APG Resin vs Vacuum Casting Resin for Instrument Transformers
APG vs Vacuum Casting Resin for Instrument Transformers
APG resin and vacuum casting resin are not the same and cannot be directly interchanged. They differ in formulation, process, and performance.
Core Differences
| Item | APG Resin | Vacuum Casting Resin |
|---|---|---|
| Formulation | Semi-solid / thixotropic epoxy with curing agent and accelerator | Liquid two-component epoxy, room or medium temperature curing |
| Process | Pressure injection + heated mold (80–120°C), pressure holding and shrinkage compensation, demolding in 10–20 minutes | Gravity or vacuum casting, room or low temperature curing, no pressure compensation |
| Performance | High density, porosity <0.1%, dimensional accuracy ±0.1mm | Porosity about 0.5–3%, accuracy ±0.5mm |
| Application | Instrument transformers, transformers, insulators | Structural parts, potting |
APG is especially suitable for instrument transformers, where void-free insulation and precise dimensions are critical. Vacuum casting is often used for larger structural parts or applications where pressure injection is not required.
CNYIHU uses both epoxy resin automatic pressure gelation (APG) machines and vacuum casting plants in production. The choice of resin and process depends on product type, voltage class, and performance requirements. For manufacturing details, see our Voltage Transformer Manufacturing Process and Current Transformer Manufacturing Process articles.
