345KV Autotransformer Spec(08.29.2012)

7/28/2019 345KV Autotransformer Spec(08.29.2012)

1/56

TECHNICAL SPECIFICATION FOR

LCRA

345/138/13.2 kV

477; 672; 800 MVA

THREE WINDING

AUTOTRANSFORMERS

1


2/56

TECHNICAL SPECIFICATIONS TABLE OF CONTENTS

4.14 GENERAL

4.16 PERFORMANCE

4.16.1 Loading

4.16.2 Nominal Voltage

4.16.3 Taps

4.16.4 Dielectric Insulation Levels

4.16.5 Vector Relations

4.16.6 Transformer Impedance

4.16.7 Sound Level

4.16.8 Losses

4.16.9 Short Circuit Requirements

4.16.10 Auxiliary Power

4.17 ACCESSORIES

4.17.1 Bushings

4.17.2 Bushing Current Transformers (BCT)

4.17.3 De-energized Tap Changer

4.17.4 Load Tap Changing Equipment

4.17.5 Surge Arresters

4.18 CONSTRUCTION

4.18.1 Windings and Core

4.18.2 Tank

4.18.3 Grounding

4.18.4 Wiring and Controls

4.18.5 Control Cabinet

2


3/56

4.18.6 Radiators and Cooling Equipment

4.18.7 Autotransformer Nameplate

4.18.8 Oil Preservation

4.18.9 Oil

4.18.10 Indicating Devices

4.19 CONTRACTOR DATA

4.20 TESTS

4.21 SHIPPING

4.22 SCHEDULES, DRAWINGS, MANUALS, and FACTORY VISITS

3


4/56

4.14 GENERAL:

This Technical Specification describes the requirements for one (1) three phase, outdoor, oil-immersed, three winding, 60 Hz, 345/138/13.2 kV, 477; 672; and 800 MVA EHVautotransformers for installation at LCRA TSCs designated Substation (s).

The autotransformer covered by this specification shall be designed, built, and tested inaccordance with the latest applicable ANSI, NEMA, IEEE and EEI standards and shall include alladditional features required by this specification.

4.16 PERFORMANCE REQUIREMENTS:

Autotransformer shall be 3 phase, three winding, 60 Hz, with ONAN/ONAF/ONAF cooling. Theautotransformer will be used as a system tie autotransformer designed to operate in either a step upor step down mode, but will primarily be used for step-down operation. Contractor shall followgood engineering and manufacturing practices to produce a transformer, including accessories,which in conjunction with normal maintenance will provide safe and reliable service through a 50-year life under the rigors of service in an electric utility power system.

Contractor shall completely integrate all components into the overall transformer design, includingbut not limited to the LTC, all controller relays, monitoring, indicators, etc. Please note, ratingsbelow are subject to change depending on project/site requirements, ratings shall be confirmedwith LCRA TSC purchasing group and scope documentation.

4.16.1 Loading:477.7 MVA HV to LV: 256/341.3/426.6//477.7 MVA @ 55//65 C rise672 MVA HV to LV: 360/480/600//672 MVA @ 55//65C rise800 MVA HV to LV: 428.6/571.4/714.3//800 MVA @ 55//65 C rise

477.7 MVA HV to TV: 68.5/91.3/114.1//70 MVA @ 55//65 C rise (Minimum)672 MVA HV to TV: 65/86.7/108.3//121 MVA @ 55//65 C rise (Minimum)800 MVA HV to TV: 65/86.7/108.3//121 MVA @ 55//65 C rise (Minimum)

477.7 MVA LV to TV: 37.5/50/62.5//70 MVA@ 55//65 C rise (Minimum)672 MVA LV to TV: 37.5/50/62.5//121 MVA@ 55//65 C rise (Minimum)800 MVA LV to TV: 37.5/50/62.5//121 MVA@ 55//65 C rise (Minimum)

3 PHASE CONTINUOUS FULL LOAD RATING (477.7 MVA)

Class ONAN ONAF ONAF Temp Rise oC

Voltage Winding MVA

345,000/199,200

GRD WYEH

256 341.3 426.6 55

286.6 382.2 477.7 65

138,000/79,670GRD WYE

X256 341.3 426.6 55

286.6 382.2 477.7 65

13,200Delta

Y37.5 50 62.5 55

42 56 70 65

3 PHASE CONTINUOUS FULL LOAD RATING (672 MVA)


Voltage Winding MVA

345,000/199,20 H 360 480 600 55

4


5/56

0GRD WYE

403.2 537.6 672 65

138,000/79,670GRD WYE

X360 480 600 55

403.2 537.6 672 65

13,200Delta

Y65 86.7 108.3 55

72.6 96.8 121 65

3 PHASE CONTINUOUS FULL LOAD RATING (800 MVA)


Voltage Winding MVA345,000/199,20

0GRD WYE

H428.6 571.4 714.3 55

480 640 800 65

138,000/79,670GRD WYE

X428.6 571.4 714.3 55

480 640 800 65

13,200Delta

Y65 86.7 108.3 55

72.6 96.8 121 65

4.16.1.1 Approximately 1000 KVA of station service load will be installed on theautotransformer tertiary. An additional 60 MVA of reactive compensation,

either reactive or capacitive, may be installed in the future. Theautotransformer shall be capable of simultaneous three winding operationprovided that the MVA rating of any particular set of terminals is notexceeded and that the current in the common winding does not exceed the 65degree C rise, ONAN/ONAF/ONAF ratings. (Common winding currentequals rated LV current minus Series Winding current at highest voltage tapconnection).

4.16.1.2 Autotransformer overload capability shall be 110% of maximum forcedcooled rating for a period of four (4) continuous hours without increased lossof life. Components such as bushings, tap changers, winding leads, oil

expansion capacity, gasketing, stray flux heating, etc. shall not be the limitingfactors in the autotransformers capability to meet overloads. This designoverload capability will be at an average ambient temperature of 30C duringoverload and an average ambient temperature during the 24-hour period notexceeding 40C. This design overload capability will be based on atransformer loading condition of 90% of the maximum forced cooled ratingduring the 24 hour period surrounding the overload.

4.16.1.3 The autotransformer shall be capable of operating above rated voltage asspecified by IEEE C57.12.

4.16.1.4 The Contractor shall supply information to help LCRA TSC determineloading capacity and loss of life for the autotransformer. A minimumrequirement for this information is as defined in the IEEE C57.115 standard,section 2.6.1. Top-oil temperature rise over ambient temperature2. Bottom-oil temperature rise over ambient temperature3. Average conductor temperature rise over ambient temperature4. Hottest-spot conductor temperature rise over ambient temperature5. Load loss at rated load6. No load loss7. Confirmation of oil flow design

5


6/56

Any other information regarding ratings for bushings, tap changer, connectors and leads,gaskets, oil pressure build up, etc. that would constitute a limiting factor element forconsideration in loading and loss of life calculations.

4.16.2 Nominal Voltage:

Series Winding Voltage (HV): 345 kV Grd Wye/199.2 kVCommon Winding Voltage (LV): 138 kV Grd Wye/79.67 kVTertiary Winding Voltage (TV): 13.2 kV Delta

4.16.3 Taps:

De-Energized or No Load Tap Changer (DETC/NLTC): 345 kV +/- 5% in 2.5% stepswith the LTC in Neutral position. The DETC shall be on the high voltage end of theseries winding. (See Section 4.17.3)

Load Tap Changer (LTC): Common End of Series Winding: LTC +/- 10%. Sixteen 5/8%steps above and Sixteen 5/8% steps below neutral position. (See section 4.17.4)

Common Winding (LV): No Taps Required

Tertiary Winding (TV): No Taps Required

4.16.4 Dielectric Insulation Levels:

Autotransformer shall be designed to withstand the following impulse levels based onIEEE C57.12 Table 5.

345 kv 138 kV 15 kV NeutralBIL (kV Crest) 1050 650 150 150Chopped Wave Level(kV Crest)

1155 715 165 ----

BSL (kV Crest) 870 540 ----- ----Induced Voltage TestOne Hour level (kV, rms)

315 125 ----- ----

Induced Voltage TestEnhanced Level (kV, rms)

360 145 ----- ----

Applied Voltage Test level(kV, rms)

50 50 50 50

See Test section for required tests.

4.16.5 Vector Relations:

Standard vector relationships shall be used.

4.16.6 Transformer Impedance

Impedance shall be as designated on the Purchasers Purchase Order Release.

6


7/56

Tertiary shall be completely self protected. Tertiary impedance shall be designed so themaximum allowable fault on the tertiary does not exceed 750 MVA based on the 345kVand 138kV busses being infinite.

If internal reactors are used to limit tertiary short circuit currents, those reactors shall bedesigned and constructed by the autotransformer contractor using the same highstandards as the main windings. Data shall be submitted by the contractor to verify theshort circuit capability of the reactor design.

4.16.7 Sound Level:

Autotransformer sound level shall not exceed 77dB for Oil Natural Air Natural (ONAN)rating and 80dB for maximum forced cooling rating as measured by procedures inNEMA TR1 for standard average audible sound levels.

4.16.8 Losses:

Autotransformer proposals will be evaluated based on total owning costs, including thecost of losses. The following costs will be used to evaluate losses:

No-Load: $3,020/KWLoad Loss: $1,225/KWAux. Loss: $810/KW

Guaranteed no-load and load losses shall be at rated voltage and Oil Natural Air Natural(ONAN) loading and at the 1 raise LTC position, or at the 0 LTC position whichever hasthe highest no-load losses. Guaranteed auxiliary losses shall be at maximum forcedcooled rating.

Factory tests that yield losses exceeding those guaranteed in the Proposal shall result in acredit to LCRA TSC. The credit will amount to the differences (no-load and load lossesonly) between the tested and guaranteed losses times the appropriate loss cost. Auxiliarylosses will not be used in the credit calculations. No price adjustment will be given to theContractor for losses less than those guaranteed.

