1153 Unsaturated Polyester Varnish
Class H unsaturated polyester varnish for open-type dry-type transformers
1153 is an unsaturated polyester impregnating varnish developed specifically for open-type air-cooled dry-type transformers. Light-coloured after curing, compatible with immersion and VPI processes.
- Temperature class
- Class H (180°C)
- Gel time (140°C)
- ≤10 min
- Electric strength
- ≥20 MV/m (normal)
- Curing
- 165°C / 2 h
Technical data
| Property | Unit | Value |
|---|---|---|
| Appearance | — | Free of mechanical impurities, paint film smooth and glossy |
| Viscosity (No. 4 cup, 23 ±1°C) | s | 90–150 |
| Gel time (140 ±2°C) | min | ≤10 |
| Acid value | mgKOH/g | ≤18 |
| Curing volatile content (165 ±2°C, 2 h) | % | ≤18 |
| Electric strength, normal condition | MV/m | ≥20 |
| Electric strength (180 ±2°C) | MV/m | ≥16 |
| Volume resistivity, normal | Ω·m | ≥1×10¹³ |
| Volume resistivity, after water immersion | Ω·m | ≥1×10¹² |
| Temperature class | — | Class H (180°C) |
Values are typical values or ranges from our product data. Bulk supply is subject to the approved specification, sample and test report. If a parameter you need is not listed here, ask our engineers for the full test report for that grade.
Key features
- Designed for impregnation of open-type dry-type transformers.
- Light-coloured cured film for easier visual inspection.
- Fast drying at low temperature for VPI and dip lines.
Applications
Impregnation of open-type dry-type transformers and dry-type reactor coils; VPI processes.
Why it fits
Class H performance on open-type dry-type units, with a light film that makes visual inspection easy.
Ordering information
To receive a quotation, please confirm:
- Product and grade
- Thickness and width (and roll or sheet size)
- Temperature class
- Quantity and delivery form (roll / sheet / die-cut / machined)
- Destination port and required delivery date
For machined parts, attach a drawing in PDF, DWG or STEP format. Datasheets, COAs and batch test data are available on request.
Often specified together
Send your specification
Our export team reviews the application, the process and the existing specification before recommending a construction.



