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Epoxycast® is AFP Transformers, LLC, registered trademark for cast coil transformers. The cast coil process was developed in 1968 and continued development has led to our current product line of single-phase and three-phase cast coil transformers.

Epoxycast® cast coil transformers are not conventional dry-type transformers. A conventional dry-type transformer is impregnated, most often in a VPI (Vacuum Pressure Impregnated) system with a varnish or epoxy resin. In a cast coil transformer, one or more of the transformer’s windings are cast with an epoxy material in a mold under vacuum. This casting is then cured for several hours according to a precise temperature cycle. The resulting coils have windings deeply embedded in tough, solid epoxy sealing out moisture and other contaminants. Additionally, the epoxy holds the windings firmly in place under short-circuit forces that would normally destroy a conventional dry-type transformer. The cast coil transformer will typically have a much higher BIL rating than a dry-type transformer thus making the cast coil transformer less susceptible to damage from high voltage transients.

Cast coil transformers have a wide variety of applications for single and three phase power distribution systems. Some of the most common applications are:

  • Control Power Transformers (CPTs) in metal-clad switchgear;
  • Neutral Grounding Transformers in electric utility networks and cubicles;
  • Pad-Mount Distribution Transformers within industrial plants, high-rise buildings, hotels, schools, refineries, oil drilling platforms or airports;
  • Power Transformers for mining equipment;
  • Replacement of oil filled or other types of liquid cooled transformers.

Some of the benefits that are realized by using AFP’s, Epoxycast ® cast coil transformers are:

  • Non-Flammable -The epoxy resin will not burn. After long exposure to a flame, it may char but never burns. The Epoxycast® transformer will never burst into flames or supply fuel for a fire;
  • Leak Proof -Epoxycast® cast coil transformers do not contain any liquids. The epoxy material will not revert to a liquid state in the event of over heating;
  • No Transformer Vault Required -Because Epoxycast® cast coil transformers cannot leak nor burst into flames, no transformer vault is required when installed in a building. Liquid filled transformers must be enclosed in a secure vault to contain leaks and flames. Vaults are expensive and could add 50%-100% to a liquid filled transformer’s delivered cost;
  • No Haz Mat Clean-up or Disposal -Epoxycast® transformers contain no hazardous materials after they have been manufactured. As a result, there is Haz Mat or costly clean-up issues if they ever have to be replaced;
  • Superior Short Circuit Strength -Epoxycast® cast coil transformers are designed to withstand short circuit conditions. The conductor wires are surrounded by epoxy resin that keeps the wires firmly positioned during the powerful forces experienced in a short circuit;
  • High Basic Impulse Level (BIL) -Insulating characteristics of the epoxy resin is far superior to that of air. This means Epoxycast® cast coil transformers have standard BIL ratings of 60 KV for 5 KV applications and 95 KV BIL for 15 KV applications. BIL ratings up to 170 KV are also available;
  • No Pre-Drying Required -Epoxycast® cast coil transformers can be energized immediately after installation. Conventional dry-type transformers will often require a "drying out" period after installation before energizing;
  • Virtually No Maintenance -Epoxycast® cast coil transformers require no maintenance beyond keeping the external surface free from dirt, dust or other contaminants;
  • Excellent Overload Capabilities -The epoxy insulation of Epoxycast® cast coil transformers is capable of dissipating heat that develops during overload conditions.

Epoxycast® cast coil transformers are available in several sizes, voltage ranges and phase configurations. For further information regarding cast coil transformers, please click on the pdf downloads or contact AFP Transformers via phone: (732) 248-0305, fax (732) 248-0542 or email:

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