The Contractor shall submit with their proposal, the percentage maximum totalmeasurement error for the no load loss measurement and the load loss measurementsystems. The errors must contain all components of the error including probablecalibration errors and other uncertainties in the measurement system. The data shall betraceable to the United States National Institute of Standards and Technology andcalculated per Section 8 of NBS Technical Note 1204. A system check to insure that allerrors have been properly applied may be required. Failure to submit a loss measurementsystem error or the submission of an error that is obviously erroneous will result in the

rejection of the proposal. The maximum loss measurement error that is acceptable is + 3percent as per IEEE C57.12.00-1993. Loss measurement errors greater than + 3 percentwill result in the rejection of the Contractors proposal.

4.16.9 Short Circuit Requirements:

The autotransformer shall be capable of withstanding the maximum current andassociated mechanical and thermal stresses produced by external short circuits under theconditions specified in IEEE C57.12.00 Section 12.

7


8/56

The autotransformer shall meet or exceed the requirements of IEEE C57.12.00, Section7, Short Circuit Characteristics, limited to two seconds.

The Contractor shall also show evidence that the design will meet or exceed therequirements stated by either:

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

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

The autotransformer shall be self-protecting without the aid of external impedance froma through fault standpoint. This design criteria shall apply to primary, secondary, andtertiary windings.

4.16.10 Auxiliary Power:

4.16.10.1 A 120/240 volt, 4-wire delta power supply will be provided to handle boththree-phase and single-phase loads. Fans shall operate at 240 volts, eithersingle or three-phase. Lights shall operate at 120 volts single phase. Heatersshall operate at 240 volts single-phase. Available fault current in controlcabinet may reach 20,000 amps.

4.16.10.2 Instrumentation shall be operated at 125 volts DC which will be supplied byLCRA TSC.

4.16.10.3 The LCRA TSC shall provide the necessary station service power foroperating the load tap changer and auxiliary cooling equipment.

4.16.10.4 The Contractor shall state all three-phase and single-phase kVA requirementsin the proposal form.

4.16.10.5 The AC neutral shall be electrically isolated from the equipment ground.Incoming AC terminals shall be large enough to accommodate up to andincluding 2/0 AWG copper conductors. Incoming terminals shall be providedfor single phase and three phase, 240 volt with separate neutral and groundconductor.

4.17 ACCESSORIES:

4.17.1 Bushings:

ABB, PCORE or LCRA TSC approved equivalent ratings that are required:

477.7 MVA kV BIL(kV) Supplier Cat. # - ABB or PCORE

High Voltage (345kV): 362 1300/1050 (Ext./Int.) ABB #362W2000UZ or PCORE Equivalent

Low Voltage ( 138 kV): 138 650 PCORE #POC650G3000CMS or LCRA TSC approved ABBEquivalent

Tertiary Voltage (13.2 25 150 ABB #025V0600WJ or

8


9/56

kV): LCRA TSC approved PCOREEquivalent

Neutral: HoXo 25 150 ABB #025W3000BF orLCRA TSC approved PCOREEquivalent

672 MVA kV BIL(kV) Supplier Cat. # - ABB or PCORE

High Voltage (345kV): 362 1300/1050 (Ext./Int.) ABB #362W2000UZ or

LCRA TSC approved PCOREEquivalent

Low Voltage ( 138 kV): 138 650 PCORE #POC650G3000CMS or LCRA TSC approved ABBEquivalent

Tertiary Voltage (13.2kV):

25 150 ABB #025V0600WJ or LCRA TSC approved PCOREEquivalent

Neutral: HoXo 25 150 ABB #025W3000BF orLCRA TSC approved PCOREEquivalent

800 MVA kV BIL(kV) Supplier Cat. # - ABB or PCORE

High Voltage (345kV): 362 1300/1050 (Ext./Int.) ABB #T345Z2000BD or LCRATSC approved PCORE Equivalent

Low Voltage ( 138 kV): 138 650 ABB #T138W4000UU or LCRATSC approved PCORE Equivalent

Tertiary Voltage (13.2kV):

25 150 ABB #025V0600WJ or LCRA TSCapproved PCORE Equivalent

Neutral: HoXo 25 150 ABB #025W3000BF or LCRATSC approved PCORE Equivalent

Ampere requirement based on autotransformer over-loading:

4.17.1.1 Bushings shall be furnished in accordance with IEEE C57.19 and C57.19.01.

4.17.1.2 Bushings shall be mounted in a location symmetrical with the centerline ofthe autotransformer tank. The H2 and X2 bushings shall be in line with thecenterline of the autotransformer base. Tertiary bushings shall be located withall three bushings in a straight line.

4.17.1.3 Minimum bushing spacing shall be as follows:

MINIMUM BUSHINGSPACING FOR

AUTOTRANSFORMERSNominal Operating Voltage

345kV 138 kV 15 kV

Minimum centerline-to-centerlinedimension

(At top of bushing)

128 62 24

9


10/56


11/56

Two (2) 10000:5 amp SR C800 RF 1.0and

One (1) 5000:5 amp SR C800 RF 1.5HoXo: Two (2) per Bushing 1200:5 amp MR C800 RF=1.5Delta Winding: One (1) per phase 3000:5 amp SR C800 RF1.5800 MVA:H: Four (4) per Bushing 3000:5 amp MR C800 RF=2.0X: Four (4) per Bushing 4000:5 amp MR C800 RF=2.0Y: Three (3) per Bushing

Two (2) 10000:5 amp SR C800 RF 1.0and

One (1) 5000:5 amp SR C800 RF 1.5HoXo: Two (2) per Bushing 1200:5 amp MR C800 RF=2.0Delta Winding: One (1) per phase 3000:5 amp SR C800 RF2.0

4.17.2.1 All current transformers (CTs) shall have fully distributed windings.

4.17.2.2 Relay accuracy bushing current transformers shall be multi-ratio, with ANSIstandard ratio taps, as per the latest revision of ANSI C57.13.

4.17.2.3 Each current transformer shall be mounted and wired in the appropriatebushing well.

4.17.2.4 All leads from each current transformer shall be terminated on short circuitingtype terminal blocks, Concentric Devices type 30CT04 or LCRA TSCapproved equivalent, in the control cabinet. Size 10 AWG, 600V insulationshall be used for CT wiring to terminal blocks. All CT leads shall begrounded in the control cabinet.

4.17.3 De-energized Tap Changer:

De-energized tap gauge indication shall read 1-5. Tap 1 to indicate high, tap 3 to indicateneutral, and tap 5 to indicate low. DETC shall be a Reinhausen or LCRA TSC approvedequivalent. DETCs shall comply with the requirements of Category 2 DETCs, asspecified in IEEE Std. C57.131-2012, Standard Requirements for Tap Changers. EachDETC containing insulation that depends on oil impregnation of any material besubjected, as a routine test, to a partial discharge test with voltage levels, time durationsand PD limits as prescribed in C57.131.

De-Energized Tap Voltages(with LTC in Neutral-Position)

DETCPosition

HVWinding

LVWinding

1362,250 138000

2353,625 138000

3345,000 138000

4336,375 138000

5 138000

11


12/56

327,750

4.17.4 Load Tap Changing Equipment:

The autotransformer and the on load tap changer shall be designed to operate in step upand step down modes. The LTC shall be a Reinhausen vacuum type VM or ABB vacuumtype VUC or LCRA TSC approved equivalent. The primary mode of operation of theautotransformer will be to maintain a constant low side voltage (138 kV nominal). LTCtap windings shall be located on the common end of the series windings. The load-tapchanging equipment shall consist of a low current resistance bridging device; a motor-driven mechanism; and control devices. Designs that allow regulation through the coreare not acceptable. The regulating winding voltage shall be fully distributed.

1) The LTC shall be provided in accordance with IEEE Std. C57.131-2012.2) The LTC shall include a protective circuit that senses when the vacuum bottleoperates when it should not.3) Door swings of any doors on the LTC compartments, including doors to be openedon side mounted LTCs, shall be noted on the outline drawing.

4.17.4.1 The LTC shall provide +/- 10% voltage regulation with sixteen - 5/8% stepsabove and sixteen 5/8% steps below neutral position. The LTC shall be fullcapacity above rated voltage and reduced capacity (constant current) belowrated voltage. Please refer to Figure 1 below for outline of required nameplateexample nomenclature. The highlighted region depicts LCRA TSCs schemeof raising and lowering taps based on secondary voltage.

Figure 1 Nameplate Rating Outline Diagram

12


13/56

LTC control shall be implemented using the raise and lower scheme (16RAISE to 16 LOWER). LCRA TSC controls voltage levels based solely onthe transformer secondary. (See 4.17.4.12 for additional info). Figure 2 belowshows an example of the tap position indicator that conforms to Figure 1. The16 RAISE to 16 LOWER nomenclature shall be used for LTC tap indication.

Figure 2 Tap Position Indicator

4.17.4.2 LTC shall be located in completely separate compartment(s) from the mainautotransformer core and coils, either internal or external to the main tank.Single phase LTC compartments are preferred over three phase. If the LTCcompartment is external to the main tank, the bottom of the interruptingcompartment shall be located approximately three feet above the base of theautotransformer to facilitate maintenance of the LTC without use of laddersor scaffolds. The inside of each LTC compartment shall be painted white toimprove inspection visibility. If an in-tank LTC design is provided, eachLTC mechanism shall have provisions for lifting and removal from the LTCcompartment to facilitate maintenance of the device.

4.17.4.3 Resistance bridging-type LTC shall include the following features:

(1) Transition roller contacts and stationary contacts on the bridging deviceshall have copper tungsten arcing surfaces.

(2) After contact separation the arc between breaking contacts shall beextinguished at the first current zero.

(3) The resistance bridging contact life shall be the same as the service lifeof the autotransformer.

