compartment.

(6) A Qualitrol sudden…