Welcome to
Switchgear Solutions Ltd.
“Comparing Transformers:
Applications, Types &
Accessories”
Presented by:
Scott St. Pierre
VP Sales & Marketing
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@SwitchgearSol
WHO ARE WE?
Switchgear Solutions Ltd. (SSL) was established in 2004 as a manufacturers’ representative
specializing in power distribution products with particular focus on design, engineering, specification,
and application. With 10 years of experience at Siemens Energy & Automation and 2 different
electrical distributors in the NYC market, Steve Mowery returned to his hometown of Lancaster, PA to
start a business from the ground up. Having no previous experience in the Pennsylvania market,
SSL first began its’ business model by offering services, field site surveys, system studies, and a
handful of distribution products including several sub-represented lines to our existing NY/NJ
customer base while growing our relationships with distributors, contractors, agencies, consultants,
and endusers in the PA/DE market. With hard work, diligence, attention to detail, and most
importantly a dedication to customer service and response, SSL began to capture market share and
therefore offer great value to quality manufacturers looking for representation in our markets.
It has always been our focus to represent quality, technical electrical distribution equipment
manufacturers that complement each other and allow us to package our partners to the market
portraying each manufacturers’ individual strengths as a total package offering. From a 138KV
incoming dead-end structure to a 208V retrofit panel and all points in between, it has always been
our commitment to add value to every phase of the project including the system studies and field
start-up. SSL was built on the idea of rolling our sleeves up and getting involved with our customers
to make sure that the project is done quickly, cost effectively, and with attention to detail and quality
that set us apart from our competitors. With recent personnel additions including market vice
presidents, insides sales staff, project managers, and engineering, we continue to position ourselves
to support our growing markets and customer base over many years to come. Our success is
directly tied to our performance and the satisfaction of our customers.
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WHAT DO WE PACKAGE?
High Voltage Distribution
Substation / Switchyard Packages including the following scope:
Steel Structures, Aerial Bus, Insulators, Connectors, Air Switches, CT’s, PT’s, Surge Arresters,SF6 Dead Tank
Circuit Breakers, Control Houses with Protection & Control including Relaying, Metering, and SCADA
Medium Voltage Distribution
Metal Enclosed Load Interrupter Switchgear, Low Profile Pad Mounted 15 & 25KV Switch & Fuse, Custom
Metal-Clad Drawout Circuit Breaker Switchgear, Utility Primary Metering Cubicles, Arc Resistant Switchgear,
Paralleling Switchgear, Catenary Switchgear, Generator Breakers, Shore Power & Mining Skidded
Substations, MV Segregated & Non-Segregated Busway
Low Voltage Distribution
UL 1558 & UL 891 Drawout Circuit Breaker Switchgear & Switchboards, Unit Substation Secondary
Switchgear, Generator Connection Cabinets, LV Segregated & Non-Segregated Busway
Transformers
Medium and Large Power Transformers (5MVA to 650MVA/750kV), UL Listed Cast Coil Transformers, Liquid
Filled Pole & Pad Mounted Transformers, Dry Type Substation/Drive Isolation Transformers, General Purpose
Transformers, Ultra Efficient & Harmonic Mitigating Transformers, Remanufactured/Refurbished Transformers
(Rental/Sale),Transformer Application/Design/Core-coil Replacements/Retrofit Services
Services
Power Systems Studies including Short Circuit, Coordination, Arc Flash & Harmonic Analysis,
Retrofit/Remanufacture/Match & Lineup of Existing Switchgear, Circuit Breakers, & Starters,Start-up &
Testing of Equipment Packages, NYC Advisory Board Submissions,
Seismic Certification
Miscellaneous
Utility and Customer Metering Cabinets, Power Control Centers/Modular Switchgear Enclosures,
Neutral Grounding Resistors, Unitized Substations with Composite Drawings,
Solid State Starters, LV and MV VFD’s, Motor Starters
AC/DC Power Supply & Battery Systems, Battery Chargers, Custom & Complex UPS Designs,
New/Refurbished Circuit Breakers/Switches/Bus Plugs/MCC Buckets/Strap Kits
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Why a presentation on different
types and applications of
transformers?
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Overview of presentation
• What is a transformer?
• Core
• Coils
• Insulation
• Ratings
• Enclosure
• Different types of transformers
• Uses and applications
• Minimum and maximum ratings
• Common accessories
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What is a transformer?
•
A transformer is an electrical device
that transfers energy between two
circuits through electromagnetic
induction and is typically used to step
up or step down voltage.
•
A transformer most commonly
consists of two windings of wire that
are wound around a common core to
provide tight electromagnetic
coupling between the windings. The
core material is often a laminated
iron core. The coil that receives the
electrical input energy is referred to
as the primary winding, while the
output coil is called the secondary
winding.
•
It is also a vehicle or object that can
transform into a robot but that is for
another discussion…
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Core: What is it?
The iron or steel core provides a controlled path for the magnetic flux
generated in the transformer by the current flowing through the windings.