4.17.4.4 Contacts, switches, and all other components of the LTC mechanism shall becapable of continuously carrying the required current at any tap voltage.

13


14/56

4.17.4.5 Current transformers for LTC shall be sized and provided by themanufacturer.

4.17.4.6 The LTC automatic control unit shall be a Beckwith M-2001B or LCRA TSCapproved equivalent. Mode of communication required is DNP.

4.17.4.7 The LTC paralleling control relay shall be a Beckwith M-0115A or LCRATSC approved equivalent.

4.17.4.8 An excessive circulating current lockout relay shall be provided to stopoperation of the load ratio control motor before circulating current reaches anunsafe value. The relay is to lockout the automatic operation only andprovides a contact for lockout alarm. The relay shall be Beckwith M-0127Aor LCRA TSC approved equivalent low burden, sensitive AC current relay.

4.17.4.9 An Under/Over voltage relay shall be provided to lockout the tap changer onunder/over voltage conditions. It shall be a Beckwith M-0329B or LCRATSC approved equivalent. The relay shall lock out the automatic operationonly and provide a contact for lockout alarm. The factory preset fixed deadband shall be one (1) volt.

4.17.4.10 The LTC shall have manual, automatic, and remote control capability viaLCRA TSC supervisory equipment. The Contractor shall provide one manual,Raise-Off-Lower selector switch for local operation of the LTC. TheContractor shall also provide one manual Remote-Local selector switch toselect between local or supervisory control of the LTC. In the Remoteposition, LCRA TSC will provide dry contact inputs from supervisoryinterface panels to raise or lower the LTC tap position. In the Local mode,the LTC tap position will be controlled from the LTC automatic control unit.A raise command shall cause the secondary voltage to increase and causethe tap indication to move towards 16 RAISE. A lower command shall

cause the secondary voltage to decrease and cause the tap indication to movetowards 16 LOWER.

4.17.4.11 The Contractor shall provide a ventilated weatherproof cabinet with hingeddoors. The doors shall provide access to the control devices and haveprovisions for padlocking. All cabinet and door hardware shall be non-ruststainless steel. The LTC manual controls shall be located on the same side ofthe autotransformer as the tap position indicator. A hand crank or hand wheelfor manual operation of the driving mechanism shall be provided. If a handcrank or spoke type of hand wheel is provided, it shall be electricallyinterlocked to prevent operation by the motor when the crank or spoke type

hand wheel is removed from its storage position. If the hand crank or handwheel is detachable, a storage place shall be provided.

4.17.4.12 The LTC shall have a tap position indicator with maximum/minimum draghands, resettable from ground level. The tap position indicator will be labeledfrom 16 LOWER to 16 RAISE with tap position N denotative of theneutral position. A raise command will result in the tap indication moving inthe RAISE direction.

14


15/56

4.17.4.13 The LTC shall provide tap position indication to both the main LTCcontroller and LCRA TSC supervisory. A Beckwith M-2025 or LCRA TSCapproved equivalent shall be provided for tap position indication into the M-2001B main LTC controller and LCRA TSC supervisory. Three separatesignals, a 0-1mA signal, a 4-20mA signal, and a resistive network, shall beprovided and wired to Contractor terminal blocks for LCRA TSC supervisoryindication.

4.17.4.14 A mechanical operations counter shall be provided and shall be accessiblefrom ground level.

4.17.4.15 A separate nameplate shall be provided for and mounted on the LTCmechanism. The nameplate shall include the following minimum data inaddition to the IEEE C57.131 specified items:

Model number of mechanismType of drive mechanismRatio of any series transformerLTC manufacturer nameModel number of MechanismYear of ManufactureMaximum rated through current of mechanismBIL RatingOil Volume in mechanism compartmentType of transition impedance (resistor)Method of Arc interruptionType of drive mechanism

4.17.4.16 The Contractor shall provide one (1) sudden pressure sensing unit mountedon each LTC compartment. The unit shall be equipped with test plugs tosimulate a sudden pressure rise, so that the unit can be tested periodically.Circuitry from this device shall be provided to a seal-in relay. This seal-inrelay, reset button, indicating light, and 63X trip and alarm contacts shall bemounted in the main control cabinet. Indicating light shall indicate SPR -LTC (Sudden Pressure Relay - LTC) trip and shall remain lit until the suddenpressure relay has been manually reset. All circuitry and relays associatedwith the sudden pressure relay scheme for the LTC shall be independent fromthe sudden pressure relay scheme for the main tank. The sudden pressuresensing unit shall be a Qualitrol Series 910 or LCRA TSC approvedequivalent Rapid Pressure Rise Relay. The seal-in relay shall be a QualitrolSeries 909 or LCRA TSC approved equivalent Seal-In Relay. Trip contactsshall be identified on the drawings and wired out to terminal blocks forLCRA TSC use. Alarm contacts shall be provided in accordance with Section

4.18.5.13, with one set wired to a terminal block for LCRA TSC use andanother set wired to the annunciator, Terminal block points shall be providedfor LCRA TSC to supply 125volts DC exclusively to the LTC SPR seal-inrelay.

4.17.4.17 The tap changer ratings shall exceed all operating conditions at 110% asdescribed in section 4.16.1.2. However, varistors may be used to provideadded voltage protection during transient conditions.

15


16/56

4.17.4.18 A separate annunciator alarm shall be provided to indicate when thetemperature of the oil in the LTC compartment is 3 degrees Celsius or greaterthan the oil temperature in the main tank at the corresponding level. Thetemperature differential monitor device shall be a Barrington ConsultantsModel TDM System 3, Transformer Temperature Differential Monitor.

4.17.4.19 The LTC Motor shall be 120/240 volt, single phase, 60 Hz. It shall beaccessible and replaceable from the control cabinet. The motor shall beequipped with over current protection of 10 amps with a manual reset. Notransformer shall be required between the motor and its power source.

4.17.4.20 Mechanically operated electric limit switches and mechanical stops shall beprovided on the drive mechanism to prevent over travel beyond the maximumraise and lower positions.

4.17.4.21 An over current automatic-trip air circuit breaker with manual reset forcontrol of the power circuit at the motor drive shall be provided.

4.17.4.22 An over current automatic-trip air circuit breaker with manual reset forcontrol of the potential circuit to the automatic control devices shall beprovided.

4.17.4.23 The Contractor shall provide one (1) automatic pressure relief device, whichcan be reset manually mounted on each LTC compartment. Circuitry fromthis device shall be routed to the main control cabinet where alarm contactsand a local trip flag shall be provided. The automatic pressure relief deviceshall be a Qualitrol Series 208 Pressure Relief Device.

4.17.4.24 The Contractor shall provide one (1) magnetic liquid level gauge with lowliquid level alarm contacts for the LTC. The contacts set by the Contractor toalarm when the oil level drops below normal operating level. The liquid levelgauge shall have a six (6) inch dial. The magnetic liquid level gauge shall be aQualitrol Series 032 Magnetic Liquid Level Gauge.

4.17.4.25 The Contractor shall supply trip contacts for LCRA TSCs use per LTCmanufacturers recommendations, and shall clearly label their purpose.

4.17.5 Surge Arresters:

Surge Arrestors shall be provided by the Contractor for all terminals

4.17.5.1 The autotransformer shall be provided with metal oxide station class surge

arresters. The housing for all surge arresters shall be porcelain. Surge arrestersshall be 5.0BG 7.0/0.4.light gray in accordance with Munsell.

4.17.5.2 Acceptable arresters and their ratings are as follows: (Ohio Brass or LCRATSC approved equivalent)

Arrester Ratings

Terminals Brand MCOV (kV) Duty (kV)

16


17/56

H1, H2, H3 Ohio Brass 220 276

X1, X2, X3 Ohio Brass 88 108

Y1, Y2, Y3 Ohio Brass 15.3 18

4.17.5.3 The Contractor shall provide rigid mounting for the arresters in accordancewith Section 4.18.2.8. The Contractor shall minimize the distance between thesurge arrester and the bushing.

4.17.5.4 The Contractor shall provide a surge arrester ground pad for each arrester inaccordance with ANSI/IEEE C57.12.10-1988, section 5.5.1. The groundingpad shall be mounted on the side of the tank as close as possible to thearrester.

4.17.5.5 All surge arresters shall be manufactured and tested in accordance withANSI/IEEE C62.11-2005.

4.17.5.6 All surge arresters shall be designed with a pressure relief rating of 65kA,rms, symmetrical.

4.17.5.7 All surge arresters shall be provided with a NEMA 4" x 4", 4-hole terminalbronze or tin plated bronze pad.

4.18 CONSTRUCTION:

4.18.1 Windings and Core:4.18.1.1 Copper or silver bearing copper conductor is required for all winding, leads,

and other current carrying parts. Contractor shall state winding material intheir proposal.

4.18.1.2 All windings for Core and Coil type construction, (cross-sections), shall beround. This includes internal current limiting reactors, if used. Please notethat tertiary shall be brought out on all MVA classes.

Joints are permissible at locations external to the windings, specifically atcrossovers between layers or disks. A joint is defined in this context as thephysical joining of two or more separate winding conductors by means ofwelding, brazing, soldering or crimping. Internal joints, i.e., joints madewithin the body of the winding layer or winding disk, are not permissibleunless the joint involves a single strand of a multiple (at least five) strandconductor.

Design of conductor joints and connections shall limit circulating currents andoverheating such that abnormal aging or deterioration does not occur whenthe apparatus is operated within the scope of service conditions specified.

Contractor shall have an effective quality assurance procedure for verifyingthat conductors are free from defects in joints and that conductor burr, nicksor indentations, dimensional tolerances and mechanical strength are withinacceptable limits for the application.

17


18/56

Design shall have the following preferred maximum dielectric stresses in thehigh-low space(s):1) 15.0 kV/mm (380 kV/in) during full wave impulse2) 2.6 kV/mm (66.0 kV/in) during normal operating voltageExceeding these levels is allowed but shall be discussed during the designreview.

