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WAPA TRANSFORMER SPECIFICATIONS

Table of Contents

ATTACHMENT A, PART 1 - WAPA GENERAL TRANSFORMER SPECIFICATIONS

1.1 GENERAL:

1.2 FALL PROTECTION:

1.3 TAP CHANGERS:

1.4 SURGE ARRESTERS:

1.5 BUSHINGS:

1.6 TERMINAL CONNECTORS:

1.7 CURRENT TRANSFORMERS:

1.8 WINDINGS:

1.9 CORE:

1.10 OIL PRESERVATION EQUIPMENT:

1.11 TANK:

1.12 BASE:

1.13 COOLING EQUIPMENT:

1.14 STANDARD ACCESSORIES:

1.15 CONTROL CABINETS AND TERMINAL BOXES:

1.16 TERMINAL BLOCKS:

1.17 CONTROL WIRING:

1.18 INSULATING OIL:

1.19 FACTORY ASSEMBLY AND TESTS:

1.20 TOOLS AND APPLIANCES:

1.21 PAINTING:

1.22 SPARE PARTS:

1.23 VOLTAGE REQUIRED FOR OPERATION OF THE EQUIPMENT:

1.24 ELECTRICAL DRAWINGS AND DATA:

1.25 REFERENCE DRAWINGS AND DATA:

1.26 SUBMITTALS AND CORRESPONDANCE:

ATTACHMENT A, PART 2 - OPERATION CONDITIONS AND TRANSFORMER RATINGS

2.1 OPERATING CONDITIONS:

2.2 BUSHING LOCATIONS:

2.3 TEMPERATURE RISE FOR EQUIPMENT:

2.4 VOLTAGE RATINGS, CURRENT RATINGS, BIL RATINGS AND DESIGN IMPEDANCE

2.5 AUDIBLE SOUND LEVEL

ATTACHMENT A, PART 3 – OTHER REQUIREMENTS

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3.1 PLACE OF DELIVERY & DELIVERY CONDITION:

3.2 TOOLS, APPLIANCES, AND SPARE PARTS:

3.3 POST AWARD FACTORY MEETING:

3.4 IMPACT RECORDER AND SWEEP FREQUENCY RESPONSE ANALYZER REPORTS

3.5 ASSEMBLING TRANSFORMER

3.6 PACKING LIST:

3.7 REPAIR AND RESTORATION:

3.8 QUALITY ASSURANCE:

ATTACHMENT A, PART 1 - WAPA GENERAL TRANSFORMER SPECIFICATIONS

1.1 GENERAL:

The Contractor shall furnish the transformer complete with tank-mounted surge arresters, insulating oil, features, and accessories as specified. All material necessary for the operation of the transformer shall be provided. The manufacturer shall supply a Bill of Materials list that identifies all of the transformer components by quantity, manufacturer, country of origin, and model number.

Unless otherwise specified in this solicitation, the transformer shall be designed and manufactured in accordance with the latest applicable standards including those from the Institute of Electrical and Electronics Engineers, Inc. (IEEE), National Electrical Manufacturers Association (NEMA) and the American Society for Testing and Material (ASTM). Specifically, the design and manufacture of the transformer shall be in accordance with IEEE C57 Series Standards including IEEE C57.12.00. Only new equipment of current and present-day manufacture shall be furnished.

The transformer, including bushings and all accessories, shall operate within all loading and temperature rise limitations of IEEE C57.91 as applicable. Transformer minimum clearances from live parts shall be in accordance with Table 124-1 of the latest IEEE C2. In the event of contradictory requirements between IEEE standards and these requirements, the terms of these requirements shall apply. Transformers shall have the full MVA rating at the specified substation elevation. The Contractor’s erecting engineer shall make all the arrangements to send empty nitrogen bottles and any other items that need to be returned to the required return location. Bolts, nuts, washers, and locknuts outside the transformer tank shall be galvanized or stainless steel.

1. Support Systems:

a. All busses, leads, connectors, conductors, and associated details shall be taped and insulated using paper tape and/or tube to withstand rated voltage, including the neutral bus and leads. All connections shall be made with locking hardware. The use of cotter pins as a locking device is not acceptable.

b. All busses and cabling leads shall be supported by support structures. The use of plastic cable ties to support structures is not acceptable. All current transformer wiring shall be contained within insulated tubes. Similarly, all fiber optic probe cables shall be contained within insulated tubes.

c. No PVC, PCB, asbestos, or lead (Pb) material shall be used.

2. Materials:

a. All materials shall be of recent manufacture, unused, and free of defects or irregularities.

b. All fasteners shall be ASTM Grade 5 (Metric 8.8) or above.

c. All fasteners shall be registered with Industrial Fastener Institute (IFI).

d. All nuts, bolts, studs and U-bolts shall be of the appropriate hardness and strength for the application.

e. All threaded parts shall be in accordance with the latest ANSI standards.

f. All external hardware including, Belleville washers, nuts, bolts, etc. shall be stainless steel.

g. Use stainless steel Belleville washers where appropriate.

h. All "liquid-tight flexible metal conduit (LFMC)" shall be Anaconda Sealtite Type UA or equal. It shall meet Article 350 of the NEC and comply with UL360 and CSA C.22.2 No. 56. Contractor shall provide submittal for LFMC for approval.

