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THREE PHASE PADMOUNTED TRANSFORMER TRAINING
•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
What is a Three-Phase Pad Mounted Transformer?
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
What is a Three-Phase Pad Mounted Transformer?
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 2500KVA’s
The outside of a Three-Phase Pad Mounted Transformer
Side View of a 150KVA Pad Mounted Transformer
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
The Inside of a Three-Phase Pad Mounted Transformer
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, middle is zero boost)
Bayonet Fuses, Protect Primary Side of Transformer
Primary Compartment
Load Break Elbows
Sizes: #2, 1/0, 3/0
Lightning Arrestor Elbows (radials, and open points)
Static Drain Wires (#14, and #10 Cu.)
Grounding Loop #2BTN, One HLC
Primary Bushings
Standoff Bushing Slots (open point)
Inside a Three-Phase Pad Mounted Transformer
Primary L/B Elbow
Load Break Elbow, Bushing, Static Drain Wire, and Primary Cable
Detail in Spec. Package
Follow Mfg. Instructions
Pulling Eye
Test Point, & Cap
5’ of Taped Neutral
#2 EPR Insulated May be Hylinked
Sealing Strip, 36” Below Hose Clamp
Inside a Three-Phase Pad Mounted Transformer
Primary Bushing
Supplied by LIPA with L/B, L/A Elbow
Screws in
Must be Kept Clean, Contamination Will Cause Electrical Failure
#14 Static Drain Wire From Eyelet to Grounding Split Bolt
L/B Elbow Should Cover Yellow (now RED) Band
Inside a Three-Phase Pad Mounted Transformer
Secondary Compartment (right side)
Secondary Spades; X0, X1, X2, X3
Nema 2 Hole Lugs (tinned alum. Or Cu.)
Al Lug - Extra Belleville Washer Req
Oxide Inhibitor on Al
Cu to be Tinned, or Alloy plated
750 Cu now Accepted
Buss Supports
Inside a Three-Phase Pad Mounted Transformer
Secondary Compartment
Color Coding
120/208v or 277/480v
Integrated/Isolat ed
8 Sets Max
Grounding Pads, Loop, Split Bolts, Ground Rods
Oil Drain Valve
Inside a Three-Phase Pad Mounted Transformer
Secondary Compartment
•Pressure Relief Valve
•Do Not Pull•Oil Fill Level•Oil Temperature Gauge
•Oil Level Gauge
Inside a Three-Phase Pad Mounted Transformer
Nameplate
Identifies Primary and Secondary Voltage
Indicates Voltage on Different Tap Settings
Shows Internal Coil Configuration
Indicates Transformer Weight
Indicates Transformer Impedance
Inside a Three-Phase Pad Mounted Transformer
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
Inside a Three-Phase Pad Mounted Transformer
What are its Applications?
Typical for Large Load, Non- Residential Customers; Long Distance From Existing Facilities; and Looped Commercial Industrial Parks
Pad Mounted Transformers are LIPA’s Standard Installation, Non-Standard is Submersible, or Network
Transformer is Delivered, Owned, and Maintained by LIPA for Secondary Metered Service
How is the Three-Phase Pad Mounted Transformer Installed?
Set on a Three Piece Vault, Always Provided by 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 it onto Vault
How is the Three-Phase Pad Mounted Transformer Installed?
Boom Truck
Can Deliver All Transformers
Line Truck
Delivers up to 500 kVA
Who Wires the Three-Phase Pad Mounted Transformer?
LIPA Provides
Three Load Break Elbows (rated for 200 ampere)
Three Lightning Arrestor Elbows
With Three NEMA 2-Hole Lugs
One Hot Line Clamp
Bushings Come as a Pair With L/B Elbow and L/A Arrestor Elbow
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 Bolts
CIPUD Installation
Contractor Supplies and Wires Secondary
LIPA Wires Primary & Grounding
Who Wires the Three-Phase Pad Mounted Transformer?
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
Primary Cables
Phases Must be Identified (1, 2, 3 rings), on Both Extremities
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
Specification Package Details
Secondary Services
480v - One Service
Exception: Fire Pumps
208v - Multiple Services
Services Must be LabeledCables
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
Specification Package Details
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
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
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QUESTIONS
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