Internal arrester elements shall not be used to protect any part of thewindings.

4.18.1.3 A core ground connection shall be brought out of the autotransformer tankthrough an appropriate device so that core ground readings may be takenwithout having to remove a manhole cover. The core ground bushing shall beclearly labeled on the autotransformer and shall be shown on the outlinedrawing. Each separate core shall have a separate core bushing and groundconnection. Core ground bushings shall be housed in a weatherproof metalhousing. Magnetic cores shall be directly grounded without any impedanceor fuse-like elements connected in series. A warning plate shall be providednear this bushing stating, Core Ground Must Always Be Connected WhenEquipment Is Energized.

4.18.1.4 All material used or proposed for use in the autotransformer shall be testedand shall have passed the autotransformer oil compatibility test using themethod outlined in ASTM D3455. All material used in the autotransformershall be subject to rigid quality assurance and control standards. TheContractor shall have complete traceability on all material from receivinguntil final installation in the autotransformer. Material quality assurancereports shall be made available upon request.

4.18.1.5 The maximum allowable burrs on the slit or cut edge of the electrical steelused in the core shall not exceed 0.7 mils. Excessive edge or surface damageduring manufacture may result in rejection of the core.

4.18.1.6 The Contractor shall design the core such that the maximum flux magnitudein the core at nominal operating voltage will not exceed 1.7 Tesla.

4.18.1.7 The maximum temperature within the core at nominal operating voltage shallnot exceed 125 deg. C at 30 deg. C ambient and 130 deg. C for the conditionof highest core over-excitation, full load and 40 deg. C ambient.

4.18.1.8 Coil winding insulation shall be Dennison paper for the entire length andthickness of all windings and leads.

4.18.1.9 Leads and lead supports shall be designed for all dielectric, mechanical, andthermal effects that could be encountered. The design shall not permitpermanent deflection of supports and leads due to forces acting on the leadduring transport or service.

Tap leads and series or parallel crossover leads and supports shall be designedto provide significant safety margins above the worst case dielectric stressesthat would occur during specified lightning and switching surge and powerfrequency voltages, as though these voltages were applied at each tap

18


19/56

position. Similarly, line leads shall be designed to provide reasonable safetymargins during these conditions.

Direct permanent connections shall be used between the series and commonwindings of autotransformers, rather than using the low voltage bushing as acollection point for these leads.

Wooden members used for core, coil or lead supports shall be free from knotsand other defects.

4.18.2 Tank:

See Indicating Devices section for required gauges and monitoring devices attached tothe tank.

4.18.2.1 Main tank cover shall be welded on. Shipping Covers are not acceptable. Abase plate to facilitate installation of fall protection equipment shall be weldedin the center of the main cover as shown in drawings in SpecificationAppendix 1. Fall protection equipment will be supplied by LCRA TSC andwill consist of a detachable tie off pole mounted to the tank cover. The polewill induce certain shear and bending moment forces to the tank cover, not toexceed 3000 psi.

4.18.2.2 A minimum of two manholes with bolted covers shall be provided in the topcover of the autotransformer. Manholes shall be round and shall be aminimum of 20 inches in diameter. Additional manholes and/or hand holesshall be provided as needed for maintenance and testing. Covers weighinggreater than 45 pounds shall be hinged.

4.18.2.3 Tank shall be furnished with 2 NPT, globe type, bottom drain valve withsampling device, and 2" NPT upper filter press valve connections. All valvesshall have a pipe plug in the open end. The drain valve shall have a built-insampling device which shall be located on the side of the valve between themain valve seal and the pipe plug. The sampling device shall be supplied witha 5/16-inch, 32 threads per inch, male connector equipped with a cap.

4.18.2.4 Tank shall be designed for vacuum filling in the field with 3" or 4 NPTconnectors. Tank and conservator shall be designed for full vacuum withoutdeformation.

4.18.2.5 Top of autotransformer tank shall be slightly domed to promote watershedding and shall have a skid-resistant surface.

4.18.2.6 Autotransformer tank shall have two pressure relief devices. Devices shallhave auto reset, visual indication and alarm contacts terminated in controlcabinet.

4.18.2.7 Autotransformer shall be designed for skidding in any direction.4.18.2.8 Brackets for mounting three (3) surge arresters near the high, low, and tertiary

bushings shall be provided. Brackets shall have three 11/16" mounting holes,120 degrees apart, on a 10 inch bolt circle. Arrester brackets shall be spacedsuch that the center of each arrester will be on the same line as the center ofthe top of each bushing, which the arrester is protecting. The supports for

19


20/56

each tertiary voltage arrester shall be extended beyond the arrester mountingplate in such a way as to provide vertical flanges which will be used to attachlow voltage bus support mountings. These flanges shall include four 13/16inch holes on 7 inch bolt circles, with the top pair of holes and the bottom pairof holes on horizontal centerlines respectively. Each flange and support shallbe designed to support rated arrester loading and shall be rigid enough tominimize deflection caused by external conditions and forces.

4.18.2.9 Two (2) arrester ground pads shall be located near the top of the tank for eachset of arresters; HV, LV, and TV. Six (6) pads total at the top for arresterground connections.

4.18.2.10 Autotransformer exterior shall be painted with a primary coat applied over aproperly prepared surface. Finish shall be two coats of ANSI 70 gray paint fora total thickness of not less than 4 mils. Paint will be inspected and tested ondelivery. The top of the autotransformer tank shall have a non-skid surface.The Contractor will be expected to correct any deviation from thesespecifications. All paint and primer shall be lead-free. The autotransformertank top shall be covered with protective silicon coating, room temperaturevulcanizing (RTV) insulation of silicon rubber technology, Product No. 587,as manufactured by MIDSUN Group, Southington, CT, (Phone 1-800-MIDSUN), or LCRA TSC approved equivalent. The coating shall be appliedper paint manufacturers instructions and shall have the followingcharacteristics:

(a) Dielectric strength (ASTM D149), 375 volts/mil.(b) Volume Resistivity (ASTM D257), ohm-cm 3.0x 1015

(c) Dissipation Factor (ASTM D2m7), 100Hz. 100 kHz: .01(d) Dielectric constant (ASTM D150), 100Hz 100kHz: 4.0(e) Shrink factor: Nil(f) Coating shall be adequate to prevent grounding of the low voltage

bushing by snakes, varmints, etc. with a minimum thickness of 30 mils.(g) The autotransformer tank top after application of the RTV coating shall

be skid resistant and its color shall match the rest of the tank.

4.18.2.11 The inside of the autotransformer tank shall be painted white to improveinspection visibility. Provide picture to depict proper coloring in the testreport.

4.18.2.12 The following moving and handling facilities shall be provided:

Lifting eyes for lifting the cover only

Lifting facilities for the complete autotransformer

Lifting facilities for the core and coil Pulling eyes for moving the autotransformer in any direction

Lifting eyes for radiators

Suitable jacking pads on each corner near the base

Smooth base suitable for skidding in any direction

Lifting eyes for conservator, if used

4.18.2.13 All gaskets shall be one piece and made of NITRILE rubber. Other gasketmaterial must be approved by LCRA TSC prior to its application. If one piece

20


21/56

is not available, the gasket shall have a vulcanized scarf joint. Butt splicejoints are not acceptable.

4.18.2.14 A confined space rescue safety plate shall be mounted near each manhole perLCRA TSC drawing UHOIST in Specification Appendix 1. Safetymounting plates shall be welded to the tank cover.

4.18.3 Grounding:

4.18.3.1 Grounding pads shall be provided per IEEE C57.12.10 Section 5.5.

4.18.3.2 A copper neutral bus bar shall be furnished and attached to the side of theautotransformer at a location as close to the neutral (HoXo) bushing aspossible. The bus bar shall be made of 1/2 by 4 copper bar and shall beconnected directly to a four hole pad stud connector on the neutral bushing.The bus bar must be supported approximately every three feet and the bottomof the bus bar shall have a NEMA four hole drilling at 6 inches above thebase of the autotransformer. The bus bar shall be painted the same color as theautotransformer.

4.18.3.3 Tank Ground Pads: A NEMA 2-hole, 4-hole, or 6-hole steel based copper-faced pad shall be welded to the tank in each of the following locations:

a) Adjacent to the Xo or HoXo bushing.b) Six inches up from the bottom on left and right corners when facing low

voltage side.c) Six inches up from tank bottom on left and right corners when facing

high voltage side.

4.18.3.4 Surge Arrester Grounding: The surge arresters furnished on theautotransformer shall be grounded to the surge arrester ground pads listedabove in Section 4.18.2.9. These grounds shall be copper bars with suitablesupports on tank for all bars.

4.18.3.5 LCRA TSC will connect tank ground pads to substation ground grid tocomplete adequate autotransformer grounding protection.

4.18.4 Wiring and Controls:

4.18.4.1 All wiring external to cabinets shall be 600 volt flame resistant, moistureproof wire in rigid galvanized steel (RGS) conduit with all terminals tagged.Crouse Hinds or T&B weatherproof receptacles and plugs shall be furnishedfor flexible connections to fans.

4.18.4.2 All wiring external to cabinets shall be in rigid galvanized steel conduitexcept for local connections to individual fans. Use of tank wall bracing wellsis acceptable in combination with rigid galvanized conduit.

4.18.4.3 All wire terminals shall be crimp type nylon insulated, with ring tongue endsand shall be electro-tin plated copper.