Stacked core being assembled
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Stacked core installed with coils
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Coil: What is it?
Aluminum or Copper conductors are wound into coils. They consist of a
primary winding and a secondary winding. The primary winding induces
voltage through the secondary winding.
Coil being wound
Rectangular wound coils
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Round wound coils installed on core
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KVA/MVA: What is it?
KVA/MVA is "apparent power." They are acronyms for Kilo-Volt-Amps & Mega
or Million-Volt-Amps. It is the sum of real power which are called Watts, and
imaginary power which is called Volt-Amps-Reactive (VAR). Basically,
KVA/MVA is the “size” or “output capacity” of the transformer.
75KVA General Purpose
Transformer
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60MVA Power Transformer
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Volts: What is it?
The difference in electric potential between two points of a conductor when
an electric current of one ampere dissipates one watt of power between those
points.
480V Primary
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69,000V Primary
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Other ratings:
Temperature Rise: What is it?
Transformer temperature rise is defined as the average temperature rise of
the windings above the ambient (surrounding) temperature, when the
transformer is loaded at its nameplate rating.
Impedance (Iz): What is it?
The percentage impedance of a transformer is the volt drop on full load due
to the winding resistance and leakage reactance expressed as a percentage
of the rated voltage. If percentage impedance of transformer increases, then
losses will increase and efficiency will decrease.
BIL Rating: What is it?
BIL is "basic impulse level" which implies the limit up to which an insulator
could withstand impulse due to lightning strikes or other spikes in voltage.
BIL levels increase proportionally with higher voltage ratings of transformers.
Different styles of transformers also have different base or standard BIL
ratings.
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ANSI Transformer BIL Ratings
Application
Distribution
Power
Nominal System voltage,
rms (kV0
1.2
2.5
5.0
8.7
15.0
25.0
34.5
46.0
69.0
1.2
2.5
5.0
8.7
15.0
25.0
34.5
46.0
69.0
115.0
138.0
161.0
230.0
345.0
500.0
765.0
Basic lightning impulse insulation levels
(BIL) in common use (kV crest)
30
--------45
---------60
---------75
---------95
---------150
125
------200
150
125
---250
200
------350
250
------45
30
------60
45
------75
60
------95
75
------110
95
------150
---------200
---------250
200
------350
250
------550
450
350
---650
550
450
---750
650
550
---900
825
750
650
1175
1050
900
---1675
1550 1425 1300
2050
1925
-------
Dry Type Transformers
Liquid Filled Transformers
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Transformers can be categorized in 2 types:
Dry Type
Or
Liquid Filled
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Dry Type Transformers:
Dry Type transformers evolved due to high maintenance and
environmental factors of Liquid Filled transformers.
• Typically used indoors although outdoor enclosures are
available.
• Usually larger footprint than liquid filled transformers.
• Cooled by natural air convection or forced air via fans
within the transformer enclosure.
•
•
•
AA = Ambient Air cooled only via natural air convection
FA = Forced Air fan cooled (can increase transformer capacity by 33%)
FFA = Future Forced Air same as AA rating w/ provisions for fans
Next we will discuss different coil designs used in dry type transformers and then follow up
with the individual types of dry type transformers:
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Dry Transformers:
VPI = Vacuum Pressure Impregnated
VPE = Vacuum Pressure Encapsulated
Coils are dipped in Varnish then placed in vacuum while curing.
Advantages:
Dis-advantages:
Coils being dipped in varnish
Low cost, environmentally friendly
Poor in harsh environments such as dusty factories,
high humidity locations or outdoors where wind
driven rain and snow may get into enclosure.
Vacuum curing chamber
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Assembled VPI coils
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Dry Transformers:
Resin Encapsulated
An encapsulated transformer has the core and coil surrounded by an epoxy
resin and sand encapsulation material, which is baked, effectively becoming a
“brick” that is locked into the enclosure, effectively sealing out moisture and
contaminants from the core and coil
Advantages:
Dis-advantages:
Low cost, great in humid or wet locations
Technology maxes out around 30KVA
Resin Encapsulated
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Dry Transformers:
Cast Coil
Coils are rigidly bound in epoxy via a vacuum casting process
Advantages:
Dis-advantages:
Cross section cutout of cast coil
winding
Environmentally friendly, great protection in harsh
environments and wet locations, superior
mechanical strength and reliability.
Price is typically higher than VPI/VPE
Cast coil being mounted
on core
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Assembled Cast Coil
(no enclosure)
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Dry Transformers:
General Purpose Distribution Transformers
Coil Technology used:
Rating:
Voltages:
Enclosure:
Wire terminations:
VPI, Encapsulated
VPI – 9KVA to 500KVA
Encapsulated - 3KVA to 30KVA
600V Max
Indoor or outdoor; ceiling, wall, or floor mounted
VPI are typically made on the windings
Encapsulated are typically made to wire leads
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Dry Transformers:
Power/Unit Substation
Coil Technology used:
Rating:
Voltages:
Enclosure:
Terminations:
VPI, VPE, Cast Coil
75KVA (rare) to 15MVA
35KV Max
Indoor or outdoor, floor mounted
Close coupled to MV or LV switchgear
Made in ATC “Air Terminal Chamber”
Directly to windings or internal bussing (typically
1000KVA and below)
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Dry Transformers:
Power/Unit Substation
USS VPI Dry Transformer with HV ATC and LV Transition
for close couple to LV Switchboard
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Dry Transformers:
Power/Unit Substation
USS Dry Transformer close coupled to MV switch and LV UL1558 Switchgear.
