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The cast-resin coil dry-type transformer represents the high-end tier of power distribution. Distinct from standard impregnation processes, its windings are integrally cast in a dedicated vacuum mold using high-strength epoxy or specialized resins. This forms an impenetrable, rock-solid dielectric shell around the oxygen-free copper coils. Delivering unparalleled resistance to short-circuits, fire, moisture, and dust, it is the ultimate choice for highly demanding environments such as high-rise skyscrapers, Tier IV data centers, subway systems, and top-tier hospitals.
Core Parameters:
• Structure: Integral Vacuum Mold Casting (Ultra-low partial discharge).
• Voltage Configuration: 10kV / 20kV / 35kV to 0.4kV.
• Insulation Class: Class F (155℃) / Class H (180℃).
Product Features
Unlike standard dipping, the copper coils are placed in a mold and injected with liquid resin under strict vacuum. This creates a dense, bubble-free, rock-hard insulation shell.
The solid-cast resin structure provides immense resistance to the massive electromagnetic forces generated during short-circuits, preventing coil deformation or cracking.
100% oil-free and utilizing premium flame-retardant epoxy resin, it acts as a self-extinguishing barrier. It is the safest choice for densely populated high-rise buildings and subways.
Pairs the cast oxygen-free copper coils with a 45° step-lap high-permeability silicon steel core, minimizing both no-load iron losses and operational acoustic noise.
Standard Natural Air (AN) cooling provides silent base loads, while Forced Air (AF) fan activation securely boosts the operational capacity by 30%~50% during demand spikes.
The impenetrable resin casting blocks out extreme humidity, coastal salt spray, and industrial dust, rendering the unit virtually maintenance-free across its lifetime.
Key Specifications (Cast Coil Series)
| Parameter | Typical Value | Description |
| Rated Capacity | 10kVA ~ 2500kVA | Scalable from local precision instruments to massive commercial substation hubs. |
| Rated Voltage | HV: 10kV / 20kV / 35kV LV: 0.4kV | Highly precise distribution output to directly power 3-phase machinery and grids. |
| Vector Group | Dyn11 / Yyn0 | Standard connection ensuring robust handling of severe unbalanced electrical loads. |
| Insulation Class | Class F (155℃) / Class H (180℃) | Premium thermal endurance ensuring stable operation without insulation breakdown. |
| Partial Discharge | Extremely Low | Integral vacuum casting eliminates air pockets, ensuring zero internal arcing risks. |
| Cooling Method | AN / AF | Natural air handles standard loads; Forced air (AF) safely boosts capacity by 30%~50%. |
[Image of cast-resin coil dry-type transformer]
Full Series Technical Reference (30kVA ~ 3150kVA)
| Capacity (kVA) | Impedance (%) | No-Load Loss (W) | Load Loss (W) | Total Weight (kg) | Dimensions W×D×H (mm) |
| 30 | 4.0 | 180 | 600 | 250 | 800×600×900 |
| 50 | 4.0 | 240 | 870 | 320 | 850×650×950 |
| 100 | 4.0 | 380 | 1500 | 550 | 950×700×1000 |
| 160 | 4.0 | 540 | 2000 | 750 | 1050×750×1050 |
| 200 | 4.0 | 620 | 2400 | 880 | 1100×800×1100 |
| 250 | 4.0 | 720 | 2800 | 1050 | 1150×800×1150 |
| 315 | 4.0 | 880 | 3400 | 1250 | 1200×850×1200 |
| 400 | 4.0 | 980 | 4100 | 1450 | 1250×900×1250 |
| 500 | 4.0 | 1160 | 4900 | 1700 | 1300×950×1300 |
| 630 | 4.5 | 1340 | 6200 | 1950 | 1350×1000×1350 |
| 800 | 4.5 | 1520 | 7500 | 2300 | 1400×1000×1400 |
| 1000 | 4.5 | 1770 | 8800 | 2700 | 1450×1050×1450 |
| 1250 | 4.5 | 2090 | 10800 | 3200 | 1550×1100×1550 |
| 1600 | 4.5 | 2450 | 13200 | 3800 | 1650×1150×1650 |
| 2000 | 4.5 | 3000 | 16000 | 4500 | 1750×1250×1800 |
| 2500 | 4.5 | 3600 | 19500 | 5300 | 1850×1300×1900 |
| 3150 | 4.5 | 4300 | 24000 | 6500 | 2000×1400×2100 |
* The comprehensive table above displays the standard parameter range for dry-type technology. Cast-coil technology typically yields highly stable dimensions matching these standard footprints, ensuring seamless upgrades.
FAQ
While both are excellent dry-type technologies, Integral Cast Coil transformers represent the high-end tier for critical applications due to three main factors:
1) Structural Rigidity: In a cast coil transformer, the copper windings are placed inside a mold and flooded with epoxy resin under vacuum. Once cured, it forms a thick, solid block of resin. This provides vastly superior mechanical strength to withstand extreme short-circuit forces compared to the thin varnish layer applied in VPI processes.
2) Absolute Moisture & Dust Barrier: The thick resin casting completely seals the conductors. Unlike VPI, which can be susceptible to long-term harsh humidity if the varnish cracks, cast coils are practically impervious to heavy moisture, chemical vapors, and heavy industrial dust.
3) Partial Discharge Elimination: The strict vacuum casting process removes 100% of air bubbles from within the winding block. This results in an exceptionally low partial discharge rate, ensuring the transformer will not suffer from internal electrical breakdown over its 25+ year lifespan.
A cast coil transformer uses epoxy resin vacuum casting to encapsulate windings. It features strong insulation, low partial discharge, good moisture and dust resistance. The solid epoxy structure prevents coil movement under short-circuit force. It requires little maintenance, works reliably in humid, polluted environments, and has low fire risk, widely used in power distribution, industrial and building power supply systems.
Our cast coil transformers serve indoor power distribution projects. Typical scenarios include commercial buildings, hospitals, data centers, metro stations, chemical plants and mining sites. They fit places demanding high safety and low maintenance. Custom voltage ratios and capacity options are available to match different grid requirements, stable for continuous heavy-load daily operation.
Our cast coil transformers adopt optimized core and winding design to control operating noise. Under rated load, the noise value meets international industry standards. The epoxy encapsulated coils deliver excellent heat dissipation. Temperature rise stays within allowable limits during long-time rated operation. We can adjust cooling methods, natural air or forced air cooling, based on customer site conditions.
Yes, we support customized cast coil transformers. We can adjust rated capacity, primary & secondary voltage, impedance and mounting dimensions. For high altitude, damp or corrosive sites, we upgrade insulation and protective coatings. Our engineering team reviews your technical specifications first, then offers drawings and technical data before formal production to meet special project demands.
Whatsapp: +86-13961294414
E-mail: junqiu.wang@czguanghui.cn
jocelyn.duan@czguanghui.cn
ADD: No. 1, Yulong Middle Road, Xuejia Town, Xinbei District, Changzhou City, China
Mobile: 0086-15380068868