4.18.4.4 All terminals blocks shall be screw type.

21


22/56

4.18.4.5 All control components shall be readily available in the U.S.A.

4.18.5 Control Cabinet:

4.18.5.1 A weatherproof metal control cabinet shall be provided complete with athermostatically controlled heater and shall follow IEEE C57.142-2011 unlessotherwise stated below. Cabinet shall have provisions for termination ofinsulated auxiliary wiring on screw type terminal blocks. Current transformercircuits shall be wired to terminal strips equipped with shorting bars(Concentric Devices 30CT04 or equivalent). All other control wiring shall bewired to #10-32 barrier type terminal strips properly sized to handle the loads(General Electric Type EB-25 or equivalent). All CT wiring shall be No. 10AWG copper wire, 600 Volt insulation, NEC THW rated. All other cabinetwiring shall be a minimum size of No. 12 AWG copper wire, 600 voltinsulation, NEC THW rated, flame resistant. One side of terminal blockssupplied for LCRA TSCs cable connections shall be completely free of theContractors wiring. (Exception is for CT shorting jumpers.)

4.18.5.2 Cabinet shall be accessible from ground level and shall be positioned in a safeand convenient location. A scale drawing of the control cabinet internalphysical layout shall be provided in the drawing set.

4.18.5.3 Control cabinet shall be furnished with an interior light, a door-operated lightswitch, and a 120 volt, 20 amp, duplex receptacle with GFI protection. Lightshall be furnished with a safety shield to prevent accidental breakage.

4.18.5.4 The inside of the control cabinet shall be painted white.

4.18.5.5 Control cabinet shall have a removable blank conduit plate large enough toaccommodate eight (8) 2 conduits located in the bottom center of thecabinet. Cover plate will be field drilled or punched as needed.

4.18.5.6 Control cabinet shall include a metal pocket inside the door for storage of theinstruction manuals and drawings.

4.18.5.7 Stainless steel hardware shall be furnished on all doors and panels for allcabinets or enclosures used on the autotransformer.

4.18.5.8 Cabinet doors shall have a weather seal to prevent driving rain from enteringthe cabinet. Door shall be provided with wind latches.

4.18.5.9 All conduit entrances shall be on the sides or bottom. No conduit shall enterthe top of the control cabinet.

4.18.5.10 All cabinets shall have padlocking provisions.

4.18.5.11 Station Service:(1) The LCRA TSC will provide the necessary station service power for

operating the load tap changer and auxiliary cooling equipment.(2) The voltage available is 120/240 volt, 4-wire delta to handle both three-

phase and single-phase loads. The Contractor shall state the single-phaseand three-phase kVA requirements in the Proposal section of thisspecification.

22


23/56

(3) The AC neutral shall be electrically isolated from the equipment ground.Incoming AC terminals shall be large enough to accommodate up to andincluding 2/0 AWG copper conductors. Incoming terminals shall beprovided for single phase, 240 volt with separate neutral and groundconductor.

(4) Molded case circuit breakers rated for 240VAC/250VDC shall be usedfor all control and auxiliary equipment power. Knife switches or fusesare not allowed.

(5) The cabinet shall have a grounding connector for safety grounding.

4.18.5.12 Annunciators(1) The Contractor shall provide one or more Puleo Type PE103-48-2B

annunciator(s) or LCRA TSC approved equivalent to handle allannunciator points specified.

(2) Wiring shall be provided between the alarm contact terminal blocks andthe annunciator input point module terminals.

(3) The terminals of the annunciators point modules shall be properly andpermanently labeled to indicate the alarm function.

(4) The Contractor shall provide as many annunciators as is necessary tomake available to LCRA TSC all alarm points provided.

(5) Each of the annunciator power supply circuits shall be connected to a125 VDC power supply terminal block. The annunciator power supply(s)will be supplied by a separate LCRA TSC connection from the other 125VDC devices on the autotransformer.

(6) Each of the annunciator's relay module output contact terminals shall beterminated on terminal blocks for LCRA TSC's connections.

(7) Annunciator alarms shall include, but are not limited to, the following:a) Sudden pressure relay operation - Main Tankb) Sudden pressure relay operation - LTCc) High winding temperatured) Combustible gas detector relay operation (Buchholz relay)e) Pressure relief device operation - Main Tankf) Pressure relief device operation - LTCg) High liquid temperatureh) Low oil level - Main tanki) Low oil level - LTCj) AC failure alarm - 120/240 VACk) LTC control relay failure alarml) Combustible Gas-In-Oil alarmm) Cooling Fan Failure - AC Failuren) DC failure alarm 125VDCo) Oil filtration system oil level differential alarmp) Oil filtration system low oil level alarm

q) Oil filtration system pressure differential across filter alarmr) Tap changing incomplete

4.18.5.13 Non-grounded minimum-level alarm contacts shall be provided, suitable forinterrupting, at 250 VDC, a maximum of:

(a) 0.02 amperes direct-current inductive load(b) 0.20 amperes direct-current non-inductive load

23


24/56

These alarm contacts and any additional or spare contacts shall be brought outas individual alarms and terminated in the control cabinet on a properlylabeled (description and whether Normally Open NO, or Normally ClosedNC) terminal block for alarms. The terminal block shall meet therequirements specified herein.

4.18.6 Radiators and Cooling Equipment:

4.18.6.1 All radiators shall be removable and interchangeable and shall be mounteddirectly on the transformer tank. If radiators cannot be interchanged, theymust be labeled and identified in such a way to indicate the proper assemblyposition. Radiator flanges shall be blanked off and sealed with blanking platesand rubber gaskets prior to shipment and radiators filled with dry air.

4.18.6.2 Each radiator bank shall include upper and lower vent and drain plugs anddrain coupling. Coupling shall be APS plug.

4.18.6.3 Top and bottom shut off valves shall be furnished on radiators.

4.18.6.4 All fan motors shall be three-phase delta, 240 volt AC. Fan motors shall betotally enclosed with sealed, permanently lubricated ball bearings and shall beequipped with reset thermal protectors. Replacement fans shall bemanufactured and readily available in the U.S.A.

4.18.6.5 All fans shall have one piece blades and galvanized fan guards that meetapplicable OSHA standards. Fiberglass fan blades are not acceptable. Fanguards shall prevent birds and other small animals from entering the fanhousing.

4.18.6.6 Automatic control for auxiliary cooling actuated from fiber optic recordedwinding temperature shall be Qualitrol/Neoptix, or approved equal, withseparate contacts for high temperature alarm in accordance with Section4.18.10.3.

4.18.6.7 All fans shall have waterproof electrical plugs for easy fan removal.

4.18.6.8 A switch shall be provided for manual operation of the fans overriding thewinding temperature controls. Controls shall be provided for selection ofwhich fan bank leads the other on ONAN/ONAF/ONAF units. Over currentprotection with manual reset shall be provided for each fan bank.

4.18.6.9 All fans shall be capable of automatic operation twice during a 24 hourperiod.

4.18.6.10 A loss of AC voltage relay with 2 N.O. and 2 N.C. contacts shall be providedfor the fan power circuits. This relay shall have an adjustable time delay of upto five (5) minutes. Alarm contacts shall be provided in accordance withSection 4.18.5.13, with one set wired to a terminal block for LCRA TSC useand another set wired to the annunciator.

4.18.7 Autotransformer Nameplate:

4.18.7.1

24


25/56

Information to be included shall be per requirements of Nameplate C of Table 7 ofC57.12.00-2010, plus the following:1) Connection diagrams and ratings of all internal electrical components

including current limiting reactors, series transformers, tap changers, non-linear resistors or protective devices, current transformers, fuses, number andgeneral locations of all intentional core grounds, etc.

2) Ratios and accuracy classifications, type and model or style of all CTs,including hot spot CTs

3) Winding form (cylindrical or shell).

4.18.7.2 The nameplate shall be manufactured of stainless steel. An autotransformer nameplateshall be furnished and attached to the autotransformer tank at a point easily accessiblefrom ground level.

4.18.8 Oil Preservation:

A conservator type oil preservation system with a rubber bladder bag shall be used toexclude air contact with the oil. Bladder shall have proven 20 year plus life expectancy.

The bottom of the expansion tank must be at least 4 above the top of theautotransformer cover and above the highest oil to air gasketed joint. The tank shall beconstructed so that the bag will not block the pipe to the autotransformer at low oillevels. Isolation valves shall be provided between the conservator tank and the main tank.Appropriate bleed valves shall be located on the main tank and conservator for filling theautotransformer. A Buchholz-style gas detector relay shall be located in the pipingbetween the conservator tank and main tank. The Buchholz relay shall be wired to aseparate seal-In relay inside the control cabinet. The gas detector relay shall be aQualitrol Series 038 Gas Detector Relay, or a GE Type GEK-4817 Gas Detector Relay.Non-grounded alarm contacts shall be provided in accordance with Section 7.02.07 ofthis specification.

4.18.9 Oil:

4.18.9.1 Oil shall be furnished in the necessary quantity with 0.3% DBPC, (Type IIoil). Acid refined oil is preferred if available.

4.18.9.2 Any oil used or supplied to fill the autotransformer shall have PCB content ofless than 1part per million. All oil furnished shall be certified as non-PCBand the nameplate shall state that the oil is PCB free.

4.18.9.3 All autotransformer oil shall be in accordance with ANSI/ASTM latest issuestandards for new oil.

The physical properties of the insulating oil as received shall meet the following requirements:

25


26/56

Characteristic Value (Related Standard)

Aniline point 63-78oC (ASTM D611)

Color 0.5, max (ASTM D1500)

Oxidation Stability (rotating bombtest)

195 minutes, min (ASTM D2112)

Chlorides and Sulfates None (ASTM D878)

Corrosive Sulfur Noncorrosive ASTM D1275B)Dielectric Breakdown Voltage 35 kV @ 60 Hz, min (ASTM D877)

Dielectric Breakdown Voltage,Impulse Conditions

145 kV, min (ASTM D3300)

Flash Point 145oC, min (ASTM D92)

Interfacial Tension 40 dyne/cm @ 25oC, min (ASTM D971)

Moisture Content 30 PPM max (ASTM D1533)

Neutralization Number 0.015 mg KOH/g, max (ASTM D664)

Pour Point -40oC max (ASTM D97)

Power Factor 0.01% @ 60 Hz, 100oC, max(ASTM D924)

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

Viscosity 66 SUS @ 40oC, max (ASTM D88)

Saturation Concentration 60 PPM H2O @ 25oC, max

Oxidation Inhibitor 0.3% by mass DBPC (ASTM D1473)

Poly Chlorinated Biphenyl < 1.0 PPM

26


27/56

OIL TEST ANALYSIS

The contractor shall perform an oil analysis and submit a certified test report to LCRA TSC on thecontents of oil used for filling the Autotransformer tank. Tests shall be made both at the time of factoryfilling and at the time of final fill at LCRA TSCs substation site to show that the requirements of thecharacteristic chart above have been met or exceeded.

