/CAST COIL TRANSFORMERS/
Cast Coil Transformers
Epoxy vacuum-cast, resin-encapsulated coils built for indoor vaults, mechanical rooms, and fire-sensitive occupancies — no oil, no containment pit, no scheduled fluid testing. Designed, built, and tested to NEMA, ANSI C57, IEEE, and UL standard, with same or next-business-day quotes.
/Type 01 Nameplate/
kVA Range
300 – 6,000 kVA
Voltage Class
Up to 15 kV
Insulation
Class F · 80°C Rise
Enclosure
NEMA 1 / 2 / 3R
Standards
NEMA · ANSI C57 · UL 1562
/Specifications/
Built for the spaces oil-filled units can't reach.
Magnetics Design cast coil transformers use a vacuum-cast, epoxy-resin-encapsulated winding system — eliminating mineral oil, fire-resistant vaults, and containment pits in installations where indoor space, occupant safety, or fire code is the deciding factor. Each unit is wound, encapsulated, and tested in accordance with NEMA, ANSI C57.12.01, IEEE C57.12.01, and UL 1562, and meets DOE 2016 efficiency levels as standard.
300–6,000 kVA
Power rating
Up to 15 kV
Primary voltage
Class F / 80°C
Insulation & rise
Standard — included
- Epoxy vacuum-cast, resin-encapsulated copper windings
- Class F (155°C) insulation, 80°C average rise over 40°C ambient
- NEMA Type 2 ventilated indoor enclosure, gray polyester powder coat
- Electrostatic shield between primary and secondary windings
- Full-capacity primary taps — two 2.5% above, two 2.5% below nominal
- Copper ground pad and integral lifting / jacking provisions
- Sound levels within NEMA ST 20 limits
- DOE 2016 efficiency compliant as standard
Optional Upgrades
- Forced-air cooling fans (AFA), up to 33% added capacity
- RTD winding temperature monitors with alarm & trip contacts
- K-factor rated windings (K-4, K-13, K-20) for nonlinear loads
- 115°C or 150°C rise insulation systems for added overload margin
- NEMA 3R outdoor-rated enclosure
- Low-sound enclosure package
- Seismic certification (IBC 2018 / OSHPD)
- Isolated electrostatic shield with dedicated ground terminal
Available Certifications
UL 1562
Listed
cUL Listed
(CSA C9 equivalent)
IEEE
C57.12.01
ANSI
C57.12.01
NEMA ST 20
sound compliance
DOE 2016
efficiency verification
Seismic IBC / OSHPD
certification (project-specific)
options.
/Options/
Built for every indoor load, from a mechanical room to a hospital vault.
Cast coil construction scales from light commercial service to critical medium-voltage loads. Choose the configuration that matches your occupancy and voltage class, then layer in stock, custom, or remanufactured delivery.
GENERAL PURPOSE CAST COIL
Low-Voltage Indoor
kVA: 300 – 2,500 kVA · Voltage: up to 5 kV class
Right-sized for office buildings, schools, parking structures, and light commercial tenant spaces where a compact, low-maintenance indoor unit is the priority.
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MEDIUM-VOLTAGE CAST COIL
Critical Facility Indoor
kVA: 1,000 – 6,000 kVA · Voltage: up to 15 kV class
Sized for hospitals, data centers, and high-rise risers, where fire-code restrictions on oil-filled equipment and uptime requirements both favor a dry-type, no-fluid design.
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Hit your lead time with stock and custom options.
Magnetics Design keeps common cast coil sizes in stock for fast delivery and builds custom units with some of the best lead times in the industry.
STOCK
Ready to Ship
Hit project deadlines with common kVA sizes and voltages, in stock and ready to ship.
CUSTOM
Built to Spec
Build exactly what you need with extensive enclosure, tap, and insulation customizations.
REMANUFACTURED
Like-New, Faster
Save time and money with remanufactured cast coil units, rebuilt and tested to like-new standards.
/Customization/
Meet any spec with extensive customizations.
Meet your exact application requirements with cast coil units designed, built, and tested in accordance with NEMA, ANSI, DOE, and IEEE as applicable.
Forced-Air Cooling
Fan-assisted (AFA) cooling adds up to 33% additional capacity beyond the unit’s natural-convection (AA) rating, without increasing the frame size.
Temperature Monitoring
Factory-installed RTDs track winding temperature continuously and trigger alarm or trip contacts before a thermal event becomes downtime.
K-Factor Windings
K-4, K-13, or K-20 rated windings are sized to handle the harmonic heating caused by variable-frequency drives, UPS systems, and other nonlinear loads.
NEMA 3R Enclosure
An outdoor-rated enclosure option for cast coil units installed in semi-protected or weather-exposed locations without moving to a liquid-filled design.
Low-Sound Package
Additional acoustic dampening and core treatments bring sound output below standard NEMA ST 20 levels for noise-sensitive occupied spaces.
Seismic Certification
IBC 2018 and OSHPD-compliant anchoring and bracing for installations in seismic design categories that require certified equipment.
/Get a Quote/
Tell us the spec. We'll size it for you.
Give us a kVA rating, voltage, and delivery window and a dedicated rep will follow up with pricing and lead time — most quotes turn around the same or next business day.
What Our Clients Say
by Magnetics Design substations.
Advanced transformer solutions designed to improve power quality, reduce harmonics, and maximize system performance.
We were struggling with severe harmonic distortion on our main drive lineup. Magnetics Design engineered a 24-pulse phase shifting unit that dropped our THD well below IEEE 519 limits.
Brian John
My Client
Magnetics Design turned around a quote for a custom 18-pulse transformer the same day. The build quality was exceptional, and it arrived right on schedule for our shutdown window.
Felix Chou
My Client
The VFD isolation properties on these units are bulletproof. We source all our specialty phase shift transformers from the Magnetics Design team because they get the specs right the first time.
Anna Choux
My Client
Questions engineers ask
What makes a cast coil transformer different from an oil-filled unit?
The windings are vacuum-impregnated and encapsulated in solid epoxy resin instead of being submerged in mineral oil. That removes the fire load, the need for containment pits or fire-rated vault construction in many occupancies, and the ongoing oil sampling and testing that liquid-filled units require.
What insulation class is standard, and can it run harmonic-heavy loads?
Standard units use a Class F (155°C) insulation system with an 80°C average winding rise over a 40°C ambient. For nonlinear loads such as VFDs or UPS systems, K-factor rated windings (K-4, K-13, K-20) are available to handle the additional harmonic heating.
What enclosure options are available for indoor installs?
NEMA Type 1 and Type 2 ventilated enclosures cover most indoor mechanical room and vault installations. A NEMA 3R outdoor-rated enclosure is available for semi-protected or weather-exposed locations without switching to a liquid-filled design.
What's a typical lead time?
Common kVA sizes and voltages are kept in stock and can ship within days. Custom configurations — including special taps, K-factor windings, or seismic certification — are built to order, and your rep will confirm a firm lead time with your quote.
Do cast coil transformers need less maintenance than oil-filled units?
Yes. Without oil there’s no dielectric fluid to sample, test, or replace. Routine maintenance is largely limited to periodic visual inspection, cleaning of ventilation paths, and verifying winding temperature monitoring if it’s installed.