1.2 FALL PROTECTION:

The Contractor shall furnish and install fall prevention equipment for use during installation, commissioning, and maintenance. Each system shall be in accordance with the requirements below:

1. The Contractor shall furnish and install three base plates, 3M™ DBI-SALA® Advanced™ Bare

Steel Uni-Anchor with Tie-Off, weld-on application part #8517412. These floor mounts shall be welded at three different locations on the top of the transformer tank, one which shall be adjacent to the tank’s perimeter.

2. WAPA will determine the location of the floor mounts on the top of the transformer tank during the review of the informational drawings. WAPA will provide a marked up copy of the outline drawing showing the location for the floor mount. The transformer manufacturer may suggest locations for the floor mount which work best for the transformer design. In this case WAPA will review the suggested location and determine if it will be suitable.

1.3 TAP CHANGERS:

DE-ENERGIZED TAP CHANGER: A de-energized tap changer manufactured by Reinhausen shall be furnished as identified in Attachment A, Part 2 and meet the following specifications:

a. The tap changer shall be externally operated and arranged for padlocking in each tap position. A 3/8” diameter hole shall be provided for padlocking the de-energized tap changer in each position and arranged to prevent locking the tap changer in an off-tap position. An integral keypad lock is not acceptable. A means to read the tap changer position shall be provided for a person standing at the same level as the transformer base without the need to unlock the de-energized tap and shall include an operating lever or hand wheel with means to operate the tap changer position at this same level.

b. The tap changer operating mechanism shall be mounted approximately 2 feet from the top cover of the transformer. The operating mechanism and contacts shall be fully and easily accessible through manholes in the transformer top cover without untanking. Alternatively, the operating mechanism and contacts may be fully and easily accessible through an access door located in the tank wall.

c. The tap changer shall meet or exceed the latest requirements of IEEE C57.131 and in addition:

1) The tap changer shall be of a rotary type.

2) A design that incorporates moving contacts in a ring shape mating to a round post type stationary contact will not be allowed.

3) Contact material shall be silver plated copper contacts for both the stationary and moving contacts.

4) The contact rating shall be at least two times the maximum HV winding rating.

5) The tap changer shall be designed to withstand the applied potential test of the winding to which it is connected.

6) The tap changer shall be capable of withstanding, without damage, the maximum short-circuit stresses which would be imposed upon it when the transformer itself is subjected to short-circuit currents in accordance with the requirements specified in this solicitation.

1.4 SURGE ARRESTERS:

The surge arresters shall meet all applicable requirements of the latest IEEE C62.11, shall be the metal-oxide (MO) type with porcelain housings. Polymer housings are acceptable only if required to meet seismic and/or fault duty requirements. Surge arresters shall meet the following specifications:

1. They shall be mounted on the transformer tank with the base at least 8.5 feet above the transformer base except as otherwise required.

2. Color of the arrester shall be gray. One surge arrester is to be supplied for each external winding terminal on each transformer, for all voltages that are required to be furnished on the equipment.

3. The surge arresters shall have sufficient mechanical strength to withstand, without damage, the mechanical forces that will be imposed on the equipment and meet the same seismic requirements as stated for the associated transformer that the surge arresters are mounted on.

4. The surge arresters shall be tank mounted for maximum protection of the equipment. Surge arresters for this transformer shall provide protective margins equal to or better than those listed in Part 2 - Table C.

5. Surge arresters shall be installed so that the top of the arrester is level or higher than the top of its associated bushing.

6. Surge Arrester Brackets: Surge arrester brackets shall be located on the tank adjacent to their respective high and low voltage bushings and shall meet the following requirements:

a. A minimum of one NEMA ground pad shall be located on the top of the main tank for each arrestor mounting bracket. The manufacturer shall also provide the necessary ground bus of at least 0.5 square inch cross section of copper between the tank ground pads and the ground pads located at the bottom of the tank.

b. Mounting holes are to be oriented such that the arrester vent points away from the tank.

c. The height of the arrester terminals shall approximately match the height of associated bushings.

d. Brackets shall be spaced so that the clearance between live parts of the surge arresters shall be at least 10” greater than the minimum clearance between live parts based on transformer

BIL.

7. For voltage ratings of 34.5-kV and below, the surge arresters shall be installed so that the top of the arrester is 15 inches lower than the top of its associated bushing (if bushings and arresters are mounted horizontally).

1.5 BUSHINGS:

The bushings shall be of a porcelain type, shall be manufactured by PCORE or ABB and shall conform to the latest IEEE C57.19.00 and C57.19.01. The bushings shall be located on the transformer in accordance with Attachment A, Part 2, paragraph 2.2 and the bottom of each bushing shall be a minimum of 8.5 feet above the base of the transformer.

All porcelain used in bushings shall be wet process, homogeneous, and free from cavities or other flaws. The glazing shall be gray, uniform in color, and free from blisters, burns, and other defects.

Each high-voltage bushing shall have a capacitance tap for use with a bushing potential device having a burden as shown in Appendix A of the latest NEMA Publication No. SG 4. Porcelain parts of each bushing rated below 450-kV BIL shall be of one piece. Porcelain parts of each bushing rated 450-kV BIL and above may be constructed of one piece or of multiple parts provided the multiple parts are assembled by one of the following methods:

1. By flanged segments;

2. By placing suitable firing material in the joints between the segments and the entire porcelain part fired in one piece;

3. By securely holding the parts together with a clamping device through the centerline of the bushing. The joint must be at right angles to the longitudinal centerline of the bushing if this method is used;

4. By cementing or bonding the joints. If the Contractor proposes to use this method, the Contractor shall submit for approval a complete description of the process and material used; bending test and electric test results on a completed joint; and results of aging tests on the joint showing mechanical strength and electrical strength.