These test reports shall be submitted to LCRA TSC prior to any oil being placed in the transformer.

If oil properties do not meet or exceed the requirements in the Table listed above, corrective action will betaken at the expense of the contractor of the Autotransformer to bring the properties of the oil to thecorrect specification or drain and change the oil and correct any damage resulting from defective oil.

Proof of passing compliance with all tests listed in the table shall be submitted. Of specific interest is testD1275B for corrosive sulfur. The contractor shall provide D1275B test results on all oil prior to placing itin the transformer.

4.18.10 Indicating Devices:

All alarm contacts from indicating devices, relays, and other monitoring equipment shallbe wired to terminal points inside the control cabinet for LCRA TSCs use. All gaugeswith manual resets shall be mounted in a position accessible from ground level. Allgauges shall be labeled on the dial face of the gauge or have a suitable nameplateattached adjacent to the gauge. Gauges shall have a 6 dial face.

The following equipment is required:

4.18.10.1 Liquid Level Gauge(s), dial type, with alarm contacts. Qualitrol CAS-771-1

or LCRA TSC approved equivalent shall be provided for the main tank andLTC tank. The contacts shall be set by the Contractor to alarm when the oillevel drops below normal operating level. Alarm contacts shall be provided inaccordance with Section 4.18.5.13, with one set wired to a terminal block forLCRA TSC use and another set wired to the annunciator.

4.18.10.2 Two (2) Sudden Pressure Relay (Qualitrol Series 900 or 910 depending onapplication) shall be provided on opposite sides of the main tank. The relayshall be wired to separate Seal-In relays (Qualitrol 909-200-01) located in thecontrol cabinet and wired for 125V DC operation. Alarm contacts shall beprovided in accordance with Section 4.18.5.13, with one set wired to a

terminal block for LCRA TSC use and another set wired to the annunciator.Terminal block points shall be provided for LCRA TSC to supply 125 VDCexclusively to the Main Tank SPR seal-in relays.

4.18.10.3 Liquid Temperature Indicator, dial type, with four (4) separate adjustablealarm contacts. Monitor face shall be labeled Liquid Temperature. Themonitor shall be a Qualitrol Series 509-DW, or LCRA TSC approvedequivalent. Alarm contacts shall be provided in accordance with Section4.18.5.13, with one set wired to a terminal block for LCRA TSC use andanother set wired to the annunciator.

27


28/56

4.18.10.4 Winding Temperature Indicators on the H2, X2, and Y2 windings. Dial typewith four (4) separate adjustable contacts. Monitor face shall be labeledWinding Temperature. The monitor shall be a Qualitrol Series 509-DW, orLCRA TSC approved equivalent. Alarm contacts shall be provided inaccordance with Section 4.18.5.13, with one set wired to a terminal block forLCRA TSC use and another set wired to the annunciator.

4.18.10.5 Fiber Optic Hotspot & Top Oil System

The following specifications shall be met for the addition of fiber optic probesand monitoring devices:

4.18.10.5.1 The manufacturer shall furnish and install a fiber optic windinghotspot & top oil monitoring system manufactured byNEOPTIX/Qualitrol or LCRA TSC approved equivalent.

4.18.10.5.2 The fiber optic system shall include:

Item Quantity Description

1 16 T2 Fiber optic temperature probe for oil filled power transformer,oil immersed Teflon sheathing reinforced with spiral wrap,temperature range of -80C to 200C

2 16 Optical feed through to match with Neoptix products, 150Coperating temperature, NPT ANSI treads, no moving parts orOrings.

3 8 External fiber optic extension cable, ST connectors at both ends,3mm O.D. polyurethane with Kevlar reinforcement, ST-ST matingincluded.

4 1 Transformer tank wall mounting plate in stainless steel for 16Neoptix OFT optical feed throughs, including junction protectionbox. The OFTs should be assembled on the tank wall plate andleak tested at 100 PSI at the factory by Neoptix.

5 1 8-channel fiber optic temperature monitoring system for transformer winding (Model T/Guard Link or MOD-638) with 8numbers of 4-20 mA analog outputs, 485/DNP 3.0 communication.

6 1 DIN power supply, 24 volts for T/Guard Link system

4.18.10.5.3 The Qualitrol 509-DW or LCRA TSC approved equivalent forthis application shall have six (6) form C output contacts, orrelays.

4.18.10.5.4 Probes shall be installed in the following locations:Three (3) probes in the series winding, one (1) per phaseThree (3) probes in the common winding, one (1) per phaseOne (1) probe in the Core hot spot per design evaluationOne (1) top oil probe, near top of middle phase coil

4.18.10.5.5 The manufacturer shall guarantee that all probes shall befunctional. All fiber optic probes should be routed inside thecontrol cabinet and 8 of them will be connected to the

28


29/56

temperature monitor. All 16 probes shall be monitored duringthe heat run test with results communicated. This data shall beincluded as part of the certified test report.

4.18.10.5.6 The Transformer Tank Wall Feed through Plates (TWFP) shallbe located on the top third of the side wall of the transformer,where they shall be accessible during operation of thetransformer. Location of the TWFPs shall be a confirmed byLCRA TSC prior to installation.

4.18.10.5.7 Each fiber optic probe and cable shall be identified on drawingsand tagged. Probe placement and identification are to bedetermined by manufacturer and shall be communicated toLCRA TSC during design review. The manufacturer shallindicate the exact location of each probe after the hot spotcalculation is done. The probe installation details shall beprovided for approval and issued along the certified drawings.

4.18.10.5.8 The Qualitrol 509-DW or LCRA TSC approved equivalentshall provide alarm and trip functions for Top Oil and WindingHot Spot, control of the cooling system, and provide visibilityof the transformer temperatures.

4.18.10.5.9 All probes installed by the manufacturer shall be secured insidethe transformer tank such that the probe cannot be damaged byshipping, seismic or short circuit forces.

4.18.10.5.10 The fiber optic probes inside the tank shall be routed in such away that they are not subject to damage during assembly or

dismantling of the transformer, and shall have sufficient slackto avoid taut internal connections and allow for theinterchanging of probes.

4.18.10.5.11 A NEMA 4 box with removable cover shall be mounted overthe tank wall plates. A inch or larger rigid conduit shall berouted from the NEMA 4 box to the control cabinet.

4.18.10.5.12 Installation procedure must be validated by Neoptix/Qualitrolprior the beginning of the installation. Neoptix trainedprofessional shall be present on manufacturer site during the

installation of FO probes for each first of series. All routing ofprobes from tank plate shall pass through rigid conduit into thecontrol box.

4.18.10.5.13 The hot-spot monitoring system shall be linked to the Qualitrol509-DW or LCRA TSC approved equivalent through theauxiliary RS-485 port.

4.18.10.5.14 A yellow panduit and/or FO corrugated plastic conduit shall beused exclusively for the FO extensions inside the control

29


30/56

cabinet. The FO extensions shall not be bundled or tie wrappedwith the control cable. The FO cables that are not connected tothe temperature monitor shall be coiled in a 12 inch (305mm)diameter and secured in a permanent fashion such that they arenot subject to damage but are accessible. The manufacturershall instruct all personnel working on the transformer that thefiber optic cables are glass and must be treated only inaccordance with vendor specified procedure.

4.18.10.5.15 During Heat Run: The fiber optic thermometers shall be used tomeasure the temperatures. Should the fiber optic thermometersrecord hot spot temperatures in excess of those submitted bycalculations the manufacturer shall justify the use of calculatedvalues and LCRA TSC may require the test be repeated.

4.18.10.6 One Serveron model TM8 Autotransformer analyzer or LCRA TSC approvedequivalent shall be provided with enclosure cabinet and alarms. All cablingbetween sensors and alarm cabinet shall be provided. Alarm contacts shall be

provided in accordance with section 4.18.5.3 with one set wired to a terminalblock for LCRA TSC use and another set wired to the annunciator. Powersupply requirements for this device shall be 1.5 times the monitormanufacturers recommendation. (Internally supplied primary and customerprovided backup options shall be available).

4.18.10.7 One (1) cover mounted automatic pressure relief device with external targetthat can be reset manually for each 10,000 gallons of oil. Circuitry from thesedevices shall be routed to the main control cabinet where alarm contacts and alocal trip flag shall be provided. The pressure relief devices shall be locatedsuch as to provide equal coverage on the cover. The automatic pressure relief

device shall be a Qualitrol Series 208 Pressure Relief Device. Alarm contactsshall be provided in accordance with Section 4.18.5.13, with one set wired toa terminal block for LCRA TSC use and another set wired to the annunciator.

4.18.10.8 One (1) transformer monitor and control unit, Dynamic Ratings DRMCC-E3,or LCRA TSC approved equivalent. The following analog and digital inputsshall be provided to the monitor control unit:

a. Top oil temperatureb. Ambient temperaturec. Primary voltage winding current

d. Secondary voltage winding currente. Tertiary voltage winding currentf. Terminal blocks to bring in potentials for Primary, Secondary, Tertiaryg. Fan switch positionh. Fan motor current monitoring (provide fan current sensing CT, one per

fan bank group.)i. Multi-gas monitor sensorsj. Moisture-in-oil sensork. LTC position sensorl. Main tank low oil level

30


31/56

m. LTC low oil leveln. LTC sudden pressure alarmo. Pressure relief alarmp. Gas detector (Buchholz relay) alarm

A separate NEMA cabinet shall be installed adjacent to the main cabinet with theDynamic Ratings monitor inside. Conduit from the temperature monitors, gas monitors,and tap changer controllers shall be installed, and communication wire shall be providedfrom each monitor to the Dynamic Ratings unit. The communication conduit shall beseparate from control and power wiring. Communication wiring shall consist of two (2) -CAT 6 STP (8 conductors shielded twisted pair) going from each monitor to theDynamic Ratings cabinet. The Dynamic Ratings monitor shall be utilized as a dataconcentrator having communications coming from all other monitors installed on thetransformer.

