Medium Voltage Dry-Type Transformers
Unit substation dry-type transformers are designed for medium voltage power distribution where liquid-cooling is not an option, such as indoor power distribution line-ups, or outdoor areas with environmental concerns.
Transformer Specifications
kVA: 300 – 5,000 kVA
Maddox medium voltage dry-types are designed, built, and tested in accordance with the highest industry standards including NEMA, ANSI C.57, DOE, and IEEE as applicable. They can be configured for general purpose and unit substation applications and are customizable to give you greater control over your unit’s function and safety.
Voltage: up to 35 kV
Standard Features
- Self-cooled (AA)
- Aluminum windings
- Voltage adjustment taps
- Impedance 5.75 % (±7.5%)
- NEMA 1 indoor enclosure
- High-grade silicon-steel core
- Ground pads/lugs
- 150 degree C rise
- VPI windings
- Stub-up/down bus
- Stainless steel hardware
Optional Upgrades
- Forced air cooling system (AA/FA)
- Copper windings
- NEMA 3R outdoor enclosure
- Lightning arresters
- 80 C or 115 C degree rise
- Solar step-up design
- Electrostatic shielding
- K-rated design
- Cast-coil windings
- Bus to ends
- Transition section/terminal chambers
- Temperature monitoring system
- Primary load-interrupter switch
- Double-thick varnish for corrosion protection
Available Certifications
- Maddox MV dry type transformers are available with UL, CSA, or ETL certifications.
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Hit Your Lead Time with Stock and Custom Options
Maddox keeps medium voltage dry-type transformers in stock for fast deliveries and builds custom ones with some of the best lead times in the industry.
Stock
Hit project deadlines with common kVA sizes and voltages, in stock and ready to ship.
Custom
Build exactly what you need with extensive transformer customizations available.
+800 5-Star Reviews
Maddox medium voltage dry-type transformers provide reliable power to critical projects across the United States.
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Meet Any Spec with Extensive Customizations
Meet your exact spec with customized transformers designed, built, and tested in accordance with the highest industry standards including NEMA, ANSI, DOE, and IEEE as applicable.
High-Grade Silicon-Steel Core
High-Grade Silicon-Steel Core
Improve efficiency while keeping losses and operating noise lower under normal and heavy load conditions.
Copper or Aluminum Windings
Copper or Aluminum Windings
Choose the winding material that meets your spec and budget, achieving dependable performance and service life with either option.
VPI or Cast-Coil Windings
VPI or Cast-Coil Windings
Select the insulation system that fits your environment—VPI for enhanced moisture resistance or cast-coil for maximum protection in harsh, high-contaminant conditions.
Frequently Asked Questions
Medium vs. Low Voltage
Does my application require a low or medium voltage dry-type transformer?
General purpose low voltage dry-type transformers are suitable for applications requiring 800 volts or less. All other applications will require a Maddox medium voltage dry-type transformer.
Cast Coil vs. VPI
Do Maddox medium voltage dry-type transformers use cast coil or VPI windings?
While standard designs use VPI windings, cast coil windings are available upon request. Learn more about cast coil transformers here.
Maintenance
How can I clean my dry-type transformer to prevent performance issues?
We recommend cleaning the windings, insulating surfaces, connections, and vent filters on an annual basis. Learn how to clean your dry-type transformer here.
Enclosure Types
What types of enclosures are available for Maddox medium voltage dry-type transformers?
While standard designs use NEMA 1 enclosures, additional NEMA ratings are available upon request for applications that require increased protection. Learn about the types of transformer enclosures here.
K-Factor Rated
Are Maddox medium voltage dry-type transformers K-factor rated?
While standard designs do not feature K-factor rated components, these are available upon request for applications that require protection against harmonics. Learn about K-factor rated transformers here.
Electrostatic Shields
Do Maddox medium voltage dry-type transformers feature electrostatic shields?
While standard designs do not feature electrostatic shields (e-shields), these are available upon request for applications that require higher tolerances for voltage disturbances. Learn about e-shields here.
Cooling Class
Which cooling class do Maddox medium voltage dry-type transformers feature?
While standard designs feature ventilated self-cooled ratings (AA), additional cooling classes are available upon request. Learn about transformer cooling classes here.
Close Coupling
Can Maddox close couple dry-type transformers with switchgear?
Yes, Maddox can close couple metal-enclosed switchgear to a medium voltage dry-type transformer upon request. Learn more about switchgear and close coupled designs here.
Remanufactured
Are Maddox remanufactured medium voltage dry-type transformers reliable?
Yes, Maddox remanufactured medium voltage dry-type transformers are tested in accordance with NEMA, ANSI, DOE, and IEEE standards as applicable. Learn about remanufactured transformers here.
Returns & Exchanges
Can I return or exchange a Maddox medium voltage dry-type transformer?
Yes, medium voltage dry-type transformers may be eligible for return or exchange within six months of shipment date. Terms and conditions apply. Learn about the Maddox return and exchange policy here.