1.6 TERMINAL CONNECTORS:

1. Terminal connectors shall be furnished on each bushing and surge arrester.

2. All neutral and tertiary bushings on top of the transformer tank shall be furnished with NEMA Standard CC 1, 4-hole type terminal pads. The current ratings of the terminal connectors shall match or exceed the current ratings of the associated bushings.

3. All high voltage (230-kV & 161-kV) bushings on top of the transformer tank shall be furnished with studs for connection to the isolating test terminals being provided for “Doble®” testing.

4. Isolating test terminals for “Doble®” testing shall be made with aluminum, and shall be “PCORE Electric”, or approved equal. These test terminals shall be furnished for each 230-kV and 161-kV bushing, and are to be installed on the top of transformer bushings during transformer installation. The test terminal connections to the bushings are to be made to the bushing stud terminals and the external connections to the test terminals are to be made using NEMA 4-hole pad terminals. The current ratings of the test terminals and their terminal connectors shall match or exceed the current ratings of the associated bushings.

1.7 CURRENT TRANSFORMERS:

Current transformers shall be in accordance with IEEE C57.13 and shall meet the following requirements:

1. All secondary leads shall be brought to short-circuiting-type terminal blocks in the control cabinet.

Splicing of current transformer pigtail wiring and wiring to main control cabinet is not permitted.

2. All current transformers specified are in addition to those which may be required for operation of temperature relays. For bushing-type current transformers, the turns between any two taps on the secondary winding shall be uniformly distributed along the entire core.

3. Bushing type, multi-ratio, current transformers shall be provided and arranged to be accessible and removable from outside the transformer tank through top cover manholes.

4. All current transformers shall be located on the top section of the core and coil assembly.

5. The transformer shall be furnished with multi-ratio bushing current transformers as shown below in Attachment A, Part 2, Table D and E.

1.8 WINDINGS:

1. Winding conductors shall be copper, shall be free from scale, burrs, and splinters, and shall be insulated with paper. Permanent current-carrying joints or splices shall be mitered and welded with silver alloy having a melting point not lower than 1,100 degrees F (593 degrees C) and all joints and splices shall be welded or brazed, properly formed, finished, and insulated, except that compression-type fittings may be used outside of the core winding.

2. The transformer core and coil assemblies shall be power class, round core/circular coil design and construction. High voltage and low voltage windings for the main core/coil assembly shall be either disk or helical construction; layer/barrel windings are not acceptable. All windings shall be either rectangular magnet wire or continuous transposed cable.

3. Weidmann Systems International shall be used for insulation components used in transformers which includes insulation boards, insulation paper, various insulation components, high temperature NOMEX winding insulation, and Weidmann wire products for the construction of the windings.

4. If clamping rings are utilized in the transformers design, full circumference rings shall be used.

5. Core and coils shall be dried using a vapor phase system prior to oil filling.

6. Transformer shall utilize conductor and lead insulation of specially treated paper to maintain the required tensile, bending, and bursting strengths; to increase the thermal stability of the insulation; and to insure normal life expectancy.

7. The completed winding assembly shall be securely held in place so that there will be no disarrangement or deformation by stresses caused by shipping. All leads from the windings to the terminal board and bushings shall be supported to prevent damage from vibration or normal installation flexing.

1.9 CORE:

1. Nuts, bolts, and clamps of the core assembly shall be provided with positive locking devices to prevent loosening by vibration or change of shape or position during transportation or operation.

Core bolt clamping insulation shall be class 150 degrees C minimum.

2. The core shall be securely grounded to the tank. An external core ground, via an external core bushing, shall be provided to allow testing the core ground without exposing the internal parts to possible contamination. The core ground shall be connected to the tank with a detachable connector and the assembly shall be enclosed with a removable cover.

3. The manufacturer shall demagnetize the core just prior to shipping transformer(s).

1.10 OIL PRESERVATION EQUIPMENT:

1. The oil preservation system provided shall operate under the pressure limitations outlined under paragraph 1.10 (Tank) without loss of inert nitrogen gas or dry air over the entire temperature range specified. The use of auxiliary apparatus to compress or chill the gas will not be permitted.

2. Sufficient nitrogen gas, if required, shall be furnished for the initial flushing, filling, and operation of the transformer. The Contractor’s erecting engineer shall return these cylinders to the required return location as soon as the nitrogen bottles are empty and no longer needed for installation.

3. Transformer shall be equipped with the following system of oil preservation defined in the latest

IEEE C57.12.80:

a. SEALED CONSERVATOR CONSTANT PRESSURE SYSTEM:

1) Conservator System:

a) For the constant pressure system, separation of oil from the atmosphere shall be accomplished by means of a nitrile air cell bladder confined to an auxiliary tank. The auxiliary tank shall be of sufficient volume to operate over the entire ambient temperature range specified in the solicitations. The air cell shall vent air to the atmosphere by means of a weather tight breather through a desiccant such as silica gel. The desiccant container shall be at the transformer tank potential and located (approximately 6 feet above base) so it can be replaced, refilled, and maintained while the transformer is energized.

b) If a cell is damaged, the unit shall fail safe, by acting as a conservator. A leaking air cell bladder shall activate an alarm from a Buchholz type relay attached to the conservator tank. Transformer(s) shall have means of isolating the auxiliary tank during installation and inspections. The auxiliary tank shall be equipped with a sump chamber and 1” drain line with a ball valve. The auxiliary tank shall be designed for full vacuum filling. A pressure-vacuum bleeder shall protect the system in the event of incorrect overfilling or under filling during installation.

c) The conservator tank shall have two inspection openings, one in each end, to allow easy inspection/replacement of the air cell.

d) The conservator shall be constructed in a way to avoid accumulation of water on the exterior surface. A flat level is not acceptable.

e) A gas accumulation relay (specified elsewhere) shall be mounted so that the accumulation gauge can be read from ground level.

f) A liquid level gauge (specified elsewhere) is required for each conservator or conservator compartment. The device shall be mounted at an angle such that the gauge can be read easily from ground level.