4.19 CONTRACTOR DATA:

4.19.1 All Contractor data, after award of contract, shall be submitted to the LCRA TSCs

project engineer designated in the purchase order at:

Lower Colorado River AuthorityP.O. Box 220Austin, Texas 78767Attn: Substation Engineering

4.19.2 A design review meeting (to be held at LCRA TSCs transmission engineering offices inAustin, Texas) will be required as part of the approval drawing process. Written notice ofthe meeting shall be supplied to LCRA TSC three weeks in advance of meeting date.LCRA TSC will most likely have a consultant attending the design review that is

experienced in the design and manufacture of large autotransformers. The duration of themeeting will be a minimum of two full workdays. Approval drawings defined in section1.11, items (1), (2), and (3), which are outline, nameplate, and wiring and schematicdrawings shall be submitted to the LCRA TSC 3 weeks prior to the design meeting.These drawings, with LCRA TSCs comments and markups will be reviewed with theContractor as part of the design review meeting agenda.

31


32/56

IMPORTANT NOTE REGARDING THE DESIGN REVIEW MEETING

Changes may be proposed by LCRA TSC and their consultant that modify core, windings, tank/framematerials, insulation, clearances, spacings, oil flow characteristics, electrical and magnetic fields, andcooling capacity of the autotransformer. These changes shall be included in the final design andmanufacture of the autotransformer at no additional charge or time delay to LCRA TSC. The Contractorshall use caution in contracting for any core, coil, frame, tank and insulation materials that may beaffected by LCRA TSC initiated design changes prior to the design review meeting. LCRA TSC will notaccept any cost increase for design review changes or consider any excuses by the manufacture that theyhave already bought these materials and cant make proposed changes due to economic or timeconstraints.

ALL VALUES FOR LENGTH, AREA, FORCE, AND PRESSURE SHALL BE IN ENGLISH

UNITS WHEN PRESENTED BY THE CONTRACTOR AT THE DESIGN REVIEW MEETING.

Metric units are not acceptable except for temperature in degrees centigrade. The Contractor shall makeall these conversions on documentation presented prior to the design review meeting. Simply statingconversion factors for use at the meeting is totally unacceptable. If the Contractor arrives at the designreview meeting and has failed to carry out the provisions of this paragraph, the meeting will be

immediately terminated and rescheduled at the manufactures expense for a future date at the LCRATSCs offices, once Contractor has made these conversions on all documentation.

LCRA TSC will present an agenda format of the design review meeting to the Contractor and theContractor may add agenda items prior to the design review meeting. All written agenda informationthat the Contractor will discuss at the design review meeting shall be provided to LCRA TSC a

minimum of three weeks prior to the meeting for review.

The design review will include, but is not limited to, the following topics that may affect changesto the Contractors design as described above:

1. Contractor analytical tools:

a. Transient voltage distribution and calculation methodsb. Thermal analysis calculation methodsc. Short circuit stress calculation methods

1) Types of through faults considered2) Calculation of coil stresses3) Calculation of mechanical structure stresses

d. Leakage magnetic field calculation method

2. Core design:a. Core design configurationb. ASTM material specifications for core material and source of supply (Core

material data sheet to be supplied)c. Core geometry, thickness and flux density valuesd. Lamination burr tolerancee. The residual flux density in the core in percent of nominal excitation and times

normal inrush current.f. No load loss and excitation parametersg. Number of cooling ducts in the core and calculated hotspot locations with their

respective temperaturesh. What type of verification is used to determine if hot spot temperatures and

locations are accurate

32


33/56

i. Core loss and excitation curve review

3. Winding design:a. Winding arrangement or construction to be used including description of

transpositions and interleaving, number and size of axial and radial spacersused, spacing and insulating barriers between windings, and description ofcooling fluid pat within the winding structure

b. Winding material ASTM material designation and parameters including tensileand ultimate strength of copper (Provide material data sheet of proposed coppermaterial)

c. Ratio of strength to stress for each mode of failure and the method used tocalculate these values

d. Type of voltage regulation and regulating winding designe. Voltage distribution in windings; turn-to-turn, disk-to-disk, etc.f. Winding conductor eddy and stray loss calculations and determination of need

for tank wall shielding, and shielding locationsg. Review of all dielectric clearances and impulse distribution calculationsh. Review of winding splice and tap locations

4. Insulation design:a. Insulation material used (Provided insulation suppliers data sheet)b. Major insulation clearance locationsc. Insulation configuration and materialsd. Voltage distribution and electrical stresses at in major insulation thickness

locations

5. Load loss and impedance.

6. Thermal design:

a. Type and amount and type of cooling equipment used to attain the guaranteednameplate KVA cooling design

b. Winding temperature rise values and locations and how these are calculated.c. Average temperature and hot spot temperature calculationsd. Directed or non directed oil flow used in the coil windings and size of oil duct

openingse. Fluid flow and heat transfer rates at 65 deg. C ratingf. Life expectancy of cooling equipment components

7. Leakage magnetic field analysis:a. Control of leakage fields

b. Localized temperature calculation due to leakage fields

8. Sound level design.

9. Tap changer equipment and how selection and sizing of this equipment was made.This includes the effects of a raise/lower command, the direction of movement ofthe tap indication, the tap position numbering convention and labeling on thenameplate, and the nature of the tap indication output used by the LCRA TSC.

10. Coil and core stabilization methods and description of clamping systems:

33


34/56

a. Materials and geometry used for end rings, pressure plates, and other specialcomponents

11. Tank and fitting design:a. Conservator and bladder designb. Weights and dimensionsc. Design for transportation including the shipping forces that the clamping and

end frame structure is designed to withstand in Gs.d. Number and location of tank weldse. Painting and electrical insulating paint application

12. Accessories:a. Bushings including connections of leads, bolting arrangements and sizesb. Gauges and indication devicesc. Controls, wiring, conduit, etc.d. List of recommended spare parts and source locations for obtaining theme. Oil specification data sheet of oil to be supplied

13. Testing and test plan:a. Review of specification testing requirementsb. SFRA testing detailsc. Acceptance criteriad. Applicable test standards

4.20 TESTS:

Autotransformer shall be tested completely assembled, including all permanent bushings andcooling equipment. LCRA TSC reserves the right to visit the manufacturing facility and observe

any and all tests and inspections. LCRA TSC shall be notified a minimum of three (3) weeks priorto the implementation of the required tests. The following test sequence shall be used:

Routine TestsLoad Loss MeasurementsNo Load Loss and Excitation Current MeasurementsSingle Phase Excitation Test110% Excitation TestTemperature TestsDielectric TestsImpulse

Switching SurgeAppliedNo Load Loss and Excitation Current TestsNoise TestInduced Test - The induced test with partial discharge measurement shall be made last.Sweep Frequency Response Analysis (SFRA)

4.20.1 All tests shall be made in accordance with applicable sections of latest revision of IEEEStandard C57.12.90.

34


35/56

Required tests shall include the following:

4.20.1.1 Resistance measurements on the rated voltage connection and at all tapextremes. All resistance values shall be converted to 20deg. C temperature.

4.20.1.2 Ratio and regulation tests.

4.20.1.3 Polarity and phase relation tests on all windings and BCTs.

4.20.1.4 No load loss at rated voltage and at 110% rated voltage before and afterimpulse tests. Tests shall be performed at LTC positions 16L, Neutral, 1R,and 16R.

4.20.1.4.1 Single Phase Excitation Tests Single phase excitation tests shall beperformed at 10KV with either Doble M2HD or M4000 test system.Measurements shall be made for each primary winding according to Dobleprocedures for making such measurements. Measurements shall beperformed with DETC on highest voltage tap setting and on all LTC taps.

Reports shall be delivered in both the Doble Test Assistant version 5.4 (orlater) file format and on printed test reports with the certified test results.

4.20.1.5 Exciting current at rated voltage and at 110% rated voltage. The Contractorshall perform a 24 hour excitation test at 110% voltage. Oil samples shall betaken for gas in oil analysis immediately before and after the excitation testand an additional sample be taken eight to 12 hours after completion of thetest. The measured gas levels shall be corrected to an equivalent 10,000gallon oil level before comparison. The maximum increases in the gas levelsbased on the 10,000 gallon level are as shown:

Ethylene 1 ppmMethane 2 ppmEthane 2 ppmAcetylene Non detectable

4.20.1.6 Measured impedance, both positive and zero sequence.

4.20.1.7 Load loss and auxiliary loss at base 55oC rise over ambient rating, and at

maximum 65oC rating.