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Liquid Filled Transformers:
•
Typically used outdoors or sometimes indoors for small footprint reasons
•
Better cooling of the core/coil as oil circulates through fins or radiators to
cool naturally or with help of forced air (fans) ONAN/ONAF or KNAN/KNAF
• ONAN – Oil Natural Air natural cooled only via natural convection and
air flowing across the fins/radiators
• ONAF = Oil Natural Air Forced. Forced Air fan cooled (can increase
transformer capacity by 33%)
• KNAN/KNAF – Same as ONAN/ONAF but when used in conjunction
with environment friendly fluids.
•
Able to use in HV & MV applications. (Dry Transformers max out at 35KV)
•
Environmentally unfriendly unless used with biodegradable fluid.
• Next we will discuss different fluids used in liquid transformers and then follow up
with the individual types of liquid filled transformers:
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Liquid Filled Transformers:
Fluid Types:
•
•
•
•
Mineral Oil: Most commonly used in units up to 60MVA. Not
biodegradable
Envirotemp FR3 / Biotemp: Non-toxic to aquatic life, readily
biodegradable and provides a lower volatility and higher
flash point than Mineral oil. More expensive than mineral
oil.
Silicone: Higher flash point than Mineral or FR3 but less
biodegradable, abrasive fluid causing wear on moving
internal components.
Luminol – Similar to FR3 but used more in large power transformers.
Higher than 60MVA. More resistant to voltage spikes.
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Liquid Filled Transformers:
Polemount Transformers
Fluid used:
Rating:
Voltages:
Terminations:
Uses:
Mineral Oil, FR3 or Silicone
10KVA to 500KVA
35KV maximum
Via bushings on top or side of tank
Overhead utility distribution in residential and light
commercial locations
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Liquid Filled Transformers:
Padmount Transformers
Fluid used:
Rating:
Voltages:
Terminations:
Uses:
Mineral Oil, FR3 or Silicone
75KVA to 15MVA
35KV maximum
Via live or dead front bushings located in lockable
compartmentalized cabinet on front of tank
Areas open to public, underground utility
distribution in residential and industrial locations
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Liquid Filled Transformers:
Power/Unit Substation Transformers
Fluid used:
Rating:
Voltages:
Terminations:
Uses:
Mineral Oil, FR3 or Silicone
75KVA to 15MVA
35KV maximum
Live front bushings located on the side of the tank
in throats or ATC “Air Terminal Chambers”
When close coupling to MV & LV Switchgear, NOT
tamperproof, always installed where accessible only
to qualified personnel
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Liquid Filled Transformers:
Power/Unit Substation Transformers
Inside tank of Unit Substation Liquid Filled Transformer
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Liquid Filled Transformers:
Power/Station Transformers
Fluid used:
Rating:
Voltages:
Terminations:
Uses:
Mineral Oil, FR3 or Silicone
5MVA to 1000MVA
No limit
Bushings typically located on top of tank
Utility transmission, heavy industrial, solar/wind
farm inter-tie
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Accessories on Transformers:
Common Liquid Filled Transformer Accessories:
•
•
•
•
•
•
•
•
•
•
•
Surge Arrestors
Internal Fusing
Pressure Vacuum Gauge
Oil Temperature Gauge
Winding Temperature Gauge
External De-energized Tap Changer
Liquid Level Gauge
Pressure Relief Valve
Cover Mounted Pressure Relief Device
Sudden Pressure Rise Relay
On Load Tap Changer (for larger Power Transformers)
Common Dry Type Accessories:
•
•
Surge Arrestors
Cooling Fans with Temperature Monitor
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Accessories on Transformers:
Power/Station & Padmount Transformers
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Accessories on Transformers:
Power/Station Transformers
HV
Bushing
LV Bushing
Cooling
fans
On Load Tap Changer
*Continuously monitors voltage for
increases and decreases and
automatically adjusts taps to
maintain output voltage.
Fins/Radiators
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Oil drain valve w/ sampler
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Accessories on Transformers:
Padmount Transformers
Open cabinet showing HV & LV termination points and accessories. Dead front, Loop feed
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Accessories on Transformers:
Padmount Transformers
Bayonet
Fusing
LV
Bushing
connection
Partial
Range
Current
Limiting
Fusing
De-energized
Tap Changer
Inside padmount transformer tank prior to filling with oil
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Accessories on Transformers:
Dry Type Unit Substation Transformers
Cooling Fans
Temperature Monitor
Cast Coil Unit Substation Transformer
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