2) Conservator Oil Lines:

a) All oil lines used shall be steel pipe (black iron) with Class 150 welded pipe flanges

(ANSI B16.5). The minimum pipe size shall be ¾-inch NPS with a minimum wall thickness of 2.5 mm between oil under static pressure and the atmosphere. (This is to minimize the possibility of puncture by power arc and the continued supply of oil to a fire that may result.)

b) A shut-off valve shall be provided in the oil line between the expansion tank and the gas accumulation relay; a second shut-off valve shall be installed between the gas accumulation relay and main transformer tank.

c) The pipe flange connections shall be designed for O-rings or gaskets. All piping systems shall be adequately supported.

1.11 TANK:

1. The shell, cover, and bottom of each tank, including auxiliary tanks, shall be of welded steel plate construction with all seams welded so as to remain oil-tight and gastight. During welding of the transformer cover, an inorganic gasket shall be permanently located between the cover and the tank flange to prevent weld spatter from entering the tank. Flanged horizontal joints which must be broken to untank the core and coil shall be designed for breaking and remaking in the field.

The tops of the tank and all compartments shall be slightly sloped or crowned to prevent water accumulation. Two 24-inch diameter access cover openings, gasketed and secured with bolts, are required on the top cover of the transformer, located diagonally opposite corners of the tank.

These access covers shall be raised 3” above tank top with bolted flanges.

2. The tanks, except auxiliary tanks vented to the atmosphere, shall be capable of withstanding, without leakage or permanent distortion, an internal pressure of 15-pounds-per-square-inch gauge and of withstanding a vacuum which produces a differential pressure of 15 pounds per square inch across the tank wall. Auxiliary tanks shall be capable of withstanding a differential pressure of 15 pounds per square inch.

3. The interior of the main tank shall be painted with a non-hydroscopic white paint. Manufacturer shall ensure that the paint is non-toxic and compatible with long-term exposure to high temperature oil. In addition, the paint is not to deteriorate with temperature and release combustible gases.

4. All flanged joints shall be provided with gaskets set in machined grooves to prevent over compression of the gaskets. The gaskets shall be of Viton or nitrile rubber which will not deteriorate under the action of hot oil and will remain oil-tight at temperatures up to 120 degrees.

All gaskets shall be one-piece. Glued gaskets are not acceptable. Gaskets consisting of cork material are not acceptable.

5. All flanges, valve fittings, compartments and accessories which are removed for shipment or are to be installed in the field shall have bolted connections using recessed retained type reusable gaskets made of viton or nitrile rubber.

6. Unless otherwise approved by the Contracting Officer, all piping connections shall be made with flanged joints. Flanges shall be welded to pipe sections and bolted together with suitable gaskets. All valves shall be mounted to the tank with flanged connections. Access to openings shall not be blocked by conduit, piping, or accessories. All valves and pipe flanges must be designed with gaskets that can be easily replaced in the field.

7. Grooves for O-rings shall be located on the upward facing flange, where practical.

8. All doors, access covers, and hand hole covers shall be gasketed with recessed-type, reusable gaskets using bolted-type construction.

9. No leads or lead support structures shall limit entry into the unit for internal inspections. The internal arrangement of the core and coil assembly shall permit personnel entry in the transformer for visual inspection of the complete core and coil assembly, series transformer, lead structure, etc.

10. The transformer bushing turrets and unfilled access covers shall be designed to channel all gases to a gas accumulation relay.

11. Stiffeners required for the tank shall be selected and arranged in order to minimize the collection of dirt particles, rain, or snow.

12. Lifting lugs and jacking pads shall be suitable for lifting a transformer full of oil by crane or by jacks and shall be designed in accordance with IEEE C57.12.10 clause 5.3. Sharp edges shall be eliminated from all points with which the lift cable makes contact during normal lifting operations. Jacking pads (plates) at least 12 inches in length shall be located on the tank walls as near to the corners as possible and shall be suitable for jacking the complete transformer filled with oil. The tank walls below the level of the pads shall be free from obstructions (valves, cooler pipes, etc.) for the length of the pads plus 6 inches from each end of the pads. The jacking pad dimensions shall be shown on the transformer outline drawing. Lifting eyes and hooks shall have a minimum inner diameter of 6 inches.

13. Lifting eyes shall be installed on the tank cover for lifting the tank cover by itself. Lifting eyes shall have a minimum inner diameter of 6 inches.

14. The location of the centers of gravity, (c.g) shall be permanently marked on two adjacent sides of the transformer tank of the completely assembled transformer and filled with oil and appropriately identified “c.g. complete”. The location of centers of gravity, (c.g) shall be permanently marked on two adjacent sides of the transformer tank for shipment without oil and shall be appropriately identified “c.g. for shipment”.

