Pad Mounted Threephase Transformer

8/11/2019 Pad Mounted Threephase Transformer

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What is a Three-Phase Pad Mounted Transformer?

What are its Applications?

How is it Installed?How is it Wired?

The Specification Package

The Specification Letter

Miscellaneous

What We Will Cover


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Outside

Metal Encased, Tank, Fins, Cabinet

Sits on a Three Piece Vault

Fragile Enclosure, Not for Storage

Inside Contains

Oil Tank, Windings, Terminals

Primary and Secondary Compartments

Grounding Loop

Cables and Terminations


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Steps Down Primary Voltage to Secondary

Primary Side (4kV, 13kV, or both)

Secondary Side (120/208v, 277/480v)

Three Phase Wye Configuration Only

Pad Mounted, or Submersible

Di-Electric Fluid (insulates and cools)

LIPA Sizes Range From:

75KVA to 1000KVA for 120/208

75KVA to 1500KVA for 277/480

Special Order 2500KVAs


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The outside of a Three-Phase Pad Mounted Transformer

Side View of a 150KVA Pad Mounted Transformer


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The Outside of a Three-Phase Pad Mounted Transformer

Orientation Away From Building

Clearances

5 From Transformer to Building Wall

10 to Vent Openings, Doors, Windows

25 to Non-Fire-Rated Openings

Auditorium Exits

Truck Accessible (delivery & removal purposes)

NEC Class 1, Division 1, and 2 Locations Shall Require a

Minimum 25 ft. Clearance (oil, gas, etc)

Set Vault Level, Grade to Slope Away

Traffic Protection


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The Inside of a Three-Phase Pad Mounted Transformer


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Inside a Three-Phase Pad Mounted Transformer

Primary Compartment(left side)

Primary Connections(radial, or loop)

Incoming - H1C, H1A,H1B

Outgoing - H2B, H2A,H2C

No Load Tap Changer

A Through E (2.5%increments, middleis zero boost)

Bayonet Fuses, ProtectPrimary Side ofTransformer


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Primary Compartment

Load Break Elbows

Sizes: #2, 1/0, 3/0

Lightning ArrestorElbows (radials, and

open points)

Static Drain Wires(#14, and #10 Cu.)

Grounding Loop

#2BTN, One HLC

Primary Bushings

Standoff BushingSlots (open point)



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Primary L/B Elbow

Load Break Elbow, Bushing,Static Drain Wire, and PrimaryCable

Detail in Spec. Package

Follow Mfg. Instructions

Pulling Eye

Test Point, & Cap

5 of Taped Neutral

#2 EPR Insulated May beHylinked

Sealing Strip, 36 Below HoseClamp



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Primary Bushing

Supplied by LIPA withL/B, L/A Elbow

Screws in

Must be Kept Clean,Contamination WillCause ElectricalFailure

#14 Static Drain WireFrom Eyelet toGrounding Split Bolt

L/B Elbow ShouldCover Yellow (nowRED) Band



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Secondary Compartment(right side)

Secondary Spades;X0, X1, X2, X3

Nema 2 Hole Lugs(tinned alum. Or Cu.)

Al Lug - ExtraBelleville Washer Req

Oxide Inhibitor on Al

Cu to be Tinned, orAlloy plated

750 Cu now Accepted

Buss Supports



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SecondaryCompartment

Color Coding

120/208v or

277/480v

Integrated/Isolated

8 Sets Max

Grounding Pads,Loop, Split Bolts,Ground Rods

Oil Drain Valve



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SecondaryCompartment

Pressure

Relief ValveDo Not Pull

Oil Fill Level

Oil

TemperatureGauge

Oil Level

Gauge



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Nameplate

Identifies Primary andSecondary Voltage

Indicates Voltage onDifferent Tap Settings

Shows Internal CoilConfiguration

Indicates TransformerWeight

Indicates TransformerImpedance



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Common equipment

Primary Cable

Sizes: 3-2/c#2, 1/0, 3/0

Secondary Cable

Sizes: Minimum #2, Maximum 750

Maintain 5 min. Slack in Vault

Maintain as Much Physical Separation as Possible

Grounding Pads, Lugs, and Split Bolts

Bare #6 Cu to Ground Rods

Bare Tinned Copper #2 for Ground Loop



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What are its Applications?

