High‑voltage instrument transformers, when operated over long periods, are subjected to electric field concentration, thermal‑stress variations, and moisture ingress, which can easily lead to excessive partial discharge, resin cracking, and insulation degradation. However, conventional epoxy systems suffer from inherent limitations—such as high viscosity, significant internal stresses generated during curing, and difficulties in vacuum degassing—making it challenging to meet the stringent requirements of high‑voltage instrument transformers for… Insulation and Long-Term Stability Comprehensive requirements.

In the encapsulation process for high-voltage instrument transformers, engineers typically encounter the following technical challenges: 

1. Operability : On-site potting requires room-temperature curing and exhibits excellent self-degassing, making it well-suited for large-scale production. 

2. Insufficient liquidity During potting, the encapsulant struggles to penetrate the coil gaps, leading to the formation of air bubbles and voids. 

3. High insulation requirements : When subjected to high-voltage electric fields over long periods, it must exhibit excellent dielectric strength and electrical insulation properties. 

4. Low Stress and Corrosion Resistance : During the curing process, a high shrinkage rate can lead to stress concentration, compromising the structural stability of the coil.

Recommended solution: Hinnel HN6330EV Epoxy potting compound 

Product Introduction: 

HN6330EV It is a two-component, heat-curable epoxy potting compound with a weight ratio of… A:B=100:100 。 It offers an exceptionally long operating life and is compatible with automated vacuum potting processes. After stepwise heating and curing, it forms a high‑hardness, dense solid with low cure shrinkage, minimal internal stress, and excellent resistance to thermal cycling. The product exhibits outstanding insulating properties, with a dielectric strength reaching 25~30 kV/mm 。

It also boasts excellent thermal conductivity, providing insulation, moisture resistance, and seismic protection for power components such as high‑voltage windings and current transformers. After curing, it exhibits outstanding thermal conductivity, water resistance, oil resistance, corrosion resistance, and electrical insulation properties. It is ideally suited for potting and encapsulating applications requiring high‑temperature stability, crack resistance, and superior insulation in motors, film capacitors, high‑voltage transformers, sensors, and other similar devices. 

Product Application Advantages: 

• Environmentally friendly, solvent-free, and free of curing by-products. 
• It exhibits low shrinkage during curing and the cured product has good toughness. 
• The cured product exhibits a glossy surface and excellent electrical insulation properties. 
• Excellent mechanical properties and resistance to damp heat. 
• It exhibits excellent adhesion to metal and plastic housings. 

Hinnel HN6330EV Epoxy resin potting compound application process:

Hinnel HN6330EV Properties of epoxy resin potting compound after curing:

Recommended procedure for potting: 

I. Thoroughly pre-treat the components to be potting. 

Source of the hazard: Oil, moisture, or dust on the surfaces of components such as coils and iron cores can compromise the adhesion and insulation performance of potting compounds. This may lead to delamination between the compound and the components, creating air gaps that trigger partial discharges or reduce thermal dissipation efficiency. 

Practical operational recommendations: Prior to potting, the interior of the current transformer must be thoroughly cleaned. Wipe with anhydrous ethanol or a dedicated cleaning agent, and ensure that all components are completely dry before potting; if necessary, preheat them to remove any residual moisture. 

II. Adoption of a Stepwise Potting and Defoaming Process 

Source of the hazard: Pouring a large volume of encapsulant in a single operation can easily entrain air, forming bubbles, while bubbles trapped within complex internal structures are difficult to remove. These internal bubbles can become weak points in the insulation; under an electric field, they may trigger partial discharges and disrupt thermal conduction paths, leading to localized overheating. 

Practical operational recommendations: For deep cavities or transformers with complex structures, it is recommended to pour the material in stages and slowly. After injecting a portion of the adhesive, gently vibrate or tilt the component to facilitate bubble release; if necessary, use vacuum equipment to degas before proceeding with the subsequent potting process. 

III. Accurate Selection to Match Application Scenarios 

Source of the hazard: Encapsulating potting compounds of different formulations vary in thermal conductivity, temperature rating, viscosity, and cure‑shrinkage. Selecting the appropriate grade is essential to ensure that performance meets specified requirements. Improper selection—such as using a compound with an inadequate temperature rating in high‑temperature applications—can lead to softening or cracking of the material, resulting in the loss of its insulating and protective functions. 

Operational Recommendations: Clearly define the equipment’s operating temperature range, thermal management requirements, and potting‑encapsulation space configuration. For example, for current transformers that must operate continuously at elevated temperatures, priority should be given to selecting models explicitly rated as capable of… “ High-temperature resistant ” A model with functionality and a temperature rating higher than the actual operating conditions, such as Hinnel HN6330EV Instrument transformer epoxy potting compound, temperature-resistant. -40~200℃ 。

In summary, selecting an appropriate potting compound for high‑voltage instrument transformers is of paramount importance. Only by carefully choosing a formulation that aligns with the operating conditions—balancing dielectric strength, thermal‑stress resistance, and processability—can we mitigate various insulation risks, extend product service life, and meet the stringent performance requirements of power‑equipment applications. For more information about this potting compound, please contact us to discuss technical solutions and request samples.

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°   Whatsapp:  86- 18301723907.