Megapoxy E

For high-impact encapsulation of instrument transformers, lighting transformers, small power transformers, and coils, Megapoxy E provides high-dielectric casting insulation for electrical components operating under demanding physical and thermal stress.

Casting and encapsulation performance

Megapoxy E is a high-impact pouring epoxy formulated for casting electrical switchgear components and mechanical applications requiring chemical resistance. When cured, the system delivers high static and dynamic mechanical properties, maintaining bond strength and electrical insulation under cyclic operational loads. The system is configured using Part A resin paired with one of two hardeners depending on the continuous service temperature of the encapsulated electrical components.

• Hardener E: For electrical components in service at temperatures up to 80ºC.
• Hardener 155: For electrical components in service at temperatures up to 150ºC.

Numbers that matter

• Dielectric strength (50Hz, 25°C): 18 KV/mm (Hardener E) or 19 KV/mm (Hardener 155) to prevent electrical breakdown across cast insulation barriers.
• Ultimate compressive strength: 80 MPa with Hardener E or 100 MPa with Hardener 155, protecting internal components against heavy mechanical loads.
• Martins heat distortion temperature: 65°C with Hardener E or 127°C with Hardener 155, indicating the limit before the cured casting softens under thermal load.
• Working time (at 25°C): 60 minutes with Hardener E or 30 minutes with Hardener 155, defining the pour window before curing begins.
• Bond strength: 20 MPa with both hardeners to secure adhesion to casting surfaces and encapsulated items.

Limitations

• Wire brushing is not an adequate surface preparation and will produce poor adhesion; any surface impurities on the casting surfaces can reduce bond strength or inhibit the bond.
• Do not apply to unprepared substrates; all casting surfaces must be cleaned with acetone or isopropyl alcohol to ensure proper adhesion.

Application and preparation

Achieving rated adhesion requires thorough pre-treatment of all casting surfaces. Clean all surfaces using acetone or isopropyl alcohol prior to pouring. Mix Part A with your chosen hardener according to the specified ratios:

• With Hardener E: Mix ratio is 5:1 by weight (3:1 by volume).
• With Hardener 155: Mix ratio is 10:1 by weight (6:1 by volume).

The minimum curing time for both configurations is 24 hours at 25ºC. To keep mixing implements and working tools clean, use Megapoxy Thinners. Wear disposable rubber gloves during mixing and application to protect hands.