15. Non-skid paint shall be applied to the top of the transformer tank cover. Non-skid paint shall not be applied to tank access covers, bolts, nuts, and other removable hardware.

16. To minimize tripping hazards on top of the transformer, the transformer manufacturer shall limit obstacles on the top of the transformer and limit obstacle height to a maximum of 12 inches above the top of the tank (bushings are exceptions); piping and conduit shall be routed around the outside of the tank. If piping and/or conduit is required on the top of the transformer, WAPA will have final approval of location.

17. The construction of the main tank, auxiliary tanks, and the oil-preservation apparatus shall be such as to insure an adequate cushion of gas in applicable parts of the apparatus for the following conditions:

a. INTERNAL GAS PRESSURE: For any of the systems of oil preservation, except the sealed tank system, the internal gas pressure shall be not less than 0 pounds per square inch nor more than 6.5 pounds per square inch, with transformer temperature changes attained between de-energized condition and up to 110 percent maximum rated load condition with an ambient air temperature range as specified in solicitation. For the sealed tank system, the internal gas pressure limits may be increased to those values given in IEEE C57.12.10, paragraph 5.7.

b. LOSS OF GAS OR OIL: If a constant pressure system is furnished, the system shall operate without the loss of oil and without the loss of the seal between the transformer interior and the atmosphere over the entire temperature range specified from minus 40 degrees C to plus 55 degrees C and the entire range of operating conditions. The main transformer tank shall be constructed to withstand the range from full vacuum to the maximum oil pressure that will be exerted during oil filling, oil processing, and vacuum processing to remove moisture and to withstand all operating conditions from de-energized up to 110 percent of maximum rated load.

1.12 BASE:

1. The transformer tanks shall be provided with a fabricated structural-steel base. The base shall be provided with pulling eyes to permit pulling the transformer and shall be designed in accordance with IEEE C57.12.10 clause 5.3. The base shall be designed and built to allow skidding or moving on rollers in either direction. Flat plate bases without internal or external reinforcing structural members are not acceptable.

2. Transformer bases shall be designed to permit anchoring to the concrete foundation by means of welding to embedded steel members to be furnished by the Government. The Contractor shall show, on an informational outline drawing, the location, size, type, and lengths of anchor plates and weld patterns, including foundation loads for each anchorage assembly and the foundation overturning moment, so that the Government can complete its foundation design in advance of shipment. These information drawings shall be provided per Table A.

1.13 COOLING EQUIPMENT:

1. Forced-cooling equipment shall be used and be grouped electrically in not less than 2-groups per stage of cooling so that loss of any group will cause a negligible reduction in forced-cooling effect. Each group is to have individual motor contactor and breaker protection. Cooling pumps are not acceptable.

2. The auxiliary power supply for cooling equipment will be single- or three-phase at nominal 208Y/120 VAC, 60Hz. One feeder circuit will be provided to the transformer control cabinet for all auxiliary power needs (see control cabinet specification section for more detail).

3. Transformer shall be designed with radiators or cooling units to ensure operation at the ratings and temperature rise indicated in this specification. The radiators or cooling units shall be constructed to withstand full vacuum to the maximum oil pressure that is experienced during oil filling procedures and worst case operating conditions.

4. Cooling units shall be designed for installation without special bracing and constructed such that excessive vibration will not develop from internal or external sources. All units shall be of materials with melting points in excess of 1000°C; the material used for welding or brazing shall also have melting points in excess of 1000°C.

5. Cooling units shall be connected to the tank by bolted, machined steel flanges, with the flanges welded to the cooling units and to the tank. Flanges shall be provided with gaskets and valves and shall be installed on each cooling unit connection, so that any individual cooling unit may be removed without taking the transformer out of service. An oil-tight, blank flange shall be provided for each connection, for use when cooling units are detached.

6. Each cooling unit shall have a lifting eye, an oil drain, and a vent. If the cooler units furnished are of the finned-tube type, the tubes, fins, and tube sheets shall be designed to permit replacement of individual cooler tube groups. The finned tube assembly tubes and fins shall be unpainted and shall be galvanized steel. Cooling units shall be flushed clean with transformer oil prior to shipment.

7. Transformer shall be capable of operating with the conditions outlined in IEEE C57.91, paragraph 9.8. Sufficient cooling equipment shall be provided to operate the transformer at full rated capacity without exceeding the guaranteed temperature rise. Forced air cooling shall be accomplished by using fans.

8. FANS:

a. All fans shall be equipped with guards having no more than ½-inch spacing in accordance with OSHA requirements and shall be designed for outdoor use. Fans shall be factory mounted on the cooling units with all wiring terminated in a control cabinet on the base of the cooling unit. Fan motors shall be of the totally enclosed design. Fans shall be mounted on side of cooling units. Fans shall not be mounted on undersides of radiators.

b. The leads for the fan motors shall be enclosed in liquid-tight, flexible metal conduit. As an alternate, the connections to the supply circuits may be made by means of watertight plugs and receptacles provided the interconnecting cables are mechanically protected by use of ducts or flexible conduits. Flexible conduit and cable shall be sunlight resistant and not require replacement for at least 30 years.