4.20.1.8 Temperature rise tests at self cooled and maximum forced cooled ratings. Atest shall also be performed to verify the 110% overload rating as defined insection 4.16.1.2, unless the Contractor can clearly demonstrate, based on selfcooled and forced cooled test results, that the autotransformer is capable ofmeeting the overload requirement specified. Temperature rise data onduplicate units is not acceptable. Oil samples shall be taken for gas in oilanalysis both before and after temperature rise testing. Test results and theContractors analysis shall be submitted to LCRA TSC prior to acceptance forautotransformer shipment. Any increased level of combustible gases betweenthe before and after tests shall be addressed by the Contractor andpresented to LCRA TSC for approval. The measured gas levels shall be

35


36/56

corrected to an equivalent 10,000 gallon oil level before comparison. Themaximum increases in the gas levels based on the 10,000 gallon level are asshown:

Hydrogen 20 ppmEthylene 3 ppmMethane 5 ppmEthane 5 ppmAcetylene Non detectableCarbon Monoxide 75 ppmCarbon Dioxide 250 ppm

4.20.1.9 Applied potential tests. The applied voltage test shall be made in accordancewith the appropriate ANSI/IEEE standards and with the following testvoltages:

HV 50 kVLV 50 kV

TV 50 kVNeutral 50 kV

Partial Discharge (PD) measurements shall be taken during the applied test.PD in picocoulombs should be measured and recorded at 15 second intervals,shall be less than 500 pC and shall not increase by more than 100 pC duringthe test.

4.20.1.10 Induced potential tests as specified in ANSI C57.12.90-1993, also, partialdischarge testing and measurements must be taken during the test, includingthe one hour duration test. Failure will be as specified in IEEE C57.12.90-

2010, section 10.8.5. Oil samples shall be taken before and after inducedtests.

a) The corona shall be measured and recorded at the 150% level as thevoltage is being increased to the enhancement level of 173%.

b) The corona shall be measured and recorded at the enhancement level.c) The first reading at 150% following the enhancement shall be taken five

(5) minutes after the voltage reaches the 150% level and every five (5)minutes thereafter for one (1) hour.

d) The corona level shall not exceed 100 micro volts during the hour. Thecorona level shall not increase more than 30 micro volts during the hour

using the value at 150% prior to the enhancement as the base reading.There shall be no continuous increase during the hour or during the last20 minutes of the hour.

e) In the event that the 100 micro volts limit, the 30 micro volts increase, orthe continuous increase requirement are exceeded, the cause shall bedetermined and corrected.

4.20.1.11 Insulation power factor tests by IEEE C57.12.90, Method II, (not to exceed

0.5% corrected to 20oC in accordance with Doble Temperature Charts).

36


37/56

Insulation power factor tests shall be performed with either Doble M2HDor the M4000 test systems. Reports shall be delivered prior to unit shipmentin both the Doble Test Assistant version 5.4 (or later) and on printed testreports included with the certified test results. In Table 4, Method II is therequired technique.

4.20.1.12 Insulation resistance test. Each winding to ground and to other windings andcore to ground shall be tested. (Core to ground test shall be made just prior toshipment.) Insulation resistance measurements shall be performed when theunit under test is at ambient temperature. The insulation resistance tests shallinclude the HV to TV and ground, HV to ground, HV to TV, TV to HV andground, TV to ground, and TV to HV. These tests shall be performed withinstrumentation that includes a guard circuit. Printed test results will beincluded with certified test results. Test voltage and time duration of each testshall be included in the documentation.

4.20.1.13 Leak test on tanks, coolers, and piping. Test shall be conducted using the

following procedure:a) Pull a vacuum of 1 Torr on the autotransformerb) Close valve connecting the autotransformer to the vacuum pumpc) Begin monitoring the pressured) Maximum permissible Torr rise after 15 minutes is 0.20 Torr

4.20.1.14 Dew point test: Test shall be made of the sealing gas prior to shipping.However, the Contractor must wait a minimum of 48 hours after installing thegas before taking the dew point test. Contractor shall include tank pressureand winding temperature at time of test. Acceptable dew point shall indicatethe moisture content in the insulating paper is less than 0.5% and shall be less

than the allowable maximum dew point as calculated in the formula:

Max. dew point in C < [ 0.75 x (Winding temp in C 80)]

4.20.1.15 Insulating oil test. The Contractor shall supply LCRA TSC specifications onwhich oil was ordered and from which refiner and oil test data performed bythe refiner shall be provided. Oil must be certified non-PCB.

4.20.1.16 The Contractor shall perform the Lightning Impulse Tests per IEEEC57.12.90 section 10.3 and C57.98. All windings and neutrals shall be testedfor the BIL specified. H1, H2, H3, X1, X2, X3, Y1, Y2, and Y3 winding tests

shall consisting of:

One (1) Reduced Full WaveOne (1) Full WaveTwo (2) Chopped WavesOne (1) Full WaveOne (1) Reduced Full Wave

Neutral tests shall consist of:

One (1) Reduced Full Wave

37


38/56

Two (2) Full WaveOne (1) Reduced Full Wave

Oil samples shall be taken before and after impulse tests, same as 7.1.8 above.

Special requirements for the chopped wave are:1) Actual chopping time, Tch, from the instant of chopping to the time of

first voltage zero shall not exceed 0.65 s as shown in the figure below,2) Overswing magnitude after chopping shall not be limited artificially to lessthan 40 % of the chopped wave crest value,3) The current trace, with a sweep time of 10 to 25 s, shall be recorded andcompared before and after the chop during the chopped wave tests.

Figure 13 - Tch = Allowable Chopping Time

The required crest voltage for the LI tests shall be increased if the actual fronttime exceeds 2.0 s or the actual tail time (time to 50% crest value) is lessthan 40 s. If the front time exceeds 2.0 s, then the crest test voltage of boththe full and chopped waves shall be increased by 2 % per each additional0.1s above 2.0 s.

If the time to 50 % crest value is less than 40 s the crest test voltage of the

full wave impulse shall be increased such that the kV-seconds above 80 % ofthe rated full wave voltage (e.g., as integrated by a digital oscilloscope) forthe adjusted impulse wave equals the kV-seconds above 80 % of the BIL for a2.0/40 s (double exponential) wave. In the event that the front exceeds 2.0s and the tail is less than 40 s, the increases in required test voltage shall beapplied additively, e.g., a 10 % increase for the front and 4 % increase for thetail result in a required increase of 14 % in the crest test voltage. Thefollowing table lists the total corrections factors computed for many waveshapes based on these requirements.

38


39/56

LI Test Voltage Correction Factors

4.20.1.17 Switching Impulse Test shall be performed on H1, H2, H3, X1, X2, and X3bushings per ANSI/IEEE C57.12.90 Section 10.2.

HV 870 kV crestLV 540 kV crest

1) Reduced and both full voltage and current wave shapes shall match until coresaturation takes effect.2) Connections on three-phase transformers shall be such that 1.5 times the appliedvoltage is generated and withstood between phases without the use of external barriersbetween the bushings.

Note: This voltage shall be applied or induced into the high voltage end of theautotransformer. If this exceeds the rating of other winding parts, theinsulation shall be increased to allow the application or inducing of 870 kV.

4.20.1.18 Noise level Test: Noise tests shall be made in accordance with C57.12.90-2010 NEMA TR1. The autotransformer shall be connected in nominal345kV/138kV position for the noise test.

4.20.1.19 Other Tests: The following tests shall be performed on each currenttransformer in accordance with ANSI C57.13:

39


40/56

(1) Ratio and phase angle(2) Impedance and excitation measurements(3) Polarity(4) Dielectric tests(5) Insulation resistance tests(6) Winding and lead resistance tests

4.20.1.20 Sweep Frequency Analysis: The Contractor shall perform a sweep frequencyresponse analysis using the Doble Model 5100 or equivalent instrument. Thesweep frequency analysis shall be performed over a frequency range of 10 Hzto 2 MHz. Data shall be provided in hard copy and electronic files. Electronicfile format will be defined later. LCRA TSC preferred test connections:DETC Tap Setting at Nominal Voltage, LTC at extreme raise voltage setting.

4.20.2 Short Circuit Data:

4.20.2.1 The autotransformer is expected experience numerous external short circuits(through faults) during its service life. The transformer and all its accessories

shall be designed to mechanically endure such through faults, without thermaland mechanical failure, per the requirements of Section 7 of IEEE C57.12.00-2010 or latest revision.

4.20.2.2 Conformance of through fault thermal and mechanical requirements may besatisfied by submission of certified data indicating that the proposed design isexpected to successfully pass the short circuit tests, as required by Section 12of C57.12.00-2010 or latest revision, with at least 5 % margin, based onactual test experience on a prototype or similar design. Tap position(s) duringthe tests on a prototype design shall be the one(s) that creates the worstmechanical condition(s)

4.20.3 Control and Power Wiring:

Low frequency withstand voltage tests shall be performed on all control and secondarywiring. All low voltage wiring including control and indication wiring shall be given acontinuity check. All control circuits shall be functionally tested by simulating internaland external control functions.

4.20.4 Test data shall be submitted to the LCRA TSC prior to notification for shipment.

Test failures, questionable test results, failure to meet any guaranteed or specifiedrequirements, and important quality defects shall be brought immediately to the attention

of LCRA TSC for resolution prior to proceeding with fabrication, repair, testing orshipment. In the case of a test failure in the factory, the manufacturer shall advise LCRATSC and provide an opportunity to witness teardown. Further, the Contractor shallprovide a detailed failure report to LCRA TSC including photographs of the damaged ordefective items and an explanation of the measures taken to insure that the problem doesnot reoccur. Electromagnetic field plots and other supporting data shall be provided byContractor upon request, where appropriate to the mode of failure.

The Contractor shall not initiate repair of failed or defective components as specifiedabove until LCRA TSC has agreed to the proposed repair, procedure or modification.

40


41/56

4.20.5 Final Field Acceptance:

When the autotransformer has been vacuum processed and filled with oil, LCRA TSCwill complete the tests listed below. The final acceptance of the autotransformer will bebased on the results of these tests. If these tests limits are not achieved, the Contractorshall find and correct the problem.

a) Take a DC core ground resistance measurement. This measurement shall be withinthe limits specified by the Contractor in its Instruction and Maintenance Manual.

b) Make the following insulation power factor measurements of the autotransformer.The power factor shall be less than 0.5% uncorrected.1) 345 kV and 138 kV windings

345KV Autotransformer Spec(08.29.2012)

Documents

Transcript of 345KV Autotransformer Spec(08.29.2012)