Typical for Large Load, Non-Residential Customers; Long

Distance From ExistingFacilities; and LoopedCommercial Industrial Parks

Pad Mounted Transformers areLIPAs Standard Installation,Non-Standard is Submersible, orNetwork

Transformer is Delivered,Owned, and Maintained by LIPA

for Secondary Metered Service


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How is the Three-Phase Pad Mounted TransformerInstalled?

Set on a Three Piece Vault, Always Providedby Contractor (see approved vendor list)

Pad Orientation

Primary Side, Secondary Side

Doors to Face Away From Building

10 Clear in Front of Pad for Switching

Grade Away 1% Slope

Old Way Poured Foundation (slab) Primary and Secondary Cables Have no

Slack

Boom Truck Delivers Transformer, Lifts itonto Vault


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How is the Three-Phase Pad Mounted Transformer

Installed?

Boom Truck

Can Deliver All

Transformers

Line Truck

Delivers up to500 kVA


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Radial Installation

Contractor Installs Primary and Secondary Cable

Contractor Wires L/B and L/A Elbows

Contractor Makes Secondary Connections

Contractor Wires All Grounding

Contractor Supplies Secondary Lugs, Static Drain

Wires, Ground Rods, Ground Wire, and Grounding

Split BoltsCIPUD Installation

Contractor Supplies and Wires Secondary

LIPA Wires Primary & Grounding

Who Wires the Three-Phase Pad MountedTransformer?


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Specification Package Details

Provides Information Common to All Jobs

Pad Specifications, Vault Details

Primary Side, Secondary Side

Contractor to Discuss Location Before Pad is Set

Knock Outs: 4 PVC Sleeve Flush With Wall, Concreted in Place

Duct Seal or Cap Unused Conduits

Galvanized Conduits Require Bonding

Protection From Traffic

Bollard 3.5 Heavy Steel Wall (minimum)

Concrete Filled

Must be Painted Yellow

Doors Must be Able to Open

Required on All Sides Subject to Vehicular Traffic


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Primary Cables

Phases Must be Identified (1, 2, 3 rings), on BothExtremities

15kV Tree-Retardant Cross-Linked Polyethylene for

Aluminum (TR-XLPE)

Ethylene Propylene Rubber (EPR) for Copper

Semi-Con 12 Mil

Insulation 220 Mil, Insulation Shield 30 Mil Semi-Con

Jacket 50 Mil Semi-Con



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Secondary Services

480v - One Service

Exception: Fire Pumps

208v - Multiple Services

Services Must be Labeled

Cables

480v (must be installed in conduit)

USE-2, XHHW-2, or RHW-2

8 Sets Max

208v

USE-2, THW-2, THWN-2, XHHW-2, or RHW-2*

*With neoprene or hypalon jacket only



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Three-Phase Specification Letter

Gives Project Specific Details, Such as:

Reiterates Customer Load Letter

Designated Riser Pole, or Point of Termination

Describes Cable Ownership

Provides Costs, if Any

Inrush Information, Motor Starting Limitations

Restates Basic Installation Rules,

Call Before You Dig

Repeats Primary and Secondary Cable

Specifications


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Miscellaneous

Provide Advance Notification of Projects

Access to an Energized Vault is Forbidden

Industrial Code Rules 753, and 57

These Requirements Conform to the NEC

Contractor to Comply With:

Applicable Codes

Three Phase Transformer Spec. Package

Redbook

Lists Distribution Design Representatives

www.lipower.org


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QUESTIONS

?

Documents

Pad Mounted Threephase Transformer