9. CONTROL EQUIPMENT FOR FANS:

a. Automatic control equipment shall be provided for starting and stopping control for each stage of cooling. The control equipment shall include a circuit breaker for the incoming circuit, a circuit breaker for each stage group of fans, contactors with overload protection in each phase, MANUAL-OFF-AUTOMATIC control switches for each fan group, STAGE 1-STAGE 2 selector switches for fan groups, and any other necessary devices.

b. The Contractor shall furnish all control transformers, fuses, circuit breakers, indicating lamps, terminal blocks, magnetic-type starters, fused or un-fused disconnect switches, test pushbuttons or switches, and auxiliary and timing relays for the control, protection, annunciations, and remote indication of the fans. All fuses and circuit breakers shall be capable of accepting lock out tag out (LOTO) locks.

c. Fuse cartridges and their clips shall be mounted inside the cover of the fuse enclosure and shall be disconnected from the circuit when the cover is removed for fuse replacement.

1.14 STANDARD ACCESSORIES:

The contacts of all relays, gauges, control devices, and thermometers shall be insulated from ground and shall be of a positive, snap-action type. Mercury-type relays and contacts are not acceptable.

All relays and contactors shall be provided with covers. Contacts should close for abnormal conditions and shall be wired to terminal blocks for external cabling to control room building. Each of these contacts shall be rated for 125 V dc.

The leads from all gauges shall be run to the main control cabinet in rigid metal conduit and be appropriately terminated. A short section, maximum of three-foot length, of sunlight-resistant liquid-tight flexible metal conduit can be used on the device end.

All gauges and meters shall be calibrated in United States Standard designation; i.e., pounds per square inch, etc. All nameplates and designation labels shall be in the English language.

Transformer shall be equipped with the following listed accessories (Items 1 – 17):

1. RESISTANCE TEMPERATURE DETECTOR(S) (RTD’s): Resistance temperature detectors shall be provided to measure top oil temperature in the main tank and ambient temperature.

a. Two RTD’s shall be provided for the top oil temperature for redundancy.

b. RTD’s shall be 3 or 4 wire 100 ohm platinum Class A sensors and shall be wired as inputs to transformer monitoring system specified elsewhere.

2. SUDDEN PRESSURE RELAY: A separate sudden pressure relay complete with seal-in relay and control switch shall be provided for each transformer. The relay shall be a Qualitrol type Model 900-010 or equal and shall be mounted to the transformer with a full-flow ball valve. The seal-in relay shall be a Qualitrol Model 909-300-01 or equal. The relays shall be actuated by sudden pressure rise inside the main tank and shall not operate on gradual pressure change within the normal operating range of the transformer.

a. The sudden pressure relays, auxiliary relays, and control switches shall be mounted in such a way that mechanical vibration, such as that due to a close-in fault, will not cause false operation of the relay scheme.

b. The relaying scheme shall provide two normally open, electrically separate contacts, one for tripping and one for alarm. A control switch shall be mounted in the terminal cabinet on the transformer and shall be wired in series with the tripping contact of the seal-in relay to cut out the tripping function of the sudden pressure relay during maintenance. This switch shall be an Electroswitch series 24.

3. PRESSURE-RELIEF DEVICE ON THE MAIN TANK: A pressure relief device shall be included on the main tank of the transformer and the LTC tank if applicable. The device shall be self-resetting, without the use of expendable parts. The device shall have directed oil flow. The device, and all parts thereof, shall have a service life comparable to that of the transformer of which it is a part. Semaphore and alarm contacts shall be provided on the device to give visual and electrical indication of operation. The pressure relief device shall be in the Messko MPreC series (or equal) and sized for the transformer.

4. VALVES: All valves except radiator isolation valves and drain valves with sampling ports shall be full port ball type. Drain valves with sampling ports may be globe or ball type. Radiator isolation valves may be butterfly or ball type. Valves shall be readily accessible and shall be full vacuum rated. The valves should be lockable in both open and closed position. Welded or flanged valves shall have a carbon steel or stainless steel body. Ball valves shall be of two-piece construction (multi-piece bolted bodies are unacceptable.) and shall consist of stainless steel ball, stem, and packing nut.

a. One 2-inch diameter drain valve with sampling port is required for each main tank. One 1-inch diameter drain valve is required for each accessory compartment, including cooling unit bottom and top headers.

b. One 2-inch diameter fill valve is required for each main tank.

c. One oil sampling valve for each main tank and each oil filled compartment is required.

Sampling ports integral to drain valves are acceptable for this requirement.

d. One 1-inch diameter ball valve is required on the top and bottom of each cooling unit header assembly. The open-end valve shall be capped with either a plug or cap with National Pipe Threads (NPT).

e. One 4-inch diameter vacuum valve shall be mounted to the conservator tank with vacuum port at a downward angle or the top of the main tank with vacuum port parallel to the ground arranged for ease of connecting vacuum lines. A 1-inch ball valve, for vacuum gauge connection during vacuum processing and filling or tank venting purposes, shall be installed vertically on the top of the main tank in a convenient location.

f. A 1-inch diameter ball valve for pressure equalization of conservator air cell and oil space during vacuum processing and oil filling shall be installed.

5. OIL LEVEL GAUGE: A MESSKO MTO series liquid level gauge, or WAPA approved equivalent, shall be provided for each oil filled compartment. Every effort shall be made to make these gauges visible from ground level. This device shall have one low-level contact for alarm and one additional lower-level (critical level) contact for tripping.

6. UPPER AND LOWER FILTER-PRESS CONNECTIONS.

7. LIQUID THERMOMETER: The dial-type liquid thermometer gauge/relay (26 Q) shall have adjustable alarm and trip contacts set at 80°C and 85°C, respectively, for 55°C temperature rise, or as recommended by the transformer manufacturer. Preferred type of device includes the MESSKO COMPACT series.

