Cast-Resin Dry-Type Transformers
2 to 3,000 kVA, up to 36 kV, K-1 through K-20
Inside a hospital, a data hall or a high-rise electrical room, a liquid-filled transformer brings a fire-load calculation, a containment bund and a code argument with it. A cast-resin dry-type unit does not. Atlas Energy supplies epoxy-encapsulated transformers from 2 kVA to 3,000 kVA, with LV below 1 kV (typically 208 to 480 V) and MV from 1 kV to 36 kV in the 15 kV, 24.2 kV (25 kV class) and 36.2 kV (38 kV class) ranges. Insulation is class F or H and the climatic, environmental and fire classification is C2 / E2 / F1 to IEC 60076-11.
Harmonics are the other half of the specification. Non-linear load heats a transformer through eddy-current loss that rises with the square of harmonic order, which is why these units are offered from K-1 through K-20 with K calculated per IEEE C57.110-2018 as K = Σ (Ih/I1)² × h². Enclosures run IP00 to IP66, covering NEMA 1, 12, 3R and 4X equivalents, indoor or outdoor, with or without flange. Cooling is AN natural with optional AF forced ventilation for uprating. Vector groups are Dyn1, Dyn11 and YNyn0, in three-phase, two-phase or single-phase, at 60 Hz or 50 Hz. Every unit carries a 24-month warranty.
Why it matters
The plug-in disconnectable primary terminal lets you carry out maintenance without de-energizing the network upstream. In a hospital or a data hall, that is the difference between a maintenance window and an outage notice.
K-factor is specified, not guessed. K-1 for linear load below 5% THDi, up to K-20 for critical electronic load at 35 to 50% THDi, with K calculated to IEEE C57.110-2018 rather than assigned by rule of thumb.
PT100 sensors and a digital temperature relay with alarm and trip come as part of the design, so the thermal protection is matched to the winding it is protecting.
IP66 enclosures make washdown environments practical. Food processing, mining and water treatment can put the transformer where the load is instead of in a separate dry room.
Routine factory testing covers insulation resistance, turns ratio, dielectric withstand, no-load and load losses, temperature rise, short circuit, and dimensional and visual inspection. The test report ships with the unit.
Ratings
Power: 2 kVA – 3,000 kVA
Voltage: LV below 1 kV (208–480 V typical); MV 1 kV to 36 kV
MV classes: 15 kV, 24.2 kV and 36.2 kV
Insulation class: F or H, epoxy resin encapsulated
Phases: Three-phase, two-phase or single-phase
Frequency: 60 Hz or 50 Hz
Enclosure: IP00 to IP66 (NEMA 1 / 12 / 3R / 4X equivalents), indoor or outdoor, with or without flange
Cooling: AN natural; AF forced ventilation optional for capacity uprating
K-factor: K-1 through K-20
Vector groups: Dyn1, Dyn11, YNyn0
Climatic / environmental / fire class: IEC 60076-11 C2 / E2 / F1
Routine factory tests: Insulation resistance · turns ratio · dielectric withstand · no-load and load losses · temperature rise · short circuit · dimensional and visual inspection
Warranty: 24 months
Extended range
K-1: THDi < 5% — linear loads: motors, resistive heating
K-4: 5–15% — mixed loads, light electronics
K-9: 15–25% — moderate electronic content
K-13: 25–35% — high electronic concentration
K-20: 35–50% — critical electronic loads
Typical K-factor by sector: Hospitals K-4…K-13 · Data centers K-13…K-20 · Industrial automation K-9…K-13 · Solar PV K-4…K-13 · Commercial buildings K-4…K-9
Options: Forced ventilation, bidirectional casters, voltmeter and ammeter, industrial receptacles and cable entries
Standards
IEEE C57.110-2018 (harmonic loading, K = Σ (Ih/I1)² × h²)
IEC 60076-11:2018
IEC 60076-1/-3
EN 50541-1
NFPA 850 · NFPA 70B (2023) referenced for installation and maintenance
Applications
Hospitals and healthcare campuses
Data centers
Shopping centers and high-rise buildings
Mining, steel and food processing (IP65/IP66 washdown)
Water and sanitation
Solar PV plants
Questions engineers ask
Which K-factor do I need for my load? Match it to measured current distortion. K-1 covers linear load below 5% THDi. K-4 covers 5 to 15%, K-9 covers 15 to 25%, K-13 covers 25 to 35% and K-20 covers 35 to 50%. By sector, hospitals typically fall in K-4 to K-13 and data centers in K-13 to K-20. Calculate K per IEEE C57.110-2018 from a real harmonic spectrum.
Can a cast-resin transformer be installed outdoors or in a washdown area? Yes. Enclosures run from IP00 up to IP66, equivalent to NEMA 1, 12, 3R and 4X, indoor or outdoor, with or without flange. IP65 and IP66 versions are specified for food processing, mining and water treatment where the area is hosed down. The climatic, environmental and fire class is C2 / E2 / F1 to IEC 60076-11.