8. WINDING TEMPERATURE RELAYS & WINDING HOTSPOT DETECTORS: The autotransformer shall be furnished with a winding temperature relay, plus a current transformer and a heater well, which shall be installed in each winding, of at least one phase of the 3 phase transformer, and shall be responsive to the loading in such winding.

a. Each relay shall be equipped with a minimum of four electrically separate, adjustable sequence contacts set to represent hotspot winding temperatures of 70ºC, 80ºC, 95ºC and 105ºC, or as recommended by the transformer manufacturer, to typically operate fan stage 1, fan stage 2, alarm, and trip, respectively. For maximum durability, interposing relays shall be used to switch inductive loads. Each relay shall be furnished with a dial-type thermometer on the tank for hotspot indication. Preferred type of device includes the MESSKO COMPACT series. Accessory equipment shall also be furnished for automatic control of the cooling equipment, if furnished, from the winding temperature relays.

b. A winding hotspot temperature detector shall be furnished on each winding (on at least one phase of each of the 3 phases of the autotransformer. The winding hotspot temperature detector shall work as part of or in conjunction with the winding temperature relays. The heaters for the detector shall be connected in series to the secondary of current transformers which have as their primary the (series, common, and tertiary) windings of the autotransformer. The heaters shall be located in the oil near the top of the autotransformer.

The detector shall be calibrated to reflect the maximum hotspot temperature that can occur in any winding in any tap position.

9. DIAGRAMMATIC NAMEPLATE: The transformer shall be provided with stainless steel nameplates, which shall be sun and fade resistant. Nameplate information shall be etched, stamped, or engraved into the metal. The nameplates shall be located approximately 6 feet above the base on the tank wall or control cabinet door.

a. The rating nameplate is to include all the information as required by IEEE C57.12.5.12, Table 6. In addition to these requirements, the following should also be on the rating nameplate:

1) Main tank shipping weight without oil and oil filled.

2) Radiator weight without oil and oil filled.

3) Oil volume in main tank, radiators, and conservator.

4) Current transformer ratio at all taps with accuracy classification, location, primary current ratings, and thermal rating factor.

5) Maximum elevation design (feet).

6) The amount of vacuum (inches) and positive pressure (psi) the tank, radiators/coolers and conservator will withstand; (maximum operating pressure of liquid preservation system).

7) The contract number.

8) Induced voltages: one hour ____enhanced _____for each winding.

9) Applied voltage (kV RMS):_____for each winding.

10) Maximum short-circuit current (kA) asymmetrical current for each winding.

11) Bushing BIL

12) Zero Sequence Impedance

13) The operating temperature range and emergency rating capability as specified under the

Operating Conditions

14) Seismic rating in accordance with IEEE 693.

b. Each bushing shall have a nameplate indicating the manufacturer, type, catalog number, and rating including its tested capacitance values and power factor.

c. A Valve and Piping nameplate clearly showing all pipe and valve locations and sizes, including LTC oil filtration system if required, shall be provided.

d. The transformer serial number shall be stamped into the main tank, jacking pad, and on the conservator tank.

10. GROUNDING PADS AND CABLE: Two copper or stainless steel grounding pads shall be furnished on diagonally opposite sides near the base of each transformer tank and terminal connectors suitable for 4/0 AWG through 500 kcmil copper cable for each pad. In addition, one grounding pad and terminal connector shall be mounted on the transformer tank near the base of each set of arresters and the neutral bushing. The Contractor shall provide bare copper cable, neatly supported, from each of the two grounding pads at the base of the transformer tank up to the arresters and neutral bushing pads interconnected at the top of the tank. The minimum size of copper cable to be furnished for the transformers is 4/0 AWG copper cable. The grounding cables shall be arranged to create a complete copper cable loop from one ground pad at the base of the transformer up to the grounding connections on the top of the transformer and down to the second ground pad at the base of the transformer. For certain locations, 500 kcmil will be required.

11. GAS ACCUMULATION RELAY (BUCHHOLZ RELAY): The BUCHHOLZ relay shall be a

MESSKO MSAFE or WAPA approved equal and have an alarm contact responsive to low levels of gas accumulation and a tripping contact responsive to both sudden oil flow and excessive gas accumulation. The tripping contact shall be wired to a Qualitrol Model 909-300-01 or equal seal-in relay. The seal-in relaying scheme shall provide two normally open, electrically separate contacts, one for tripping and one for alarm. A control switch shall be mounted in the terminal cabinet on the transformer and shall be wired in series with the tripping contact of the seal-in relay to cut out the tripping function of the Buchholz relay during maintenance. This switch shall be an Electroswitch series 24. Full-flow ball valves shall be installed in the piping on each side of the Buchholz relay to facilitate testing, inspection, and replacement of the relay.

12. WEATHERTIGHT BREATHER: The breather shall be equal to the Messko MTraB series operating at 120 VAC and sized correctly for a transformer specified with conservator tank.

13. SUMP CHAMBER AND DRAIN VALVE IN RESERVOIR TANK.

14. ELECTRONIC TEMPERATURE MONITOR: The transformer shall be equipped with a Schweitzer Engineering Laboratories (SEL) 2414 transformer monitor (model number: SEL 241421ABA91743A1030) to monitor the top oil and winding temperatures.

a. The RTD’s for the top oil temperature and ambient temperature shall be wired into the SEL

2414. A set of 3 phase currents from the hot spot (H, X, and Y voltage) bushing CT’s shall be wired into the SEL 2414 to monitor winding temperature. The monitor shall be powered by its own dc supply circuit protected by a circuit breaker.

b. The SEL 2414 shall be programmed for cooling stages, alarm, and trip points respectively for a transformer designed for a 65C temperature rise. The installation and programming of the SEL 2414 shall be done in accordance with the SEL 2414 instruction book and shall be housed in the main control cabinet.

c. The contractor shall also mount and wire a States brand test switch (part number: FMS-

10A1) below the SEL 2414 for use of cooling stages, alarm, and trip points.

15. FIBER OPTIC TEMPERATURE MONITOR: The transformer shall be equipped with the following fiber optic temperature monitor:

a. Rugged Monitoring T301 (model number: T301-08-E2-A8-R8-M4) with Rugged Monitoring

TSENS fiber optic temperature sensors. The sensor probe and accessories located in the main tank are to be free of metallic parts and compatible with winding hot-spot temperature (200°C).

b. The 8 fiber optic probes shall be embedded and installed at each winding hot spot per transformer manufacture’s recommendations. At a minimum, probes shall be embedded in the winding where the temperature is the highest and where the oil temperature in a winding cooling duct is the highest. The manufacturer is to submit data showing where the probes are located.

c. Fiber-optic cable is to be protected in a rigid insulating tube and routed to the tank wall or cover penetration. The fiber-optic cables are to be brought out of the main tank through and oil-tight pod. The fiber-optic cables shall be run to the main control cabinet in a conduit separate from other cables.

d. The monitor shall be powered by its own separate dc supply circuit protected by a circuit breaker. The analog outputs shall be wired into the SEL 2414 analog inputs if provided. The transformer manufacturer shall install the monitor in compliance with the manufacturer’s specifications and recommendations as it applies to each transformer and shall be housed in the main control cabinet.

16. ELECTRONIC ON-LINE DISSOLVED GAS ANALYZER AND BUSHING MONITOR: A Camlin Power TOTUS TTM9 (model number: T1-G9INT9) shall be provided and shall be able to monitor through fault current and include direct fiber optic connections for communications. The monitor shall be installed in compliance with the manufacturer’s specifications and recommendations as it applies to this transformer. Any auxiliary equipment necessary for the proper installation, operation and remote communication to the monitoring equipment is the transformer manufacturer’s responsibility (sensors, leads, aux relays, oil lines, fiber patch cables, etc).

Software to setup, interrogate, retrieve and view data shall be provided. On-site training for maintenance personnel shall be provided when the monitor is commissioned by the factory representative. One complete set of programming/monitoring software shall be provided to

WAPA.

17. FIBER-OPTIC TERMINATION AND INTERCONNECTION CENTER: Corning WIC-012 Fiber Wall-mount Interconnection Center with multimode ST inserts shall be mounted in the same control cabinet where the monitoring equipment described above is located. Fiber entryways shall be kept clear of terminal blocks, auxiliary relays, wire bundles, etc.

18. ACCESS COVERS:

a. Access holes of at least 16 inches minimum diameter shall be furnished to provide easy access to the bushing current transformer terminal boards and lower ends of bushings.

Bushing mounting plates shall be of sufficient size to permit the removal of bushing current transformers.

b. Access holes, manholes, or hand-holes shall be provided to allow connecting the winding leads to bushings when bottom connected bushing are provided. The manholes or hand-holes shall allow making the winding to bushing connection without requiring a full confined space entry into the transformers.

c. The access holes, and all other openings, in the tank cover employing gaskets or O-rings, shall have flanges raised a minimum of 3 inches above the cover surface to prevent the accumulation of water around the gasket joints and facilitate installation of any devices on the flange surface requiring nuts and bolts.

d. Each access hole shall have a bolted gasketed cover with lifting handles. Access holes on tank top not designed to channel generated gases shall be filled with solid dielectric.

e. Oil filled compartment mounted on the side of the tank shall have a 3/8-inch minimum raised lip along the bottom edge to prevent dripping of oil with the cover removed.

f. Where access to the tank bottom alongside the core and coils is available to a person, a rectangular opening of sufficient sized to permit entry of a 24-inch sphere shall be provided for emergency evacuation of a disabled and possibly injured or unconscious person. The location of such openings shall be approximately 24-inches above the transformer base.

19. FACILITIES FOR LIFTING CORE AND COIL ASSEMBLY INTO AND OUT OF THE MAIN TANK

1.15 CONTROL CABINETS AND TERMINAL BOXES:

1. The Contractor shall furnish and install one main control cabinet for the transformer and all other cabinets for auxiliary devices where needed. A separate CT control cabinet shall be used if space requirements cannot be met in the main control cabinet and shall follow all requirements of the main control cabinet. All cabinet(s) shall meet the NEMA Type 4x rating and shall have a continuous hinged door(s) with a single, heavy-duty, lockable handle. The door handle shall include provisions for attaching a padlock with a 3/8” diameter shackle for locking. All doors shall be full width of the cabinet. All cabinet hardware (locking devices, handles, and hinges) shall be stainless steel. The height, width, and depth of the cabinets, and the bottom of the cabinets to the base of the transformer dimensions, shall be shown on the outline drawing of the transformer.

2. The main control cabinet shall meet IEEE C57.148 unless specified elsewhere. The main control cabinet door(s) shall have a minimum of three latching contact points located at the top, middle, and bottom of the door and shall have a device that automatically latches the door in the open position at a minimum of 130° and requires manual action to disengage it to close the door.